Search Results (103)

This study presents the first investigation into the distribution of microplastics (MPs) in Sasebo City, Japan, using principal component analysis (PCA) in conjunction with water flow velocity and salinity variables. The mean MP abundance was 82.4 ± 47.7 items/m³ (SSB1–SSB4), showing no significant difference among sampling points. The fragment-to-fiber ratio was 76:24, and polypropylene and polyethylene (each 41%) were the main polymers. Fragment abundance increased with decreasing particle size, while fibers were rare below 700 μm. PCA indicated distinct MP polymer and shape distributions corresponding to stagnant water (SSB1), high-flow conditions (SSB2 and SSB3), and seawater (SSB4). Based on the literature, the study area represents a case of a small-scale aquatic system with limited anthropogenic influence due to moderate population, short river length, efficient effluent discharge, minimal industry, good water quality, and the absence of significant spatial variation in MP abundance. The infrequent precipitation during the sampling event supports the findings of the present study as a reliable baseline for objectively assessing MP contamination. Compared to aquatic systems of varying scales and anthropogenic influence, this baseline is applicable to both small-scale and large-scale aquatic systems with significant influences. This will serve as a valuable reference for future MP studies across diverse freshwater environments. Full article

(1) Background: Affected by multiple factors, the decline in fish species diversity in some aquatic ecosystems has become increasingly pronounced. At a broad spatial scale, economic development has been widely recognized as one of the key factors influencing the fish distribution pattern. However, at a small scale, within a single river basin, the effects of economic development on the freshwater fish distribution and communities remain largely uninvestigated. (2) Methods: environmental DNA (eDNA) samples were collected from 26 sampling sites of the Lixian River in both the summer (June) and winter (November). Economic data from the Lixian River basin were collected, and analyses, including multivariate regression tree analysis and generalized linear model fitting, were performed using R 4.3.2. (3) Results: A total of 65 fish species was characterized, and the Chao1 diversity indices in the upstream (13.42) and downstream (13.00) were significantly higher than those in the middle reaches (8.55, p < 0.01) of this river. The species communities exhibited an obvious gradient changing pattern from the upstream to the downstream reaches, with parameters of water quality, including transparency, pH, dissolved oxygen and temperature, and climatic factors functioning as the key variables. Furthermore, the generalized linear model analysis revealed significant positive correlations between agricultural population (p = 0.00106), total grain production (p = 0.00476), total population (p = 0.00192) and the Chao1 index. (4) Conclusions: Climatic factors are the key factors affecting the fish diversity in the Lixian River. In less economically developed areas, the development of local economic activities may enhance fish diversity. Full article

Carbon emissions from freshwater aquaculture can exacerbate the greenhouse effect, thereby impacting human life and health. Consequently, it is of great significance to explore the carbon peak process and the role of emission reduction data in China’s freshwater aquaculture industry. This study innovatively employs the Logarithmic Mean Divisia Index model (LMDI) and the Tapio decoupling model to conduct an in-depth analysis of the relationship between carbon emissions and output values in the freshwater aquaculture industry, accurately identifying the main driving factors. Meanwhile, the global and local Moran’s I indices are introduced to analyze its spatial correlation from a new perspective. The results indicate that from 2013 to 2023, carbon emissions from China’s freshwater aquaculture industry exhibited a quasi-“N”-shaped trend, reaching a peak of 38 million tons in 2015. East China was the primary contributor to carbon emissions, accounting for 46%, while South China, Central China, and Northeast China each had an average annual share of around 14%, with Southwest, North China, and Northwest China contributing relatively small proportions. The global Moran’s I index showed a decreasing trend, with a p-value ≤ 0.0010 and a z-score > 3.3, indicating a 99% significant spatial correlation. High-high clusters were concentrated in some provinces of East China, while low-low clusters were found in Northwest, North, and Southwest China. The level of fishery economic development positively drove carbon emissions, whereas freshwater aquaculture production efficiency, industrial structure, and the scale of the aquaculture population had negative effects on carbon emissions. During the study period, carbon emissions exhibited three states: weak decoupling, strong decoupling, and expansive negative decoupling, with alternating strong and weak decoupling occurring after 2015. Full article

Malting is one of the most energy-intensive stages in beer brewing, yet its environmental impacts remain under-characterized despite recent efficiency gains. Barley and malt transport drive significant greenhouse gas emissions in import-dependent countries, while local, small-scale production can offset those savings through lower process efficiencies or higher resource use. This study conducted a cradle-to-gate Life Cycle Assessment (LCA) of three Italian malthouses—small, medium, and large—using SimaPro 10.2.0.0 and a functional unit of 1 kg of malted barley delivered by bulk truck to local breweries. Primary data on barley, water, methane, and electricity consumption, as well as waste generation, were collected via questionnaires; secondary data were sourced from Ecoinvent and Agri-Footprint. Impact categories were evaluated using the Cumulative Energy Demand (CED) and Product Environmental Footprint (PEF) methodologies. Barley cultivation dominates the footprint (84–92% of total impacts when using local grain). Drying and transport contribute 3.7–4.4% and 0–8.4% of impacts, respectively, depending on facility scale and import share. Smaller malthouses exhibit higher per-kilogram impacts due to lower energy efficiency and transportation modes. Mitigation strategies —including sustainable agriculture, renewable energy adoption, logistics optimization, and process improvements—can substantially reduce impacts. Notably, sourcing barley from low-impact suppliers alone lowers the carbon footprint from 0.80 to 0.66 kg CO_2e/kg, freshwater eutrophication from 227 to 32 CTU_e/kg, land use from 196 to 136 Pt/kg, and overall PEF from 192 to 81 µPt/kg. These results underscore the critical role of feedstock sourcing and process efficiency in decarbonizing malt production and provide a quantitative baseline for targeted sustainability interventions. Full article

Understanding the factors influencing amphibian populations is essential for effective freshwater conservation, particularly for species with biphasic life histories. This study examined how pond- and landscape-level characteristics shape larval amphibian occupancy, abundance, and detection in a remnant Tupelo-Cypress wetland in southeastern Illinois. Given the small number of available ponds (n = 4), we standardized survey effort across sites and incorporated robust hierarchical Bayesian models to evaluate environmental effects at both community and species levels. Occupancy probabilities were generally high across species, with canopy cover significantly increasing both community and species occupancy, particularly for salamanders (up to 6.4-fold). Predatory backswimmers and fish substantially reduced occupancy (by 21.7-fold and 6.0-fold, respectively). Anurans, especially Pseudacris spp., were more abundant than salamanders, with abundance positively associated with canopy cover, leaf litter, and pond perimeter. Detection probabilities were generally low and varied by species, with predatory invertebrates reducing detection up to 83.3-fold. These findings underscore the importance of maintaining canopy cover while mitigating predation risks to support amphibian populations. The application of multi-species hierarchical models provides a nuanced understanding of species-specific responses, offering valuable insights for conservation strategies in regions affected by habitat loss and climate change. However, given the limited spatial replication, these findings should be interpreted cautiously and validated through additional studies across broader temporal and spatial scales. Full article

Agriculture is the largest consumer of freshwater resources, accounting for approximately 70% of total water withdrawals. In semi-arid regions like Zacatecas, Mexico, water scarcity and climate variability pose critical challenges to small-scale farmers. This study evaluates the effectiveness of integrating modern irrigation technologies with traditional water management practices to enhance agricultural resilience. Analysis of climatic data (1961–2020) revealed a statistically significant increase in annual precipitation of 2.01 mm year⁻¹ in the Leobardo Reynoso module (p < 0.05), while the Miguel Alemán module exhibited a decline ranging from −0.54 mm year⁻¹ to −2.22 mm year⁻¹, exacerbating water scarcity. Pressurized irrigation systems in Leobardo Reynoso improved application efficiency to 87.5%, compared to 50% in traditional furrow irrigation. Despite these advancements, conveyance efficiency remains low (60%) due to extensive open canal networks. Climate projections indicate a 6–11% increase in irrigation water demand for staple crops by 2065, driven by rising evapotranspiration rates. Findings underscore the need for policy interventions, infrastructure upgrades, and financial support to sustain agricultural productivity in water-stressed environments. Full article

Land use is known to be an important factor in the composition and function of adjacent freshwater lotic ecosystems. However, the relative effects of land use type, extent, intensity, and proximity on aquatic ecosystem quality are not fully understood. We evaluate these questions in low-order streams within 30 watersheds in developed, agricultural, and less developed landscapes of central Ohio, USA. We assess the relationships of land use cover percentage and spatial scale with stream macroinvertebrate community diversity and biotic integrity. We also investigate the importance of impervious cover and subsurface tile drainage within each watershed and Active River Area (ARA). We find that the percentage of coverage of developed land at the watershed scale is the strongest predictor of stream macroinvertebrate community diversity and integrity. High-intensity development is a stronger negative correlate than low-intensity development or agriculture. There is a significant decline in stream macroinvertebrate diversity and biotic integrity at the watershed and ARA scales when undeveloped land coverage falls below 20–30%. We do not find a significant relationship between stream macroinvertebrate metrics and land use at the 1 km² scale or in comparison with any instream habitat attributes except sinuosity. Impervious cover has a significant negative relationship with both macroinvertebrate taxon richness and biotic integrity at the watershed and ARA scales. However, subsurface tile-drained land does not have a significant relationship with the stream macroinvertebrate community at any scale. We conclude that impervious land cover at the watershed and ARA scales is a critical factor for the biotic integrity of small streams in this region. Collectively, our conclusions provide evidence to support practices of ecologically sensitive land use planning. Full article

Inland lakes and reservoirs are critical components of global freshwater resources. However, traditional water level monitoring stations are costly to establish and maintain, particularly in remote areas. As an alternative, satellite altimetry has become a key tool for lake water level monitoring. Nevertheless, conventional radar altimetry techniques face accuracy limitations when monitoring small water bodies. The Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2), equipped with a single-photon counting lidar system, offers enhanced precision and a smaller ground footprint, making it more suitable for small-scale water body monitoring. However, the water level data obtained from the ICESat-2 ATL13 inland water surface height product are limited in quantity, while the lake water level accuracy derived from the ATL08 product is relatively low. To overcome these challenges, this study proposes a Spatial Distribution-Based Hierarchical Clustering for Photon-Counting Laser altimeter (SD-HCPLA) for enhanced water level extraction, validated through experiments conducted at the Danjiangkou Reservoir. The proposed method first employs Landsat 8/9 imagery and the Normalized Difference Water Index (NDWI) to generate a water mask, which is then used to filter ATL03 photon data within the water body boundaries. Subsequently, a Minimum Spanning Tree (MST) is constructed by traversing all photon points, where the vertical distance between adjacent photons replaces the traditional Euclidean distance as the edge length, thereby facilitating the clustering and denoising of the point cloud data. The SD-HCPLA algorithm successfully obtained 41 days of valid water level data for the Danjiangkou Reservoir, achieving a correlation coefficient of 0.99 and an average error of 0.14 m. Compared with ATL08 and ATL13, the SD-HCPLA method yields higher data availability and improved accuracy in water level estimation. Furthermore, the proposed algorithm was applied to extract water level data for five lakes and reservoirs in Hubei Province from 2018 to 2023. The temporal variations and inter-correlations of water levels were analyzed, providing valuable insights for regional ecological environment monitoring and water resource management. Full article

Mangrove swamp rice (MSR) production is critical for the diet of small farmers of coastal Guinea-Bissau. In mangrove swamp agroecosystems, rice is grown during the rainy season when freshwater and nutrients are abundant. However, small-scale farmers face challenges like unpredictable rainfall and rising sea levels, which increase soil salinity and acidity. This study aims to assess soil physical–chemical properties, paired with farmers’ local practices, to evaluate fertility constraints, and to support sustainable soil–plant management practices. This co-designed research contributes to filling a gap concerning the adoption of sustainable agricultural practices adapted to specific contexts in West Africa. In two regions, Oio (center) and Tombali (south), rice yields were measured in semi-controlled trials both in two agroecological settings: Tidal Mangrove (TM) and Associated Mangrove (AM) fields. 380 soil samples were collected, and rice growing parameters were assessed during the 2021 and 2022 rice sowing, transplanting, and flowering periods. Principal Component Analyses (PCA) and Multivariate Regression Analysis (MRA) were applied to understand trends and build fertility proxies in predicting yields. Significant spatial and temporal variability in the soil properties between agroecologies was found. Salinity constraints in Oio TMs limit production to an average of 110 g/m², compared to 250 g/m² in Tombali. Yield predictions account for 81% and 56.9% of the variance in TMs and AMs, respectively. Variables such as organic matter (OM), nitrogen (N), potassium (K), and precipitation positively influence yields, whereas sand content, pH, and iron oxides show a negative effect. This study advances the understanding of MSR production in Guinea-Bissau and underscores the importance of incorporating farmers’ knowledge of their diverse and complex production systems to effectively address these challenges. Full article

In the mixing zone, where submarine groundwater carrying ferrous iron [Fe(II)] meets seawater with dissolved oxygen (DO), the oxidative precipitation of Fe(II) occurs at the pore scale (nm~μm), and the resulting Fe precipitation significantly influences the seepage properties at the Darcy scale (cm~m). Previous studies have presented a challenge in upscaling fluid dynamics from a small scale to a large scale, thereby constraining our understanding of the spatiotemporal variations in flow paths as porous media evolve. To address this limitation, this study simulated subsurface mixing by injecting Fe(II)-rich freshwater into a DO-rich saltwater flow within a custom-designed syringe packed with glass beads. Micro-computed tomography imaging at the representative elementary volume scale was utilized to track the development of Fe precipitates over time and space. Experimental observations revealed three distinct stages of Fe hydroxides and their effects on the flow dynamics. Initially, hydrous Fe precipitates were characterized by a low density and exhibited mobility, allowing temporarily clogged pathways to intermittently reopen. As precipitation progressed, the Fe precipitates accumulated, forming interparticle bonding structures that redirected the flow to bypass clogged pores and facilitated precipitate flushing near the syringe wall. In the final stage, a notable reduction in the macroscopic capillary number from 3.0 to 0.05 indicated a transition from a viscous- to capillary-dominated flow, which led to the construction of ramified, tortuous flow channels. This study highlights the critical role of high-resolution imaging techniques in bridging the gap between pore-scale and continuum-scale analyses of multiphase flows in hydrogeochemical processes, offering valuable insights into the complex groundwater–seawater mixing. Full article

Poyang Lake is the largest freshwater lake in China and plays a significant ecological role. Deep-learning-based video surveillance can effectively monitor bird species on the lake, contributing to the local biodiversity preservation. To address the challenges of multi-scale object detection against complex backgrounds, such as a high density and severe occlusion, we propose a new model known as the YOLOv8-bird model. First, we use Receptive-Field Attention convolution, which improves the model’s ability to capture and utilize image information. Second, we redesign a feature fusion network, termed the DyASF-P2, which enhances the network’s ability to capture small object features and reduces the target information loss. Third, a lightweight detection head is designed to effectively reduce the model’s size without sacrificing the precision. Last, the Inner-ShapeIoU loss function is proposed to address the multi-scale bird localization challenge. Experimental results on the PYL-5-2023 dataset demonstrate that the YOLOv8-bird model achieves precision, recall, mAP@0.5, and mAP@0.5:0.95 scores of 94.6%, 89.4%, 94.8%, and 70.4%, respectively. Additionally, the model outperforms other mainstream object detection models in terms of accuracy. These results indicate that the proposed YOLOv8-bird model is well-suited for bird detection and counting tasks, which enable it to support biodiversity monitoring in the complex environment of Poyang Lake. Full article

A small-scale organic crop producing the protected geographical indication (PGI) cultivar “Faba Asturiana”, located in northern Spain, was considered to be a case study for analyzing the environmental impacts associated with the production of this legume (Phaseolus vulgaris L.). The life cycle assessment (LCA) methodology was employed for the analysis with a “cradle-to-gate” perspective, with 1 kg of dry beans as the functional unit. The results demonstrated that the main contributor to the environmental impacts was electricity consumption (with percentages above 75% for ionizing radiation, freshwater eutrophication, terrestrial ecotoxicity, and non-carcinogenic toxicity). A carbon footprint (CF) of 1.20 kg CO₂eq per kg of dry beans was obtained (around 1000 kg CO₂/ha·y). Electricity consumption was the major contributor to the CF, followed by atmospheric emissions from waste incineration and diesel use. Furthermore, some environmental improvements were suggested, and three alternative scenarios were investigated. In conclusion, it can be established that the CF of the studied PGI bean is within the range reported by other researchers for leguminous crops. The easiest way to reduce the CF for this particular crop would be to compost the organic waste instead of burning it. Additionally, the most effective strategy would be to reduce energy consumption or use renewable energy sources. For example, if the energy supply were obtained through in situ solar production, the CF could be reduced by more than 40%. Full article

Plastic production on a commercial scale began in the 1950s, reaching an annual production of 460 million metric tons in 2019. The global release of 22% of produced plastics into the environment has raised concerns about their potential environmental impacts, particularly on aquatic ecosystems. Here, we quantify and categorize plastic debris found along Richland Creek, a small, heavily forested watershed in western North Carolina, USA. Plastics within the riparian zone of seven 50 m reaches of Richland Creek and its tributaries were sampled two or three times. The 1737 pieces of collected plastic debris were returned to the lab where they were measured and categorized. A small-scale laboratory study using seven of the items collected was performed to determine their ability to break down into microplastics (particles < 5 mm in size). The majority (76%) of collected items were made of either plastic film (particularly bags and food wrappers, 43%) or hard plastics (e.g., bottles, 2%). However, when viewed on a surface area basis, films and synthetic fabrics (e.g., clothing, sleeping bags) equally dominated. Roughly three-quarters of the items collected had a width less than 10 cm, due primarily to the fragmentation of the original items; over two-thirds of the collected items were fragmented. Items composed of foams and films exhibited the highest fragmentation rates, 93% and 86%, respectively. Most collected plastics were domestic in nature, and the number of items increased downstream through more developed areas. Laboratory studies showed that plastic debris has a propensity to break down into microplastics. We believe the data collected here should be replicated in other streams, as these freshwater environments are the source of plastics that eventually enter the oceans. Full article

Small-scale open-pit, non-artisanal mining of low-value ores is an understudied practice despite its widespread occurrence and potential impact on freshwater resources due to mining-induced land-use/cover changes (LUCCs). This research investigates the long-term impacts of andesite mining in Pasuruan, Indonesia, on the Umbulan Spring’s water discharge within its watershed. System Dynamics (SD) modeling captures the systemic and systematic impact of mining-induced LUCCs on discharge volumes and groundwater recharge. Agricultural and reservoir-based land reclamation scenarios then reveal post-mining temporal dynamics. The no-mining scenario sees the spring’s discharge consistently decrease until an inflection point in 2032. With mining expansion, reductions accelerate by ~1.44 million tons over two decades, or 65.31 thousand tons annually. LUCCs also decrease groundwater recharge by ~2.48 million tons via increased surface runoff. Proposed post-mining land interventions over reclaimed mining areas influence water volumes differently. Reservoirs on reclaimed land lead to ~822.14 million extra tons of discharge, 2.75 times higher than the agricultural scenario. Moreover, reservoirs can restore original recharge levels by 2039, while agriculture only reduces the mining impact by 28.64% on average. These findings reveal that small-scale non-artisanal andesite mining can disrupt regional hydrology despite modest operating scales. Thus, evidence-based guidelines are needed for permitting such mines based on environmental risk and site water budgets. Policy options include discharge or aquifer recharge caps tailored to small-scale andesite mines. The varied outputs of rehabilitation scenarios also highlight evaluating combined land and water management interventions. With agriculture alone proving insufficient, optimized mixes of revegetation and water harvesting require further exploration. Full article

Indo-Pacific tropical island streams are home to freshwater pipefish (Microphis spp., Syngnathidae). Otoliths were used to uncover life history traits in four species, including a New Caledonian endemic. All four species present the same methodological challenge: their otoliths are small, fragile and mute for growth marks using basic observation tools. Strontium (Sr) is calcium substituent in the mineral lattice, driven by salinity conditions, and thus useful to study diadromous migrations. Synchrotron-based scanning X-ray fluorescence 2D high-resolution mapping allowed us to tackle the global and hyperfine strontium (Sr) distribution. We developed analytical imaging processes to retrieve biological information from otoliths from the data generated via synchrotron analysis. We uncovered plasticity in the life cycle: all species were amphidromous, apart from some freshwater residents from New Caledonia. Understanding life cycle modalities is crucial to categorize species distribution limits and to implement adapted conservation measures, especially when endemic species are at stake. 2D fine-scale images outlined the heterogeneity of Sr distribution: in addition to the trivial Sr incorporation driven by environmental ionic conditions, there is an unusual mosaic arrangement of Sr distribution and we hypothesize that biological control, especially growth during the early life stages, may sometimes overrule stoichiometry. This shows that it is worth studying otolith formation and element integration at imbricated scales, and our methods and results provide a strong basis for future works and prospects in otolith science. Full article