Heavy Metal Pollution Research Articles

How Has the Source Apportionment of Heavy Metals in Soil and Water Evolved over the Past 20 Years? A Bibliometric Perspective

Exploring soil heavy metal sources is of great significance for ensuring the safety of ecological environments and agricultural product safety, as well as for guiding pollution control and management policies. This paper retrieved 452 research papers on soil heavy metal source analysis published over the 2004–2024 period from the Web of Science database. The collected literature was subjected to multidimensional bibliometric analysis using the CiteSpace 6.3.R1. The results showed significantly increasing trends in the scientific outputs and the number of papers on heavy metal source analysis in soils and water over the study period. In addition, related research topics have expanded from single to multiple heavy metal elements in environmental media and have increasingly recognized the impact of water pollution on soil contamination. Research methods have also evolved from basic statistical analysis to complex spatial analysis techniques, covering agricultural and urban soils. Previous related studies have focused on heavy metal pollution in different areas, and related research on heavy metal source analysis has now extended from ecological environments to associated human health risks. The present study provides directions for future related research and guidance for ensuring effective source control of heavy metal pollution and safe utilization of land and water resources.

Analysis of heavy metal characteristics and health risks of edible mushrooms in the mid-western region of China.

This study determined the content of metal elements (As, Cd, Cr, Hg, Pb) in 9 edible mushrooms using ICP-MS, and evaluated the harm of long-term consumption of edible mushrooms to human health. The results showed that the concentrations of metal elements decreased in the order of Cd > As > Cr > Pb > Hg in edible mushrooms. The concentrations of Cd, As, Pb, and Hg were 22.95%, 8.20%, 1.64%, and 3.28% higher, respectively, than the maximum standards in China, whereas Cr did not exceed the limit. The detection rate of metal elements in Morchella esculenta (L.) Pers (M. esculenta), and Agaricus blazei Murill (A. blazei) were relatively high. The results of single factor evaluation and target hazard coefficient (THQ, HI) indicated that Dictyophora indusiata (Vent.ex Pers) Fisch (D. indusiata), A. blazei and M. esculenta were the main sources of risk. In addition, the HI values in ascending order were: Pb (0.43) < Cr (0.68) < Hg (0.92) < Cd (7.21) < As (14.02), indicating that Cd and As were the primary sources of health risks in edible mushrooms. To ensure food safety, it is recommended to strengthen the supervision of edible mushrooms, make reasonable choices, and reduce exposure levels of heavy metal pollution.

Engineering a Graphene Quantum Dot‐Enhanced Surface Plasmon Resonance Sensor for Ultra‐Sensitive Detection of Hg2⁺ Ions

AbstractThe contamination of soil and water by heavy metals poses a significant environmental and public health concern worldwide. To address this issue, a novel graphene quantum dot (GQD)‐based surface plasmon resonance (SPR) sensor is developed for the detection of mercury ions (Hg2+), a notorious heavy metal pollutant. The thiol and amine‐functionalized GQDs (S,N‐GQDs), synthesized via pyrolysis of citric acid and L‐cysteine, are directly immobilized onto the SPR chip surface without prior pretreatment, demonstrating their potential as efficient sensing materials. The SPR sensor exhibits high sensitivity and selectivity toward Hg2+ ions, as confirmed by kinetic binding analysis and isotherm modeling. The Langmuir isotherm model, which accurately describes the interactions between Hg2+ and S,N‐GQDs, provides insights into the sensor's mechanism of action. Furthermore, the sensor demonstrates robustness and reusability, with recoveries ranging from 98% to 104% over multiple cycles of analysis. Given the presence of contaminants in tap water, the developed sensor system holds significant importance for environmental monitoring and public health protection, offering a rapid, accurate, and cost‐effective solution for detecting Hg2+ ions in such samples. Overall, this study represents a significant advancement in the field of heavy metal detection, with potential implications for addressing environmental pollution and ensuring water quality.

Heavy metal pollution in farmland soils surrounding mining areas in China and the response of soil microbial communities

Mining activities lead to significant heavy metal pollution in nearby farmland soils, affecting the soil's microbial community and functions. To comprehensively investigate the heavy metal contamination in farmland soils caused by mining activities and the impacts on soil microbial communities and functions, we collected 87 soil samples from farmlands near 29 mining sites nationwide, measured levels of cadmium, lead, copper, and zinc. Our findings revealed that 75.8% of the sampled farmlands exhibited varying degrees of heavy metal pollution. Cadmium contamination stood out, being 2.84 to 5.35 times higher compared to other metals. This pollution notably decreased microbial diversity in agricultural soils (P ≤ 0.04), causing a shift from intricate interconnected microbial co-occurrence modules to a higher number of simpler ones, indicating a fragmentation of the microbial interaction network. Additionally, heavy metal contamination led to a 10.9% increase in the importance of the heterogeneous selection process in community assembly. Despite reduced microbial alpha diversity, we observed an increase in the diversity and abundance of metal resistance genes (MRGs) and intensified microbe-MRG interaction. This suggests that microbial communities, even when altered, maintain functionality through enhanced redundancy, which probably facilitates the preservation of microbial activities. We also identified key taxa with intense connectivity in the microbial interaction networks, 58% of which have been recognized in previous studies for their predictive effects on soil health. These findings offer important insights for developing strategies to enhance soil health, such as promoting the presence of "super-connectors" in microbial networks for the maintenance of microbial community.

Hyperspectral Inversion of Soil Cu Content in Agricultural Land Based on Continuous Wavelet Transform and Stacking Ensemble Learning

Heavy metal pollution in agricultural land poses significant threats to both the ecological environment and human health. Therefore, the rapid and accurate prediction of heavy metal content in agricultural soil is crucial for environmental protection and soil remediation. Acknowledging the limitations of traditional single linear or nonlinear machine learning models in terms of prediction accuracy, this study developed an ensemble learning model that integrates multiple linear or nonlinear learning models with a random forest (RF) model to improve both the prediction accuracy and reliability. In this study, we selected a typical copper (Cu) polluted area in the Pearl River Delta of Guangdong Province as the research site and collected Cu content data and indoor soil reflectance spectral data from 269 surface soil samples. First, the soil spectral data were preprocessed using Savitzky–Golay (SG) smoothing, multiplicative scattering correction (MSC), and continuous wavelet transform (CWT) to reduce noise interference. Next, principal components analysis (PCA) was employed to reduce the dimensionality of the preprocessed spectral data, eliminating redundant features and lowering the computational complexity. Finally, based on the dimensionality-reduced data and Cu content, we established a stacked ensemble learning model, where the base models included SVR, PLSR, BPNN, and XGBoost, with RF serving as the meta-model to estimate the soil heavy metal content. To evaluate the performance of the stacking model, we compared its prediction accuracy with that of individual models. The results indicate that, compared to the traditional machine learning models, the prediction accuracy of the stacking model was superior (R2 = 0.77; RMSE = 7.65 mg/kg; RPD = 2.29). This suggests that the integrated algorithm demonstrates a greater robustness and generalization capability. This study presents a method to improve soil heavy metal content estimation using hyperspectral technology, ensuring a robust model that supports policymakers in making informed decisions about land use, agriculture, and environmental protection.

Preparation of cellulose nanofiber/polyvinyl alcohol-based composite films for metal ion detection by starch/disodium calcium ethylenediaminetetraacetate synergistic complexation effect

Heavy metal pollution causes irreversible damage to plants, animals, and humans. Therefore, it is meaningful to develop facile, fast, and efficient strategies for heavy metal ion (HMI) detection. Here, a portable composite film (CPSE) was designed for HMI detection with high sensitivity and wide detection range. The CPSE was prepared by using cellulose nanofibers (CNF)/polyvinyl alcohol (PVA) as the matrix and utilizing modified starch (HPS) to assist disodium calcium ethylenediaminetetraacetate (EDTA-Ca) to form stable complexes with HMI. The R, G and B values (the three primary colors of light) were captured using an image acquisition system to produce an HMI standard color card successfully. Specifically, the composite film can effectively distinguish Cu2+, Pb2+ and Fe3+. The response time of the composite film to HMI was 2–4 s, and the detection ranges of Cu2+ and Fe3+ were 5–700 ppm and 10–1000 ppm, respectively. Additionally, the synergistic effect of HPS and EDTA-Ca led to the increase in tensile strength (1.59–1.71 times), tear strength (3.29–3.57 times), and glass transition temperature (~ 6 °C) compared to CNF/PVA/HPS and CNF/PVA/EDTA-Ca films. This study confirms the value of CPSE films as materials for HMI detection and suggests innovative ideas for designing similar biomass detection materials in the future.

Soil moisture determines the consistency of organic matter decomposition in field and lab test patterns

Litter decomposition serves as the primary process for soil organic matter formation and renewal. However, few studies have been conducted to validate field large-scale litter decomposition patterns. In this study, cotton strips and Solanum nigrum were used to explore the decomposition differences between standardized litter and conventional litter, along with the release of heavy metal Cadmium (Cd). The indoor characteristics of organic matter decomposition were further verified. After 6 months of Cd pretreatment, litter was placed on the surface of soil collected from 15 sites across the China for 3 months of lab tests. The results indicated that the decomposition rates of both litter types were regulated by soil moisture and generally showed a trend of deceleration from east to west, consistent with the field decomposition pattern. In addition, the mass loss of cotton strip was significantly lower than S. nigrum due to the higher Cd concentration. With the decomposition process, both litter types showed a decreasing trend in Cd concentration, especially the cotton strip. Interestingly, our study found soil factors had the highest relative influence on decomposition. A higher soil microbial moisture use efficiency in the mid-latitude region during litter decomposition may be attributed to the adaptability of microorganisms. Our research demonstrated the consistency of lab test patterns with the field experiments, emphasizing the distinctions between standardized and conventional litter. This study not only revealed the influence mechanism of soil moisture and Cd on litter decomposition rate but also emphasized the important role of microorganisms in the litter decomposition process, which provided a new perspective for a deeper understanding of the ecosystem carbon cycle and heavy metal pollution.

Eu-doped carbon dots-MOF based turn-on fluorescent probe for trace Hg2+ and Pb2+ and construction of the simultaneous detection model

Multiple trace heavy metal pollutants present a serious threat to the aquatic environment, and their coexistence also affected the detection efficiency. This work prepared Eu doped metal organic framework (MOF) complexed with S-containing carbon dots (CD(s)) exhibited dual-emission fluorescence. Its chelation-enhanced fluorescence with heavy metals replaced the original agglomerative fluorescence quenching of pure CD(s), which was utilized to construct a “turn on” fluorescence sensing probe. Based on the XPS, DFT and fluorescence lifetime results, the N, S functional groups on the surface of the materials could bind specifically to Hg2+ and Pb2+ with enhanced sensitivity. The limit of detection reached 76.67 nM for Hg2+ and 5.12 nM for Pb2+ within 2 min detection time. Furthermore, due to the different response mechanism of the two signal peaks to Hg2+ and Pb2+, a three-dimensional data model was developed for simultaneous detection in the co-existence system. The model had been successfully applied to actual Hg2+-Pb2+ containing water samples with recoveries ranged from 93.15 ∼ 105.08 %. The results provided a new strategy for simultaneous detection of trace environmental pollutants.

Biosorption of Pb2+, Cd2+ and Zn2+ from aqueous solutions by Agrobacterium tumefaciens S12 isolated from acid mine drainage

Heavy metal pollution is a global environmental issue, and microorganisms play a crucial role in the bioremediation of heavy metal-contaminated wastewater. The study isolated heavy metal-resistant bacterium and observed their absorption ability toward Pb2+, Cd2+ and Zn2+. We isolated Agrobacterium tumefaciens S12 from acid mine drainage. The various factors influencing its adsorption performance, including pH, biomass dosage, initial metal ion concentration, and adsorption temperature, were investigated in detail. Chemisorption controls the adsorption rate due to the results better fitted by pseudo-second order kinetics. The maximum adsorption capacities of Pb2+, Cd2+ and Zn2+ on A. tumefaciens S12 were 234, 58 and 51 mg g−1 at 30 °C from Langmuir isotherm, respectively. The adsorption processes for the three heavy metal ions were spontaneous and exothermic in nature. In bimetallic systems, biosorption of Pb2+ ions was preferential to that of Cd2+ and Zn2+. Furthermore, scanning electron microscopy coupled to energy dispersive spectroscopy, Fourier-transform infrared spectra and X-ray photoelectron spectroscopy analysis demonstrated that the adsorption mechanisms include ion-exchange, complexation interaction between the heavy metal ions and the functional groups on the surface of biomass. The obtained results indicated that A. tumefaciens S12 can be applied as an efficient biosorbent in bioremediation technology to sequestrate heavy metal ions from aqueous solution.

Mitigating Health Risks Through Biosorption: Effective Removal of Nickel (II) and Chromium (VI) from Water with Acid-Treated Potato Peels

Introduction: Nickel (Ni(II)) and chromium (Cr(VI)) are associated with serious health risks, including respiratory problems, kidney damage, and cancer, along with potential threats to ecosystems. Given their persistence and significant toxicity, effective removal from contaminated water is essential to mitigate these health risks. This study explores the efficacy of acid-treated potato peels (ATPP) as an economical and readily accessible biosorbent for the removal of Ni(II) and Cr(VI) from water solutions. Methods: The study explored two biosorbents: raw potato peels (RPP) and ATPP. Fourier Transform Infrared (FTIR) spectroscopy was utilized to analyze changes in surface functional groups. Batch biosorption experiments were performed using distinct contact times (30-180min), pH (3–11), and biosorbent dosages (0.1–0.5 g). The Mann-Whitney U test was applied for the statistical analysis. Results and Discussion: The FTIR analysis indicated an enhancement in carboxyl groups on the ATPP surface after acid treatment, with stronger transmittance peak at 1645 cm⁻¹. ATPP showed significant improvements in biosorption capacity compared to RPP, removing 18.23% of 10 mg/L Ni(II) at pH 5 in 120minutes using 0.5 g of ATPP. For Cr(VI), 52.28% removal was achieved at pH 7 with 0.2 g of ATPP within the same time frame. Statistical analysis confirmed the superior performance of ATPP in removing Ni(II) (p = 0.024) and Cr(VI) (p = 0.004). Conclusion: ATPP offers significantly higher biosorption capabilities than RPP attributed to the increased presence of carboxyl groups on the modified surface, indicating potential for eco-friendly effective material in mitigating the heavy metal pollution's health risks.

Usability of Robinia pseudoacacia in monitoring changes and reducing airborne palladium pollution

Palladium (Pd), whose use has been increasing in recent years, is one of the heavy metals that pose a danger to the environment and human health, and it is known that heavy metals can be extremely harmful when inhaled from the air and taken into the human body. Therefore, monitoring and reducing the change of Pd pollution in the air is very important. This study aimed to determine the usability of Robinia pseudoacacia, which is grown intensively in urban areas where heavy metal pollution may be high, to monitor and reduce the change in Pd pollution in the air. Within the scope of the study, changes in Pd concentration in Robinia pseudoacacia stem sections grown in Düzce, among the 5 most polluted cities in Europe, depending on organ, direction, and age range in the last 60 years, were evaluated. As a result, it was determined that Pd pollution in the region may have been released into nature through agricultural activities or transported from much more distant sources. It was also determined that the species is not a suitable biomonitor that can be used to monitor the change in Pd pollution. Still, it is an accumulator species that is extremely suitable for reducing Pd pollution.

Evaluation and risk assessment of heavy metals in wetland soil in the University of Lagos

A study was conducted to evaluate the concentration of heavy metals, and the physicochemical and microbiological properties of wetland soils at the University of Lagos. Soil samples were randomly collected from the Faculty of Science (FSC), Lagoon Front, and Distance Learning Institute areas at depths of 5 cm, 10 cm, 15 cm, and 20 cm using a soil auger. The samples were stored in sterile nylon bags, appropriately labelled, and transported to the University of Lagos Central Research Laboratory for chemical analysis. The physicochemical characteristics measured included soil pH, determined using a pH meter, and moisture content, assessed through the oven-drying method. Heavy metal concentrations were analyzed using an Atomic Absorption Spectrophotometer. Microbial population diversity was examined using the disc diffusion method. Statistical analysis was performed using SPSS version 20, and mean values were evaluated using Tukey’s multiple comparison test at a probability level of P &lt; 0.05. The results revealed that soil pH ranged from 7.20 to 8.81, with the highest value (8.81) recorded near the Faculty of Science (FSC-3). Eight heavy metals, including Pb, Ni, Cr, Cd, Fe, Cu, Mn, and Zn, were analyzed. Lead concentrations ranged from 0.02 to 0.29 ppm, followed by nickel, which ranged from 0.01 to 0.13 ppm. Chromium ranged from 0.0 to 0.25 ppm, cadmium from 0.03 to 0.08 ppm, iron from 1.02 to 2.96 ppm, copper from 3.31 to 4.60 ppm, manganese from 3.31 to 5.16 ppm, and zinc from 1.67 to 9.17 ppm. Lead and zinc concentrations were found to be below the permissible limit at all locations, while chromium and cadmium were within permissible limits. However, Zn, Mn, Cu, Fe, and Ni exceeded the permissible limits. Correlation analysis revealed a significant correlation (P &lt; 0.05) between Pb and Zn, likely due to effluents from human waste and seepage from nearby dumpsites into the lagoon, streams, or beaches. The isolated microbial flora included three bacterial genera, Bacillus megaterium, Bacillus spp, and Enterobacter spp, as well as four fungal genera, Aspergillus, Penicillium, Aspergillus flavus, and Fusarium. Bacterial counts were lower than fungal counts in polluted soils, likely due to the nutrient status of the soil. The isolates were found to be tolerant to slightly alkaline pH and heavy metal pollutants, with microbial variation attributed to the impact of pH and heavy metals on the microbial population.

Remediation of biochar-supported effective microorganisms and microplastics on multiple forms of nitrogenous and phosphorous in eutrophic lake.

Lots of studies on eutrophication, but there is a lack of comprehensive research on the repair of multiple forms of nitrogen and phosphorus under combined heavy metals (HMs) pollution. This work investigated the various forms of nitrogen and phosphorus in the water-sediment systems of eutrophic lakes with the application of biochar, Effective Microorganisms (EMs) and microplastics, aiming to deliberate the repair behavior of multiple forms of nitrogen/phosphorus and the integrated repairment of these nutrients and HMs in different remediations. For amended-groups, the application of biochar-supported EMs (BE) achieved the most desirable remediation for removing nitrogen, phosphorus and HMs in water and improved their stability in sediment due to the improved microbial activity and the developed biofilm system created by biochar. The addition of aging microplastics (MP) obviously reduced the systematic levels of nitrogen, phosphorus and HMs due to the stimulation of microbial activity and the adsorption of biofilm/EPS, but its high movability also increased the Fe(II) and S(-II) levels and the pollutants' ecological risks in sediment. The co-application of BE and MP (MBE) destroyed the ecosystem and decreased the removal of nitrogen and phosphorus, while greatly removing HMs by the superfluous biofilms/EPS. The application of biochar (BC) preferentially adsorbed and degraded dissolved nitrogen and phosphorus, releasing HMs into water. From these amended-groups, it's also knew that the removal of nitrogen and phosphorus mainly came from the degradation/assimilation of NH3-N, SRP and dissolved matters, particularly those molecular weight below 3 kDa; the higher removal of phosphorus than nitrogen was attributed to the coprecipitation of Fe-S-P hydroxides and the adsorption of particulates; however, the colloidal (3-100 kDa) nitrogen and phosphorus had low accessibility and bioavailability, and it also showed the competitive adsorption with colloidal HMs, causing their relatively low removal in water. This study provides insight into the comprehensive repair of nitrogen, phosphorus and HMs in various forms by biochar-immobilized microbes and the influence of microplastics on nutrients and HMs in eutrophic lakes.

Spatial pattern, source apportionment, and source-oriented health risk quantifying of heavy metals in farmland soils of southern China.

The contamination of heavy metal has permeated many parts of China, especially in densely populated and industrialized southern China. This study focused on the degree of pollution in farmland soil heavy metals (HMs), and its spatial distribution characteristics and source apportionment. Meanwhile, we conducted an evaluation of the health risks attributed to soil HMs and analyzed the factors that impact them. We found that the distribution of five heavy metals is mainly concentrated in the east-central and southern parts of the study area. Specifically, Cd and Hg have high levels of pollution and present potential ecological risks. The pollution sources of five HMs were analyzed utilizing positive matrix factorization. The results revealed that the contribution of different sources keeps the following order: natural source (42.42%), agricultural activities (29.93%), industrial pollution source (20.49%), and atmospheric deposition pollution (7.16%). The non-carcinogenic risks to residents were acceptable, whereas the carcinogenic risks were relatively high. Children and the elderly are more vulnerable to the negative effects of Cr, As. Using structural equation modeling, we found soil property is a vital factor affecting soil contamination, with the soil organic matter and cation exchange capacity having a relatively greater impact on heavy metals pollution. Our study provides some data reference and guidance for soil ecological protection and restoration.

A Study on Removal of Heavy Metal Ions by MgFe-Layered Double Hydroxides

Heavy metal pollution has posed great threats to the ecological environment, food security and human health. To date, various approaches have been explored, among which mineralization of heavy metals via layered double hydroxides (LDHs) are reported as a promising way to solve the addressed issue. In line with this, the current study attempts to the fabrication of two typical MgFe-LDHs containing different intercalated anions (denoted as MgFe-CO3 and MgFe-NO3) for mineralization of Cd2+. In the experiments, the as-prepared MgFe-NO3 exhibited a high maximum adsorption capacity of 444.44 mg/g, which was 2.82 times higher than that of the contrast sample MgFe-CO3 (157.48 mg/g). Such difference in adsorption capacity can be attributed to the different mineralization mechanism: For MgFe-NO3, the mineralization process was dominated by isomorphous substitution and the CdFe-LDH was the main product, while for MgFe-CO3, the formation of CdCO3 can be observed. This work paves a way in treating Cd2+ by MgFe-NO3 through super-stable mineralization and its further application in the removal of co-existent Cd2+ and AsO43- ions can be expected.

Prediction of Spatiotemporal Pollution of Soil Heavy Metal in Mining Areas Based on Grey Neural Network Algorithm

Prediction of Spatiotemporal Pollution of Soil Heavy Metal in Mining Areas Based on Grey Neural Network Algorithm

Exploring Spatial Dynamics of Water Quality in a Tropical Lake Affected by Aquaculture

Lake Maninjau, like many surface water bodies worldwide, faces significant water pollution challenges due to extensive aquaculture activities, making it an ideal site to study the impact of fish farming on water quality, which has contributed to eutrophication and declining water quality. This study investigates the physicochemical parameters and pollution levels in the lake, aiming to provide insights into its environmental health. In August 2022, a comprehensive sampling campaign was undertaken at nine stations within the upper layers of open water and littoral zones of Lake Maninjau. In situ measurements, including temperature, dissolved oxygen, and pH, were conducted, accompanied by water sample collection for laboratory analysis of trace elements and heavy metals. Our study revealed notable variability in water parameters across different sites, with surface water layers exhibiting the greatest differences. While certain parameters such as temperature and conductivity remain relatively stable, pH levels show a decreasing trend with increasing water depth. Dissolved oxygen levels vary widely, while oxidation–reduction potential indicates water pollution, particularly in littoral zones. Potassium dominance within cations likely suggests anthropogenic influences, notably from aquaculture activities, that may also contribute to nutrient enrichment and heavy metal pollution. Elevated levels of total nitrogen and ammonia underscore the lake’s moderate pollution levels, with heavy metals such as mercury exceeding permissible limits, posing risks to aquatic life and human health.

Effects of combined application of Se and ammonium fertilizers on the growth and nutritional quality of maize in Hg-polluted soil under two irrigation conditions and its health risk assessment

The interactive effects of Se (Na2SeO3) and ammonium fertilizers ((NH4)2SO4 and NH4Cl) on the growth and quality of maize (Zea mays L.) in mercury (Hg)-contaminated soil were studied under different water conditions. This study determined how two nutrient sources (Se and NH4+-N) interacted to improve the yield, quality, and safety of maize to ensure food security and quality assurance under the stress of heavy metal Hg. The experiment was conducted under two irrigation conditions: W1 (complete irrigation condition, 60-70% of water-holding capacity) and W2 (restricted irrigation condition, 40-50% of water-holding capacity). The combined treatment of Se and ammonium fertilizers significantly improved the growth of maize and the quality of grain in Hg-polluted soil. When Na2SeO3 and (NH4)2SO4 were combined, the growth and quality of maize increased the highest among all treatments. The interaction between Na2SeO3 and ammonium fertilizers significantly affected the available Hg/methylmercury (MeHg) content in soil and the Hg/MeHg concentration in maize. NH4Cl significantly increased the content of available Hg/MeHg in soil and increased the accumulation of Hg/MeHg in maize tissues due to Cl-. However, the treatments containing Na2SeO3 or (NH4)2SO4 significantly reduced the content of available Hg/MeHg in soil, reduced the accumulation of Hg/MeHg in maize tissues, and significantly reduced the possible health risks to human beings. The treatments containing Na2SeO3 or (NH4)2SO4 promoted maize growth by increasing the Se content in maize tissues and reducing the Hg/MeHg content, relieving the stress induced by Hg, and increasing the nutrient content. The combined treatment of Na2SeO3 and (NH4)2SO4 had the best effect in this experiment. This study also showed that this strategy is helpful in reducing the opportunities for consumers to accumulate Hg/MeHg by eating maize and its derivatives, thus ensuring food safety. Se and ammonium fertilizer can be used together to increase maize yield and develop agricultural production in Hg-polluted areas, which may have a significant impact on global food production. In addition, this simple method can help farmers manage soil affected by heavy metal pollution.

Nymphaea lotus Distribution in Oguta Lake: Implications for Heavy Metal Pollution in Surface Water and Sediments

Water quality is increasingly deteriorating and has affected lakes, which are important sources of freshwater. Heavy metals are of great concern because they are mostly toxic and resistant to decomposition. Aquatic macrophytes serve as stable biological filters that purify water bodies by accumulating dissolved metals and toxins in their tissues. Given their ability to trap various toxic heavy metals, the macrophyte Nymphaea lotus, which is observed on the surface waters of Oguta Lake, was studied to estimate the concentrations of six heavy metals in the water, sediment, and macrophytes. This was achieved by studying the spatial and temporal distribution of Nymphaea lotus in the lake and analysing the concentrations of heavy metals in the surface water, macrophytes, and sediment samples. Descriptive statistics, exploratory data analysis, and correlation analysis were used to analyse data obtained. Results revealed that the population of Nymphaea lotus declines over time from June to November in all regions. Upstream had the highest concentration of macrophytes (64%), while the downstream area has the lowest (2%). The heavy metal concentrations in the three samples ranges from 0.16 mg/kg to 2.96 mg/kg in sediments and Nymphaea lotus, and from 0.16 mg/L to 2.16 mg/L in water, with lead showing the highest concentration across all sample type. This highlights heavy metal contamination in the lake. The sparsely populated Nymphaea lotus exhibits selective bioaccumulation of lead, mercury, and zinc, while it seems to exclude or inefficiently absorb arsenic and chromium. Correlation analysis suggests a close interdependence between the concentrations of metals in sediments, water, and macrophytes, with sediments playing a key role in both water contamination and macrophyte metal absorption. Corrective and preventive measures should be taken to restore the lake.

Heavy Metals Pollution Evaluation, Health Risk Assessment, and Source Identification in the Reservoirs, Northern Anhui Province, China

Heavy Metals Pollution Evaluation, Health Risk Assessment, and Source Identification in the Reservoirs, Northern Anhui Province, China