Special Issue "Heavy Metals and Potentially Toxic Elements (PTEs) in Water"

A special issue of Water (ISSN 2073-4441).

Deadline for manuscript submissions: closed (30 November 2017)

Special Issue Editor

Guest Editor
Prof. Dr. Andrew Hursthouse

1. School of Science and Sport, University of the West of Scotland, UK
2. High End Expert Scholar, Hunan Provincial Key Laboratory of Shale Gas Resource Utilization, Hunan University of Science and Technology, Xiangtan 411201, China
Website | E-Mail
Phone: +441418483213
Interests: environmental geochemistry; isotopes; risk assessment; soil sediment pollution; aquatic contamination

Special Issue Information

Dear Colleagues,

The term “Heavy Metal” relates to metallic chemical elements of relatively high density and toxicity at low concentrations. The presence of elements, such as mercury, cadmium, arsenic chromium thallium, and lead in water, can lead to direct toxicity or enter the food chain and bioaccumulate. Other trace elements are essential for metabolic function but become toxic at higher concentrations. A broader definition of potentially toxic elements (PTEs) recognises that exposure leads to a range of doses of numerous elements. They can enter the water system through direct waste release from industrial or consumer discharges, deposition from the atmosphere near emission sources, the weathering of rocks and mineral constituents, naturally or enhanced through environmental disturbance such as from mining or acid rain. Their migration within the aqueous environment is controlled by many variables driven by the chemical reactivity of the element and detailed environmental conditions, such as composition of the water, and isolation from surface environments. This Special Issue will provide a forum for publications on topics related advancing our understanding of the release and transport of elements, chemical species and compounds where the aquatic system is the dominant environmental medium. This may relate to both field studies and laboratory experiments, new tools and techniques and examples of studies of leaching and transport, modeling of chemical species reactivity, bioaccumulation and effects on wider ecosystems and human health. The reports should be scientifically rigorous and hypothesis driven, providing demonstrable contributions to new knowledge and fall within the wider scope and aims of the journal.

Prof. Dr. Andrew Hursthouse
Guest Editor

Manuscript Submission Information

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Keywords

  • aqueous geochemistry;

  • metal speciation;

  • pollution discharge and transport;

  • geochemical modelling;

  • waste; mining;

  • bioaccumulation;

  • exposure;

  • deposition;

  • solubility;

  • complexation

Published Papers (11 papers)

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Research

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Open AccessFeature PaperCommunication Gemini Surfactant-Modified Activated Carbon for Remediation of Hexavalent Chromium from Water
Water 2018, 10(1), 91; doi:10.3390/w10010091
Received: 30 November 2017 / Revised: 10 January 2018 / Accepted: 18 January 2018 / Published: 21 January 2018
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Abstract
Gemini surfactants, with double hydrophilic and hydrophobic groups, offer potentially orders of magnitude greater surface activity compared to similar single unit molecules. A cationic Gemini surfactant (Propyl didodecyldimethylammonium Bromide, PDDDAB) and a conventional cationic surfactant (Dodecyltrimethylammonium Bromide, DTAB) were used to pre-treat and
[...] Read more.
Gemini surfactants, with double hydrophilic and hydrophobic groups, offer potentially orders of magnitude greater surface activity compared to similar single unit molecules. A cationic Gemini surfactant (Propyl didodecyldimethylammonium Bromide, PDDDAB) and a conventional cationic surfactant (Dodecyltrimethylammonium Bromide, DTAB) were used to pre-treat and generate activated carbon. The removal efficiency of the surfactant-modified activated carbon through adsorption of chromium(VI) was investigated under controlled laboratory conditions. Fourier-transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) were used to investigate the surface changes of surfactant-modified activated carbon. The effect of important parameters such as adsorbent dosage, pH, ionic strength and contact time were also investigated. The chromium(VI) was adsorbed more significantly on the Gemini surfactant-modified activated carbon than on the conventional surfactant-modified activated carbon. The correlation coefficients show the data best fit the Freundlich model, which confirms the monolayer adsorption of chromium(VI) onto Gemini surfactant-modified activated carbon. From this assessment, the surfactant-modified (especially Gemini surfactant-modified) activated carbon in this study showed promise for practical applications to treat water pollution. Full article
(This article belongs to the Special Issue Heavy Metals and Potentially Toxic Elements (PTEs) in Water)
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Open AccessCommunication Considering a Threshold Energy in Reactive Transport Modeling of Microbially Mediated Redox Reactions in an Arsenic-Affected Aquifer
Water 2018, 10(1), 90; doi:10.3390/w10010090
Received: 14 November 2017 / Revised: 12 January 2018 / Accepted: 19 January 2018 / Published: 20 January 2018
Cited by 1 | PDF Full-text (1001 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The reductive dissolution of Fe-oxide driven by organic matter oxidation is the primary mechanism accepted for As mobilization in several alluvial aquifers. These processes are often mediated by microorganisms that require a minimum Gibbs energy available to conduct the reaction in order to
[...] Read more.
The reductive dissolution of Fe-oxide driven by organic matter oxidation is the primary mechanism accepted for As mobilization in several alluvial aquifers. These processes are often mediated by microorganisms that require a minimum Gibbs energy available to conduct the reaction in order to sustain their life functions. Implementing this threshold energy in reactive transport modeling is rarely used in the existing literature. This work presents a 1D reactive transport modeling of As mobilization by the reductive dissolution of Fe-oxide and subsequent immobilization by co-precipitation in iron sulfides considering a threshold energy for the following terminal electron accepting processes: (a) Fe-oxide reduction, (b) sulfate reduction, and (c) methanogenesis. The model is then extended by implementing a threshold energy on both reaction directions for the redox reaction pairs Fe(III) reduction/Fe(II) oxidation and methanogenesis/methane oxidation. The optimal threshold energy fitted in 4.50, 3.76, and 1.60 kJ/mol e for sulfate reduction, Fe(III) reduction/Fe(II) oxidation, and methanogenesis/methane oxidation, respectively. The use of models implementing bidirectional threshold energy is needed when a redox reaction pair can be transported between domains with different redox potentials. This may often occur in 2D or 3D simulations. Full article
(This article belongs to the Special Issue Heavy Metals and Potentially Toxic Elements (PTEs) in Water)
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Open AccessArticle Integrated Assessment of Shallow-Aquifer Vulnerability to Multiple Contaminants and Drinking-Water Exposure Pathways in Holliston, Massachusetts
Water 2018, 10(1), 23; doi:10.3390/w10010023
Received: 28 November 2017 / Revised: 21 December 2017 / Accepted: 22 December 2017 / Published: 29 December 2017
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Abstract
Half of U.S. drinking water comes from aquifers, and very shallow ones (<20 feet to water table) are especially vulnerable to anthropogenic contamination. We present the case of Holliston, a Boston, Massachusetts suburb that draws its drinking water from very shallow aquifers, and
[...] Read more.
Half of U.S. drinking water comes from aquifers, and very shallow ones (<20 feet to water table) are especially vulnerable to anthropogenic contamination. We present the case of Holliston, a Boston, Massachusetts suburb that draws its drinking water from very shallow aquifers, and where metals and solvents have been reported in groundwater. Community concerns focus on water discolored by naturally occurring manganese (Mn), despite reports stating regulatory aesthetic compliance. Epidemiologic studies suggest Mn is a potentially toxic element (PTE) for children exposed by the drinking-water pathway at levels near the regulatory aesthetic level. We designed an integrated, community-based project: five sites were profiled for contaminant releases; service areas for wells were modeled; and the capture zone for one vulnerable well was estimated. Manganese, mercury, and trichloroethylene are among 20 contaminants of interest. Findings show that past and/or current exposures to multiple contaminants in drinking water are plausible, satisfying the criteria for complete exposure pathways. This case questions the adequacy of aquifer protection and monitoring regulations, and highlights the need for integrated assessment of multiple contaminants, associated exposures and health risks. It posits that community-researcher partnerships are essential for understanding and solving complex problems. Full article
(This article belongs to the Special Issue Heavy Metals and Potentially Toxic Elements (PTEs) in Water)
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Open AccessArticle Unraveling the Long-Term Effects of Cr(VI) on the Performance and Microbial Community of Nitrifying Activated Sludge System
Water 2017, 9(12), 909; doi:10.3390/w9120909
Received: 30 October 2017 / Revised: 20 November 2017 / Accepted: 21 November 2017 / Published: 23 November 2017
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Abstract
The long-term effects of different influent Cr(VI) concentrations (0–0.5 mg L−1) on the nitrification activities and microbial community structures of nitrifying activated sludge system were investigated in this study. Results showed that the performance of ammonia oxidation was significantly inhibited, and
[...] Read more.
The long-term effects of different influent Cr(VI) concentrations (0–0.5 mg L−1) on the nitrification activities and microbial community structures of nitrifying activated sludge system were investigated in this study. Results showed that the performance of ammonia oxidation was significantly inhibited, and the effluent concentration of ammonia nitrogen (NH4+-N) increased markedly when the influent Cr(VI) loading was equal or greater than 0.2 mg L−1. The specific oxygen utilization rate (SOUR), specific ammonium oxidation rate (SAOR), and specific nitrite oxidation rate (SNOR) of the system decreased from 53.24, 6.31, and 7.33 mg N g−1 VSS h−1 to 18.17, 1.68, and 2.88 mg N g−1 VSS h−1, respectively, with an increase of Cr(VI) concentration from 0 to 0.5 mg L−1. The protein/polysaccharide (PN/PS) ratio increased with the increasing Cr(VI) concentration, indicating that excessive PN secreted by microorganisms was conducive to resisting the toxicity of Cr(VI). High-throughput sequencing revealed that the relative abundance of ammonia-oxidizing bacteria (Nitrospira) and nitrite-oxidizing bacteria (Nitrosomonas and Nitrosospira) all decreased with the increasing Cr(VI) concentration, and ammonia-oxidizing bacteria were more sensitive to heavy metal toxicity than nitrite-oxidizing bacteria. The activities of nitrifying activated sludge system could not be completely recovered after a 30-d recovery process. Full article
(This article belongs to the Special Issue Heavy Metals and Potentially Toxic Elements (PTEs) in Water)
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Open AccessArticle Reactive Transport Modeling for Mobilization of Arsenic in a Sediment Downgradient from an Iron Permeable Reactive Barrier
Water 2017, 9(11), 890; doi:10.3390/w9110890
Received: 2 October 2017 / Revised: 3 November 2017 / Accepted: 11 November 2017 / Published: 14 November 2017
Cited by 1 | PDF Full-text (1317 KB) | HTML Full-text | XML Full-text
Abstract
Arsenic (As) can be naturally present in the native aquifer materials and can be released to groundwater through reduction dissolution of iron oxides containing As. While granular iron permeable reactive barriers (PRBs) can be effective for the treatment of arsenic in groundwater, the
[...] Read more.
Arsenic (As) can be naturally present in the native aquifer materials and can be released to groundwater through reduction dissolution of iron oxides containing As. While granular iron permeable reactive barriers (PRBs) can be effective for the treatment of arsenic in groundwater, the mobilization of arsenic in the sediment downgradient of the PRB might be an issue due to the reduced geochemical conditions generated by reactions in the PRB. The release of arsenic in the sediment downgradient from a proposed iron PRB was studied through laboratory column experiments and reactive transport modeling. The laboratory column experiments showed a significant removal of arsenic from the groundwater by granular iron (from the influent concentration of about 0.7 mg L−1 to less than 0.006 mg L−1 at the effluent); however, arsenic can be flushed out from the aquifer sediments (up to 0.09 mg L−1). The reactive transport modeling based on the geochemical reactions as suggested from the experiments, i.e., reductive dissolution of As-bearing goethite, was successful to reproduce the observed geochemical trends in the column experiments. This study can provide implications regarding the installation of iron PRBs to treat arsenic in groundwater and also be useful to understand geochemical behavior of arsenic under reduced conditions. Full article
(This article belongs to the Special Issue Heavy Metals and Potentially Toxic Elements (PTEs) in Water)
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Open AccessCommunication Cadmium and Lead Sorption/Desorption on Non-Amended and By-Product-Amended Soil Samples and Pyritic Material
Water 2017, 9(11), 886; doi:10.3390/w9110886
Received: 28 September 2017 / Revised: 31 October 2017 / Accepted: 8 November 2017 / Published: 13 November 2017
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Abstract
Batch-type experiments were used to study cadmium (Cd) and lead (Pb) sorption/desorption on forest soil, vineyard soil and pyritic material samples, on the by-products mussel shell, oak ash, pine bark and hemp waste, and on forest soil, vineyard soil and pyritic material amended
[...] Read more.
Batch-type experiments were used to study cadmium (Cd) and lead (Pb) sorption/desorption on forest soil, vineyard soil and pyritic material samples, on the by-products mussel shell, oak ash, pine bark and hemp waste, and on forest soil, vineyard soil and pyritic material amended with 48 t ha−1 of oak ash, mussel shell, and hemp waste. The main results were that the forest soil showed higher Cd and Pb retention than the vineyard soil and the pyritic material. Regarding the byproducts, sorption was in the following order: oak ash > mussel shell > hemp waste > pine bark, with desorption following an inverse sequence. The pH was the parameter that most influenced Cd and Pb sorption. Cd and Pb sorption curves showed better fitting to the Freundlich than to the Langmuir model, indicating the dominance of multilayer interactions. Oak ash and mussel shell were the amendments causing higher increase in Cd and Pb sorption on both soils and the pyritic material (close to 100% with the oak ash amendment), as well as more a pronounced decrease in desorption. These results could be used to favor an effective management of the by-products studied, which could retain Cd and Pb in soils and degraded areas, preventing water pollution. Full article
(This article belongs to the Special Issue Heavy Metals and Potentially Toxic Elements (PTEs) in Water)
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Open AccessFeature PaperArticle Survey of Heavy Metal Contamination in Water Sources in the Municipality of Torola, El Salvador, through In Situ Sorbent Extraction
Water 2017, 9(11), 877; doi:10.3390/w9110877
Received: 29 September 2017 / Revised: 3 November 2017 / Accepted: 8 November 2017 / Published: 10 November 2017
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Abstract
The presence of heavy metals in water resources directly affects consumer health. The quality of surface water resources in Central America is usually low due to the presence of metals and other pollutants. The lack of analytical instrumentation to perform routine monitoring of
[...] Read more.
The presence of heavy metals in water resources directly affects consumer health. The quality of surface water resources in Central America is usually low due to the presence of metals and other pollutants. The lack of analytical instrumentation to perform routine monitoring of water has encouraged the development of easy tools to facilitate the determination of heavy metals in waters in remote sites. In this study, we evaluated the use of different sorbents, such as Adsorbsia As600 (titanium dioxide), Iontosorb Oxin, 8-hydroxyquinoline bearing functional groups, and Duolite GT-73, with thiol functionality, for Cd, Ni, Cu, Zn, and Al extraction. It was found that both Adsorbsia As600 and Iontosorb Oxin allowed the adsorption of all metals, and the recovery was achieved using either HCl or ethylenediaminetetraacetic sodium salt (EDTA) solutions. Hence, Adsorbsia As600 was employed for in situ sampling in the metal contamination evaluation of water samples (from 15 wells and nine storage tanks) from the municipality of Torola, Mozarán, El Salvador. The developed procedure allowed all the metals in the samples to be detected, and Ni and Al were found to be above Salvadoran guidelines for drinking water quality. Full article
(This article belongs to the Special Issue Heavy Metals and Potentially Toxic Elements (PTEs) in Water)
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Open AccessFeature PaperCommunication Wheat Straw as a Bio-Sorbent for Arsenate, Chromate, Fluoride, and Nickel
Water 2017, 9(9), 690; doi:10.3390/w9090690
Received: 2 July 2017 / Revised: 5 September 2017 / Accepted: 7 September 2017 / Published: 9 September 2017
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Abstract
Batch-type experiments were used to study As(V), Cr(VI), F, and Ni2+ sorption/desorption on wheat straw. For the lowest concentration added (0.5 mmol·L−1), the sorption sequence was F > Ni2+ > Cr(VI) >> As(V) (93%, 61%, 29%,
[...] Read more.
Batch-type experiments were used to study As(V), Cr(VI), F, and Ni2+ sorption/desorption on wheat straw. For the lowest concentration added (0.5 mmol·L−1), the sorption sequence was F > Ni2+ > Cr(VI) >> As(V) (93%, 61%, 29%, 0.3%), but changed to Ni2+ > F > Cr(VI) >> As(V) when 3.0 and 6.0 mmol·L−1 were added (with 65%, 54%, 25%, 0%, and 68%, 52%, 27%, 0% sorption, respectively). Overall, As(V) showed the lowest sorption, whereas it was 25–37% for Cr(VI), 61–68% for Ni2+, and 52–93% for F. For As(V), pH in the equilibrium solution was always above the pH of the point of zero charge (pHPZC) for wheat straw, decreasing sorption efficiency. For Cr(VI), pH was below pHPZC, but not enough to reach high sorption. For F, pH in the equilibrium was above pHPZC, which could reduce sorption. For Ni2+, pH in the equilibrium was always below pHPZC, which made sorption difficult. The satisfactory fitting of Cr(VI), F, and Ni2+ data to the Freundlich model suggests multilayer-type adsorption. Desorption was high for F, whereas Ni2+ showed the lowest desorption. This research could be especially relevant when focusing on the use of wheat straw as a bio-sorbent, and in cases where straw mulching is used. Full article
(This article belongs to the Special Issue Heavy Metals and Potentially Toxic Elements (PTEs) in Water)
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Open AccessArticle Aspects of Hexavalent Chromium Pollution of Thebes Plain Aquifer, Boeotia, Greece
Water 2017, 9(8), 611; doi:10.3390/w9080611
Received: 12 June 2017 / Revised: 4 August 2017 / Accepted: 8 August 2017 / Published: 16 August 2017
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Abstract
The present work focuses on the environmental problem of Thebes Plain—since considerable amounts of Cr (VI) have been reported—and tries to find out the reasons of such a phenomenon and the sources of the pollution. For this issue, a complete chemical analysis of
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The present work focuses on the environmental problem of Thebes Plain—since considerable amounts of Cr (VI) have been reported—and tries to find out the reasons of such a phenomenon and the sources of the pollution. For this issue, a complete chemical analysis of 20 samples from the study area was conducted as well as an isotopic analysis of Cr and Sr isotopes. Hexavalent chromium pollution can be triggered by human pollutant activity or specific geological environments. Stable Cr isotopic analysis gave δ53Cr positive values in several samples which supports the second hypothesis, but the limitations of that theory do not allow safe conclusions in all cases. Nitrates and Sr ratios suggest fertilizer contamination and the presence of SiO2-leaching of silicate rocks. Full article
(This article belongs to the Special Issue Heavy Metals and Potentially Toxic Elements (PTEs) in Water)
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Review

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Open AccessFeature PaperReview The Potential for the Treatment of Antimony-Containing Wastewater by Iron-Based Adsorbents
Water 2017, 9(10), 794; doi:10.3390/w9100794
Received: 1 September 2017 / Revised: 11 October 2017 / Accepted: 12 October 2017 / Published: 16 October 2017
Cited by 1 | PDF Full-text (274 KB) | HTML Full-text | XML Full-text
Abstract
Antimony (Sb) and its compounds are considered as global priority pollutants. Elevated concentrations of antimony in natural and industrial process wastewater are of global concern, particularly given interest in the potential toxicity and harm to the environment from aquatic exposure. Iron-based materials for
[...] Read more.
Antimony (Sb) and its compounds are considered as global priority pollutants. Elevated concentrations of antimony in natural and industrial process wastewater are of global concern, particularly given interest in the potential toxicity and harm to the environment from aquatic exposure. Iron-based materials for treatment by adsorption are widely regarded to have potential merit for the removal of trace contaminants from water and especially in the search for efficient and low-cost techniques. In this paper, we review the application of iron-based materials in the sorption treatment of antimony contaminated water. The interaction of Sb is discussed in relation to adsorption performance, influencing factors, mechanism, modelling of adsorption (isotherm, kinetic and thermodynamic models), advantages, drawbacks and the recent achievements in the field. Although iron-based adsorbents show promise, the following three aspects are in need of further study. Firstly, a select number of iron based binary metal oxide adsorbents should be further explored as they show superior performance compared to other systems. Secondly, the possibility of redox reactions and conversion between Sb(III) and Sb(V) during the adsorption process is unclear and requires further investigation. Thirdly, in order to achieve optimized control of preferential adsorption sites and functional groups, the mechanism of antimony removal has to be qualitatively and quantitatively resolved by combining the advantages of advanced characterization techniques such as Fourier transform infrared spectroscopy(FTIR), X-ray photoelectron spectroscopy (XPS), Atomic force microscope(AFM), X-ray absorption near edge structure(XANES), and other spectroscopic methods. We provide details on the achievements and limitations of each of these stages and point to the need for further research. Full article
(This article belongs to the Special Issue Heavy Metals and Potentially Toxic Elements (PTEs) in Water)

Other

Jump to: Research, Review

Open AccessShort Note Arsenic Transformation in Swine Wastewater with Low-Arsenic Content during Anaerobic Digestion
Water 2017, 9(11), 826; doi:10.3390/w9110826
Received: 17 September 2017 / Revised: 17 October 2017 / Accepted: 23 October 2017 / Published: 27 October 2017
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Abstract
In this study, the raw wastewater (RW), and effluents from the acidogenic phase (AP) and methanogenic phase (MP) in a swine wastewater treatment plant were collected to investigate the occurrence and transformation of arsenic (As), as well as the abundance of As metabolism
[...] Read more.
In this study, the raw wastewater (RW), and effluents from the acidogenic phase (AP) and methanogenic phase (MP) in a swine wastewater treatment plant were collected to investigate the occurrence and transformation of arsenic (As), as well as the abundance of As metabolism genes during the anaerobic digestion (AD) process. The results showed that total concentrations of As generally decreased by 33–71% after AD. Further analysis showed that the As species of the dissolved fractions were present mainly as dimethylarsinic acid (DMA), with arsenite (As(III)) and arsenate (As(V)) as the minor species. Moreover, real-time PCR (qPCR) results showed that As metabolism genes (arsC, arsenate reduction gene; aioA, arsenite oxidation gene and arsM, arsenite methylation gene) were highly abundant, with arsM being predominant among the metabolism genes. This study provides reliable evidence on As biotransformation in swine wastewater treatment process, suggesting that AD could be a valuable treatment to mitigate the risk of As in wastewater. Full article
(This article belongs to the Special Issue Heavy Metals and Potentially Toxic Elements (PTEs) in Water)
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