Geochemical Equilibrium and Processes in Seawater

A special issue of Geosciences (ISSN 2076-3263). This special issue belongs to the section "Geochemistry".

Deadline for manuscript submissions: closed (31 August 2018) | Viewed by 22837

Special Issue Editors


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Guest Editor
1. Rudjer Boskovic Institute, Division for Marine and Environmental Research, Zagreb, Croatia
2. Department of Geology, Faculty of Science, University of Zagreb, Zagreb, Croatia
Interests: marine geochemistry; environmental geochemistry; coastal ecosystems; environmental impact assessment; redox equilibria in marine systems

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Guest Editor
Ruđer Bošković Institute, Division for Marine and Environmental Research, Bijenička Cesta 54, 10000 Zagreb, Croatia
Interests: trace elements; toxic metals; environmental geochemistry; water quality; environmental pollution; mass spectrometry
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Special Issue Information

Dear Colleagues,

This Special Issue of Geosciences addresses new contributions related to the geochemistry of nutrients and trace elements in coastal and open sea environments.

In coastal waters, nutrients and trace elements are supplied not only by riverine inputs, but also by atmospheric pathways and submarine groundwater discharges—the latter including the discharge of fresh and saline groundwater as well as the advection of sediment porewater. Recent studies highlighted the importance of atmospheric transport and deposition modes and mentioned groundwater discharges on the overall nutrient and trace element fluxes in the marine environments, as well as their influence on marine (bio)geochemistry.

However, the relative importance of certain sources of nutrients and trace metals to the coastal waters varies both spatially and temporally, with different studies providing different emphasis on the balance of the fluxes. 

Within the context of multiple factors influencing the pathways and fate of environmental chemicals, a need for further field studies is evident, whereas the collected data could be used for the validation of numerical models in the description of chemical equilibrium in low-temperature geochemical systems, and serve to enhance our understanding of nutrient and trace element inputs and behaviour in marine systems.

We will invite authors to submit original research articles as well as review articles that focus on geochemical equilibrium and processes of nutrients and trace elements in seawater, and seek to define the interaction between their different sources in coastal and open sea environments.

Prof. Goran Kniewald
Dr. Željka Fiket
Guest Editors

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Keywords

  • marine geochemistry
  • coastal and open sea environments
  • nutrients and trace elements
  • geochemical equilibrium
  • geochemical modeling
  • interaction of sources
  • anthropogenic influence

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Published Papers (6 papers)

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Editorial

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6 pages, 191 KiB  
Editorial
Geochemical Equilibrium and Processes in Seawater
by Željka Fiket and Goran Kniewald
Geosciences 2018, 8(12), 493; https://doi.org/10.3390/geosciences8120493 - 17 Dec 2018
Viewed by 2249
Abstract
The geochemical equilibrium in seawater must be observed taking into account the chemical and geological, as well as biological, processes. The concept of equilibrium takes into account the composition of the system and the kinetics of the reactions taking place therein. In coastal [...] Read more.
The geochemical equilibrium in seawater must be observed taking into account the chemical and geological, as well as biological, processes. The concept of equilibrium takes into account the composition of the system and the kinetics of the reactions taking place therein. In coastal waters, nutrients and trace elements can be delivered not only through rivers but also through atmospheric input and submarine groundwater discharges. In addition to natural sources, levels of different elements can also be influenced by growing and diverse human activities along coasts. Consequently, the pathways and fate of different environmental chemicals in coastal areas are governed by various factors. The multiparameter approach, combined with different statistical tools, is a well-established way of interpreting their inputs and behaviour in marine systems. Nevertheless, the data for the karst regions, as found in the Mediterranean, are particularly scarce. This Special Issue—Geochemical Equilibrium and Processes in Seawater—of Geosciences gathers five articles on different topics related to water and sediment geochemistry of the coastal karst areas of the Mediterranean, including Slovenia, Croatia and Egypt. The topics included in this Issue refer to (1) geochemistry of sediments in the area of intensive anthropogenic activity; (2) the geochemistry of sediment and biota in a protected area under increasing pressure due to tourist activity; (3) the influence of a thermal power plant on the geochemistry of the surrounding area; (4) the influence of underground water discharges on water quality; and (5) the possibility of monitoring natural and anthropogenic processes in karst systems by using a specific group of elements. Full article
(This article belongs to the Special Issue Geochemical Equilibrium and Processes in Seawater)

Research

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18 pages, 3937 KiB  
Article
Selenium, Sulphur, Trace Metal, and BTEX Levels in Soil, Water, and Lettuce from the Croatian Raša Bay Contaminated by Superhigh-Organic-Sulphur Coal
by Gordana Medunić, Željka Kuharić, Adela Krivohlavek, Marija Đuroković, Kristina Dropučić, Ankica Rađenović, Borna Lužar Oberiter, Aleksandra Krizmanić and Mladen Bajramović
Geosciences 2018, 8(11), 408; https://doi.org/10.3390/geosciences8110408 - 08 Nov 2018
Cited by 27 | Viewed by 3912
Abstract
This paper elaborates soil, water, and lettuce contamination status with respect to selenium, sulphur, trace metals, and BTEX (benzene, toluene, ethylbenzene, and xylenes) in a coal-based area (Raša Bay, Adriatic Sea, Croatia). A local coal-fired power plant polluted soil with S, Se, Cd, [...] Read more.
This paper elaborates soil, water, and lettuce contamination status with respect to selenium, sulphur, trace metals, and BTEX (benzene, toluene, ethylbenzene, and xylenes) in a coal-based area (Raša Bay, Adriatic Sea, Croatia). A local coal-fired power plant polluted soil with S, Se, Cd, and PAHs due to the combustion of domestic superhigh-organic-sulphur coal. The locality is dotted with waste from coal mining/separation, coal combustion, former metal factories, untreated municipal and coal mine effluents, along with various harbour activities, which contribute to environmental contamination. The methodology involved ICP-MS and GC-MS for the measurement of trace elements and BTEX, respectively, while soil sulphur was determined with Eschka’s mixture. The max values of the analysed trace elements in soil (mg/kg) are reported: Hg 1.14, Cd 3.29, V 624, Se 10.3, Pb 872, Cr 1860, Zn 6580, Cu 1850, and U 25.2. According to ecological indices, these values fall into the category of an extremely high level of soil pollution. Elevated total Se values in surface water are ascribed to leaching of seleniferous coal, ash, and coal-polluted soil. Levels of BTEX in water samples were very low (0–0.83 µg/L). The data provide basic information on the inorganic and organic contamination status of the Raša Bay area. Full article
(This article belongs to the Special Issue Geochemical Equilibrium and Processes in Seawater)
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18 pages, 6942 KiB  
Article
Heavy Metal Signature and Environmental Assessment of Nearshore Sediments: Port of Koper (Northern Adriatic Sea)
by Nastja Rogan Šmuc, Matej Dolenec, Sabina Kramar and Ana Mladenović
Geosciences 2018, 8(11), 398; https://doi.org/10.3390/geosciences8110398 - 31 Oct 2018
Cited by 17 | Viewed by 3549
Abstract
Heavy metal abundance and potential environmental risks are reported for surface sediments (n = 21) from the Port of Koper area, Republic of Slovenia. The enrichment factor (EF) indicates minor enrichment in arsenic (As), cadmium (Cd), copper (Cu), molybdenum (Mo), lead (Pb), [...] Read more.
Heavy metal abundance and potential environmental risks are reported for surface sediments (n = 21) from the Port of Koper area, Republic of Slovenia. The enrichment factor (EF) indicates minor enrichment in arsenic (As), cadmium (Cd), copper (Cu), molybdenum (Mo), lead (Pb), antimony (Sb), and zinc (Zn), moderately to severely enriched with nickel (Ni). The trace metal chemistries, in the context of sediment quality guidelines (SQG), imply adverse threshold effect concentrations (TEC) and probable effect concentrations (PEC), for Ni only. Sediment sequential leaching experiments demonstrated that the majority of heavy metals were of natural lithogenic origin and low bioavailability. The heavy metals’ potential for “Risk Assessment Code” values exhibited no or low anthropogenic environmental burden, with the exception of Mo. Full article
(This article belongs to the Special Issue Geochemical Equilibrium and Processes in Seawater)
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17 pages, 5122 KiB  
Article
Geochemical and Isotopic Evidence of Groundwater Salinization Processes in El Dabaa Area, Northwestern Coast, Egypt
by Mustafa A. Eissa, Hosam Shawky, Amira Samy, Mostafa M. H. Khalil and Mohamed El Malky
Geosciences 2018, 8(11), 392; https://doi.org/10.3390/geosciences8110392 - 29 Oct 2018
Cited by 14 | Viewed by 4437
Abstract
El Dabaa city is located along the northwestern coast ridge zone of Egypt, where the groundwater is the major water source for drinking, domestic, and agricultural purposes. The groundwater salinity increased over the last decades, therefore, geochemical techniques and environmental isotopes have been [...] Read more.
El Dabaa city is located along the northwestern coast ridge zone of Egypt, where the groundwater is the major water source for drinking, domestic, and agricultural purposes. The groundwater salinity increased over the last decades, therefore, geochemical techniques and environmental isotopes have been utilized to identify the main groundwater recharge and salinization sources. The study area comprises two main groundwater aquifers: the porous oolitic Pleistocene and the fractured limestone Miocene aquifers. The groundwater salinity of the Pleistocene aquifer ranges from 751 to 27,870 mg/L, with an average value of 6006 mg/L. The salinity of the Miocene aquifer ranges from 3645 to 41,357 mg/L, with an average value of 11,897 mg/L. Fresh and brackish groundwater have been recorded in the shallow hand-dug wells, while saline groundwater has been found in deeper wells close to the shoreline. Groundwater samples have been categorized into two distinct groups according to the salinity ranges, hydrochemical ion ratios, and stable isotopic content. Group I is composed of groundwater with salinity less than 10,000 mg/L, and depleted stable isotopic content (−5.64 < δ18O < −2.45; −23.5 < δ2H < −0.02), while Group II contains groundwater with salinity values above 10,000 mg/L and relatively enriched stable isotopic content (−1.86 < δ18O < −0.48; −10.3 < δ2H < −2.0). The weight mass balance mixing model shows that Group I falls close to the rain and/or water extract samples, indicating meteoric water origin that has evolved due to leaching and dissolution processes. Group II is mostly located between the rainwater and the seawater samples, revealing mixing with water of marine origin due to groundwater overexploitation. The estimated seawater mixing index (SMI) of groundwater samples of Group II is greater than one, which confirms mixing with seawater. The water-rock reaction NETPATH (geochemical groundwater reaction and mixing code) model scenarios representing Group I suggests that gypsum, dolomite, and halite are dissolved, while calcite is formed with a slight influence from evaporation processes. Six mixing models representing Group II are used to investigate seawater mixing scenarios. The models suggest that illite and dolomite are dissolved, while calcite and gypsum are precipitated with a seawater mixing ratios ranging from 28% to 98%. In conclusion, due to the scarcity of annual groundwater recharge in the El Dabaa area, groundwater withdrawal should be well managed to avoid groundwater salinization and further seawater intrusion. Full article
(This article belongs to the Special Issue Geochemical Equilibrium and Processes in Seawater)
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12 pages, 2251 KiB  
Article
Is the Kornati National Park Still an Acceptable Reference Area for Environmental Studies?
by Anja Ilenič, Sonja Lojen, Ivan Župan, Tomislav Šarić, Zoran Šikić, Petra Vrhovnik and Matej Dolenec
Geosciences 2018, 8(11), 385; https://doi.org/10.3390/geosciences8110385 - 23 Oct 2018
Cited by 2 | Viewed by 3819
Abstract
The Kornati National Park (Croatia) is considered an environment with minimal anthropogenic input. The purpose of this study was to determine the isotopic characteristics of the sediment and muscle tissues of the banded dye-murex Hexaplex trunculus. We selected locations in the park [...] Read more.
The Kornati National Park (Croatia) is considered an environment with minimal anthropogenic input. The purpose of this study was to determine the isotopic characteristics of the sediment and muscle tissues of the banded dye-murex Hexaplex trunculus. We selected locations in the park according to their estimated risk of anthropogenic pollution (large, lower, and minimal). Isotopic analyses of the sedimentary organic carbon (δ13Corg values) showed that the sedimentary organic matter in locations with P. oceanica meadows (Piškera, Vrulje) was enriched in 13C compared to that of locations with the influx of terrestrial organic matter. The δ13C and δ15N values of the muscle tissues of H. trunuclus were the highest in the two locations with the highest possible anthropogenic impact (−14.47‰ and −15.66‰ for δ13Corg, +8.87‰ and +10.4‰ for δ15N). The high δ values may indicate the presence of the pigment indirubin (C16H10O2N2) and other derivatives that cause the purple coloration but are also elevated because of the discharge of untreated sewage from a nearby marina and village. Full article
(This article belongs to the Special Issue Geochemical Equilibrium and Processes in Seawater)
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18 pages, 2068 KiB  
Article
Distribution of Rare Earth Elements in Sediments of the Marine Lake Mir (Dugi Otok, Croatia)
by Željka Fiket, Marina Mlakar and Goran Kniewald
Geosciences 2018, 8(8), 301; https://doi.org/10.3390/geosciences8080301 - 10 Aug 2018
Cited by 11 | Viewed by 4133
Abstract
The Lake Mir represents a small, isolated, and shallow marine lake situated in the south-eastern part of the Dugi otok Island, in a karstic landscape of the eastern Adriatic coast. The surrounding karstic background, with occasional occurrences of red soil, characterizes the sediments [...] Read more.
The Lake Mir represents a small, isolated, and shallow marine lake situated in the south-eastern part of the Dugi otok Island, in a karstic landscape of the eastern Adriatic coast. The surrounding karstic background, with occasional occurrences of red soil, characterizes the sediments in the lake as coarse grained and carbonate rich. Previous studies suggested the prevailing influence of the lake bathymetry, that is, the proportion of carbonates and grain size characteristics of the sediments, on the variability of the element composition of the lake sediments. To confirm previous assumptions and obtain a better understanding of the factors influencing sediment composition of this marine lake, the distribution of rare earth elements in sediments of the Lake Mir and the nearby Telašćica Bay, as well as surrounding soils, was investigated. In the lake sediments, the sum of rare earth elements, including Y (hereinafter referred as ΣREY), ranged from 10.6 mg kg−1 to 25.3 mg kg−1; in the Telašćica Bay sediments, ΣREY were higher compared to the lake and ranged from 56.4 mg kg−1 to 85.2 mg kg−1, while the highest ΣREY, from 83.3 mg kg−1 to 227 mg kg−1, were observed in soils surrounding the lake. Despite the difference in the levels of the rare earth elements, the REY normalized patterns and associated fractionation parameters (ΣLREE/ΣHREE, (La/Yb)N, and (Nd/Yb)N) showed similarities between the lake sediments and the surrounding soils, confirming a significant influence of local lithology on the lake composition. The results of the statistical analysis, on the other hand, suggest the contribution of both the carbonate (e.g., calcite) and non-carbonate minerals (i.e., alumosilicates and Al–Fe-hydroxides) on the total REY content in the lake sediments. Full article
(This article belongs to the Special Issue Geochemical Equilibrium and Processes in Seawater)
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