Heavy Metal Pollution Research Articles

Responses of magnetic properties to heavy metals pollution recorded by sediments of Nanchang City reach of Ganjiang River, East China.

In this paper, sediment samples from the HT and QS profiles of the Ganjiang River are selected to represent the river reach that does not enter and entered the Nanchang City urban area, respectively. Environmental magnetism, granulometry, and heavy metal of these samples were analyzed to assess the relationship between magnetic properties and heavy metal. The results showed that the mean χ value of QS profile is 20.32 × 10-8m3/kg, which is higher than that in HT profile (3.80 × 10-8m3/kg), indicating the higher magnetic mineral concentrations. The relatively higher S-100mT, S-300mT, and lower χARM/χ, χARM/SIRM values of QS profile suggest the lower imperfect antiferromagnetic mineral proportion and the coarser magnetic minerals grains, respectively. The heavy metals (i.e., As, Cd, Sb, Cr, Cu, Zn, Pb) concentration of QS profile is markedly higher than that of HT profile. The PLI of QS profile ranges from 0.5 to 3.33, higher than that in HT profile (0.22 to 2.02), revealing the more serious pollution in urban areas and would be attributed to human activities. In QS and HT profile, the concentration-dependent magnetic parameters (e.g., χ, SIRM, HIRM) are significantly positively correlated with heavy metals and PLI. We also found that with a similar particle size composition, the sediment samples with higher pollution levels exhibit higher χ, SIRM, S-100mT, S-300mT, and lower χARM/χ, χARM/SIRM values, indicating the response of magnetic properties to heavy metal pollution. Magnetic parameters can be used as a heavy metal pollution indicator in the Ganjiang River.

Mechanisms of Heavy Metal Tolerance in Bacteria: A Review

Heavy metal pollution from industrial activities and poor waste disposal poses significant environmental and health threats to humans and animals. This calls for sustainable approaches to the cleanup of heavy metals. This review explores metal tolerance mechanisms of bacteria such as the formation of biofilms, efflux systems, and enzymatic detoxification. These mechanisms allow bacteria communities to adapt and survive in contaminated environments. These adaptations are enhanced by mutations in the bacteria genes and by horizontal gene transfers, enabling bacteria species to survive under environmental stress while simultaneously contributing to nutrient cycling and the decomposition of organic matter. This review further explores the symbiotic interactions between bacteria, plants, and animals. These relationships enhance the metal tolerance ability of the different living organisms involved and are also very important in the bioremediation and phytoremediation of heavy metals. Plant growth-promoting rhizobacteria, Rhizobium, and Bacillus species are very important contributors to phytoremediation; they improve heavy metal uptake, improve the growth of roots, and plants resilience to stress. Moreover, this review highlights the importance of genetically engineered bacteria in closed-loop systems for optimized metal recovery. This offers environmentally friendly and sustainable options to the traditional remediation methods. Engineered Cupriavidus metallidurans CH34 and Pseudomonas putida strain 15420352 overexpressing metallothioneins have shown enhanced metal-binding capabilities, which makes them very effective in the treatment of industrial wastewaters and in biosorption applications. The use of engineered bacteria for the cleanup of heavy metals in closed-loop systems promotes the idea of a circular economy by recycling metals, thus reducing environmental waste. Multidisciplinary research that integrates synthetic biology, microbial ecology, and environmental science is very important for the advancement of metal bioremediation technologies. This review’s analysis on bacterial metal tolerance, symbiosis, and bioengineering strategies offers a pathway to effective bioremediation options, for the reclamation of heavy metal-polluted environments while promoting sustainable environmental practices.

Elucidating the leaf-based heavy metal bioindication in two significant plant taxa from Caucasus

The present study was aimed at assessing the potential of two important plants of the Transcaucasia – Betula medwediewii Regel (Caucasian birch) and Veratrum album L. (white hellebore) - as bioindicators of pollution of the environment. Betula medwediewii is a subalpine and alpine deciduous tree species that is significant for soil and habitat development. Veratrum album is found in the high altitude regions, is also known to withstand extreme conditions and has been used in herbal medicine. Elemental analysis was conducted on the plant leaves for total heavy metals such as aluminium, cadmium, cobalt, lead, and zinc. Results of the study showed that, in the leaves of B. medwediewii, aluminium, cadmium, and zinc heavy metals were found to be within permissible levels but levels of cobalt and lead were above permissible levels. For V. album cadmium and zinc also remained within the normal range but aluminum, cobalt and lead levels were notably high. The results of the study indicate the distinct accumulation characteristics that these species possess a unique behaviour in the presence of heavy metal pollution in the Transcaucasian environment and both plants have a potential capability as bio indicators.

UV-C Exposure Enhanced the Cd2+ Adsorption Capability of the Radiation-Resistant Strain Sphingomonas sp. M1-B02

Microbial adsorption is a cost-effective and environmentally friendly remediation method for heavy metal pollution. The adsorption mechanism of cadmium (Cd) by bacteria inhabiting extreme environments is largely unexplored. This study describes the biosorption of Cd2+ by Sphingomonas sp. M1-B02, which was isolated from the moraine on the north slope of Mount Everest and has a good potential for biosorption. The difference in Cd2+ adsorption of the strain after UV irradiation stimulation indicated that the adsorption reached 68.90% in 24 h, but the adsorption after UV irradiation increased to 80.56%. The genome of strain M1-B02 contained antioxidant genes such as mutL, recA, recO, and heavy metal repair genes such as RS14805, apaG, chrA. Hydroxyl, nitro, and etceteras bonds on the bacterial surface were involved in Cd2+ adsorption through complexation reactions. The metabolites of the strains were significantly different after 24 h of Cd2+ stress, with pyocyanin, L-proline, hypoxanthine, etc., being downregulated and presumably involved in Cd2+ biosorption and upregulated after UV-C irradiation, which may explain the increase in Cd2+ adsorption capacity of the strain after UV-C irradiation, while the strain improved the metabolism of the antioxidant metabolite carnosine, indirectly increasing the adsorption capacity of the strains for Cd2+.

The Stress Response of Aphids to the Accumulation of Heavy Metals Along Vicia faba L. Under Cadmium Treatment

Due to the intensification of human activities, the ecosystems are being polluted by heavy metals. The pollution of heavy metals in agricultural systems has become a serious issue of global concern. This study detected the bioaccumulation of cadmium (Cd) in broad beans and aphids through continuous exposure to varying concentrations of Cd pollution (0, 3.125, 6.25, 12.5, 25, 50 mg/L) and subsequently examined its effects on aphid energy metabolism and reproductive ability. The results showed that Cd can be transmitted and accumulated between Vicia faba L. and aphids along the food chain, and the amount of accumulation was related to the Cd treatment concentration. Quantitative real-time PCR results showed that the expression levels of trehalase (TRE) and trehalose-6-phosphate synthase (TPS) in F1 were significantly upregulated, and those of vitellogenin (Vg) were varied across the five generations of aphids after Cd treatment, which were up-regulated, and others down-regulated. Compared with the control group, the glycogen content and two types of trehalase activities of the first-generation Cd-treatment aphids were decreased, while trehalose content increased; there was no significant change in the carbohydrate content and trehalase activity of the fourth and fifth generations of aphids. In addition, the reproduction of female aphids was inhibited. This research is helpful for studying the toxic effects of heavy metals on insects and the adaptation mechanisms of insects to extreme environments. It also provides a theoretical basis for further exploring the molecular mechanisms of Cd homeostasis in plants and insects under Cd stress.

A Comparative Review on Low-Cost Adsorbent based Alkali-Activated Materials by Adsorption Study

The degradation of the condition of wastewater is becoming more and more serious due to the endless development. One of the main reasons is heavy metal contamination, which causes significant harm to the climate and humanity, such as bad health consequences, environmental degradation, and air pollution. Adsorption, which uses proven adsorbents such as activated carbon, is one of the most common methods for heavy metal removal in wastewater. However, since activated carbon is very expensive to build and repair due to complex production, most people choose another material to overcome this problem. Researchers have recently focused on finding low-cost adsorbents, which are typically industrial, agricultural and food wastes that can generate in large quantities. However, Alkali-Activated Materials (AAMs) have been recognized as a novel possible adsorbent because they are cheap, made from solid aluminosilicate and extremely alkaline activator solution, making them appropriate for usage in the civil engineering specialty. Moreover, they have become an option for various applications due to their unique geopolymer structure, which is highly mechanically, chemically and thermally stable. Hydroxyapatite (HAP) can be extremely useful in this application, as it is a promising biomaterial that has great potential for a low-cost AAMs adsorbent. The purpose of this study is to analyze the present development of a potential economic alternative adsorbent, particularly based on alkali-activated materials (known as geopolymers), for the elimination of heavy metal pollutants in wastewater using adsorption techniques.

Comprehensive review of the environmental impacts of mining and smelting at the Baiyinchang Cu-Zn-Pb ore deposit, Gansu Province, China, with new inputs from the sulfide compositions

This review paper presents an in-depth synthesis of the environmental aspects associated with the mining of the Baiyinchang Cu-Zn-Pb deposit in China. The review covers contamination by atmospheric deposition and sewage irrigation, soil contamination, and ecosystem health to evaluate current environmental conditions, identify potential impacts, and suggest sustainable mitigation measures for the Baiyin district. With a focus on soil, river water, and crop pollution levels, our review indicates that several heavy metals (HMs), particularly Cd, have been gradually accumulated in soils and streams due to the natural occurrence of the deposits close to the surface and mining-smelting activities, and pose a serious environmental threat. Detailed studies on sulfide minerals have found that although Cd is mainly hosted in sphalerite, all common sulfide minerals (galena, chalcopyrite, pyrite) also contain Cd. There were significant spatial variations in HM speciation; upstream areas near ore deposits exhibited lower pH and higher Zn concentrations, due to acidic mine drainage and the presence of sphalerite. As the stream flows through the Baiyin district, the increasing influence from domestic wastewater led to a rise in pH, impacting HMs mobility. Mining-smelting activities were identified as the primary source of HM pollution. Crops grown near the ore district and irrigated with contaminated water were most susceptible to contamination due to combined soil and atmospheric HM uptake. Our review highlights the importance of stricter pollution control measures, cleaner irrigation sources, and careful crop selection to safeguard food safety and ecosystem health.

Fate and Effects of Heavy Metals in Fishes: Antioxidant Defense System, miRNA/Gene Expression Response, and Histopathological Reproductive Manifestations.

Heavy metal pollution is a major environmental concern and in particular for aquatic ecosystems. With heavy metals exceeding safe and recommended limits, they pose significant threats to the environment and its inhabitants, including fish. Heavy metals, when accumulated in the different organs of the fish, result in toxicity in fish by producing reactive oxygen species (ROS) through the generation of oxidizing radicals. This oxidative stress mechanism is a key factor in the detrimental effects of heavy metal pollution on aquatic life. Heavy metal exposure profoundly affects fish behavior and physiology. In this review, an attempt was made to report the effects of heavy metals on fish physiology, focusing on toxicological effects on antioxidant enzymes, microRNAs (miRNAs) and molecular genetic responses, histopathology of organs, and underlying molecular mechanisms. This review also highlighted the heavy metal impact on fish gonads (testes and ovaries) and the hormones associated with it. The detection methods and the incorporation of latest developments in AI-based technology for the detection of heavy metals are also included in this review. Understanding the above effects is important for assessing the ecological impact of heavy metal pollution and developing strategies to mitigate its adverse effects on aquatic life. Understanding the consequences listed above is important for analyzing the ecological impact of heavy metal pollution and devising measures to reduce its negative effects on aquatic life and human health.

Sources, Contamination and Risk Assessment of Heavy Metals in Riparian Soils of the Weihe River Based on a Receptor Model and Monte Carlo Simulation

The riparian ecosystem is highly susceptible to pollution, particularly heavy metals (HMs), due to its unique spatial position and landscape characteristics. Therefore, assessing the risks of HM pollution and identifying potential sources are crucial for formulating effective prevention and control measures. This study investigates the characteristics of HMs (Ni, Cr, Zn, Cd, Cu, Pb) pollution in the Weihe River riparian zone, identifies their sources, and assesses the associated ecological and human health risks. The results indicate that Ni, Zn, and Cd are the primary pollutants in riparian soil, with the average Cd concentration being 5.64 times higher than the background value, indicating a high potential ecological risk. Spatially, the average HM concentrations in the middle and upper reaches are higher than in the lower reaches. Vertically, as the distance from the riparian increases, the HM content exhibits a “U”-shaped pattern (increase-decrease-increase). The Absolute principal components multiple regression (APCS-MLR) receptor model identified four potential pollution sources: traffic sources; agricultural sources; industrial sources; and natural sources. Additionally, the Monte Carlo simulation-based human health risk assessment indicates that the non-carcinogenic health risk indices for all HMs are within acceptable ranges. For carcinogenic health risk indices, there is a 1.14% probability for children. However, the vast majority of the risks fall within acceptable or no-risk categories.

​Quantitative assessment of heavy metal concentrations, pollution levels, and sources apportionment in one of China's top 10 most livable cities.

Urban topsoil is not only an essential part of the urban ecosystem, but also a powerful carrier of pollutants in the urban environment. In this paper, 130 topsoil samples from urban area of Xinyang in central-eastern China were selected, the aim is to quantitatively investigate the concentrations, pollution levels, and sources apportionment of 8 heavy metals (HMs, encompassing arsenic (As), cobalt (Co), copper (Cu), chromium (Cr), lead (Pb), nickel (Ni), vanadium (V), and zinc (Zn)) via geochemical method. The main conclusions are as follows. (1) The eight HMs in the topsoil have been artificially enriched to varying degrees, which are lower than the street dust levels sampled in pairs. (2) Cu, Zn, and Pb were significantly contaminated, and As, Co, Ni, Cr, and V were relatively low levels of contamination. Overall, comprehensive pollution levels were particularly severe, with 30.0%, 39.2%, and 30.8% for slight, moderate, and serious pollution, respectively. (3) Co, Ni, V, and Cr predominantly originated from natural sources, the percentage contribution of which is 6.3%; Pb, As, Cu, and Zn were predominantly derived from traffic-derived sources, with a percentage contribution of 93.7%. Thus, the first-order source of HMs in the topsoil originates from traffic-induced activities, similar to the case of street dust. Our findings can be beneficial in providing local governments with a reference to formulate environmental pollution controls, and also provide a case study for environmental pollution control in the other livable cities in China.

Spatial Distribution, Pollution Assessment, and Source Analysis of Soil Heavy Metals Under Different Land Use Types in the Southern Area of Laizhou Bay

To ascertain the status of the surface soil heavy metal pollution in the southern area of Laizhou Bay, 263 surface soil samples were collected from seven different land use types in the study area and the contents and pH of eight soil heavy metals （As, Cr, Ni, Cu, Zn, Cd, Pb, and Hg） were determined. The pollution assessment was carried out using the geo-accumulation index method, Nemerow comprehensive index method, and potential ecological risk index method. Then, the source of heavy metal pollution was discussed using correlation analysis and the source analysis was carried out through positive matrix factorization （PMF）. The results showed that the surface soil in the study area was weakly alkaline； As, Ni, Zn, and Hg slightly exceeded the background values of Weifang and the spatial distribution of heavy metals showed a trend of low in the north and high in the south. The results of the geo-accumulation index indicated that the study area was pollution free and the geo-accumulation index of different land types was arranged in the order of As>Ni>Zn>Cr>Pb>Hg>Cu>Cd. The results of the Nemerow comprehensive pollution index indicated that the study area was lightly polluted and the Nemerow comprehensive pollution index of different land types was arranged in the order of town>grassland>forest>agricultural land>vegetable land>industrial land>mudflat. The results of the potential ecological risk index indicated that the study area belonged to low ecological risk and the potential ecological risk index of different land types was arranged in the order of agricultural land>town>forest land>grassland>vegetable land>industrial land>mudflat. The results of PMF analysis indicated that the heavy metal pollution sources in the study area mainly included natural sources, transportation sources, agricultural sources, and industrial sources, with contribution rates of 38.06%, 26.38%, 26.21%, and 9.35%, respectively.

Heavy Metal Pollution Characteristics and Risk Assessment of Soil-crop System in Gold Mine Activity Area

A contamination analysis was conducted on the soil and crops in the Liu Jia Dian gold mining area of the Pinggu District, Beijing, utilizing the contents and seven-step forms of heavy metals （Hg, Cd, Cr, Pb, and As） in soil and the heavy metal contents in crops at the same location. An assessment of ecological risk caused by heavy metal contamination in the soil and crops was carried out using the enrichment coefficient method and the risk assessment coding method. The study investigated the process of heavy metal absorption and enrichment in the soil-crop system, aiming to establish a scientific foundation for preventing and controlling soil pollution, as well as ensuring the safety of edible crops in the study area. Evidence indicated the presence of soil contamination by heavy metals in the study area, with Cd, Pb, and As being the primary pollutants. Moreover, the distribution of pollution levels could be categorized as severe, moderate, and mild, with proportions of 26.09%, 4.35%, and 10.87%, respectively. The content of each heavy metal decreased following the implementation of environmental governance； however, the ecological risk remains present. Hg, Cr, Pb, and As posed minor ecological risks； however, Cd had a high ecological risk, making it the primary soil ecological risk factor. Fruits, nuts, and cereals in the Pinggu gold mining area remained uncontaminated. Various degrees of contamination were found in melons, rhizomes, and leafy vegetables. The Chinese cabbage, Chinese chive, radish, and eggplant were heavily contaminated, with Cd and Pb being the primary sources of contamination. The accumulation of heavy metals in crops was intricately linked to gold mines and their mining operations. The accumulation of Cd in crops was mainly influenced by the high availability of Cd in soil, whereas the accumulation of Pb was mainly influenced by the high concentration of Pb in the soil. The concentration of heavy metals in the soil and their bioavailability in the Pinggu gold mining area indicated the accumulation of metal elements in crops and impacted the geographical distribution of heavy metal pollution in crops. The physiological characteristics of crops could affect the degree of heavy metal enrichment in the gold mining area. The order of heavy metal accumulation, from highest to lowest, was as follows： leafy vegetables, melons, rhizomes, cereal, fruits, and nuts. Peppers and eggplants were limited in their planting variations for melons, while leeks and cabbages were restricted for leafy vegetables, given the current agricultural planting conditions in the study area.

Heavy Metal Pollution Characteristics and Ecological Risk Assessment of Kafang Tin Tailings Pond

To study the pollution characteristics and ecological risks of heavy metals in tailings ponds is an important prerequisite for protecting the surrounding environment and human health. The total amount and morphology of five "toxic" heavy metals （As, Cr, Cd, Pb, and Hg） in Kafang tin tailings pond were determined. Based on the aforementioned, we analyzed the distribution characteristics of heavy metals. The potential ecological risks of heavy metals in tailings ponds were studied from the aspects of total amount and morphology. Sample data were analyzed using the geo-accumulation index method, potential ecological risk assessment method, and risk assessment criteria. The results showed that, from the perspective of the total amount of heavy metals, the spatial distribution of As was different, and the pollution was serious； the spatial distribution of Cd, Hg, Cr, and Pb was relatively uniform； the pollution of Cd and Hg was slight； and the pollution of Cr and Pb was controllable. From the perspective of the morphology of heavy metals, As, Cr, Pb, and Hg in tailings were mainly in the residual state and had low environmental pollution risk, whereas Cd in tailings was mainly in an oxidizable state and had high environmental pollution risks. Therefore, Kafang tin tailings pond should strengthen the control of As in tailings and pay attention to the potential pollution risks of Cd in tailings and the overall pollution risks of Hg, Pb, and Cr in the entire reservoir were controllable.

Source Apportionment and Influence Factors Analysis of Heavy Metals in Soils Around a Coal Gangue Heap Using the APCS-MLR Model and GeoDetector

To analyze the source apportionment and influence factors of heavy metals in soils surrounding a coal gangue heap in Chongqing, the absolute principal component scores-multiple linear regression （APCS-MLR） model and GeoDetector were used. The results showed that Cd was the primary pollutant and the average values of Cd, Hg, Pb, Cr, Cu, Zn, and Ni were 1.33, 0.29, 32.9, 142, 68.8, 118, and 54.6 mg·kg-1, respectively. Using the APCS-MLR model analysis, mining sources, which were mainly affected by long-term accumulation of the coal gangue heap, had a contribution rate of 37.1% and the main heavy metal pollutants were Cd, Hg, and Pb. Agriculture and transportation sources, mainly affected by pesticide and fertilizer application and vehicle emissions, had a contribution rate of 36.2%, with the main heavy metal pollutants being Cu, Zn, and Ni. Natural sources, which were mainly affected by geotechnical weathering processes of their parent materials, had a contribution rate of 26.7% and the main heavy metal pollutant was Cr. Using GeoDetector analysis, the "distance from coal gangue heap" had the strongest explanatory power for the contents of Cd, Hg, and Pb, whereas the "distance from rural settlements" had the strongest explanatory power for the contents of Cr, Cu, Zn, and Ni. However, the interaction of each influencing factor was enhanced, which indicated that the spatial distribution characteristics of heavy metals were influenced by multiple factors. The combined application of the APCS-MLR model and GeoDetector can make the results of source apportionment and influence factors more comprehensive, accurate, and reliable.

Significant Shifts in Predominant Plant Dispersal Modes in Pine Forests of the Southern Urals (Russia): Responses to Technogenic Pollution and Ground Fires

The purpose of this work was to assess the functional diversity of herb–shrub layer com munities determined by their dispersal mode in pine boreal forests depending on two factors: (i) the degree of technogenic heavy metal pollution and (ii) the time passed since the last fire. We tested two hypotheses: (1) the functional diversity of communities determined by their diaspore dispersal mode decreases in polluted forests and in forests disturbed by recent fires; (2) the abundance, i.e., participation of anemochorous species in communities, is relatively greater in polluted forests and in forests disturbed by recent fires than in unpolluted or in forests that have not burned for a long time. We analyzed 77 vegetation relevés made in polluted and unpolluted pine forests to obtain the impact gradient of the Karabash copper smelter (South Urals, Russia). The studied forests also had different durations of time since the last ground fire—from 1 to 60 years. Two classifications of the diaspore dispersal modes were used. We found that community functional diversity and predominant dispersal modes changed significantly in response to technogenic pollution and, to a lesser extent, in response to ground fires. In polluted forests, the importance of species with a long diaspore dispersal distance—anemochores and zoochores—increased. This result suggests conducting a specific study of long-distance diaspore migration as a possibly underestimated factor of community formation under severe technogenic disturbances. The importance of zoochores in a broad sense, including species with diaspores dispersed by vertebrates and invertebrates, increased in post-fire succession. This result coincides with the known pattern of increasing abundance of zoochorous plants in regenerative successions in tropical forests. Therefore, the data on plant–animal interactions can possibly provide valuable information on succession mechanisms in taiga forests.

Research on Plant-amendment Combined Remediation Technology of Heavy Metals Contaminated Soil

With the rapid development of industrialization and urbanization, the problem of heavy metal pollution in soil is becoming more and more serious, posing a serious threat to the ecological environment and human health. Phytoremediation technology is valued for its environmental friendliness and cost-effectiveness. In order to provide a scientific basis for the remediation of heavy metal contaminated soil and the promotion of the safe, efficient and sustainable use of heavy metal contaminated cultivated soil, We reviewed the application of plants, amendments, and plant-amendment combinations in the remediation of heavy metal contaminated soils, and The effects of different plants and amendments and their combined application on heavy metal contaminated soil were discussed.

A Preliminary Health Risk Assessment of Heavy Metal Contamination in Chembarambakkam Lake, Tamil Nadu, South India

Chembarambakkam Lake, an important freshwater reservoir in Chennai that provides drinking water to the city, has noticed a decline in water quality as a result of heavy metal pollution. This study aimed to evaluate the heavy metal contamination in the environment of Chembarambakkam Lake with a health risk assessment. This study involved a comprehensive analysis of toxic heavy metal levels in five waters, sediments, and commercially available freshwater fish samples, considering their bioaccumulation and potential risks to human health. We observed lead (Pb), cadmium (Cd), zinc (Zn), and copper (Cu) concentrations in water, sediments, and various fish species, including tilapia (Mozambique Tilapia), wild carp (Hemiculter leucisulus), pearl-spot (Etroplus maculatus), spotted barb (Barbodes binotatus), and snakehead murrel (Channa Striate). The results indicated that, in order of prominence, the metals in the water were Cu > Zn > Pb > Cd, whereas those found in sediments were Zn > Cu > Pb > Cd. The metal concentration in the sediments varied between Cd (0.52–0.82 µg/g), Cu (13.75–38.07 µg/g), Pb (1.30–3.74 µg/g), and Zn (12.60–61.12 µg/g). Similarly, the metal concentrations in the water varied between Cd (0.63–0.72 µg/L), Cu (5.35–55.17 µg/L), Pb (BDL–12.39 µg/L), and Zn (0.62–1.49 µg/L). The order of metals in the fish was Zn > Cd > Cu > Pb. The Cd concentration ranged from 0.3 to 0.60 µg/g, Cu was from BDL to 0.72 µg/g, Pb was from BDL–0.68 µg/g, and Zn was from 13.32–48.48 µg/g. The Cd and Zn concentrations were consistently the highest across the fish, sediment, and water samples. These findings shed light on the health risks associated with heavy metal pollution in Chembarambakkam Lake and suggest the need for potential bioremediation approaches.

The coupling effect and ecological risk assessment of iron, manganese, and arsenic in the water environment of the central Yangtze River Basin, China.

Excessive heavy metal in drinking water are harmful to human body. Groundwater was still the drinking water resource in most of rural areas in the central of the Yangtze River Basin. Heavy metals of Fe, Mn, and As in the low plain region of the Yangtze River Basin significantly exceeded the standard, resulting in 16.67% and 5.00% of water samples in the area reaching moderate and severe heavy metal pollution states. However, the coupling effect and ecological risks of iron, manganese, and arsenic in the water environment are unknown. This paper found that the dissolution of iron-bearing and manganese-bearing minerals into groundwater affected each other, when the burial depth of groundwater was less than 20m. Conversely, the dissolution of minerals containing iron and arsenic into the groundwater interacted with each other when the groundwater depth was greater than 20m. The precipitation of siderite (FeCO3) and rhodochrosite (MnCO3) may control the dissolved Fe and Mn in groundwater. The area between Yangtze River and Han River was more affected by industrial activities, and the south area of the Yangtze River was more affected by agricultural activities. This paper not only strengthened the understanding of the risk of heavy metal pollution in local groundwater, but also provided important scientific basis for the protection of regional groundwater ecological environment.

Review on the relationship between microplastics and heavy metals in freshwater near mining areas.

Microplastics (MPs), degraded from plastic wastes, have drawn significant attention worldwide due to its prevalence and rapid transition. Contamination of freshwater with MPs has become an emerging global issue. Heavy metals (HMs), a prominent global pollutant, also garnered much attention due to their potential interaction with MPs, presenting a multifaceted environmental threat. The primary source of HM contamination in freshwater has been identified as mining sites. Additionally, the increasing use of plastic materials within mining areas raises concerns about MP release into the surrounding freshwater environments. Recent studies only provide information on the contamination of HMs status with MPs. However, studies on the mechanism responsible for MPs contamination from both external and internal sources of freshwater MPs and HMs are limited. The knowledge gaps in the deposition and fate of MPs in various mining situations and the possibility of combined impacts of heavy metals and MPs in the ecosystem raise ecological concerns. Here, we review the origins of MPs and HM pollution within mining sites and explore the potential combined detrimental impacts on plants and animal life. We found out that polystyrene (PS) and polyethylene (PE) have higher adsorption affinity to heavy metals, and the mingle toxic consequence of the MPs and HM can depend on the MP surface properties, pH, and salinity of the neighboring water solution. The Langmuir and Freundlich isotherm models enable the efficient design of adsorption systems. The Langmuir model describes single-layer adsorption at homogeneous sites, while the Freundlich model addresses multilayer adsorption on heterogeneous surfaces. The crucial mechanism of adsorption and desorption that underlies the occurrence of both MPs and heavy metals is a decisive matter in this issue.

PREDICTING URBAN SOIL POLLUTION USING MACHINE LEARNING ALGORITHMS

Different cities of the world are facing heavy metal pollution in soils at different levels. Previous studies have found that heavy metal concentrations in urban soils tend to increase with increasing levels of urbanization, indicating a link between heavy metal content in soils and urban expansion. Thus, understanding this relationship and considering factors related to urbanization to create reliable predictions of heavy metal distribution in soils can contribute to effective management of urban health. This study examines the sources, distribution, and environmental effects of heavy metals. These elements accumulate in soil due to vehicle emissions, tire and brake wear, and abrasion of road surfaces, which carry significant environmental and health risks. The presence of heavy metals in road soil can detrimentally affect plant growth, enter the food chain, and pose a direct threat to human health when contaminated soil is ingested, or dust particles are inhaled. In this study, a random forest (RF) machine learning model was applied to predict the extent of heavy metals in soil along highways. The results showed that the RF model has high accuracy in predicting the spatial distribution of heavy metals in soil.