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Environmental Geochemistry of Toxic Elements in the Environment

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A special issue of International Journal of Environmental Research and Public Health (ISSN 1660-4601). This special issue belongs to the section "Environmental Earth Science and Medical Geology".

Deadline for manuscript submissions: closed (31 December 2023) | Viewed by 12728

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Special Issue Editors

Prof. Dr. Tangfu Xiao

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Guest Editor

School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China
Interests: environmental geochemistry of trace elements in the environment: source, mobility and health effects; boremediation of metal pollution

Dr. Mario Alberto Gomez

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Guest Editor

School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China
Interests: environmental geochemistry; mineralogy; nano-materials; mining and hydrometallurgical processes

Dr. Yizhang Liu

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Guest Editor

State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
Interests: soil environmental geochemistry of toxic elements; application of non-traditional stable isotopes in environmental sciences; migration and enrichment of toxic metals during weathering processes; soil remediation

Special Issue Information

Dear Colleagues,

Toxic elements are ubiquitous environmental pollutants with certain or possible carcinogenic and mutagenic effects. Toxic elements can originate from both anthropogenic and natural processes. Mining activities of ferrous and non-ferrous resources (i.e., As, Cd, Hg, Tl, and Sb) contribute greatly to anthropogenic processes of the toxic elements that occur in the environment. In addition, the geochemical weathering of rocks also drives toxic elements into soils and waters of high geological background areas. Toxic elements from anthropogenic and natural sources could migrate and transform across the hydrosphere, lithosphere, and biosphere. Multiple processes, including physical, chemical, and biological activities, drive geochemical cycles and environmental effects of toxic elements. At present, there are large uncertainties in the source, fate, and environmental effects of toxic elements across environmental compartments. Therefore, this Special Issue aims to solicit research from different disciplines and regions to improve our understanding of the geochemical cycling and environmental effects of toxic elements to support ecological restoration in diverse environments. Some topic examples that could be addressed in this Special Issue are the following:

Geochemical processes and fate of toxic elements in mining environment;
Natural enrichment of toxic elements in geologically high background areas and environmental impacts;
Geomicrobially driven biogeochemical cycles of toxic elements in the environment;
Bioremediation of toxic element pollution in soil and waters.

Prof. Dr. Tangfu Xiao
Dr. Mario Alberto Gomez
Dr. Yizhang Liu
Guest Editors

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Keywords

toxic elements
mining
source
anthropogenic processes
high geochemical background
geochemical cycles
geomicrobial drive
transport
environmental effects
bioremediation

Published Papers (7 papers)

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Research

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21 pages, 6308 KiB

Open AccessArticle

Investigation of the Solubility of Elemental Sulfur (S) in Sulfur-Containing Natural Gas with Machine Learning Methods

by Yuchen Wang, Zhengshan Luo, Jihao Luo, Yiqiong Gao, Yulei Kong and Qingqing Wang

Int. J. Environ. Res. Public Health 2023, 20(6), 5059; https://doi.org/10.3390/ijerph20065059 - 13 Mar 2023

Viewed by 1345

Abstract

Some natural gases are toxic because they contain hydrogen sulfide (H₂S). The solubility pattern of elemental sulfur (S) in toxic natural gas needs to be studied for environmental protection and life safety. Some methods (e.g., experiments) may pose safety risks. Measuring sulfur solubility using a machine learning (ML) method is fast and accurate. Considering the limited experimental data on sulfur solubility, this study used consensus nested cross-validation (cnCV) to obtain more information. The global search capability and learning efficiency of random forest (RF) and weighted least squares support vector machine (WLSSVM) models were enhanced via a whale optimization–genetic algorithm (WOA-GA). Hence, the WOA-GA-RF and WOA-GA-WLSSVM models were developed to accurately predict the solubility of sulfur and reveal its variation pattern. WOA-GA-RF outperformed six other similar models (e.g., RF model) and six other published studies (e.g., the model designed by Roberts et al.). Using the generic positional oligomer importance matrix (gPOIM), this study visualized the contribution of variables affecting sulfur solubility. The results show that temperature, pressure, and H₂S content all have positive effects on sulfur solubility. Sulfur solubility significantly increases when the H₂S content exceeds 10%, and other conditions (temperature, pressure) remain the same. Full article

(This article belongs to the Special Issue Environmental Geochemistry of Toxic Elements in the Environment)

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23 pages, 1570 KiB

Open AccessArticle

Toxic Metals, Non-Metals and Metalloids in Bottom Sediments as a Geoecological Indicator of a Water Body’s Suitability for Recreational Use

by Martyna A. Rzetala, Robert Machowski, Maksymilian Solarski, Daniel Bakota, Arkadiusz Płomiński and Mariusz Rzetala

Int. J. Environ. Res. Public Health 2023, 20(5), 4334; https://doi.org/10.3390/ijerph20054334 - 28 Feb 2023

Cited by 1 | Viewed by 1675

Abstract

The study of bottom sediments was conducted within the basins of water bodies used for recreational purposes (e.g., bathing, fishing and diving) in the Silesian Upland and its periphery in southern Poland. Various concentrations of trace elements were found in bottom sediments, reflected by the following levels: Pb (30–3020 mg/kg), Zn (142–35,300 mg/kg), Cd (0.7–286 mg/kg), Ni (10–115 mg/kg), Cu (11–298 mg/kg), Co (3–40 mg/kg), Cr (22–203 mg/kg), As (8–178 mg/kg), Ba (263–19,300 mg/kg), Sb (0.9–52.5 mg/kg), Br (1–31 mg/kg), Sr (63–510 mg/kg) and S (0.001–4.590%). These trace elements are present in amounts that usually exceed those found in other bodies of water or are sometimes even unprecedented among bodies of water in the world (e.g., cadmium—286 mg/kg, zinc—35,300 mg/kg, lead—3020 mg/kg, arsenic—178 mg/kg). It was found that bottom sediments were contaminated to varying degrees with toxic metals, metalloids and non-metals, as evidenced by the values of geoecological indicators, i.e., the geoaccumulation index (−6.31 < I_geo < 10.90), the sediment contamination factor (0.0 ≤

C_{f}^{i}

< 286.0), the sediment contamination degree (4.6 < C_d < 513.1) and the ratios of the concentrations found to the regional geochemical background (0.5 < I_RE < 196.9). It was concluded that the presence of toxic elements (e.g., lead, zinc, cadmium, chromium, strontium and arsenic) in bottom sediments should be taken into account when classifying water bodies as suitable for recreational use. A maximum ratio of the concentrations found to the regional geochemical background of I_RE ≤ 5.0 was proposed as the threshold for the permissibility of recreational use of water bodies. The water bodies used for recreational purposes in the Silesian Upland and its periphery do not meet the geoecological conditions for safe use in terms of recreation and leisure activities. Forms of their recreational use that directly affect the participants’ health (e.g., fishing and the consumption of fish and other aquatic organisms) should be abandoned. Full article

(This article belongs to the Special Issue Environmental Geochemistry of Toxic Elements in the Environment)

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15 pages, 3223 KiB

Open AccessArticle

Arsenic and Heavy Metals in Sediments Affected by Typical Gold Mining Areas in Southwest China: Accumulation, Sources and Ecological Risks

by Sirui Chen, Pan Wu, Xuefang Zha, Binghuang Zhou, Jingbin Liu and En Long

Int. J. Environ. Res. Public Health 2023, 20(2), 1432; https://doi.org/10.3390/ijerph20021432 - 12 Jan 2023

Cited by 4 | Viewed by 1928

Abstract

Gold mining is associated with serious heavy metal pollution problems. However, the studies on such pollution caused by gold mining in specific geological environments and extraction processes remain insufficient. This study investigated the accumulation, fractions, sources and influencing factors of arsenic and heavy metals in the sediments from a gold mine area in Southwest China and also assessed their pollution and ecological risks. During gold mining, As, Sb, Zn, and Cd in the sediments were affected, and their accumulation and chemical activity were relatively high. Gold mining is the main source of As, Sb, Zn and Cd accumulation in sediments (over 40.6%). Some influential factors cannot be ignored, i.e., water transport, local lithology, proportion of mild acido-soluble fraction (F₁) and pH value. In addition, arsenic and most tested heavy metals have different pollution and ecological risks, especially As and Sb. Compared with the other gold mining areas, the arsenic and the heavy metal sediments in the area of this study have higher pollution and ecological risks. The results of this study show that the local government must monitor potential environmental hazards from As and Sb pollution to prevent their adverse effects on human beings. This study also provides suggestions on water protection in the same type of gold-mining areas. Full article

(This article belongs to the Special Issue Environmental Geochemistry of Toxic Elements in the Environment)

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14 pages, 1557 KiB

Open AccessArticle

Calcium Enhances Thallium Uptake in Green Cabbage (Brassica oleracea var. capitata L.)

by Yanlong Jia, Tangfu Xiao, Jialong Sun, Zengping Ning, Enzong Xiao, Xiaolong Lan and Yuxiao Chen

Int. J. Environ. Res. Public Health 2023, 20(1), 4; https://doi.org/10.3390/ijerph20010004 - 20 Dec 2022

Cited by 2 | Viewed by 1331

Abstract

Thallium (Tl) is a nonessential and toxic trace metal that is detrimental to plants, but it can be highly up-taken in green cabbage (Brassica oleracea L. var. capitata L.). It has been proven that there is a significant positive correlation between Tl and Calcium (Ca) contents in plants. However, whether Ca presents a similar role for alleviating Tl toxicity in plants remains unclear, and little is known in terms of evidence for both Ca-enhanced uptake of Tl from soils to green cabbage and associated geochemical processes. In this study, we investigated the influence of Ca in soils on Tl uptake in green cabbage and the associated geochemical process. The pot experiments were conducted in 12 mg/kg Tl(I) and 8 mg/kg Tl(III) treatments with various Ca dosages. The results showed that Ca in soils could significantly enhance Tl uptake in green cabbage, increasing 210% in content over the control group. The soluble concentrations of Tl were largely increased by 210% and 150%, respectively, in 3.0 g/kg Ca treatment, compared with the corresponding treatment without Ca addition. This was attributed to the geochemical process in which the enhanced soluble Ca probably replaces Tl held on the soil particles, releasing more soluble Tl into the soil solution. More interestingly, the bioconcentration factor of the leaves and whole plant for the 2.0, 2.5, 3.0 g/kg Ca dosage group were greatly higher than for the non-Ca treatment, which could reach 207%, implying the addition of Ca can improve the ability of green cabbage to transfer Tl from the stems to the leaves. Furthermore, the pH values dropped with the increasing Ca concentration treatment, and the lower pH in soils also increased Tl mobilization, which resulted in Tl accumulation in green cabbage. Therefore, this work not only informs the improvement of agricultural safety management practices for the farming of crops in Tl-polluted and high-Ca-content areas, but also provides technical support for the exploitation of Ca-assisted phytoextraction technology. Full article

(This article belongs to the Special Issue Environmental Geochemistry of Toxic Elements in the Environment)

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15 pages, 3345 KiB

Open AccessArticle

Geochemical Contamination, Speciation, and Bioaccessibility of Trace Metals in Road Dust of a Megacity (Guangzhou) in Southern China: Implications for Human Health

by Fei Tang, Zhi Li, Yanping Zhao, Jia Sun, Jianteng Sun, Zhenghui Liu, Tangfu Xiao and Jinli Cui

Int. J. Environ. Res. Public Health 2022, 19(23), 15942; https://doi.org/10.3390/ijerph192315942 - 29 Nov 2022

Cited by 4 | Viewed by 1559

Abstract

Road dust has been severely contaminated by trace metals and has become a major health risk to urban residents. However, there is a lack of information on bioaccessible trace metals in road dust, which is necessary for an accurate health risk assessment. In this study, we collected road dust samples from industrial areas, traffic intersections, and agricultural fields from a megacity (Guangzhou), China, and conducted a geochemical enrichment, speciation, and bioaccessibility-based health risk assessment of trace metals. In comparison with local soil background values, the results revealed a significant accumulation of trace metals, including Zn, Cd, Cu, and Pb in the road dust, which is considered moderate to heavy pollution. Sequential extraction indicated that most trace metals in the road dust were primarily composed of a Fe/Mn oxide-bound fraction, carbonate-bound fraction, and residual fraction, while the dominant fraction was the organic matter-bound fraction of Cu, and the residual fractions of As, Cr, and Ni. The in vitro gastrointestinal (IVG) method revealed that high percentages of Zn, Cd, Cu, and As were bioaccessible, suggesting the possible dissolution of trace metals from adsorbed and carbonate-associated fractions in road dust exposed to the biological fluid matrix. The IVG bioaccessibility-based concentration largely decreased the noncarcinogenic health risk to a negligible level. Nevertheless, the entire population is still exposed to the cumulative probability of a carcinogenic risk, which is primarily contributed to by As, Cd, Cr, and Pb. Future identification of the exact sources of these toxic metals would be helpful for the appropriate management of urban road dust contamination. Full article

(This article belongs to the Special Issue Environmental Geochemistry of Toxic Elements in the Environment)

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18 pages, 2540 KiB

Open AccessArticle

Geochemical Fractionation and Source Identification of Pb and Cd in Riparian Soils and River Sediments from Three Lower Reaches Located in the Pearl River Delta

by Shaowen Xie, Chengshuai Liu, Bin He, Manjia Chen, Ting Gao, Xinghu Wei, Yuhui Liu, Yafei Xia and Qianying Sun

Int. J. Environ. Res. Public Health 2022, 19(21), 13819; https://doi.org/10.3390/ijerph192113819 - 24 Oct 2022

Cited by 3 | Viewed by 1301

Abstract

Pb and Cd accumulation in riparian soils and river sediments in river basins is a challenging pollution issue due to the persistence and bioaccumulation of these two trace metals. Understanding the migration characteristics and input sources of these metals is the key to preventing metal pollution. This study was conducted to explore the contents, geochemical fractionation, and input sources of Pb and Cd in riparian soils and river sediments from three lower reaches of the Pearl River Delta located in the Guangdong–Hong Kong–Macao Greater Bay Area. The total concentration of all Pb and Cd values exceeded the background values to varying degrees, and the exchangeable fraction of Cd in riparian soils and river sediments accounted for the largest proportion, while that of Pb was dominated by the residual fraction. Geoaccumulation index calculations showed that in the riparian soils, the average accumulation degree of Pb (0.52) in the Beijiang River (BJR) was the highest, while that of Cd (2.04) in the Xijiang River (XJR) was the highest. Unlike that in riparian soils, the maximum accumulation of Pb (0.76) and Cd (3.01) in river sediments both occurred in the BJR. Furthermore, the enrichment factor results also showed that Pb and Cd in the riparian soils and river sediments along the BJR were higher than those in the XJR and Dongjiang River (DJR). The relationship between enrichment factors and nonresidual fractions further proved that the enrichment factors of Cd were significantly correlated with the nonresidual fractions of Cd, which may imply various anthropogenic sources of Cd in the three reaches. Moreover, source identification based on principal component analysis (PCA) and Pb isotope ratio analysis indicated that riparian soils and river sediments have inconsistent pollution source structures. The PCA results showed that Pb and Cd were homologous inputs in the DJR, and there were significant differences only in the riparian soils and river sediments. Pb isotope tracing results further showed that the bedrock of high geological background from upstream may be the main reason for Cd accumulation in the XJR. However, the ultrahigh accumulation of Cd in the BJR is mainly caused by the input of the upstream mining and metallurgy industry. The control of upstream input sources will be the key to the prevention of trace metal pollution in these regions. Full article

(This article belongs to the Special Issue Environmental Geochemistry of Toxic Elements in the Environment)

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44 pages, 9502 KiB

Open AccessEditor’s ChoiceReview

Natural Background and the Anthropogenic Enrichment of Mercury in the Southern Florida Environment: A Review with a Discussion on Public Health

by Thomas M. Missimer, James H. MacDonald, Jr., Seneshaw Tsegaye, Serge Thomas, Christopher M. Teaf, Douglas Covert and Zoie R. Kassis

Int. J. Environ. Res. Public Health 2024, 21(1), 118; https://doi.org/10.3390/ijerph21010118 - 22 Jan 2024

Viewed by 2372

Abstract

Mercury (Hg) is a toxic metal that is easily released into the atmosphere as a gas or a particulate. Since Hg has serious health impacts based on human exposure, it is a major concern where it accumulates. Southern Florida is a region of high Hg deposition in the United States. It has entered the southern Florida environment for over 56 MY. For the past 3000 to 8000 years, Hg has accumulated in the Everglades peatlands, where approximately 42.3 metric tons of Hg was deposited. The pre-industrial source of mercury that was deposited into the Everglades was from the atmosphere, consisting of combined Saharan dust and marine evasion. Drainage and the development of the Everglades for agriculture, and other mixed land uses have caused a 65.7% reduction in the quantity of peat, therefore releasing approximately 28 metric tons of Hg into the southern Florida environment over a period of approximately 133 years. Both natural and man-made fires have facilitated the Hg release. The current range in mercury release into the southern Florida environment lies between 994.9 and 1249 kg/yr. The largest source of Hg currently entering the Florida environment is from combined atmospheric sources, including Saharan dust, aerosols, sea spray, and ocean flux/evasion at 257.1–514.2 kg/yr. The remobilization of Hg from the Everglades peatlands and fires is approximately 215 kg/yr. Other large contributors include waste to energy incinerators (204.1 kg/yr), medical waste and crematory incinerators (159.7+ kg/yr), and cement plant stack discharge (150.6 kg/yr). Minor emissions include fuel emissions from motorized vehicles, gas emissions from landfills, asphalt plants, and possible others. No data are available on controlled fires in the Everglades in sugar farming, which is lumped with the overall peatland loss of Hg to the environment. Hg has impacted wildlife in southern Florida with recorded excess concentrations in fish, birds, and apex predators. This bioaccumulation of Hg in animals led to the adoption of regulations (total maximum loads) to reduce the impacts on wildlife and warnings were given to consumers to avoid the consumption of fish that are considered to be contaminated. The deposition of atmospheric Hg in southern Florida has not been studied sufficiently to ascertain where it has had the greatest impacts. Hg has been found to accumulate on willow tree leaves in a natural environment in one recent study. No significant studies of the potential impacts on human health have been conducted in southern Florida, which should be started based on the high rates of Hg fallout in rainfall and known recycling for organic sediments containing high concentrations of Hg. Full article

(This article belongs to the Special Issue Environmental Geochemistry of Toxic Elements in the Environment)

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