Water

Research

13 pages, 2244 KiB

Open AccessArticle

Relationship of the “Dequada” Phenomenon with Mercury Methylation in Pantanal, Brazil

by Glaucia A. Nunes, Dayana D. Ramos, Juliane C. Forti, Diovany D. Ramos, Lincoln C. S. Oliveira, David S. S. Junior, Gabriel E. Santo and Felipe A. Santos

Water 2024, 16(9), 1204; https://doi.org/10.3390/w16091204 - 24 Apr 2024

Viewed by 508

Abstract

The illegal activity of gold mining in the Brazilian Pantanal is contaminating the aquatic ecosystem with mercury. This contamination has been potentiated by mercury methylation due to a typical natural phenomenon of the Pantanal ecosystem known as “dequada”. The present study estimated in [...] Read more.

The illegal activity of gold mining in the Brazilian Pantanal is contaminating the aquatic ecosystem with mercury. This contamination has been potentiated by mercury methylation due to a typical natural phenomenon of the Pantanal ecosystem known as “dequada”. The present study estimated in the laboratory the temporal production of methylmercury at two timepoints: the beginning of a flood, when the “dequada” phenomenon occurs, and the dry season without such phenomenon. After collecting water and sediment, experiments were performed with microcosms to reproduce conditions close to nature. To monitor the concentration of methylmercury, 1.0 mg L⁻¹ of Hg²⁺ was added to water and sediment experiments in the Castelo and Saracura bays, both during the “dequada” and without it; monitoring lasted for 25 days. The methylmercury concentration was analyzed using atomic fluorescence spectrometry, total organic carbon using TOC 5000A, and physical and chemical parameters such as pH, redox potential, and dissolved oxygen with a multi-parameter probe. The results led to the conclusion that the “dequada” phenomenon significantly affected mercury methylation, because the environmental changes caused by this phenomenon such as the increased concentration of organic matter, decreased dissolved oxygen, and decreased pH, potentiated mercury methylation. During the “dequada” in the Castelo bay, the methylation rate was 3.5 times higher (6297.56 ng L⁻¹) than in the experiment without the “dequada” (1827.44 ng L⁻¹). Therefore, the gold mining activity in Pantanal can cause great damage to the ecosystem because this environment favors mercury methylation, making its most toxic form active in the aquatic ecosystem of Pantanal. Full article

(This article belongs to the Special Issue Source, Occurrence, Pathway, and Fate of Heavy Metals in the Water Environment)

► Show Figures

Graphical abstract

17 pages, 2060 KiB

Open AccessArticle

Uranium and Nickel Partitioning in a Contaminated Riparian Wetland

by Peng Lin, Maxim I. Boyanov, Edward J. O’Loughlin, Wei Xing, Kenneth M. Kemner, John Seaman, Steven P. Simner and Daniel I. Kaplan

Water 2024, 16(7), 966; https://doi.org/10.3390/w16070966 - 27 Mar 2024

Viewed by 617

Abstract

Uranium (U) and nickel (Ni) released 50 years ago have been immobilized in the Tims Branch wetlands located on the Savannah River Site in the United States. Sediments were collected from seven locations to identify the factors responsible for this attenuation. Ni and [...] Read more.

Uranium (U) and nickel (Ni) released 50 years ago have been immobilized in the Tims Branch wetlands located on the Savannah River Site in the United States. Sediments were collected from seven locations to identify the factors responsible for this attenuation. Ni and U contents in the solids were significantly correlated, suggesting that depositional as opposed to chemical processes contributed to their spatial distribution. Based on sequential extractions, 63 ± 16% of the U was partitioned into the organic fraction, whereas Ni was distributed between several sediment fractions. An inverse pH-organic matter (OM) correlation and positive correlations of OM with total U and organic-bound U/Ni suggest that increased OM preservation and binding to the mineral surfaces were likely responsible for Ni- and especially U-sediment retention (Tims Branch pH = 4.84 ± 0.68). EXAFS analysis indicated the predominance of U(VI) coordinated with clay minerals (~65%), together with ~35% coordinated to either OM (in areas with elevated OM levels) or iron oxides. The desorption-K_d coefficients of U (3972 ± 1370 L/kg) and Ni (30 ± 8 L/kg) indicate that dissolved Ni poses a greater long-term risk than dissolved U for migrating downstream. This study suggests that a delicate balance of geochemical properties controls whether wetlands behave as sinks or sources of contaminants. Full article

(This article belongs to the Special Issue Source, Occurrence, Pathway, and Fate of Heavy Metals in the Water Environment)

► Show Figures

Graphical abstract

17 pages, 5357 KiB

Open AccessArticle

Using the Heavy Metal Indices and Benthic Indices to Assess the Ecological Quality in the Tidal Flats of Garolim Bay, South Korea

by Jian Liang, Hai-Rui Huang, Chae-Woo Ma, Dae-Sun Son and Seon-Kyu Kim

Water 2024, 16(5), 736; https://doi.org/10.3390/w16050736 - 29 Feb 2024

Cited by 1 | Viewed by 747

Abstract

During economic growth, anthropogenic activities have exerted detrimental impacts on the tidal flat ecosystems in South Korea. Although scholars have conducted extensive research on the ecological quality of tidal flats in South Korea, most have primarily focused on benthic indices. Hence, we utilised [...] Read more.

During economic growth, anthropogenic activities have exerted detrimental impacts on the tidal flat ecosystems in South Korea. Although scholars have conducted extensive research on the ecological quality of tidal flats in South Korea, most have primarily focused on benthic indices. Hence, we utilised two heavy metal indices and five benthic indices to assess the ecological quality in the tidal flats comprehensively. In our study, although heavy metals and total organic carbon concentrations were low in Garolim Bay, the final ecological quality at most stations was unacceptable (63%). The Benthic Opportunistic Polychaetes Amphipods Index (BOPA) demonstrated commendable outcomes in correlation and kappa analyses. However, the BOPA still had some limits. We believe that using multiple indices to assess the ecological quality in the tidal flats of Garolim Bay is more robust than using a single index. Full article

(This article belongs to the Special Issue Source, Occurrence, Pathway, and Fate of Heavy Metals in the Water Environment)

► Show Figures

Figure 1

13 pages, 1889 KiB

Open AccessArticle

Response and Resilience of Scenedesmus rubescens Microalgae to ZnO Nanoparticles

by Nikolaos Tzanakis, Andriana F. Aravantinou and Ioannis D. Manariotis

Water 2024, 16(5), 666; https://doi.org/10.3390/w16050666 - 24 Feb 2024

Viewed by 707

Abstract

Microalgae are microorganisms of great importance for aquatic ecosystems. The investigation of their interaction with potential environmental stressors like nanoparticles (NPs) is essential in order to assess their behavior and fate in aquatic ecosystems. The scope of this work is to investigate the [...] Read more.

Microalgae are microorganisms of great importance for aquatic ecosystems. The investigation of their interaction with potential environmental stressors like nanoparticles (NPs) is essential in order to assess their behavior and fate in aquatic ecosystems. The scope of this work is to investigate the response and potential toxic effects of the short-term exposure of Scenedesmus rubescens microalga to zinc oxide (ZnO) NPs with various initial nitrate concentrations in the culture medium. Scenedesmus rubescens was cultivated in four different compositions of modified BG-11 with a nitrate content varying from 0 to 300 mg/L, and it was exposed to four concentrations of ZnO NPs, ranging from 0.081 to 81 mg/L. S. rubescens was found to be resilient towards ZnO NP toxicity. The results also highlight the fact that the toxic effects of ZnO NPs on microalgae are highly dependent on the species tested. The nitrate content of the medium did not affect the toxicity of ZnO NPs but had a significant impact on cell concentration, as it was observed at an initial nitrate concentration of 300 mg/L. Further investigation should focus on studying the morphological and metabolic characteristics and mechanisms contributing to this species’ resilience. Full article

(This article belongs to the Special Issue Source, Occurrence, Pathway, and Fate of Heavy Metals in the Water Environment)

► Show Figures

Figure 1

16 pages, 2457 KiB

Open AccessArticle

Heavy Metal Contamination in Surface Water of Harike Wetland, India: Source and Health Risk Assessment

by Nafiaah Naqash, Mamdoh T. Jamal and Rahul Singh

Water 2023, 15(18), 3287; https://doi.org/10.3390/w15183287 - 18 Sep 2023

Cited by 3 | Viewed by 1559

Abstract

Amidst industrialization and urbanization, wetlands face pollution challenges. We investigated the seasonal distribution of five heavy metals (As, Cd, Cr, Pb, and Zn) in the surface water of Harike wetland. The surface water samples were collected from four different stations selected along Harike [...] Read more.

Amidst industrialization and urbanization, wetlands face pollution challenges. We investigated the seasonal distribution of five heavy metals (As, Cd, Cr, Pb, and Zn) in the surface water of Harike wetland. The surface water samples were collected from four different stations selected along Harike wetland. Our results indicate As, Cr, and Zn levels were within WHO standards, however, Cd in winter (7.07 µg/L), monsoon (4.45 µg/L), and post-monsoon seasons (3.13 µg/L) exceeded the limits. Pb surpassed the standards in winter (278 µg/L) and monsoon seasons (14.5 µg/L). In winter, Pb and Cd had higher levels, and the pollution level was classified as moderate. Cd, however, was categorized under light pollution status during the monsoon and post-monsoon seasons. The health risk assessment indicated that the hazard quotient (HQ) and hazard index (HI) values for both ingestion and dermal pathways were within the safety limits (HQ < 1 and HI < 1) for both population groups (adults and children). The multivariate statistical analysis reported the correlation and further indicated different sources of heavy metals from nearby industries, agriculture, and mining. This research highlights the importance of continued monitoring and emphasizes the potential for positive environmental changes, as exemplified by the influence of the COVID-19 pandemic. These findings hold global relevance and offer valuable input for the development of precise action plans aimed at elevating water quality standards on an international scale. Full article

(This article belongs to the Special Issue Source, Occurrence, Pathway, and Fate of Heavy Metals in the Water Environment)

► Show Figures

Figure 1

13 pages, 2572 KiB

Open AccessArticle

A Preliminary Sorption Study of Uranium on MnO₂ (Pyrolusite) in the Presence of Siderophore Desferrioxamine B—The Mechanism of a Ternary System

by Morgan Snyder, Lucy Hunley, Jordan Stanberry, Ilana Szlamkowicz, Brandon Jones and Vasileios Anagnostopoulos

Water 2023, 15(18), 3241; https://doi.org/10.3390/w15183241 - 12 Sep 2023

Viewed by 930

Abstract

Manganese oxides have influential sorptive properties to efficiently sequester metals, such as uranium. Sorption can become complicated by metal chelating siderophores, which create a ternary system that is capable of multiple feasible mechanisms. This study analyzes the sorption behavior of desferrioxamine B (DFOB) [...] Read more.

Manganese oxides have influential sorptive properties to efficiently sequester metals, such as uranium. Sorption can become complicated by metal chelating siderophores, which create a ternary system that is capable of multiple feasible mechanisms. This study analyzes the sorption behavior of desferrioxamine B (DFOB) and desferrioxamine D (DFOD) onto pyrolusite, β-MnO₂, in the presence of U(VI) at pHs 6 and 8. The electrostatic adsorption performance is shown to have a 23% difference between the DFOB and DFOD surface sorption at pH 6. Inner-sphere coordination was identified through hydrolysis products of succinate and acetate. Together, these behaviors indicate a ternary complex system where both metals and ligands interact with the surface. Therefore, uranium in the environment can be attenuated by the conditions of a complex configuration involving multiple species and functional groups. This mechanism needs to be considered for any future modeling or strategies involving radionuclide remediation. Full article

(This article belongs to the Special Issue Source, Occurrence, Pathway, and Fate of Heavy Metals in the Water Environment)

► Show Figures

Figure 1

11 pages, 1397 KiB

Open AccessArticle

Biodiesel Production Directly from Rapeseeds

by Amanda Tanner, Morgan Baranek, Taylor Eastlack, Brian Butts, Melanie Beazley and Michael Hampton

Water 2023, 15(14), 2595; https://doi.org/10.3390/w15142595 - 17 Jul 2023

Cited by 1 | Viewed by 1453

Abstract

Rapeseeds are desirable as feedstock for manufacturing biodiesel due to their high production capacity and oil yield. The standard production of biodiesel from rapeseeds is a lengthy process including multiple time-consuming steps, and the method is not environmentally friendly because of the large [...] Read more.

Rapeseeds are desirable as feedstock for manufacturing biodiesel due to their high production capacity and oil yield. The standard production of biodiesel from rapeseeds is a lengthy process including multiple time-consuming steps, and the method is not environmentally friendly because of the large energy requirements, the use of high volumes of organic solvents and water, and the need for a catalyst, which must be captured, purified, and recycled. In this study, we report a method to produce biodiesel in a single mechanical step directly from intact rapeseeds without adding a catalyst. The process is more environmentally friendly as there is less need for water than in current industrial processes, and it reduces pollutants from organic solvents, catalysts, and wastewater. Additionally, the remaining biomass shows adsorption characteristics for metals, potentially making it useful in water remediation. Full article

(This article belongs to the Special Issue Source, Occurrence, Pathway, and Fate of Heavy Metals in the Water Environment)

► Show Figures

Figure 1

18 pages, 3906 KiB

Open AccessArticle

Enrichment of Manganese at Low Background Level Groundwater Systems: A Study of Groundwater from Quaternary Porous Aquifers in Changping Region, Beijing, China

by Wencai Liu, Dajun Qin, Yong Yang and Gaoxun Guo

Water 2023, 15(8), 1537; https://doi.org/10.3390/w15081537 - 14 Apr 2023

Cited by 2 | Viewed by 1657

Abstract

Manganese (Mn) could adversely affect water quality and is a concern for drinking water safety. In contrast to Mn-contaminated groundwater systems, Mn concentrations can increase up to 2 orders of magnitude in low background level groundwater systems (Mn < 100 µg/L). It is [...] Read more.

Manganese (Mn) could adversely affect water quality and is a concern for drinking water safety. In contrast to Mn-contaminated groundwater systems, Mn concentrations can increase up to 2 orders of magnitude in low background level groundwater systems (Mn < 100 µg/L). It is interesting to explore related hydrogeological and hydrochemical processes and controlling mechanisms. Our data showed that Mn of groundwater from Quaternary porous aquifers in the Changping region of Beijing in China varied from 0.02 to 522 µg/L, with an average of 45 µg/L. The high Mn concentration (>100 µg/L) in groundwater occurred in the lower plain, while the low Mn concentration was distributed in the upper plain. Association was not obvious between the Mn concentration and the depth of the groundwater. The water–rock interaction (e.g., dissolution of Mn-bearing minerals) and redox reactions dominated the distribution of Mn in groundwater. Particularly, the reduction of Mn⁴⁺ was a major cause of increasing Mn²⁺ concentration in groundwater. This is further evidenced by declining dissolved oxygen (DO) and NO₃ in groundwater from the upper plain to the lower plain part. This study contributes to further understandings of hydrochemical processes for the enrichment of Mn in groundwater and offers a reference for the management and oversight of groundwater containing an excessive Mn level. Full article

(This article belongs to the Special Issue Source, Occurrence, Pathway, and Fate of Heavy Metals in the Water Environment)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Source, Occurrence, Pathway, and Fate of Heavy Metals in the Water Environment

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Published Papers (8 papers)

Research

Further Information

Guidelines

MDPI Initiatives

Follow MDPI