Water

22 pages, 5879 KiB

Open AccessEditor’s ChoiceArticle

A Harmony-Based Approach for Assessing and Regulating Human-Water Relationships: A Case Study of Henan Province in China

by Qiting Zuo, Wen Li, Heng Zhao, Junxia Ma, Chunhui Han and Zengliang Luo

Water 2021, 13(1), 32; https://doi.org/10.3390/w13010032 - 26 Dec 2020

Cited by 21 | Viewed by 3157

Abstract

The conflict of the human-water relationships (HWR) has further increased the water-related risks, such as water environment deterioration, water shortages, and even regional violent conflicts for obtaining usable water resources. Knowing how to evaluate and regulate the discordant HWR to form a balanced [...] Read more.

The conflict of the human-water relationships (HWR) has further increased the water-related risks, such as water environment deterioration, water shortages, and even regional violent conflicts for obtaining usable water resources. Knowing how to evaluate and regulate the discordant HWR to form a balanced growth between sustainable socio-economy and water resources protection has become a critical issue in water resources management. The harmony theory method, which provides a new perspective for solving the conflict between humans and water, has been widely used in current studies. However, this method focuses less on the quantitative study of the balance status of HWR. This study proposes a harmony theory-based HWR evaluation method that contains a systematic process of harmony assessment, indicator identification, harmony balance constraints, and harmony regulation for assessing and regulating the discordant HWR. The Henan Province of China, which has a complicated HWR, was selected as a case study to apply and verify the approach proposed in this study. The results indicated that (1) Henan Province showed a poor harmony status. The human–water harmony degree of 18 distinctions in the province varied from 0.41 to 0.76, showing an increasing trend from 2006 to 2018, indicating that the HWR was gradually improving in recent years. (2) The human–water harmony degree showed that HWR in the southwest part of Henan Province, with less human activities, was better than that in its northeast part, which had faster social development. Sanmenxia City, located in the west part of the province, had the highest human–water harmony degree because of the recent water control projects implemented in the city, indicating that human production measures could effectively help improve HWR. (3) At present, Henan Province has serious discordant indicators in these three aspects (water system health, humanistic system development, and human-water system coordination), which proves that it is still facing pressure from both socio-economy sustainable development and water resources protection. Our results provide insight into water resources management in Henan Province and other similar regions. Full article

(This article belongs to the Section Water Resources Management, Policy and Governance)

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16 pages, 2545 KiB

Open AccessEditor’s ChoiceArticle

Estimation of Hourly Flood Hydrograph from Daily Flows Using Artificial Neural Network and Flow Disaggregation Technique

by Jeongwoo Lee, Jeong Eun Lee and Nam Won Kim

Water 2021, 13(1), 30; https://doi.org/10.3390/w13010030 - 26 Dec 2020

Cited by 9 | Viewed by 3287

Abstract

Flood data on a high temporal scale are required for the design of hydraulic structures, flood risk assessment, flood protection, and reservoir operations. Such flood data are typically generated using rainfall-runoff models through an accurate calibration process. The data also can be estimated [...] Read more.

Flood data on a high temporal scale are required for the design of hydraulic structures, flood risk assessment, flood protection, and reservoir operations. Such flood data are typically generated using rainfall-runoff models through an accurate calibration process. The data also can be estimated using a simple relationship between the daily and the sub-daily flow records as an alternative to rainfall–runoff modelling. In this study, we propose an approach combining an artificial neural network (ANN) model for peak flow estimation and the steepness index unit volume flood hydrograph (SIUVFH) method for sub-daily flow disaggregation to generate hydrographs on an hourly time scale. The SIUVFH method is based on the strong relationship between the flood peak and the steepness index, which is defined as the difference between the daily flood peak and daily flow several days before the peak; it is also used for selecting a reference unit volume flood hydrograph to be scaled to obtain the sub-daily flood hydrograph. In this study, to improve the applicability of the SIUVFH method for locations with a weak relationship between the flood peak and steepness index, the ANN-based flood peak estimation was used as an additional indicator to determine a reference unit volume flood hydrograph. To apply the proposed method, ANN models for estimating the peak flows from the mean daily flows during peak and adjacent days were constructed for the studied dam sites. The optimal ANN structures were determined through Monte Carlo cross-validation. The results showed a good performance with statistical measurements of relative root mean square errors of 0.155–0.224, 0.208–0.301, and 0.244–0.382 for the training, validation, and testing datasets, respectively. An application of the combined use of the ANN-based peak estimation and the SIUVFH-based flow disaggregation revealed that the disaggregated hourly flows satisfactorily matched the observed flood hydrograph. Full article

(This article belongs to the Section Water Resources Management, Policy and Governance)

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26 pages, 1010 KiB

Open AccessEditor’s ChoiceReview

Treatment of Wastewaters by Microalgae and the Potential Applications of the Produced Biomass—A Review

by Hareb Al-Jabri, Probir Das, Shoyeb Khan, Mahmoud Thaher and Mohammed AbdulQuadir

Water 2021, 13(1), 27; https://doi.org/10.3390/w13010027 - 25 Dec 2020

Cited by 155 | Viewed by 15371

Abstract

The treatment of different types of wastewater by physicochemical or biological (non-microalgal) methods could often be either inefficient or energy-intensive. Microalgae are ubiquitous microscopic organisms, which thrive in water bodies that contain the necessary nutrients. Wastewaters are typically contaminated with nitrogen, phosphorus, and [...] Read more.

The treatment of different types of wastewater by physicochemical or biological (non-microalgal) methods could often be either inefficient or energy-intensive. Microalgae are ubiquitous microscopic organisms, which thrive in water bodies that contain the necessary nutrients. Wastewaters are typically contaminated with nitrogen, phosphorus, and other trace elements, which microalgae require for their cell growth. In addition, most of the microalgae are photosynthetic in nature, and these organisms do not require an organic source for their proliferation, although some strains could utilize organics both in the presence and absence of light. Therefore, microalgal bioremediation could be integrated with existing treatment methods or adopted as the single biological method for efficiently treating wastewater. This review paper summarized the mechanisms of pollutants removal by microalgae, microalgal bioremediation potential of different types of wastewaters, the potential application of wastewater-grown microalgal biomass, existing challenges, and the future direction of microalgal application in wastewater treatment. Full article

(This article belongs to the Special Issue On-Site Wastewater Treatment)

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23 pages, 2972 KiB

Open AccessEditor’s ChoiceReview

Review: Sources of Hydrological Model Uncertainties and Advances in Their Analysis

by Edom Moges, Yonas Demissie, Laurel Larsen and Fuad Yassin

Water 2021, 13(1), 28; https://doi.org/10.3390/w13010028 - 25 Dec 2020

Cited by 139 | Viewed by 15080

Abstract

Despite progresses in representing different processes, hydrological models remain uncertain. Their uncertainty stems from input and calibration data, model structure, and parameters. In characterizing these sources, their causes, interactions and different uncertainty analysis (UA) methods are reviewed. The commonly used UA methods are [...] Read more.

Despite progresses in representing different processes, hydrological models remain uncertain. Their uncertainty stems from input and calibration data, model structure, and parameters. In characterizing these sources, their causes, interactions and different uncertainty analysis (UA) methods are reviewed. The commonly used UA methods are categorized into six broad classes: (i) Monte Carlo analysis, (ii) Bayesian statistics, (iii) multi-objective analysis, (iv) least-squares-based inverse modeling, (v) response-surface-based techniques, and (vi) multi-modeling analysis. For each source of uncertainty, the status-quo and applications of these methods are critiqued in gauged catchments where UA is common and in ungauged catchments where both UA and its review are lacking. Compared to parameter uncertainty, UA application for structural uncertainty is limited while input and calibration data uncertainties are mostly unaccounted. Further research is needed to improve the computational efficiency of UA, disentangle and propagate the different sources of uncertainty, improve UA applications to environmental changes and coupled human–natural-hydrologic systems, and ease UA’s applications for practitioners. Full article

(This article belongs to the Special Issue Hydrological Modeling in Water Cycle Processes)

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15 pages, 3603 KiB

Open AccessEditor’s ChoiceArticle

Potential Sources of Ammonium-Nitrogen in the Coastal Groundwater Determined from a Combined Analysis of Nitrogen Isotope, Biological and Geological Parameters, and Land Use

by Anna Fadliah Rusydi, Shin-Ichi Onodera, Mitsuyo Saito, Fujio Hyodo, Morihiro Maeda, Khori Sugianti and Sunarya Wibawa

Water 2021, 13(1), 25; https://doi.org/10.3390/w13010025 - 25 Dec 2020

Cited by 24 | Viewed by 4564

Abstract

The origin of ammonium-nitrogen in Indonesian coastal groundwater has not been intensively examined, meanwhile the elevated concentration remains a concern. This research aims at tracing the potential sources of ammonium-nitrogen in the groundwater of Indramayu, Indonesia where groundwater is vital for livelihood. From [...] Read more.

The origin of ammonium-nitrogen in Indonesian coastal groundwater has not been intensively examined, meanwhile the elevated concentration remains a concern. This research aims at tracing the potential sources of ammonium-nitrogen in the groundwater of Indramayu, Indonesia where groundwater is vital for livelihood. From results, a combined examination of nitrogen isotope, coliform bacteria, land-use, and geology confirmed the natural and anthropogenic origins of ammonium-nitrogen in the groundwater. In the brackish-water aquaculture region, groundwater has δ¹⁵N_NH4 values from +1.8 to +4.8‰ signifying that ammonium-nitrogen is derived from mineralization of organic nitrogen to ammonium. Furthermore, ammonium has a significantly positive relationship with sodium indicating the exchangeable ammonium is mobilized to groundwater via cation exchange. Meanwhile ammonium-nitrogen from anthropogenic waste was detected in agricultural and residential region. The groundwater has more varied δ¹⁵N_NH4 values, from −2.9 to +16.1‰, which implies attenuation of ammonium-nitrogen from several sources namely manure, mineral fertilizer, sewage, and pit latrines. Also, the presence of E. coli confirms the indication of human and animal waste contamination. However, since ammonium has no relationship with sodium, cation exchange is not feasible and ammonium-nitrogen flows into the groundwater from anthropogenic sources along with liquid wastes. Full article

(This article belongs to the Section Hydrology)

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25 pages, 11772 KiB

Open AccessEditor’s ChoiceArticle

The Effect of Geometric Parameters of the Antivortex on a Triangular Labyrinth Side Weir

by Saeed Abbasi, Sajjad Fatemi, Amir Ghaderi and Silvia Di Francesco

Water 2021, 13(1), 14; https://doi.org/10.3390/w13010014 - 24 Dec 2020

Cited by 30 | Viewed by 2977

Abstract

Side weirs are important structural measures extensively used, for instance, for regulating water levels in rivers and canals. If the length of the opening is limited, the amount of water diverted out of the channel and the effective length can be increased by [...] Read more.

Side weirs are important structural measures extensively used, for instance, for regulating water levels in rivers and canals. If the length of the opening is limited, the amount of water diverted out of the channel and the effective length can be increased by applying a labyrinth side weir. The present study deals with numerical simulations regarding the hydraulic performance of a labyrinth side weir with a triangular plan in single-cycle mode. Specifically, six different types of antivortexes embedded inside it and in various hydraulic conditions at different Froude numbers are analyzed. The antivortexes are studied using two groups, permeable and impermeable, with three different heights: 0.5 P, 0.75 P, and 1 P (P: Weir height). The comparison of the simulated water surface profiles with laboratory results shows that the numerical model is able to capture the flow characteristics on the labyrinth side weir. The use of an antivortex in a triangular labyrinth side weir reduces the secondary flows due to the interaction with the transverse vortexes of the vertical axis and increases the discharge capacity by 11%. Antivortexes in a permeable state outperform those in an impermeable state; the discharge coefficient in the permeable state increases up to 3% with respect to the impermeable state. Finally, based on an examination of the best type of antivortex, taking into account shape, permeability, and height, the discharge coefficient increases to 13.4% compared to a conventional labyrinth side weir. Full article

(This article belongs to the Special Issue Combined Numerical and Experimental Methodology for Fluid–Structure Interactions in Free Surface Flows)

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21 pages, 2659 KiB

Open AccessEditor’s ChoiceReview

Review: Acid Mine Drainage (AMD) in Abandoned Coal Mines of Shanxi, China

by Zhaoliang Wang, Yongxin Xu, Zhixiang Zhang and Yongbo Zhang

Water 2021, 13(1), 8; https://doi.org/10.3390/w13010008 - 23 Dec 2020

Cited by 56 | Viewed by 6636

Abstract

Excessive exploitation and massive coal mine closures have brought about extensive goafs in Shanxi where 8780 coal mines have been abandoned in the last 20 years. Acid mine drainage (AMD) poses severe environmental impact and has become a prominent problem in Shanxi abandoned [...] Read more.

Excessive exploitation and massive coal mine closures have brought about extensive goafs in Shanxi where 8780 coal mines have been abandoned in the last 20 years. Acid mine drainage (AMD) poses severe environmental impact and has become a prominent problem in Shanxi abandoned coal mine areas, which has aggravated the shortage of water resources and threatened the safety of the local drinking water supply. The purpose of this review is to protect the precious water resources and maintain sustainable use in Shanxi coal mines and downstream. By retrieving and analyzing about 90 domestic and international publications, a critical review of the AMD research results in Shanxi abandoned coal mines is conducted from the perspective of the formation mechanism, migration and transformation, prediction, treatment and management. The results shows that pyrite is the prerequisite for the formation of AMD, oxygen is the inducement, water is the carrier, and Fe³⁺ and microorganisms are the catalyst. The roadway system and geological structure are the dominant control factors. Finally, current difficulties and future research are pointed out. It is necessary to further strengthen the systematic research on the geological and hydrogeological conditions of abandoned coal mines, and explore an efficient, cheap, environmental technology, and construct the pollution risk assessment model for the AMD treatment. This study provides a scientific basis for the comprehensive treatment and management of AMD in abandoned coal mines in Shanxi. Full article

(This article belongs to the Section Water Quality and Contamination)

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15 pages, 4449 KiB

Open AccessEditor’s ChoiceArticle

Biological Reduction of Organic Matter in Buji River Sediment (Shenzhen, China) with Artificial Oxygenation

by Lin Che, Wenbiao Jin, Xu Zhou, Chenbo Cao, Wei Han, Changlei Qin, Renjie Tu, Yidi Chen, Xiaochi Feng and Qilin Wang

Water 2020, 12(12), 3592; https://doi.org/10.3390/w12123592 - 21 Dec 2020

Cited by 7 | Viewed by 3044

Abstract

In this work, artificial oxygenation treatment (pure oxygen aeration or oxygen enriched water injection) combined with the introduction of exogenous microorganisms was employed to purify urban river sediment for the first time. Results showed that the developed in situ remediation strategy could increase [...] Read more.

In this work, artificial oxygenation treatment (pure oxygen aeration or oxygen enriched water injection) combined with the introduction of exogenous microorganisms was employed to purify urban river sediment for the first time. Results showed that the developed in situ remediation strategy could increase the dissolved oxygen (DO) concentration and oxidation-reduction potential (ORP) value of the sediments. Benefiting from the increase of DO concentration, the bacterial diversity was enhanced. The highest removal efficiencies of organic matter were 18.4% and 22.3% through pure oxygen aeration and oxygen enriched water injection, respectively. More importantly, overlying water quality was not affected. By comparison, oxygen enriched water injection treatment could achieve better performance on sediment purification. Introducing exogenous microorganisms further reduced the organic matter content of the sediment. In short, the current work not only proposed a promising strategy for controlling urban river sediment pollution, but also provided novel insight for the understanding of river sediment containing highly concentrated organic matter. Full article

(This article belongs to the Section Biodiversity and Functionality of Aquatic Ecosystems)

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20 pages, 7416 KiB

Open AccessEditor’s ChoiceArticle

Changing Low Flow and Streamflow Drought Seasonality in Central European Headwaters

by Vojtech Vlach, Ondrej Ledvinka and Milada Matouskova

Water 2020, 12(12), 3575; https://doi.org/10.3390/w12123575 - 20 Dec 2020

Cited by 19 | Viewed by 4100

Abstract

In the context of the ongoing climate warming in Europe, the seasonality and magnitudes of low flows and streamflow droughts are expected to change in the future. Increasing temperature and evaporation rates, stagnating precipitation amounts and decreasing snow cover will probably further intensify [...] Read more.

In the context of the ongoing climate warming in Europe, the seasonality and magnitudes of low flows and streamflow droughts are expected to change in the future. Increasing temperature and evaporation rates, stagnating precipitation amounts and decreasing snow cover will probably further intensify the summer streamflow deficits. This study analyzed the long-term variability and seasonality of low flows and streamflow droughts in fifteen headwater catchments of three regions within Central Europe. To quantify the changes in the low flow regime of selected catchments during the 1968–2019 period, we applied the R package lfstat for computing the seasonality ratio (SR), the seasonality index (SI), mean annual minima, as well as for the detection of streamflow drought events along with deficit volumes. Trend analysis of summer minimum discharges was performed using the Mann–Kendall test. Our results showed a substantial increase in the proportion of summer low flows during the analyzed period, accompanied with an apparent shift in the average date of low flow occurrence towards the start of the year. The most pronounced seasonality shifts were found predominantly in catchments with the mean altitude 800–1000 m.a.s.l. in all study regions. In contrast, the regime of low flows in catchments with terrain above 1000 m.a.s.l. remained nearly stable throughout the 1968–2019 period. Moreover, the analysis of mean summer minimum discharges indicated a much-diversified pattern in behavior of long-term trends than it might have been expected. The findings of this study may help identify the potentially most vulnerable near-natural headwater catchments facing worsening summer water scarcity. Full article

(This article belongs to the Special Issue Statistical Approach to Hydrological Analysis)

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23 pages, 6364 KiB

Open AccessEditor’s ChoiceReview

Urban Flooding Mitigation Techniques: A Systematic Review and Future Studies

by Yinghong Qin

Water 2020, 12(12), 3579; https://doi.org/10.3390/w12123579 - 20 Dec 2020

Cited by 50 | Viewed by 17353

Abstract

Urbanization has replaced natural permeable surfaces with roofs, roads, and other sealed surfaces, which convert rainfall into runoff that finally is carried away by the local sewage system. High intensity rainfall can cause flooding when the city sewer system fails to carry the [...] Read more.

Urbanization has replaced natural permeable surfaces with roofs, roads, and other sealed surfaces, which convert rainfall into runoff that finally is carried away by the local sewage system. High intensity rainfall can cause flooding when the city sewer system fails to carry the amounts of runoff offsite. Although projects, such as low-impact development and water-sensitive urban design, have been proposed to retain, detain, infiltrate, harvest, evaporate, transpire, or re-use rainwater on-site, urban flooding is still a serious, unresolved problem. This review sequentially discusses runoff reduction facilities installed above the ground, at the ground surface, and underground. Mainstream techniques include green roofs, non-vegetated roofs, permeable pavements, water-retaining pavements, infiltration trenches, trees, rainwater harvest, rain garden, vegetated filter strip, swale, and soakaways. While these techniques function differently, they share a common characteristic; that is, they can effectively reduce runoff for small rainfalls but lead to overflow in the case of heavy rainfalls. In addition, most of these techniques require sizable land areas for construction. The end of this review highlights the necessity of developing novel, discharge-controllable facilities that can attenuate the peak flow of urban runoff by extending the duration of the runoff discharge. Full article

(This article belongs to the Special Issue Rainwater Management in Urban Areas)

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20 pages, 6455 KiB

Open AccessEditor’s ChoiceArticle

Unravelling Climate and Anthropogenic Forcings on the Evolution of Surface Water Resources in Southern France

by Camille Labrousse, Wolfgang Ludwig, Sébastien Pinel, Mahrez Sadaoui and Guillaume Lacquement

Water 2020, 12(12), 3581; https://doi.org/10.3390/w12123581 - 20 Dec 2020

Cited by 6 | Viewed by 3892

Abstract

In the Mediterranean, climate change and human pressures are expected to significantly impact the availability of surface water resources. In order to quantify these impacts during the last 60 years (1959–2018), we examined the hydro-climatic and land use change evolution in six coastal [...] Read more.

In the Mediterranean, climate change and human pressures are expected to significantly impact the availability of surface water resources. In order to quantify these impacts during the last 60 years (1959–2018), we examined the hydro-climatic and land use change evolution in six coastal river basins of the Gulf of Lion in southern France. By combining observed water discharge, gridded climate, mapped land use and agricultural censuses data, we propose a statistical regression model which successfully reproduces the variability of annual water discharge in all basins. Our results clearly demonstrate that, despite important anthropogenic water withdrawals for irrigation, climate change is the major driver for the detected reduction of water discharge. The model can explain 78–88% of the variability of annual water discharge in the study catchments. It requires only two climatic indices that are solely computed from monthly temperature (T) and precipitation (P) data, thus allowing the estimation of the respective contributions of both parameters in the detected changes. According to our results, the study region experienced on average a warming trend of 1.6 °C during the last 60 years which alone was responsible for a reduction of almost 25% of surface water resources. Full article

(This article belongs to the Special Issue Impacts of Climate Change and Anthropogenic Activities on the Spatio-Temporal Variability of River Flow)

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22 pages, 10942 KiB

Open AccessEditor’s ChoiceArticle

Risk Assessment of Irrigation-Related Soil Salinization and Sodification in Mediterranean Areas

by Alexandra Tomaz, Patrícia Palma, Sofia Fialho, Ana Lima, Paula Alvarenga, Miguel Potes, Maria João Costa and Rui Salgado

Water 2020, 12(12), 3569; https://doi.org/10.3390/w12123569 - 19 Dec 2020

Cited by 29 | Viewed by 7060

Abstract

Salinization and sodification are important processes of soil degradation affecting irrigated lands. A large proportion of the global irrigated area is affected by some degree of soil salinity or sodicity caused by the intensification of irrigation. The increase of the frequency of adverse [...] Read more.

Salinization and sodification are important processes of soil degradation affecting irrigated lands. A large proportion of the global irrigated area is affected by some degree of soil salinity or sodicity caused by the intensification of irrigation. The increase of the frequency of adverse climatic conditions, like high temperatures and variations in precipitation patterns caused by climate change, will potentially amplify these processes in arid, semi-arid, and Mediterranean areas. The use of integrated approaches for the spatial and temporal prediction of the risk of salinization and sodification in irrigated areas is of great value, helping in the decision-making regarding land uses and choice of more suitable agricultural practices. In this study, based on key criteria for the assessment of irrigation-related salinization processes (e.g., climate, topography, soil drainage, water quality for irrigation, and crop irrigation method), we developed a methodology for the prediction of soil salinity and sodicity risk in irrigated lands, using two composite indices, the Salinization Risk (RSA) index and the Sodification Risk (RSO) index. The application of these indices to a real scenario (a Mediterranean area in Southern Portugal) showed that 67% of the potentially irrigated area presented a low risk of salinity development, 68% had a moderate risk of sodification, and 16% was of high risk of sodicity development. Areas under moderate risk of salinization (26%) were mostly characterized by low slopes and fine-textured soils, like Luvisols and Vertisols, with limited drainage conditions. Areas with high risk of soil sodification presented a large incidence of low slope terrain, moderate-to-restricted soil drainage, in high clay content Luvisols, Vertisols and Cambisols, and land use dominated by annual crops irrigated with surface or sprinkler systems. These risk prediction tools have the potential to be used for resource use planning by policymakers and on-farm management decision by farmers, contributing to the sustainability of irrigated agriculture in Mediterranean regions. Full article

(This article belongs to the Special Issue Multiple Stressors Effects on Soil and Freshwater Ecosystems, in a Climate Change Scenario)

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19 pages, 3439 KiB

Open AccessEditor’s ChoiceArticle

An Application of Correlation and Spectral Analysis in Hydrological Study of Neighboring Karst Springs

by Vesna Denić-Jukić, Ana Lozić and Damir Jukić

Water 2020, 12(12), 3570; https://doi.org/10.3390/w12123570 - 19 Dec 2020

Cited by 16 | Viewed by 3980

Abstract

Various methods of time series analysis have been used in studies of karst hydrological systems. Among these methods, correlation and spectral analysis have had an important role. The correlation analysis most often has been based on determination of correlation coefficients and correlation functions. [...] Read more.

Various methods of time series analysis have been used in studies of karst hydrological systems. Among these methods, correlation and spectral analysis have had an important role. The correlation analysis most often has been based on determination of correlation coefficients and correlation functions. Partial correlation functions (PCF) are a mathematical tool of the correlation analysis which practical applicability in karst hydrology is insufficiently explored. In this study, the correlation and spectral analysis are applied on the catchment of Rumin Springs located in the Dinaric karst area between Croatia and Bosnia and Herzegovina. The available daily data are the rainfall, air temperature and relative humidity from three locations, as well as the discharge from two springs. The periods before and after the construction of HPP Orlovac in 1973 are analyzed. The basic hypothesis is that a difference between PCF obtained for two neighboring karst springs describe a difference in their functioning. The results of application show that PCF can resolve some ambiguities concerning the effects included in correlation functions and can provide the additional information that cannot be obtained by other methods of time series analysis. The obtained results are mostly in accordance with the present knowledge, and they support the existing hypotheses about the functioning of Rumin Springs. Full article

(This article belongs to the Special Issue Recent Advances in Karstic Hydrogeology)

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29 pages, 3815 KiB

Open AccessEditor’s ChoiceArticle

Stable Carbon Isotopes of Phytoplankton as a Tool to Monitor Anthropogenic CO₂ Submarine Leakages

by Federica Relitti, Nives Ogrinc, Michele Giani, Federica Cerino, Mirta Smodlaka Tankovic, Ana Baricevic, Lidia Urbini, Bor Krajnc, Paola Del Negro and Cinzia De Vittor

Water 2020, 12(12), 3573; https://doi.org/10.3390/w12123573 - 19 Dec 2020

Cited by 1 | Viewed by 4558

Abstract

This study aims to validate the stable carbon isotopic composition (δ¹³C) of phytoplankton as a tool for detecting submarine leakages of anthropogenic CO_2(g), since it is characterised by δ¹³C values significantly lower than the natural CO [...] Read more.

This study aims to validate the stable carbon isotopic composition (δ¹³C) of phytoplankton as a tool for detecting submarine leakages of anthropogenic CO_2(g), since it is characterised by δ¹³C values significantly lower than the natural CO₂ dissolved in oceans. Three culture experiments were carried out to investigate the changes in δ¹³C of the diatom Thalassiosira rotula during growth in an artificially modified medium (ASW). Three different dissolved inorganic carbon (DIC) concentrations were tested to verify if carbon availability affects phytoplankton δ¹³C. Simultaneously, at each experiment, T. rotula was cultured under natural DIC isotopic composition (δ¹³C_DIC) and carbonate system conditions. The available DIC pool for diatoms grown in ASW was characterised by δ¹³C_DIC values (−44.2 ± 0.9‰) significantly lower than the typical marine range. Through photosynthetic DIC uptake, microalgae δ¹³C rapidly changed, reaching significantly low values (until −43.4‰). Moreover, the different DIC concentrations did not affect the diatom δ¹³C, exhibiting the same trend in δ¹³C values in the three ASW experiments. The experiments prove that phytoplankton isotopic composition quickly responds to changes in the δ¹³C of the medium, making this approach a promising and low-impact tool for detecting CO_2(g) submarine leakages from CO_2(g) deposits. Full article

(This article belongs to the Section Hydrology)

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20 pages, 6782 KiB

Open AccessEditor’s ChoiceArticle

Modified Convergent Flow Tracing Method for Evaluating Advective Velocity and Effective Porosity in Fractured Rock Aquifers

by Byung-Woo Kim and Hangbok Lee

Water 2020, 12(12), 3565; https://doi.org/10.3390/w12123565 - 18 Dec 2020

Cited by 1 | Viewed by 3048

Abstract

This study presented the analysis of the modified convergent flow tracing method, which is a modified virtual solute transport approach to retrieve tracer masses from a pulse image (virtual) well to an extraction well. In the convergent flow tracer test, approximate analytical solutions [...] Read more.

This study presented the analysis of the modified convergent flow tracing method, which is a modified virtual solute transport approach to retrieve tracer masses from a pulse image (virtual) well to an extraction well. In the convergent flow tracer test, approximate analytical solutions were extended for the pulse image well using a single-well tracing method. This method transformed the drift-and-pumpback conditions of the single-well tracing method. The method requires a prior information of the effective porosity. Using sodium chloride as a tracer mass, the tracer data sampled through field-scale tests were used to obtain breakthrough curves. This modified method was different from the pre-existing single method because it considers both the ambient groundwater movement (the two classes of drifts) and the constant volumetric flow rate during the pumping phase. The method was applied to the tracer test at underground research tunnel for verifying the theory inductively derived from the single tracing method. Through field tests, the values of velocity and porosity were compared to the results of the drift-and-pumpback equations of the single-well test, and the several different equations related to breakthrough curves of the two-well tests conducted on a field scale. Full article

(This article belongs to the Special Issue Applying Artificial and Environmental Tracing Techniques in Hydrogeology)

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27 pages, 1127 KiB

Open AccessEditor’s ChoiceReview

Biochar as an Eco-Friendly and Economical Adsorbent for the Removal of Colorants (Dyes) from Aqueous Environment: A Review

by Prithvi Srivatsav, Bhaskar Sriharsha Bhargav, Vignesh Shanmugasundaram, Jayaseelan Arun, Kannappan Panchamoorthy Gopinath and Amit Bhatnagar

Water 2020, 12(12), 3561; https://doi.org/10.3390/w12123561 - 18 Dec 2020

Cited by 171 | Viewed by 15162

Abstract

Dyes (colorants) are used in many industrial applications, and effluents of several industries contain toxic dyes. Dyes exhibit toxicity to humans, aquatic organisms, and the environment. Therefore, dyes containing wastewater must be properly treated before discharging to the surrounding water bodies. Among several [...] Read more.

Dyes (colorants) are used in many industrial applications, and effluents of several industries contain toxic dyes. Dyes exhibit toxicity to humans, aquatic organisms, and the environment. Therefore, dyes containing wastewater must be properly treated before discharging to the surrounding water bodies. Among several water treatment technologies, adsorption is the most preferred technique to sequester dyes from water bodies. Many studies have reported the removal of dyes from wastewater using biochar produced from different biomass, e.g., algae and plant biomass, forest, and domestic residues, animal waste, sewage sludge, etc. The aim of this review is to provide an overview of the application of biochar as an eco-friendly and economical adsorbent to remove toxic colorants (dyes) from the aqueous environment. This review highlights the routes of biochar production, such as hydrothermal carbonization, pyrolysis, and hydrothermal liquefaction. Biochar as an adsorbent possesses numerous advantages, such as being eco-friendly, low-cost, and easy to use; various precursors are available in abundance to be converted into biochar, it also has recyclability potential and higher adsorption capacity than other conventional adsorbents. From the literature review, it is clear that biochar is a vital candidate for removal of dyes from wastewater with adsorption capacity of above 80%. Full article

(This article belongs to the Special Issue Adsorbents for Water and Wastewater Treatment and Resource Recovery)

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16 pages, 5750 KiB

Open AccessEditor’s ChoiceArticle

Modelling of Flood Inundation due to Levee Breaches: Sensitivity of Flood Inundation against Breach Process Parameters

by Yohannis Birhanu Tadesse and Peter Fröhle

Water 2020, 12(12), 3566; https://doi.org/10.3390/w12123566 - 18 Dec 2020

Cited by 9 | Viewed by 3225

Abstract

This paper analyses the sensitivity of flood inundation due to river levee breach against breach process parameters using the 1996 Awash River levee breach case at Wonji, Ethiopia. A parametric levee breach model integrated into the 2D hydrodynamic numerical model Telemac-2D is used [...] Read more.

This paper analyses the sensitivity of flood inundation due to river levee breach against breach process parameters using the 1996 Awash River levee breach case at Wonji, Ethiopia. A parametric levee breach model integrated into the 2D hydrodynamic numerical model Telemac-2D is used to simulate a levee breach flood event at Wonji, Ethiopia. Levee breach process parameters are systemically varied to find out their effect on the flood inundation. The analysis of the model results shows that the flood inundation is sensitive to the final breach dimensions and breach location. However, the parameters describing the levee breach development have negligible influence on the flood inundation. This implies that final breach dimension and breach location in an event of levee breach are the most important and decisive parameters affecting the resulting inundation of the flood plain, and as such should be given due consideration when creating flood inundation maps due to levee breach. Full article

(This article belongs to the Section Hydraulics and Hydrodynamics)

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15 pages, 2351 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Effect of Plasma Activated Water Foliar Application on Selected Growth Parameters of Maize (Zea mays L.)

by Petr Škarpa, Daniel Klofáč, František Krčma, Jana Šimečková and Zdenka Kozáková

Water 2020, 12(12), 3545; https://doi.org/10.3390/w12123545 - 17 Dec 2020

Cited by 30 | Viewed by 4593

Abstract

Utilization of plasma activated water (PAW) for plant growing is mainly connected with the treatment of seeds and subsequent stimulation of their germination. A potential of PAW is its relatively simple and low-cost preparation that calls for studying its wider application in plant [...] Read more.

Utilization of plasma activated water (PAW) for plant growing is mainly connected with the treatment of seeds and subsequent stimulation of their germination. A potential of PAW is its relatively simple and low-cost preparation that calls for studying its wider application in plant production. For this purpose, a pot experiment was realized in order to prove effects of the foliar PAW application on maize growth. The stepped PAW foliar application, carried out in 7-day intervals, led to provable decrease of chlorophyll contents in leaves compared to the distilled water application. The PAW application significantly increased root electrical capacitance, but it had no provable effect on weight of the aboveground biomass. Chlorophyll fluorescence parameters expressing the CO₂ assimilation rate and variable fluorescence of dark-adapted leaves were provably decreased by PAW, but quantum yield of photosystem II electron transport was not influenced. A provably higher amount of nitrogen was detected in dry matter of plants treated by PAW, but contents of other macro- and micro-nutrients in the aboveground biomass of maize were not affected. Results of this pilot verification of the PAW application have shown a potential for plant growth optimization and possibility for its further utilization, especially in combination with liquid fertilizers. Full article

(This article belongs to the Special Issue Applications of Plasma Activated Water and Media in Medicine and Agriculture)

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20 pages, 5820 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Photocatalytic Degradation of Polyamide 66; Evaluating the Feasibility of Photocatalysis as a Microfibre-Targeting Technology

by Jae-Mee Lee, Rosa Busquets, In-Cheol Choi, Sung-Ho Lee, Jong-Kyu Kim and Luiza C. Campos

Water 2020, 12(12), 3551; https://doi.org/10.3390/w12123551 - 17 Dec 2020

Cited by 36 | Viewed by 5134

Abstract

Wastewater treatment plants (WWTPs) have been identified as main contributors to releasing microfibres into the environment, however, WWTPs do not have microfibre-targeting technologies. In this study, photocatalysis is evaluated as a potential technology to treat microfibres in WWTPs by studying the degradation of [...] Read more.

Wastewater treatment plants (WWTPs) have been identified as main contributors to releasing microfibres into the environment, however, WWTPs do not have microfibre-targeting technologies. In this study, photocatalysis is evaluated as a potential technology to treat microfibres in WWTPs by studying the degradation of polyamide 66 (PA66) microfibres using ultraviolet (UV) and titanium dioxide (TiO₂). PA66 microfibres suspended in deionised water were exposed to different combinations of UV and TiO₂. The degradation of the PA66 microfibres was monitored by changes in mass, carbonyl index and morphology using microbalance, infrared spectroscopy, and scanning electron microscopy. The formation of by-products from the degradation of the fibres was evaluated by measuring the chemical oxygen demand (COD) of the treated water. The degradation efficiency was optimised under UVC with a dose of 100 mg TiO₂/L. Under these conditions, the PA66 microfibres presented a 97% mass loss within 48 h. The photocatalytic conditions applied generated a relatively low level of by-products (<10 mg/L of COD). Therefore, photocatalysis with TiO₂ an UVC could potentially be a feasible technology to treat microfibres in WWTPs, although more investigation is required to establish if this treatment leads to the formation of nanofibres. Further work is needed to translate the present optimised conditions to WWTPs. Full article

(This article belongs to the Special Issue Microplastics and Microfibers in Water and Wastewater: A Grand Challenge)

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13 pages, 1371 KiB

Open AccessEditor’s ChoiceArticle

Nitrogen and Phosphorus Concentration Thresholds toward Establishing Water Quality Criteria for Pennsylvania, USA

by John W. Clune, J. Kent Crawford and Elizabeth W. Boyer

Water 2020, 12(12), 3550; https://doi.org/10.3390/w12123550 - 17 Dec 2020

Cited by 9 | Viewed by 4321

Abstract

Nutrient enrichment is currently a leading cause of impairment to streams in Pennsylvania. Evaluating the water quality condition and eutrophic status of streams and rivers is a challenge without established thresholds for nutrient concentrations, which can vary depending on climate and landscape characteristics. [...] Read more.

Nutrient enrichment is currently a leading cause of impairment to streams in Pennsylvania. Evaluating the water quality condition and eutrophic status of streams and rivers is a challenge without established thresholds for nutrient concentrations, which can vary depending on climate and landscape characteristics. The US Environmental Protection Agency (USEPA) has published nutrient criteria for nutrient ecoregions nationwide that are used as regional baseline values; and has encouraged states to develop more refined values if better data are available. In this study, we quantified long-term nutrient concentrations observed in streams and rivers across Pennsylvania using a robust water quality dataset compiled from monitoring data collected over the past two decades (2000–2019) by multiple agencies. We estimated nutrient criteria concentration thresholds for each ecoregion using USEPA’s percentile approach. The 25th percentile median concentrations observed in streams and rivers ranged from 0.27 to 2.30 mg/L for total nitrogen (TN), and from 0.010 to 0.053 mg/L for total phosphorus (TP). The percent of sites with available data that exceeded the 25th percentile was 53% for TN and 60% for TP, reflecting longstanding problems with nutrient pollution of rivers and streams in Pennsylvania. The 25th percentile may overestimate background condition levels, as nutrient conditions vary substantially within and among ecoregions. We compared our contemporary concentrations at the threshold values to other published recommended criteria for the region and explored the influence of landscape heterogeneity and seasonality on nutrient concentrations. The spatial and temporal variability of nutrient conditions emphasizes the importance of using percentile analysis as only a guide toward more robust response-based methods, rather than as a method for setting nutrient criteria in Pennsylvania. Our results provide environmental managers with new insights regarding the status of nutrient conditions in streams and rivers across Pennsylvania ecoregions toward further developing numeric nutrient criteria. Full article

(This article belongs to the Special Issue Advances in Aquatic Pollution Assessment and Management)

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13 pages, 2963 KiB

Open AccessEditor’s ChoiceArticle

Comparison of Different Anode Materials to Remove Microcystis aeruginosa Cells Using Electro-Coagulation–Flotation Process at Low Current Inputs

by Thenuwara Arachchige Omila Kasun Meetiyagoda and Takeshi Fujino

Water 2020, 12(12), 3528; https://doi.org/10.3390/w12123528 - 16 Dec 2020

Cited by 6 | Viewed by 4038

Abstract

Cyanobacterial blooms are a threat to the drinking water supply owing to their potential toxicity. Microcystins which are the most widespread cyanotoxins, are mainly produced by Microcystis spp. In this study, we cultured Microcystis aeruginosa cells in BG-11 medium at 25 °C to [...] Read more.

Cyanobacterial blooms are a threat to the drinking water supply owing to their potential toxicity. Microcystins which are the most widespread cyanotoxins, are mainly produced by Microcystis spp. In this study, we cultured Microcystis aeruginosa cells in BG-11 medium at 25 °C to investigate the efficiency of the electro-coagulation–flotation process to remove them. Different anode materials (Fe, Al, Cu, and Zn) along with a graphite cathode were compared separately in the 10–100 mA current range in a 0.025 M Na₂SO₄ electrolyte. Turbidity, optical density at 684 nm (OD₆₈₄), OD₇₃₀, Chl-a concentration, and DOC concentration were analyzed to clarify the mechanism by which M. aeruginosa cells are removed. The Al anode indicated the highest removal efficiencies in terms of turbidity (90%), OD₆₈₄ and OD₇₃₀ (98%), and Chl-a concentration (96%) within 30 min at 4.0 mA/cm² current density and the lowest average electrode consumption of 0.120 ± 0.023 g/L. The energy consumption of the Al electrode was 0.80 Wh/L. From these results, we found that Al was the best among the anode materials evaluated to remove M. aeruginosa cells. However, further studies are required to optimize the Al anode in terms of pH, treatment time, electrode distance, and electrolyte concentration to enhance the removal of M. aeruginosa cells. Full article

(This article belongs to the Section Water and One Health)

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16 pages, 2632 KiB

Open AccessEditor’s ChoiceArticle

Effect of Clay Colloid Particles on Formaldehyde Transport in Unsaturated Porous Media

by Theodosia V. Fountouli and Constantinos V. Chrysikopoulos

Water 2020, 12(12), 3541; https://doi.org/10.3390/w12123541 - 16 Dec 2020

Cited by 11 | Viewed by 2340

Abstract

This study examines the effects of two representative colloid-sized clay particles (kaolinite, KGa-1b and montmorillonite, ST_x-1b) on the transport of formaldehyde (FA) in unsaturated porous media. The transport of FA was examined with and without the presence of clay particles under [...] Read more.

This study examines the effects of two representative colloid-sized clay particles (kaolinite, KGa-1b and montmorillonite, ST_x-1b) on the transport of formaldehyde (FA) in unsaturated porous media. The transport of FA was examined with and without the presence of clay particles under various flow rates and various levels of saturation in columns packed with quartz sand, under unsaturated conditions. The experimental results clearly suggested that the presence of clay particles retarded by up to ~23% the transport of FA in unsaturated packed columns. Derjaguin–Landau–Verwey–Overbeek (DLVO) interaction energy calculations demonstrated that permanent retention of clay colloids at air-water interfaces (AWI) and solid-water interfaces (SWI) was negligible, except for the pair (ST_x-1b)–SWI. The experimental results of this study showed that significant clay colloid retention occurred in the unsaturated column, especially at low flow rates. This deviation from DLVO predictions may be explained by the existence of additional non-DLVO forces (hydrophobic and capillary forces) that could be much stronger than van der Waals and double layer forces. The present study shows the important role of colloids, which may act as carriers of contaminants. Full article

(This article belongs to the Section Water Quality and Contamination)

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21 pages, 3431 KiB

Open AccessEditor’s ChoiceArticle

Fish Community Responses to Human-Induced Stresses in the Lower Mekong Basin

by Vanna Nuon, Sovan Lek, Peng Bun Ngor, Nam So and Gaël Grenouillet

Water 2020, 12(12), 3522; https://doi.org/10.3390/w12123522 - 15 Dec 2020

Cited by 15 | Viewed by 4586

Abstract

The Mekong River is one of the world’s largest rivers and has an annual captured fish production of about 2.3 million tonnes, equivalent to around 11 billion USD. Although the Mekong provides important ecological and socioeconomic benefits to millions of people, it is [...] Read more.

The Mekong River is one of the world’s largest rivers and has an annual captured fish production of about 2.3 million tonnes, equivalent to around 11 billion USD. Although the Mekong provides important ecological and socioeconomic benefits to millions of people, it is facing intensive change due to anthropogenic stressors. Therefore, it is necessary to understand the changes to the spatiotemporal fish communities to inform sustainable fisheries management. Here, we aimed to characterize patterns of the fish communities and identify the ecological status of each fish community using daily catch data from 2007 to 2018 at 25 monitoring sites in the Lower Mekong Basin (LMB). The collected data were classified by a self-organizing map into four main groups. Group 4 represented the lower Vietnam Mekong Delta (VMD), while groups 1, 2, and 3 were subdivided into subgroups 1a (upper LMB), 1b (upper and middle LMB), 2a (Mekong River below the Khone Falls and Sesan River), 2b (Mekong River below the Khone Falls and Sekong, Sesan and Srepok (3S) Rivers), 3a (Floodplain-Tonle Sap and Songkhram) and 3b (upper VMD). Among the 571 species recorded, 119 were identified as indicator species. Based on the abundance and biomass comparison curves, the fish community of 2b was in a healthier condition with a positive W-statistic value while the rest had a negative W-statistic value. The highest species richness and diversity were observed in 3a and 2b, so these subgroups deserve high management and conservation priority. Likewise, 1a should also be considered as a high priority area since it harbors several endangered and long-distant migratory fishes. It was also noticed that the fish communities of groups 3 and 4, located far from the hydropower dams, remained mostly unchanged compared to those of groups 1 and 2, close to the mainstream and tributary dams in the upper LMB and 3S Rivers. Full article

(This article belongs to the Special Issue Channels for Change: Integrating Multiple Disciplines for New Frontiers in Managing the Mekong River Basin)

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40 pages, 3951 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Organic Matter Decomposition and Ecosystem Metabolism as Tools to Assess the Functional Integrity of Streams and Rivers–A Systematic Review

by Verónica Ferreira, Arturo Elosegi, Scott D. Tiegs, Daniel von Schiller and Roger Young

Water 2020, 12(12), 3523; https://doi.org/10.3390/w12123523 - 15 Dec 2020

Cited by 40 | Viewed by 11414

Abstract

Streams and rivers provide important services to humans, and therefore, their ecological integrity should be a societal goal. Although ecological integrity encompasses structural and functional integrity, stream bioassessment rarely considers ecosystem functioning. Organic matter decomposition and ecosystem metabolism are prime candidate indicators of [...] Read more.

Streams and rivers provide important services to humans, and therefore, their ecological integrity should be a societal goal. Although ecological integrity encompasses structural and functional integrity, stream bioassessment rarely considers ecosystem functioning. Organic matter decomposition and ecosystem metabolism are prime candidate indicators of stream functional integrity, and here we review each of these functions, the methods used for their determination, and their strengths and limitations for bioassessment. We also provide a systematic review of studies that have addressed organic matter decomposition (88 studies) and ecosystem metabolism (50 studies) for stream bioassessment since the year 2000. Most studies were conducted in temperate regions. Bioassessment based on organic matter decomposition mostly used leaf litter in coarse-mesh bags, but fine-mesh bags were also common, and cotton strips and wood were frequent in New Zealand. Ecosystem metabolism was most often based on the open-channel method and used a single-station approach. Organic matter decomposition and ecosystem metabolism performed well at detecting environmental change (≈75% studies), with performances varying between 50 and 100% depending on the type of environmental change; both functions were sensitive to restoration practices in 100% of the studies examined. Finally, we provide examples where functional tools are used to complement the assessments of stream ecological integrity. With this review, we hope to facilitate the widespread incorporation of ecosystem processes into bioassessment programs with the broader aim of more effectively managing stream and river ecosystems. Full article

(This article belongs to the Special Issue The Ecological Assessment of Rivers and Estuaries: Present and Future)

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20 pages, 6226 KiB

Open AccessEditor’s ChoiceArticle

Evaluation of AnnAGNPS Model for Runoff Simulation on Watersheds from Glaciated Landscape of USA Midwest and Northeast

by Marzia Tamanna, Soni M. Pradhanang, Arthur J. Gold, Kelly Addy, Philippe G. Vidon and Ronald L. Bingner

Water 2020, 12(12), 3525; https://doi.org/10.3390/w12123525 - 15 Dec 2020

Cited by 10 | Viewed by 4460

Abstract

Runoff modeling of glaciated watersheds is required to predict runoff for water supply, aquatic ecosystem management and flood prediction, and to deal with questions concerning the impact of climate and land use change on the hydrological system and watershed export of contaminants of [...] Read more.

Runoff modeling of glaciated watersheds is required to predict runoff for water supply, aquatic ecosystem management and flood prediction, and to deal with questions concerning the impact of climate and land use change on the hydrological system and watershed export of contaminants of glaciated watersheds. A widely used pollutant loading model, Annualized Agricultural Non-Point Source Pollution (AnnAGNPS) was applied to simulate runoff from three watersheds in glaciated geomorphic settings. The objective of this study was to evaluate the suitability of the AnnAGNPS model in glaciated landscapes for the prediction of runoff volume. The study area included Sugar Creek watershed, Indiana; Fall Creek watershed, New York; and Pawcatuck River watershed, Rhode Island, USA. The AnnAGNPS model was developed, calibrated and validated for runoff estimation for these watersheds. The daily and monthly calibration and validation statistics (NSE > 0.50 and RSR < 0.70, and PBIAS ± 25%) of the developed model were satisfactory for runoff simulation for all the studied watersheds. Once AnnAGNPS successfully simulated runoff, a parameter sensitivity analysis was carried out for runoff simulation in all three watersheds. The output from our hydrological models applied to glaciated areas will provide the capacity to couple edge-of-field hydrologic modeling with the examination of riparian or riverine functions and behaviors. Full article

(This article belongs to the Special Issue Hydrological Processes in Small Catchments—Runoff and Sediment Yield in Changing Environment)

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22 pages, 2567 KiB

Open AccessEditor’s ChoiceArticle

Fate of Trace Organic Compounds in Hyporheic Zone Sediments of Contrasting Organic Carbon Content and Impact on the Microbiome

by Cyrus Rutere, Malte Posselt and Marcus A. Horn

Water 2020, 12(12), 3518; https://doi.org/10.3390/w12123518 - 15 Dec 2020

Cited by 7 | Viewed by 2555

Abstract

The organic carbon in streambed sediments drives multiple biogeochemical reactions, including the attenuation of organic micropollutants. An attenuation assay using sediment microcosms differing in the initial total organic carbon (TOC) revealed higher microbiome and sorption associated removal efficiencies of trace organic compounds (TrOCs) [...] Read more.

The organic carbon in streambed sediments drives multiple biogeochemical reactions, including the attenuation of organic micropollutants. An attenuation assay using sediment microcosms differing in the initial total organic carbon (TOC) revealed higher microbiome and sorption associated removal efficiencies of trace organic compounds (TrOCs) in the high-TOC compared to the low-TOC sediments. Overall, the combined microbial and sorption associated removal efficiencies of the micropollutants were generally higher than by sorption alone for all compounds tested except propranolol whose removal efficiency was similar via both mechanisms. Quantitative real-time PCR and time-resolved 16S rRNA gene amplicon sequencing revealed that higher bacterial abundance and diversity in the high-TOC sediments correlated with higher microbial removal efficiencies of most TrOCs. The bacterial community in the high-TOC sediment samples remained relatively stable against the stressor effects of TrOC amendment compared to the low-TOC sediment community that was characterized by a decline in the relative abundance of most phyla except Proteobacteria. Bacterial genera that were significantly more abundant in amended relative to unamended sediment samples and thus associated with biodegradation of the TrOCs included Xanthobacter, Hyphomicrobium, Novosphingobium, Reyranella and Terrimonas. The collective results indicated that the TOC content influences the microbial community dynamics and associated biotransformation of TrOCs as well as the sorption potential of the hyporheic zone sediments. Full article

(This article belongs to the Special Issue Environmental Fate of Contaminants in the Aquatic Environment)

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12 pages, 1207 KiB

Open AccessEditor’s ChoiceArticle

Dissolved Organic Matter in Continental Hydro-Geothermal Systems: Insights from Two Hot Springs of the East African Rift Valley

by Andrea Butturini, Stefano Amalfitano, Peter Herzsprung, Oliver J. Lechtenfeld, Stefania Venturi, Lydia A. Olaka, Nic Pacini, David M. Harper, Franco Tassi and Stefano Fazi

Water 2020, 12(12), 3512; https://doi.org/10.3390/w12123512 - 14 Dec 2020

Cited by 5 | Viewed by 2844

Abstract

Little is known about the quantity and quality of dissolved organic matter (DOM) in waters from continental geothermal systems, with only a few reports available from the Yellowstone US National Park. In this study, we explored the chemodiversity of DOM in water samples [...] Read more.

Little is known about the quantity and quality of dissolved organic matter (DOM) in waters from continental geothermal systems, with only a few reports available from the Yellowstone US National Park. In this study, we explored the chemodiversity of DOM in water samples collected from two geothermal hot springs from the Kenyan East African Rift Valley, a region extremely rich in fumaroles, geysers, and spouting springs, located in close proximity to volcanic lakes. The DOM characterization included in-depth assessments performed by negative electrospray ionization Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Reduced, saturated and little aromatic DOM compounds were dominant in the hot spring waters collected from either the Ol Njorowa gorge (ON) or the south shore of the soda-saline Lake Elementaita (ELM). Oxygen-poor and sulfur-bearing DOM molecules prevailed in ON, probably reflecting abiotic sulfurization from sulfide-rich geofluids. Nitrogen-bearing aliphatic and protein-like molecules were abundant in ELM, possibly perfusing through the organic-rich sediments of the adjacent Lake Elementaita. Notably, the heat-altered DOM of ancient autochthonous derivation could represent an overlooked source of aliphatic organic carbon for connected lentic environments, with a potential direct impact on nutrient cycling in lakes that receive geothermal water inputs. Full article

(This article belongs to the Special Issue Dissolved Organic Matter Dynamics in Groundwater, Rivers, and Lakes)

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21 pages, 9458 KiB

Open AccessEditor’s ChoiceArticle

Composition of Sedimentary Organic Matter across the Laptev Sea Shelf: Evidences from Rock-Eval Parameters and Molecular Indicators

by Elena Gershelis, Andrey Grinko, Irina Oberemok, Elizaveta Klevantseva, Natalina Poltavskaya, Alexey Ruban, Denis Chernykh, Andrey Leonov, Natalia Guseva and Igor Semiletov

Water 2020, 12(12), 3511; https://doi.org/10.3390/w12123511 - 14 Dec 2020

Cited by 6 | Viewed by 3081

Abstract

Global warming in high latitudes causes destabilization of vulnerable permafrost deposits followed by massive thaw-release of organic carbon. Permafrost-derived carbon may be buried in the nearshore sediments, transported towards the deeper basins or degraded into the greenhouse gases, potentially initiating a positive feedback [...] Read more.

Global warming in high latitudes causes destabilization of vulnerable permafrost deposits followed by massive thaw-release of organic carbon. Permafrost-derived carbon may be buried in the nearshore sediments, transported towards the deeper basins or degraded into the greenhouse gases, potentially initiating a positive feedback to climate change. In the present study, we aim to identify the sources, distribution and degradation state of organic matter (OM) stored in the surface sediments of the Laptev Sea (LS), which receives a large input of terrestrial carbon from both Lena River discharge and intense coastal erosion. We applied a suite of geochemical indicators including the Rock Eval parameters, traditionally used for the matured OM characterization, and terrestrial lipid biomarkers. In addition, we analyzed a comprehensive grain size data in order to assess hydrodynamic sedimentation regime across the LS shelf. Rock-Eval (RE) data characterize LS sedimentary OM with generally low hydrogen index (100–200 mg HC/g TOC) and oxygen index (200 and 300 CO₂/g TOC) both increasing off to the continental slope. According to T_peak values, there is a clear regional distinction between two groups (369–401 °C for the inner and mid shelf; 451–464 °C for the outer shelf). We suggest that permafrost-derived OM is traced across the shallow and mid depths with high T_peak and slightly elevated HI values if compared to other Arctic continental margins. Molecular-based degradation indicators show a trend to more degraded terrestrial OC with increasing distance from the coast corroborating with RE results. However, we observed much less variation of the degradation markers down to the deeper sampling horizons, which supports the notion that the most active OM degradation in LS land-shelf system takes part during the cross-shelf transport, not while getting buried deeper. Full article

(This article belongs to the Special Issue Geochemistry of Water and Sediment)

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26 pages, 6313 KiB

Open AccessEditor’s ChoiceArticle

Observations of Nearbed Turbulence over Mobile Bedforms in Combined, Collinear Wave-Current Flows

by Hachem Kassem, Charlotte E. L. Thompson, Carl L. Amos, Ian H. Townend, David Todd, Richard J. S. Whitehouse and Elizabeth Chellew

Water 2020, 12(12), 3515; https://doi.org/10.3390/w12123515 - 14 Dec 2020

Cited by 2 | Viewed by 2796

Abstract

Collinear wave-current shear interactions are often assumed to be the same for currents following or opposing the direction of regular wave propagation; with momentum and mass exchanges restricted to the thin oscillating boundary layer (zero-flux condition) and enhanced but equal wave-averaged bed shear [...] Read more.

Collinear wave-current shear interactions are often assumed to be the same for currents following or opposing the direction of regular wave propagation; with momentum and mass exchanges restricted to the thin oscillating boundary layer (zero-flux condition) and enhanced but equal wave-averaged bed shear stresses. To examine these assumptions, a prototype-scale experiment investigated the nature of turbulent exchanges in flows with currents aligned to, and opposing, wave propagation over a mobile sandy bed. Estimated mean and maximum stresses from measurements above the bed exceeded predictions by models of bed shear stress subscribing to the assumptions above, suggesting the combined boundary layer is larger than predicted by theory. The core flow experiences upward turbulent fluxes in aligned flows, coupled with sediment entrainment by vortex shedding at flow reversal, whilst downward fluxes of eddies generated by the core flow, and strong adverse shear can enhance near-bed mass transport, in opposing currents. Current-aligned coherent structures contribute significantly to the stress and energy dissipation, and display characteristics of wall-attached eddies formed by the pairing of counter-rotating vortices. These preliminary findings suggest a notable difference in wave-following and wave-opposing wave-current interactions, and highlight the need to account for intermittent momentum-exchanges in predicting stress, boundary layer thickness and sediment transport. Full article

(This article belongs to the Special Issue Sediment Transport in Coastal Waters 2.0)

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22 pages, 4277 KiB

Open AccessEditor’s ChoiceArticle

Quality and Health Risk Assessment Associated with Water Consumption—A Case Study on Karstic Springs

by Ana Moldovan, Maria-Alexandra Hoaghia, Eniko Kovacs, Ionuț Cornel Mirea, Marius Kenesz, Răzvan Adrian Arghir, Alexandru Petculescu, Erika Andrea Levei and Oana Teodora Moldovan

Water 2020, 12(12), 3510; https://doi.org/10.3390/w12123510 - 14 Dec 2020

Cited by 37 | Viewed by 4876

Abstract

In rural areas without centralized water supply systems, inhabitants often use groundwater of unknown quality as drinking water, without understanding the possible negative consequences on their health. Karstic spring waters from Dobrogea region in Romania were assessed for their potential to be used [...] Read more.

In rural areas without centralized water supply systems, inhabitants often use groundwater of unknown quality as drinking water, without understanding the possible negative consequences on their health. Karstic spring waters from Dobrogea region in Romania were assessed for their potential to be used as drinking water source, according to their quality and seasonal variation. The physico-chemical parameters of waters were compared with the guideline values for drinking water established by the World Health Organization and the Directive 98/83/EC. The nitrate and Cr concentrations exceeded the guideline value in the springs from Southern Dobrogea, but met the quality criteria in those from Northern Dobrogea, thus, to be used as drinking water, the karstic springs located in Southern Dobrogea require treatment for nitrates removal. Heavy metals pollution indices showed low to medium cumulative heavy metal pollution in all springs, while the human health risk assessment by oral exposure indicated possible noncarcinogenic risks of nitrates, both for adults and children in springs from South Dobrogea. A rigorous monitoring of the water quality before human consumption is recommended for all four studied water sources. Full article

(This article belongs to the Special Issue Research on Karst Eco-Hydrology and Sediment)

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25 pages, 8769 KiB

Open AccessEditor’s ChoiceArticle

Assessment of Hydrology and Sediment Yield in the Mekong River Basin Using SWAT Model

by Ty Sok, Chantha Oeurng, Ilan Ich, Sabine Sauvage and José Miguel Sánchez-Pérez

Water 2020, 12(12), 3503; https://doi.org/10.3390/w12123503 - 13 Dec 2020

Cited by 33 | Viewed by 5837

Abstract

The Mekong River Basin (MRB) in Southeast Asia is among the world’s ten largest rivers, both in terms of its discharge and sediment load. The spatial and temporal resolution to accurately determine the sediment load/yield from tributaries and sub-basin that enters the Mekong [...] Read more.

The Mekong River Basin (MRB) in Southeast Asia is among the world’s ten largest rivers, both in terms of its discharge and sediment load. The spatial and temporal resolution to accurately determine the sediment load/yield from tributaries and sub-basin that enters the Mekong mainstream still lacks from the large-scale model. In this study, the SWAT model was applied to the MRB to assess long-term basin hydrology and to quantify the sediment load and spatial sediment yield in the MRB. The model was calibrated and validated (1985–2016) at a monthly time step. The overall proportions of streamflow in the Mekong River were 34% from surface runoff, 21% from lateral flow, 45% from groundwater contribution. The average annual sediments yield presented 1295 t/km²/year in the upper part of the basin, 218 t/km²/year in the middle, 78 t/km²/year in the intensive agricultural area and 138 t/km²/year in the highland area in the lower part. The annual average sediment yield for the Mekong River was 310 t/km²/year from upper 80% of the total MRB before entering the delta. The derived sediment yield and a spatial soil erosion map can explicitly illustrate the identification and prioritization of the critical soil erosion-prone areas of the MR sub-basins. Full article

(This article belongs to the Special Issue Fluvial Processes and Denudation)

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16 pages, 1224 KiB

Open AccessEditor’s ChoiceArticle

Carbon Fixation Trends in Eleven of the World’s Largest Lakes: 2003–2018

by Michael Sayers, Karl Bosse, Gary Fahnenstiel and Robert Shuchman

Water 2020, 12(12), 3500; https://doi.org/10.3390/w12123500 - 12 Dec 2020

Cited by 15 | Viewed by 5050

Abstract

Large freshwater lakes provide immense value to the surrounding populations, yet there is limited understanding of how these lakes will respond to climate change and other factors. This study uses satellite remote sensing to estimate annual, lake-wide primary production in 11 of the [...] Read more.

Large freshwater lakes provide immense value to the surrounding populations, yet there is limited understanding of how these lakes will respond to climate change and other factors. This study uses satellite remote sensing to estimate annual, lake-wide primary production in 11 of the world’s largest lakes from 2003–2018. These lakes include the five Laurentian Great Lakes, the three African Great Lakes, Lake Baikal, and Great Bear and Great Slave Lakes. Mean annual production in these lakes ranged from under 200 mgC/m²/day to over 1100 mgC/m²/day, and the lakes were placed into one of three distinct groups (oligotrophic, mesotrophic, or eutrophic) based on their level of production. The analysis revealed only three lakes with significant production trends over the study period, with increases in Great Bear Lake (24% increase over the study period) and Great Slave Lake (27%) and a decline in Lake Tanganyika (−16%). These changes appear to be related to climate change, including increasing temperatures and solar radiation and decreasing wind speeds. This study is the first to use consistent methodology to study primary production in the world’s largest lakes, allowing for these novel between-lake comparisons and assessment of inter-annual trends. Full article

(This article belongs to the Special Issue The Impact of Environmental Stressors on Carbon Dynamics in the Aquatic System)

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27 pages, 65014 KiB

Open AccessEditor’s ChoiceArticle

Trophic Niches, Trophic Positions, and Niche Overlaps between Non-Native and Native Fish Species in a Subalpine Lake

by Davide Cicala, Gianluca Polgar, Jordi René Mor, Roberta Piscia, Stefano Brignone, Silvia Zaupa and Pietro Volta

Water 2020, 12(12), 3475; https://doi.org/10.3390/w12123475 - 10 Dec 2020

Cited by 12 | Viewed by 5855

Abstract

In the last century, Italian freshwater ecosystems have been invaded by several non-native fish species. In the subalpine Lake Mergozzo (northern Italy), several recently introduced non-native species dramatically expanded their populations. We used carbon and nitrogen stable isotopes to describe the isotopic niches [...] Read more.

In the last century, Italian freshwater ecosystems have been invaded by several non-native fish species. In the subalpine Lake Mergozzo (northern Italy), several recently introduced non-native species dramatically expanded their populations. We used carbon and nitrogen stable isotopes to describe the isotopic niches and trophic positions of native and non-native fish species in Lake Mergozzo. We evaluated their trophic niches, trophic diversity, trophic redundancy and trophic evenness utilizing isotopic niche metrics, and estimated asymmetrical niche overlaps. The trophic traits of non-native fish species and Perca fluviatilis clearly define them as trophic generalists, in terms of among-individual variability of their isotopic niches. The historical increase in abundance of fish non-native species in this lake, their dominance by numbers and biomass within the assemblage, and their broad asymmetrical niche overlaps suggest that their higher degree of trophic generalism might have been one of the key factors that have promoted the invasion of the recipient community. Full article

(This article belongs to the Special Issue Biological Invasions in Changing Aquatic Ecosystems: Future Perspectives)

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24 pages, 11060 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Natural and Anthropogenic Groundwater Contamination in a Coastal Volcanic-Sedimentary Aquifer: The Case of the Archaeological Site of Cumae (Phlegraean Fields, Southern Italy)

by Luisa Stellato, Silvio Coda, Michele Arienzo, Pantaleone De Vita, Brunella Di Rienzo, Antonio D’Onofrio, Luciano Ferrara, Fabio Marzaioli, Marco Trifuoggi and Vincenzo Allocca

Water 2020, 12(12), 3463; https://doi.org/10.3390/w12123463 - 9 Dec 2020

Cited by 16 | Viewed by 3913

Abstract

Archeological sites close to coastal volcanic-sedimentary aquifers are threatened by groundwater contaminated by natural and anthropogenic processes. The paper reports on a hydrogeological, chemical (major, minor and trace elements) and isotopic (δD-H₂O, δ¹⁸O-H₂O, δ¹⁵N-NO₃ [...] Read more.

Archeological sites close to coastal volcanic-sedimentary aquifers are threatened by groundwater contaminated by natural and anthropogenic processes. The paper reports on a hydrogeological, chemical (major, minor and trace elements) and isotopic (δD-H₂O, δ¹⁸O-H₂O, δ¹⁵N-NO₃, δ¹⁸O-NO₃, δ¹¹B, ²²²Rn) survey of groundwater at the Cumae archaeological site, which is located in the coastal north-western sector of the volcanic district of Phlegraean Fields (southern Italy), where groundwater flooding phenomena occur. Results show the presence of a complex coastal volcanic-sedimentary aquifer system where groundwater quality is influenced mainly by: (i) aquifer lithology and localized ascent of magmatic fluids along buried volcano-tectonic discontinuities, (ii) mixing of groundwater, deep mineralized fluids and seawater during groundwater pumping, and (iii) nitrate contamination >50 mg/L from non-point agricultural sources. Moreover, δD and δ¹⁸O point toward fast recharge from seasonal precipitations, while the isotopic ratios of N and O in nitrate reveal the contribution of mineral and organic fertilizers as well as leakage from septic tanks. Results can assist the local archaeological authority for the safeguarding and management of the archaeological heritage of the Cumae site. Full article

(This article belongs to the Special Issue Focus on the Salinization Issue in the Mediterranean Area)

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35 pages, 6301 KiB

Open AccessEditor’s ChoiceArticle

A Framework for Sustainable Planning and Decision-Making on Resource Recovery from Wastewater: Showcase for São Paulo Megacity

by Mariana C. Chrispim, Fernanda de M. de Souza, Miklas Scholz and Marcelo A. Nolasco

Water 2020, 12(12), 3466; https://doi.org/10.3390/w12123466 - 9 Dec 2020

Cited by 18 | Viewed by 5944

Abstract

Currently, it is important to develop strategic frameworks to support the selection of sustainable resource recovery solutions. This study applies a new framework for planning, implementation, and assessment of resource recovery strategies for a full-scale wastewater treatment plant (WWTP) in São Paulo megacity. [...] Read more.

Currently, it is important to develop strategic frameworks to support the selection of sustainable resource recovery solutions. This study applies a new framework for planning, implementation, and assessment of resource recovery strategies for a full-scale wastewater treatment plant (WWTP) in São Paulo megacity. The framework comprises several steps based on case study-specific data and information from current literature. Data were collected from various sources: a survey with a wastewater treatment utility, national and regional databases, and review of local regulations and international literature. Treatment configuration, wastewater and by-products composition, potential demand (for water, energy, and phosphorus), stakeholder identification, and local legislation were thoroughly discussed regarding decision-making on resource recovery. Scenario analysis was used to explore suitable nutrient and energy recovery measures based on indicators. Biogas recovery and sewage sludge composting showed more favorable conditions due to similar experiences in the area and robust legislation. The proposed framework is a simplified tool, and its application can support managers to get information on resource recovery and how to plan such initiatives in easier ways to facilitate wiser decision-making, and better operation and management. The results on framework use and refinement can guide potential applications in other contexts and stimulate public policy formulation and further research. Full article

(This article belongs to the Special Issue Application of Circular Economy Principles in Water and Wastewater Utilities)

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22 pages, 1514 KiB

Open AccessEditor’s ChoiceArticle

Integrated Assessment—How Does It Help Unpack Water Access by Marginalized Farmers?

by Serena H. Hamilton, Wendy S. Merritt, Mahanambrota Das, M. Wakilur Rahman, Sumana S. Bhuiya, Lucy Carter, Michaela Cosijn, Christian H. Roth, Sambhu Singha and Geoffrey J. Syme

Water 2020, 12(12), 3444; https://doi.org/10.3390/w12123444 - 8 Dec 2020

Cited by 3 | Viewed by 2458

Abstract

Water is critical to the lives and livelihoods of rural communities in developing countries; however, access to water can be inequitable within communities. This paper uses a generalized integrated assessment approach to explore the determinants of water access by marginalized farmers in two [...] Read more.

Water is critical to the lives and livelihoods of rural communities in developing countries; however, access to water can be inequitable within communities. This paper uses a generalized integrated assessment approach to explore the determinants of water access by marginalized farmers in two villages in coastal Bangladesh, before and after the setup of local water institutions. The study was part of a broader project aimed at promoting socially inclusive agricultural intensification. An integrative framework was developed in this study to capture and link the diverse range of factors that influence the distribution of water, including the often-overlooked role of social dynamics and governance arrangements. While interventions around improving water resource infrastructure can be critical for freshwater availability, the case studies show that a breakdown of asymmetric power structures may also be needed for water access to all individuals, especially marginalized groups. Establishing a community-based water institution on its own does not necessarily address power issues in a community. It is imperative that the agency and capacities of the marginalized members are developed and that the institutional arrangements foster an enabling environment for marginalized members to influence decision making. Integrated assessment allowed the case studies to be explored from multiple perspectives so as to gain a greater understanding of the barriers and levers to obtaining equitable outcomes from water interventions. Full article

(This article belongs to the Section Water Resources Management, Policy and Governance)

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24 pages, 4527 KiB

Open AccessEditor’s ChoiceArticle

Integrating In Situ and Ocean Color Data to Evaluate Ecological Quality under the Water Framework Directive

by Ana C. Brito, Paloma Garrido-Amador, Carla Gameiro, Marta Nogueira, Maria Teresa Moita and Maria Teresa Cabrita

Water 2020, 12(12), 3443; https://doi.org/10.3390/w12123443 - 8 Dec 2020

Cited by 10 | Viewed by 2887

Abstract

The Water Framework Directive (WFD) aims at evaluating the ecological status of European coastal water bodies (CWBs). This is a rather complex task and first requires the use of long-term databases to assess the effect of anthropogenic pressure on biological communities. An in [...] Read more.

The Water Framework Directive (WFD) aims at evaluating the ecological status of European coastal water bodies (CWBs). This is a rather complex task and first requires the use of long-term databases to assess the effect of anthropogenic pressure on biological communities. An in situ dataset was assembled using concomitant biological, i.e., chlorophyll a (Chl a) and environmental data, covering the years from 1995 to 2014, to enable a comprehensive assessment of eutrophication in the Western Iberia Coast (WIC). Given the temporal gaps in the dataset, especially in terms of Chl a, satellite observations were used to complement it. Positive relationships between Chl a 90th percentile and nitrogen concentrations were obtained. The Land-Uses Simplified Index (LUSI), as a pressure indicator, showed no relationship with Chl a, except in Galicia, but it highlighted a higher continental pressure in the Portuguese CWBs in comparison with Galician waters. In general terms, the trophic index (TRIX) showed that none of the CWBs were in degraded conditions. Nevertheless, the relatively high TRIX and LUSI values obtained for the water body in front of Tagus estuary suggest that this area should be subject to continued monitoring. Results highlighted the usefulness of satellite data in water quality assessments and set the background levels for the implementation of operational monitoring based on satellite Chl a. In the future, low uncertainty and harmonized satellite products across countries should be provided. Moreover, the assessment of satellite-based eutrophication indicators should also include metrics on phytoplankton phenology and community structure. Full article

(This article belongs to the Special Issue The WFD 20 Years After—Ecological Status Assessment and Restoration of Aquatic Ecosystems)

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19 pages, 1167 KiB

Open AccessEditor’s ChoiceArticle

Evaluation of Environmental Quality of Mediterranean Coastal Lagoons Using Persistent Organic Pollutants and Metals in Thick-Lipped Grey Mullet

by Chiara Leone, Fabrizio Capoccioni, Claude Belpaire, Govindan Malarvannan, Giulia Poma, Adrian Covaci, Lorenzo Tancioni, Michela Contò and Eleonora Ciccotti

Water 2020, 12(12), 3450; https://doi.org/10.3390/w12123450 - 8 Dec 2020

Cited by 7 | Viewed by 3150

Abstract

The evaluation of past and present anthropogenic impacts affecting the ecological quality status of transitional ecosystems is crucial from the perspective of protecting them from further deterioration, and to evaluate remediation and restoration measures. Contamination patterns of thick-lipped grey mullet from two Mediterranean [...] Read more.

The evaluation of past and present anthropogenic impacts affecting the ecological quality status of transitional ecosystems is crucial from the perspective of protecting them from further deterioration, and to evaluate remediation and restoration measures. Contamination patterns of thick-lipped grey mullet from two Mediterranean coastal lagoons within a protected area in Italy were assessed and compared in order to evaluate their overall quality status and to collect information that can provide useful feedback on management choices aimed at enhancing environmental quality and biodiversity conservation. The quality status of the two lagoons was evaluated by an environmental assessment methodology based on indicators of direct and indirect human pressures, while a broad range of analyses were carried out to determine the presence and concentration of persistent organic pollutants (POPs) and metals in fish muscle tissue. A good quality status resulted for both lagoons, and an overall limited anthropogenic impact in the surrounding area. This could account for POPs and metal contamination levels found in mullet, although limited, and relating to their patterns. The overlap of results achieved with the two evaluation approaches can provide support for management choices in Mediterranean lagoon environments, especially for those committed to the protection and conservation of biodiversity. Full article

(This article belongs to the Special Issue Aquatic Ecosafety: Threats, Disturbances, Environmental Monitors and Bioremediation Actions)

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12 pages, 1660 KiB

Open AccessEditor’s ChoiceArticle

Particle Size and Pre-Treatment Effects on Polystyrene Microplastic Settlement in Water: Implications for Environmental Behavior and Ecotoxicological Tests

by Lars Eitzen, Aki Sebastian Ruhl and Martin Jekel

Water 2020, 12(12), 3436; https://doi.org/10.3390/w12123436 - 8 Dec 2020

Cited by 11 | Viewed by 3168

Abstract

Microplastic (MP) particle dispersions used in many recent publications covering adsorption or toxicological studies are not characterized very well. The size distribution of polydisperse dispersions is highly dependent on the agglomeration processes and influences experimental outcomes. Therefore, pre-treatment is a prerequisite for reproducibility. [...] Read more.

Microplastic (MP) particle dispersions used in many recent publications covering adsorption or toxicological studies are not characterized very well. The size distribution of polydisperse dispersions is highly dependent on the agglomeration processes and influences experimental outcomes. Therefore, pre-treatment is a prerequisite for reproducibility. In this study, manual/automated shaking and ultrasonic treatment as different mechanical dispersion techniques were applied for the dispersion of cryomilled polystyrene (PS). Particle numbers and size distribution of dispersions were analyzed by a light extinction particle counter and the dispersion efficiency (E_D) as the ratio between calculated volume and theoretical volume of suspended particles was used to compare techniques. PS dispersions (20 mg/L) treated for 90 min in an ultrasonic bath (120 W, 35 kHz) were evenly dispersed with a particle concentration of 140,000 particles/mL and a high reproducibility (rel. SD = 2.1%, n = 6). Automated horizontal shaking for 754 h (250 rpm) reached similar particle numbers (122,000/mL) but with a lower reproducibility (rel. SD = 9.1%, n = 6). Manual shaking by hand dispersed the lowest number of particles (55,000/mL) and was therefore found to be unsuitable to counteract homo-agglomeration. E_D was calculated as 127%, 104% and 69% for ultrasonic treatment, horizontal shaking and manual shaking, respectively, showing an overestimation of volume assuming spherical shaped particles. Full article

(This article belongs to the Special Issue Analysis and Prevention of Microplastics Pollution in Water: Current Research and Future Directions)

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13 pages, 2453 KiB

Open AccessEditor’s ChoiceArticle

Comparison of Zooplankton Community Patterns in Relation to Sediment Disturbances by Dredging in the Guemho River, Korea

by Eui-Jeong Ko, Dong-Kyun Kim, Eun-Song Jung, Yu-Ji Heo, Gea-Jae Joo and Hyun-Woo Kim

Water 2020, 12(12), 3434; https://doi.org/10.3390/w12123434 - 7 Dec 2020

Cited by 3 | Viewed by 2877

Abstract

This study aimed to determine whether a swimming-type (planktonic and epiphytic) zooplankton group compared with the taxonomic group is appropriate to indicate the environmental changes caused by dredging. Water sampling in the littoral zone was conducted from 2007 to 2015, including the dredging [...] Read more.

This study aimed to determine whether a swimming-type (planktonic and epiphytic) zooplankton group compared with the taxonomic group is appropriate to indicate the environmental changes caused by dredging. Water sampling in the littoral zone was conducted from 2007 to 2015, including the dredging period from October 2010 to June 2012. The water quality, number of species, population densities, and biotic indices were compared for both dredging period and grouping type. Nine of 11 water quality parameters were changed by the dredging period. The results showed that the rotifer and planktonic groups were consistently dominant. In all groups, population density was the lowest during the dredging period. After dredging, both the number of species and population density increased only in the epiphytic group. The dominant species, including Polyarthra vulgaris, Brachionus calyciflorus, B. rubens, and Bosmina longirostris, were included in the planktonic group for 9 years. Evenness did not differ, but diversity increased after the dredging period. This study showed that zooplankton could be used as a supplemental biological assessment tool for evaluating the impact of river dredging. Full article

(This article belongs to the Section Biodiversity and Functionality of Aquatic Ecosystems)

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17 pages, 2819 KiB

Open AccessEditor’s ChoiceArticle

Developing Pseudo Continuous Pedotransfer Functions for International Soils Measured with the Evaporation Method and the HYPROP System: I. The Soil Water Retention Curve

by Amninder Singh, Amir Haghverdi, Hasan Sabri Öztürk and Wolfgang Durner

Water 2020, 12(12), 3425; https://doi.org/10.3390/w12123425 - 6 Dec 2020

Cited by 10 | Viewed by 3662

Abstract

Direct measurements of soil hydraulic properties are time-consuming, challenging, and often expensive. Therefore, their indirect estimation via pedotransfer functions (PTFs) based on easily collected properties like soil texture, bulk density, and organic matter content is desirable. This study was carried out to assess [...] Read more.

Direct measurements of soil hydraulic properties are time-consuming, challenging, and often expensive. Therefore, their indirect estimation via pedotransfer functions (PTFs) based on easily collected properties like soil texture, bulk density, and organic matter content is desirable. This study was carried out to assess the accuracy of the pseudo continuous neural network PTF (PC_NN-PTF) approach for estimating the soil water retention curve of 153 international soils (a total of 12,654 measured water retention pairs) measured via the evaporation method. In addition, an independent data set from Turkey (79 soil samples with 7729 measured data pairs) was used to evaluate the reliability of the PC_NN-PTF. The best PC_NN-PTF showed high accuracy (root mean square error (RMSE) = 0.043 cm³ cm⁻³) and reliability (RMSE = 0.061 cm³ cm⁻³). When Turkish soil samples were incorporated into the training data set, the performance of the PC_NN-PTF was enhanced by 33%. Therefore, to further improve the performance of the PC_NN-PTF for new regions, we recommend the incorporation of local soils, when available, into the international data sets and developing new sets of PC_NN-PTFs. Full article

(This article belongs to the Special Issue Soft Computing for Water and Aquatic Resource Management)

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13 pages, 3233 KiB

Open AccessEditor’s ChoiceArticle

Sediment Carbon Variations in the Venice Lagoon and Other Transitional Water Systems of the Northern Adriatic Sea

by Adriano Sfriso, Alessandro Buosi, Yari Tomio, Abdul-Salam Juhmani, Stefania Chiesa, Marta Greco, Chiara Gazzola, Michele Mistri, Cristina Munari and Andrea Augusto Sfriso

Water 2020, 12(12), 3430; https://doi.org/10.3390/w12123430 - 6 Dec 2020

Cited by 3 | Viewed by 3154

Abstract

The concentrations of inorganic, organic and total carbon, and some sedimentary parameters (sediment density, fines, pH, and shell fragments), have been analyzed in surface sediments of the Venice Lagoon since 1987. Environmental scenarios, characterized by different anthropogenic impacts, have been considered, especially in [...] Read more.

The concentrations of inorganic, organic and total carbon, and some sedimentary parameters (sediment density, fines, pH, and shell fragments), have been analyzed in surface sediments of the Venice Lagoon since 1987. Environmental scenarios, characterized by different anthropogenic impacts, have been considered, especially in the central basin where more information is available. Data collected in 2009 in the lagoons and ponds of Po Delta, in Comacchio Valleys and Pialassa della Baiona have been also considered and analyzed together with those recorded in the whole Venice Lagoon in 2011. The results show a strong correlation of the inorganic carbon (Cinorg) with the carbonatic or siliceous origins of the sediments and changes of both Cinorg and organic carbon (Corg) according to different anthropogenic impacts, especially eutrophication and clam-fishing activities. Higher sediment density, grain-size, and pH were associated to good-high ecological conditions and the higher presence of inorganic carbon of biological origin (shell fragments and calcified macroalgal fragments). Conversely, Corg, which is associated to eutrophic conditions, was strongly affected by the sediment disturbance and the presence of high concentrations of bivalves which enhance its consumption. Full article

(This article belongs to the Special Issue Aquatic Ecosafety: Threats, Disturbances, Environmental Monitors and Bioremediation Actions)

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15 pages, 3464 KiB

Open AccessEditor’s ChoiceArticle

Small Floodplain Reservoirs in the Face of Climate Change—Sink or Source of Nutrients?

by Joanna Gmitrowicz-Iwan, Sławomir Ligęza, Jacek Pranagal, Halina Smal and Heronim Olenderek

Water 2020, 12(12), 3423; https://doi.org/10.3390/w12123423 - 5 Dec 2020

Cited by 7 | Viewed by 1998

Abstract

Despite various water protection measures, good water quality and reduction of nutrient loads seem very distant goals, largely due to limited knowledge of processes occurring in river valleys. Our study aimed at establishing the role of small floodplain reservoirs in the eutrophication processes, [...] Read more.

Despite various water protection measures, good water quality and reduction of nutrient loads seem very distant goals, largely due to limited knowledge of processes occurring in river valleys. Our study aimed at establishing the role of small floodplain reservoirs in the eutrophication processes, in the face of recent climate changes. The content of phosphorus and nitrogen compounds was determined in sediments and water of small floodplain reservoirs, (the Vistula River Valley, Poland) using spectrophotometric and Kjeldahl’s method. Nutrient loads in sediments were linked to the texture and total organic carbon content. Seasonal changes in water quality were strictly connected to changing weather conditions, flood and drought. The concentrations of PO₄³⁻ and NO₃⁻ were found to rise after summer flooding. Increases in NH₄⁺, total phosphorus (TP) and total nitrogen (TN) were correlated with the surface water area reduction in the reservoirs, which during the year of the study was on average 62%. Therefore, small floodplain reservoirs could be considered simultaneously as sinks and sources of nutrients. On the one hand, they accumulate P and N compounds carried by the river during the flood. On the other hand, climate change cause that small floodplain reservoirs may be responsible for enhanced biomass production. Full article

(This article belongs to the Section Water Quality and Contamination)

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19 pages, 2620 KiB

Open AccessEditor’s ChoiceArticle

Impact of Nutrients, Temperatures, and a Heat Wave on Zooplankton Community Structure: An Experimental Approach

by Uğur Işkın, Nur Filiz, Yu Cao, Érika M. Neif, Burak Öğlü, Torben L. Lauridsen, Thomas A. Davidson, Martin Søndergaard, Ülkü Nihan Tavşanoğlu, Meryem Beklioğlu and Erik Jeppesen

Water 2020, 12(12), 3416; https://doi.org/10.3390/w12123416 - 4 Dec 2020

Cited by 16 | Viewed by 5013

Abstract

Shallow lakes are globally the most numerous water bodies and are sensitive to external perturbations, including eutrophication and climate change, which threaten their functioning. Extreme events, such as heat waves (HWs), are expected to become more frequent with global warming. To elucidate the [...] Read more.

Shallow lakes are globally the most numerous water bodies and are sensitive to external perturbations, including eutrophication and climate change, which threaten their functioning. Extreme events, such as heat waves (HWs), are expected to become more frequent with global warming. To elucidate the effects of nutrients, warming, and HWs on zooplankton community structure, we conducted an experiment in 24 flow-through mesocosms (1.9 m in diameter, 1.0 m deep) imitating shallow lakes. The mesocosms have two nutrient levels (high (HN) and low (LN)) crossed with three temperature scenarios based on the Intergovernmental Panel on Climate Change (IPCC) projections of likely warming scenarios (unheated, A2, and A2 + 50%). The mesocosms had been running continuously with these treatments for 11 years prior to the HW simulation, which consisted of an additional 5 °C increase in temperature applied from 1 July to 1 August 2014. The results showed that nutrient effects on the zooplankton community composition and abundance were greater than temperature effects for the period before, during, and after the HW. Before the HW, taxon richness was higher, and functional group diversity and evenness were lower in HN than in LN. We also found a lower biomass of large Cladocera and a lower zooplankton: phytoplankton ratio, indicating higher fish predation in HN than in LN. Concerning the temperature treatment, we found some indication of higher fish predation with warming in LN, but no clear effects in HN. There was a positive nutrient and warming interaction for the biomass of total zooplankton, large and small Copepoda, and the zooplankton: phytoplankton ratio during the HW, which was attributed to recorded HW-induced fish kill. The pattern after the HW largely followed the HW response. Our results suggest a strong nutrient effect on zooplankton, while the effect of temperature treatment and the 5 °C HW was comparatively modest, and the changes likely largely reflected changes in predation. Full article

(This article belongs to the Special Issue Effect of Extreme Climate Events on Lake Ecosystems)

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13 pages, 2450 KiB

Open AccessEditor’s ChoiceArticle

Prediction of Water Level and Water Quality Using a CNN-LSTM Combined Deep Learning Approach

by Sang-Soo Baek, Jongcheol Pyo and Jong Ahn Chun

Water 2020, 12(12), 3399; https://doi.org/10.3390/w12123399 - 3 Dec 2020

Cited by 155 | Viewed by 11522

Abstract

A Convolutional Neural Network (CNN)-Long Short-Term Memory (LSTM) combined with a deep learning approach was created by combining CNN and LSTM networks simulated water quality including total nitrogen, total phosphorous, and total organic carbon. Water level and water quality data in the Nakdong [...] Read more.

A Convolutional Neural Network (CNN)-Long Short-Term Memory (LSTM) combined with a deep learning approach was created by combining CNN and LSTM networks simulated water quality including total nitrogen, total phosphorous, and total organic carbon. Water level and water quality data in the Nakdong river basin were collected from the Water Resources Management Information System (WAMIS) and the Real-Time Water Quality Information, respectively. The rainfall radar image and operation information of estuary barrage were also collected from the Korea Meteorological Administration. In this study, CNN was used to simulate the water level and LSTM used for water quality. The entire simulation period was 1 January 2016–16 November 2017 and divided into two parts: (1) calibration (1 January 2016–1 March 2017); and (2) validation (2 March 2017–16 November 2017). This study revealed that the performances of both of the CNN and LSTM models were in the “very good” range with above the Nash–Sutcliffe efficiency value of 0.75 and that those models well represented the temporal variations of the pollutants in Nakdong river basin (NRB). It is concluded that the proposed approach in this study can be useful to accurately simulate the water level and water quality. Full article

(This article belongs to the Special Issue Water-Quality Modeling)

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17 pages, 2722 KiB

Open AccessEditor’s ChoiceReview

Literature Review: Global Neonicotinoid Insecticide Occurrence in Aquatic Environments

by Josephus F. Borsuah, Tiffany L. Messer, Daniel D. Snow, Steve D. Comfort and Aaron R. Mittelstet

Water 2020, 12(12), 3388; https://doi.org/10.3390/w12123388 - 2 Dec 2020

Cited by 89 | Viewed by 9019

Abstract

Neonicotinoids have been the most commonly used insecticides since the early 1990s. Despite their efficacy in improving crop protection and management, these agrochemicals have gained recent attention for their negative impacts on non-target species such as honeybees and aquatic invertebrates. In recent years, [...] Read more.

Neonicotinoids have been the most commonly used insecticides since the early 1990s. Despite their efficacy in improving crop protection and management, these agrochemicals have gained recent attention for their negative impacts on non-target species such as honeybees and aquatic invertebrates. In recent years, neonicotinoids have been detected in rivers and streams across the world. Determining and predicting the exposure potential of neonicotinoids in surface water requires a thorough understanding of their fate and transport mechanisms. Therefore, our objective was to provide a comprehensive review of neonicotinoids with a focus on their fate and transport mechanisms to and within surface waters and their occurrence in waterways throughout the world. A better understanding of fate and transport mechanisms will enable researchers to accurately predict occurrence and persistence of insecticides entering surface waters and potential exposure to non-target organisms in agricultural intensive regions. This review has direct implications on how neonicotinoids are monitored and degraded in aquatic ecosystems. Further, an improved understanding of the fate and transport of neonicotinoids aide natural resource practitioners in the development and implementation of effective best management practices to reduce the potential impact and exposure of neonicotinoids in waterways and aquatic ecosystems. Full article

(This article belongs to the Special Issue Mitigating the Impacts of Agricultural Water Pollution on River Ecology)

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12 pages, 1442 KiB

Open AccessEditor’s ChoiceArticle

Sustainable Exploitation of Dominant Fishes in the Largest Estuary in Southeastern China

by Linlong Wang, Li Lin, Yuan Li, Yankuo Xing and Bin Kang

Water 2020, 12(12), 3390; https://doi.org/10.3390/w12123390 - 2 Dec 2020

Cited by 8 | Viewed by 2376

Abstract

Globally, marine fisheries have declined under multiple stresses including overfishing, climate change, and habitat degradation. The Min River Estuary, as the largest estuary in southeastern China, has confronted this situation over recent decades. In this study, the dominant species of fish stocks in [...] Read more.

Globally, marine fisheries have declined under multiple stresses including overfishing, climate change, and habitat degradation. The Min River Estuary, as the largest estuary in southeastern China, has confronted this situation over recent decades. In this study, the dominant species of fish stocks in the Min River Estuary, including Coilia mystus, Cynoglossus abbreviates, Collichthys lucidus, Amblychaeturichthys hexanema, Polydactylus sextarius, Harpodon nehereus, and Secutor ruconius, were evaluated by the length-based Bayesian biomass estimator method (LBB). Outcomes could be grouped into three categories as healthy, showing the lowest exploitation rate (E: 0.31–0.43) and highest relative biomass (B/B_msy: 1.30–1.90), including S. ruconius, C. mystus, and H. nehereus; overfished, with a medium E (0.50–0.58) and B/B_msy (0.68–0.79), including A. hexanema and C. abbreviates; and collapsed, with the highest E (0.89–0.92) and lowest B/B_msy (0.03–0.21), including C. lucidus and P.sextarius. Corresponding imperative countermeasures such as using larger-sized mesh gears and reducing fishing intensity should be deployed according to the current status of each species for sustainable fishery exploitation and fish conservation. Full article

(This article belongs to the Section Water, Agriculture and Aquaculture)

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17 pages, 1085 KiB

Open AccessEditor’s ChoiceReview

Water and Climate Governance in Deltas: On the Relevance of Anticipatory, Interactive, and Transformative Modes of Governance

by Annisa Triyanti, Dries L. T. Hegger and Peter P. J. Driessen

Water 2020, 12(12), 3391; https://doi.org/10.3390/w12123391 - 2 Dec 2020

Cited by 10 | Viewed by 3250

Abstract

Deltas worldwide have been experiencing pressures and challenges exacerbated by climate change. An explicit focus on deltas is lacking in various bodies of literature, although present in those bodies focusing on the resilience of social-ecological systems. However, overall, literature relevant for addressing water [...] Read more.

Deltas worldwide have been experiencing pressures and challenges exacerbated by climate change. An explicit focus on deltas is lacking in various bodies of literature, although present in those bodies focusing on the resilience of social-ecological systems. However, overall, literature relevant for addressing water and climate governance in deltas is arguably still fragmented, leading to knowledge gaps and unexplored opportunities with regards to the development of delta-oriented governance strategies. To address this knowledge gap, we conducted a systematic literature review focusing on six bodies of literature relevant to delta governance up to and including the year 2019. The results show that scholarly interest in developing transformative pathways has increased sharply over the last few years. We derived seven key governance problems and five governance solutions for resilient deltas. We found that the predominant focus is still on technocratic approaches, with limited recognition of the political dimension and few forward-looking studies. In conclusion, we suggest stimulating the development and application of more anticipatory, transformative, and interactive modes of governance to help steer the transformation to resilient and sustainable deltas. We end with suggestions for systematic, interdisciplinary, and forward-looking empirical-analytical research. Full article

(This article belongs to the Section Water Resources Management, Policy and Governance)

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21 pages, 3342 KiB

Open AccessEditor’s ChoiceArticle

Phytoplankton Community Response to Nutrients, Temperatures, and a Heat Wave in Shallow Lakes: An Experimental Approach

by Nur Filiz, Uğur Işkın, Meryem Beklioğlu, Burak Öğlü, Yu Cao, Thomas A. Davidson, Martin Søndergaard, Torben L. Lauridsen and Erik Jeppesen

Water 2020, 12(12), 3394; https://doi.org/10.3390/w12123394 - 2 Dec 2020

Cited by 30 | Viewed by 4971

Abstract

Phytoplankton usually responds directly and fast to environmental fluctuations, making them useful indicators of lake ecosystem changes caused by various stressors. Here, we examined the phytoplankton community composition before, during, and after a simulated 1-month heat wave in a mesocosm facility in Silkeborg, [...] Read more.

Phytoplankton usually responds directly and fast to environmental fluctuations, making them useful indicators of lake ecosystem changes caused by various stressors. Here, we examined the phytoplankton community composition before, during, and after a simulated 1-month heat wave in a mesocosm facility in Silkeborg, Denmark. The experiment was conducted over three contrasting temperature scenarios (ambient (A0), Intergovernmental Panel on Climate Change A2 scenario (circa +3 °C, A2) and A2+ %50 (circa +4.5 °C, A2+)) crossed with two nutrient levels (low (LN) and high (HN)) with four replicates. The facility includes 24 mesocosms mimicking shallow lakes, which at the time of our experiment had run without interruption for 11 years. The 1-month heat wave effect was simulated by increasing the temperature by 5 °C (1 July to 1 August) in A2 and A2+, while A0 was not additionally heated. Throughout the study, HN treatments were mostly dominated by Cyanobacteria, whereas LN treatments were richer in genera and mostly dominated by Chlorophyta. Linear mixed model analyses revealed that high nutrient conditions were the most important structuring factor, which, regardless of temperature treatments and heat waves, increased total phytoplankton, Chlorophyta, Bacillariophyta, and Cyanobacteria biomasses and decreased genus richness and the grazing pressure of zooplankton. The effect of temperature was, however, modest. The effect of warming on the phytoplankton community was not significant before the heat wave, yet during the heat wave it became significant, especially in LN-A2+, and negative interaction effects between nutrient and A2+ warming were recorded. These warming effects continued after the heat wave, as also evidenced by Co-inertia analyses. In contrast to the prevailing theory stating that more diverse ecosystems would be more stable, HN were less affected by the heat wave disturbance, most likely because the dominant phytoplankton group cyanobacteria is adapted to high nutrient conditions and also benefits from increased temperature. We did not find any significant change in phytoplankton size diversity, but size evenness decreased in HN as a result of an increase in the smallest and largest size classes simultaneously. We conclude that the phytoplankton community was most strongly affected by the nutrient level, but less sensitive to changes in both temperature treatments and the heat wave simulation in these systems, which have been adapted for a long time to different temperatures. Moreover, the temperature and heat wave effects were observed mostly in LN systems, indicating that the sensitivity of phytoplankton community structure to high temperatures is dependent on nutrient availability. Full article

(This article belongs to the Special Issue Effect of Extreme Climate Events on Lake Ecosystems)

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17 pages, 5676 KiB

Open AccessEditor’s ChoiceArticle

Warming of Near-Surface Summer Water Temperatures in Lakes of the Conterminous United States

by Roger W. Bachmann, Daniel E. Canfield, Jr., Sapna Sharma and Vincent Lecours

Water 2020, 12(12), 3381; https://doi.org/10.3390/w12123381 - 2 Dec 2020

Cited by 5 | Viewed by 2642

Abstract

Because warming water temperatures have widespread consequences for freshwater communities, we were interested in estimating the patterns and rates of change of near-surface summer water temperatures in United States lakes. We developed multiple regression models to relate daily surface water temperatures in lakes [...] Read more.

Because warming water temperatures have widespread consequences for freshwater communities, we were interested in estimating the patterns and rates of change of near-surface summer water temperatures in United States lakes. We developed multiple regression models to relate daily surface water temperatures in lakes of the conterminous United States to 8-day average air temperatures, latitude, elevation, and sampling month and year using data from 5723 lake samples in the months of June-September during the period 1981–2018. Our model explained 79% of the variation with a root-mean-square error of 1.69 °C. We predicted monthly average near-surface water temperatures for 1033 lakes for each year from 1981 through 2018. Lakes across the conterminous United States have been warming for the period 1981–2018 at an average heating rate of 0.32 °C per decade for the summer months (June–September). The average summer warming from 1981–2018 would be the equivalent of a lake decreasing 259 m in elevation or moving 233 km south. On the basis of national air temperatures starting in 1895, it was inferred that lake water temperatures are variable from year to year and have been steadily increasing since 1964, but that maximum temperatures in the 1930s were just as warm as those in 2008–2018. Full article

(This article belongs to the Section Biodiversity and Functionality of Aquatic Ecosystems)

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