Heavy Metal Pollution In Sediments Research Articles

The competition of heavy metals between hyporheic sediments and microplastics of driving factors in the Beiluo River Basin

Both sediments and microplastics (MPs) are medias of heavy metals (HMs) in river ecosystems. This study investigated HMs (Mn, Cr, V, As, Cu, Co, Cd, Pb, and Ni) concentration and driving factors for competitive enrichment between hyporheic sediments versus MPs. The medias basic characteristics indicated that the sediments were mostly sand and rich in Fe2O3; three polymer types were identified, with blue, fragment, less than 500μm being the main types of MPs. The results have shown that the average content of extracted HMs in MPs was much higher than that of the same metals accumulated in sediments. HMs in sediments and MPs reached heavily polluted at some points, among which As and Cd were ecological risks. Electrostatic adsorption and surface complexation, and biofilm-mediated and organic matter complexation were the interaction mechanism of HMs with sediments and MPs. Further, the driving factors affecting the distribution of HMs in the two carriers were analyzed by multivariate statistical analysis. The results demonstrated that carrier characteristics, hydrochemical factors, and the inherent metal load of MPs were the main causes of the high HMs content. These findings improved our understanding of HMs fate and environmental risks across multiple medias. Environmental ImplicationOwing to large specific surface area and hydrophobicity, microplastics adsorb heavy metals (HMs) from the surrounding environment, aggravating potential ecological hazards and posing a threat to aquatic organisms. Many laboratory experiments have confirmed the compound effect of the two, but the attribution of HMs in natural rivers under the influence of multiple factors remains to be studied.This study investigated the distribution of HMs concentrations in different media, assessed HMs pollution in sediments and microplastics, and explained the drivers of uneven HMs concentrations. The finding provides new insights for further understanding of the fate of HMs in ecosystems.

Phosphate-solubilizing bacteria improve the antioxidant enzyme activity of Potamogeton crispus L. and enhance the remediation effect on Cd-contaminated sediment

Phosphorus-solubilizing bacteria (PSB) assisted phytoremediation of cadmium (Cd) pollution is an effective method, but the mechanism of PSB-enhanced in-situ remediation of Cd contaminated sediment by submerged plants is still rare. In this study, PSB (Leclercia adecarboxylata L1–5) was inoculated in the rhizosphere of Potamogeton crispus L. (P. crispus) to explore the effect of PSB on phytoremediation. The results showed that the inoculation of PSB effectively improved the Cd extraction by P. crispus under different Cd pollution and the Cd content in the aboveground and underground parts of P. crispus all increased. The μ-XRF images showed that most of the Cd was enriched in the roots of P. crispus. PSB especially showed positive effects on root development and chlorophyll synthesis. The root length of P. crispus increased by 51.7 %, 80.5 % and 74.2 % under different Cd pollution, and the Ca/Cb increased by 38.9 %, 15.2 % and 8.6 %, respectively. Furthermore, PSB enhanced the tolerance of P. crispus to Cd. The contents of soluble protein, MDA and H2O2 in 5 mg·kg−1 and 7 mg·kg−1 Cd content groups were decreased and the activities of antioxidant enzymes were increased after adding PSB. The results showed that the application of PSB was beneficial to the in-situ remediation of submerged plants.

Assessment and Review of Heavy Metals Pollution in Sediments of the Mediterranean Sea

The impact of marine sediment pollution is crucial for the health of the seas, particularly in densely populated coastal areas worldwide. This study assesses the concentration and distribution of heavy metals in the marine sediments of the main regions of the Mediterranean Sea. The results underscore high concentrations of mercury (Hg), nickel (Ni), and copper (Cu), whereas chromium (Cr), zinc (Zn), cadmium (Cd), barium (Ba), and vanadium (V) exhibit moderate values. To assess the heavy metal results, sediment quality guidelines and pollution indices (Igeo and Geochemical Signal Type-GST) were employed, revealing a consistent trend of decreasing concentrations from the coastal zone to the open sea. Principal Component Analysis (PCA) emphasizes the significant roles of Cu, Zn, Ba, and Cr in sediment chemistry. The study suggests that the distribution patterns of heavy metals are linked to wastewater discharges in coastal areas, requiring effective management strategies to ensure the health of the Mediterranean Sea.

The Spatiotemporal Variation and Historical Evolution of Heavy Metal Pollution in Sediments from the Pearl River Estuary, China

Many tributaries of the Pearl River carry large amounts of terrestrial pollutants into estuarine areas. Heavy metals accumulate in estuarine sedimentary environments, and coupled and changing biogeochemical processes occur in estuarine areas. The results of this study showed that the heavy metal contents in the sediment were the highest near the confluence of the Humen and Jiaomen outlets in 2005 and 2019; they were the second-highest near the remaining outlets, and gradually decreased toward the lower reaches, with high contents on the western shore and low contents on the eastern shore. The heavy metal pollution mainly originated from the Pearl River runoff. The historical evolution of heavy metals in the Pearl River Estuary (PRE) effectively reflected the impacts of pollutant inputs from the river basin as well as industrial and agricultural production and anthropogenic activities in the Guangdong–Hong Kong–Macao Greater Bay Area (GBA). In 2019, the surface sediments were not contaminated with Hg, and the Pb and Zn contents decreased significantly, indicating significant advances in environmental management; however, the Cu and Cd levels still indicated heavy pollution level in the upper reaches.

Heavy Metal Pollution in Sediments of the Yu River in a Polymetallic Ore Concentration Area: Temporal–Spatial Variation, Risk Assessment, and Sources Apportionment

In a polymetallic ore concentration area, large-scale mining activities can dramatically increase heavy metal concentrations in river sediments, and their temporal–spatial variation and source apportionment are significant for understanding heavy metal migration in rivers and formulating management strategies for environmental protection and the mining industry. Sediment samples were collected along the Yu River, which flows through the Luanchan polymetallic ore concentration area in China, during high-water period (HWP), low-water period (LWP) and flat-water period (FWP) to assess the pollution level and identify the sources of Mo, Cr, W, Cu, Zn, As, Cd, Pb and Hg in the sediments. The findings revealed that Mo, Cd, W, Zn, Pb and Cu were the main pollutants, and Hg was extremely high at some specific locations. Sediments in the upstream region of the Yu River were more severely polluted by heavy metals and had greater ecological risk due to stronger mine exploration. Furthermore, consistent distribution patterns of various heavy metals during different seasons were not found. Some sharp decreases in heavy metal concentrations between adjacent sediments were observed; moreover, at some sites, heavy metal concentrations during LWP and FWP were lower than those during HWP. The results indicated that heavy metals in the Yu River mainly migrated in dissolved form. Mo, Cu, Pb and As for HWP, Mo and As for LWP and Mo, Cr and W for FWP mainly originated from Mo/W mines. Pb/Zn mines contributed to the amounts of W, Zn and Cd during HWP, Cu, Zn, Cd and Pb during LWP and Cu, Zn, Cd and Pb during FWP. Hg was mainly attributed to Au mines, and Cr was the geogenic element. The results could contribute to the sustainability of the mining industry and the formulation of science-based remediation and protection strategies for the rivers near mining areas.

Ecotoxicological risk assessment of metalloid contamination in the sediment and benthic fauna of a tropical lotic freshwater ecosystem in Southern Nigeria

The increasing exposure of freshwater bodies to pollutants and the bioaccumulation of heavy metals in body parts of aquatic organisms has raised concerns on the ecotoxicological and human health risk. This study evaluated the potential ecological and human health risk of heavy metal pollution in sediment and benthic fauna (Caridina africana) of the Osse River, Edo State, Nigeria. Using requisite equipment, samples of water sediment and C. africana were collected at designated stations from September 2015 to February 2017. Heavy metal concentrations in samples were determined using atomic absorption spectrophotometer. Result showed heavy metal contamination with concentration profiles of Fe > Zn > Mn > Cu > Ni > Pb > Cr > Cd > V in sediments and Fe > Zn > Mn > Cu > Ni > Cr > Pb > Cd > V in C. africana. The potential ecological risk index (PERI) values classified stations 1, 2 and 4 as of low ecological risk (PERI ≤ 150), while station 3 (PERI ≤ 300) was classified as of moderate ecological risk. Human health risk assessment for heavy metals in C. africana indicated significant non-carcinogenic health risk (HI > 1), and high carcinogenic risk to human health. The consumption of the contaminated C. africana, which is harvested in commercial quantities, portends health risk to the general public. There is need for urgent action in the abatement and regulation of identified anthropogenic activities responsible for the release of these heavy metals into the Osse River.

Investigating heavy metal pollution in Anzali coastal wetland sediments: A statistical approach to source identification

In this study, the pollution and bioavailability of heavy metals in the sediments of Anzali Wetland were measured by analyzing data from sequential chemical extraction of sediments, risk assessment code (RAC), and sediment pollution indices. The average RAC results indicated that the risk from Zn, Cr, Cu, and Hg was low, while the risk from Pb, Ni, As, and Cd was moderate. To identify the sources of heavy metal pollution in the sediments of Anzali Wetland, multivariate statistical techniques such as Pearson correlation analysis, cluster analysis (CA), and principal component analysis (PCA) were employed. The results of the statistical analyses at a high significance level revealed that Zn, Cr, Cu, Pb, Ni, and As were attributed to natural sources. Additionally, the statistical analyses demonstrated that the concentrations of Cd and Hg in the sediments of Anzali Wetland were influenced by non-oil organic sources and atmospheric deposition, respectively.

Assessment of heavy metals leachability characteristics and associated risk in typical acid mine drainage (AMD)-contaminated river sediments from North China

Acid mine drainage (AMD) is a worldwide environmental problem, characterized by low pH values and high concentrations of heavy metals. Heavy metal pollution of sediments caused by AMD has attracted widespread attention. However, research works on the leachability and distribution characteristics along with the ecological and health risks assessment of AMD-polluted sediment are limited. 15 sediments samples were collected from an AMD-polluted river, Shandi River, North China to analyze the leachability concentration, potential sources, and associated risk of eight metals, namely Ni, Cd, Cu, Zn, Fe2+, Fe3+, Pb, and Mn. Our results showed that Mn, Ni, Fe3+, and Fe2+ were the main leachate pollutants in the Shandi river. Certain levels of ecological risks existed in AMD-polluted stations and Ni was the common key metal that caused the high ecological risk factor in S1, S2, and S4. Cu, Ni, and Zn were the three metals that caused high or moderate risk to zebrafish. Mn and Fe were the main heavy metals that caused non-carcinogenic risks both for adults and children and Ni was another main heavy metal that caused non-carcinogenic risks for children. Ni and Cd can induce carcinogenic risks in these areas. Pearson's correlation and PCA results supported that these metals possibly originate from common AMD–polluted sources. The technology of “gravitational settling-neutralizing filter-aeration-coagulation-filtration” (GSNFACF) was an effective strategy to amend AMD and could be used for future cleaner production and environmental sustainability. These results suggested that the main contaminants in the sediments of the Shandi River should be preferentially treated by the government.

Sediment Heavy Metal Pollution Assessment in Changwang and Wuyuan Rivers in Hainan Island, China

Heavy metal pollution may pose a significant threat to aquatic ecosystems. To assess heavy metal pollution, sediment samples were collected from Changwang and Wuyuan Rivers between June and December 2019. An inductively coupled plasma mass spectrometer was used to analyze the concentrations of As, Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn. The results revealed that Changwang River had significantly high concentrations of Cr (240.70 mg kg−1), Co (36.02 mg kg−1), Ni (108.70 mg kg−1), and Cu (36.61 mg kg−1), whereas As (7.55 mg kg−1) was elevated in Wuyuan River. In addition, Cd, As, Pb and Zn concentrations were below China’s sediment quality standard limits (GB 3838-2002), but the Cr level exceeded the limit. However, Cr and Ni exceeded the probable effect concentrations (PEC) and thus may cause toxic effects. The contamination factor, geo-accumulation index, and modified degree of contamination revealed that Changwang experienced considerable to very high heavy metal pollution, while Wuyuan had low to moderate pollution. The pollution load index demonstrated that the rivers were polluted during all seasons. Additionally, the risk index showed considerable and moderate risks in Changwang and Wuyuan, respectively. The metal ecological risk was ranked as Cd > Ni > As > Co > Cu > Cr > Mn > Pb > Zn. Multivariate analyses categorized heavy metals into two groups based on their potential sources: group one included Cr, Co, Ni, Cu, Mn, and Zn, while group two contained As, Cd, and Pb. The study provides valuable data on heavy metal pollution, which needs improvement for the studied rivers. The data can be used to assess pollution risks and manage riverine sediment quality.

Heavy Metals in Sediments of Hulun Lake in Inner Mongolia: Spatial-Temporal Distributions, Contamination Assessment and Source Apportionment

The spatial and temporal distributions, contamination evaluation, and source apportionment of Cu, Zn, As, Pb, Cd, and Cr in the sediments of Hulun Lake were explored in this work. The pollution characteristics of six heavy metals were assessed by single factor pollution index (PI) and geo-accumulation index (Igeo). The sources of heavy metals in the surface sediments were analyzed by the positive definite matrix factorization (PMF) and Pearson correlation analysis. The sedimentary records of heavy metals in core sediments were reproduced by radioisotopes. The average concentrations of 6 heavy metals except Cd were lower than the corresponding background values. The spatial distributions of Cu, Zn, Cr, Cd and As were generally similar and showed higher abundances in the southwestern part of the lake. With the use and import of heavy metals, the concentration of heavy metals in core sediments increased with the fluctuation of years. The peak of heavy metal concentration was related to the high growth rate of gross domestic product in 2003-2008. The single factor pollution index and geo accumulation index results showed that the surface sediment was mainly polluted by Cd, followed by Zn and As. Natural parent material, agricultural activities and industrial activities were the main sources of heavy metal pollution in the sediments, accounting for 17.03%, 26.34%, and 56.63% of the total heavy metal accumulation, respectively. Pb was derived mainly from natural parent material. Cd and As were closely associated with agricultural activities. Cu and Zn were mainly attributed to industrial mining activities. Source apportionment of the ecological risks of heavy metals illustrated that industrial sources were the primary ecosystem risk sources (66.1%), followed by agricultural sources (23.75%) and natural sources (10.15%). The results will also provide reference data for future studies of heavy metals pollution in sediments from Hulun Lake and other lakes.

GIS-based approach and multivariate statistical analysis for identifying sources of heavy metals in marine sediments from the coast of Hong Kong.

Hong Kong is an urbanized coastal city which experiences substantially different metal loads from anthropogenic activities. This study was aimed at analyzing the spatial distribution and pollution evaluation of ten selected heavy metals (As, Cd, Cr, Cu, Pb, Hg, Ni, Zn, Fe, V) in the coastal sediments of Hong Kong. The distribution of heavy metal pollution in sediments has been analyzed using the geographic information system (GIS) technique, and their pollution degrees, corresponding potential ecological risks and source identifications, have been studied by applying the enrichment factor (EF) analysis, contamination factor (CF) analysis, potential ecological risk index (PEI), and integrated multivariate statistical methods, respectively. Firstly, the GIS technique was used to access the spatial distribution of the heavy metals; the result revealed that pollution trend of these metals was decreased from the inner to the outer coast sites of the studied area. Secondly, combining the EF analysis and CF analysis, we found that the pollution degree of heavy metals followed the order of Cu > Cr > Cd > Zn > Pb > Hg > Ni > Fe > As > V. Thirdly, the PERI calculations showed that Cd, Hg, and Cu were the most potential ecological risk factors compared to other metals. Finally, cluster analysis combined with principal component analysis showed that Cr, Cu, Hg, and Ni might originate from the industrial discharges and shipping activities. V, As, and Fe were mainly derived from the natural origin, whereas Cd, Pb, and Zn were identified from the municipal discharges and industrial wastewater. In conclusion, this work should be helpful in the establishment of strategies for contamination control and optimization of industrial structures in Hong Kong.

Contamination assessment and spatial distribution of heavy metals in the Sefidrud Delta coastal lagoons, Caspian Sea, N Iran.

Three coastal lagoons on the Sefidrud Delta, Caspian Sea, were investigated to evaluate heavy metal pollution in sediments. Amirkola Lagoon is located in the eastern part of the delta (abandoned delta lobe) and is aged more than 500 years, whereas Kiashahr and Zibakenar lagoons are in the western or active part delta lobe and formed in the last decades. One hundred six sediment samples and three sediment cores were taken from studied lagoons. The samples were analyzed by ICP-OES. Geo-accumulation index (Igeo), contamination factor (CF), degree of contamination (Cdeg), pollution load index (PLI), and Potential ecological risk index (RI) were employed to determine heavy metal pollution for Co, Cr, Cu, Ni, Pb, V and Zn. Nonparametric statistical analysis (Two-step cluster analysis, analysis of variance, and T-test technique) was used to discriminate the pollution sources. Based on contamination indices, the Kiashahr and Zibakenar lagoons show significant to moderate contamination with Co, Cu, Pb, Zn, and V, whereas the Amirkola Lagoon samples show the lowest metal contamination. PLI values demonstrated metal contamination in the Kiashahr and Zibakenar lagoons but no contamination in the Amirkola Lagoon. Although there was a notable rise in RI values from Amirkola to two other lagoons, all indicated low ecological risk. Statistical methods designated the unique interpretation of contaminant sources. Although the same geogenic origin of sediments in the Sefidrud Delta and lagoons deposits, Co, Zn, and Pb show anthropogenic sources in the newly-formed Kiashahr and Zibakenar lagoons.

Research progress and hotspot analysis of heavy metal pollution of sediments in the Bohai Sea based on CiteSpace literature metrology

Using the core collection of Web of Science and the literature of CNKI as data sources, this study uses the Citespace knowledge map analysis tool to analyze the annual publication volume, author group, publication organization, keyword clustering, and the emergence of heavy metals in Bohai Sea sediments. Then explore the research status, hotspots, and future development trends of heavy metals in Bohai Sea sediments. The organization with the most publications is the Chinese Academy of Sciences. The author with the most publications is Liu Jihua from the Qingdao National Marine Science and Technology Laboratory. The study of heavy metals in Bohai Sea sediments focuses on some areas' spatial distribution, risk assessment, and source analysis. In the future, we will further explore the large-area and long-term spatiotemporal distribution characteristics, quantitative source analysis, and comprehensive evaluation system of heavy metals in Bohai Sea sediments.

Coastal Sediment Heavy Metal Pollution Under Multifaceted Anthropogenic Stress: Insights Based on Geochemical Baselines and Source-Related Risks

Coastal Sediment Heavy Metal Pollution Under Multifaceted Anthropogenic Stress: Insights Based on Geochemical Baselines and Source-Related Risks

Understanding the Heavy Metal Pollution Pattern in Sediments of a Typical Small- and Medium-Sized Reservoir in China.

Heavy metal pollution in sediments is a common environmental issue in small- and medium-sized reservoirs not only in China but also worldwide; however, few interpretations of the pollution pattern exist. Based on the analyses of accumulation characteristics, ecological risks, and source apportionments of eight heavy metals (As, Cd, Cr, Cu, Hg, Pb, Ni, and Zn) in sediments, we derived a paradigm to describe the pollution pattern of heavy metals in sediments of a typical small- and medium-sized Tongjiqiao Reservoir. The results showed high levels of Cd, Hg, and As pollutants in the surface and upper sediment layers of the pre-dam area. Additionally, As, Cd, Hg, and Pb pollutants peaked in the middle layers of the inflow area, indicating a high ecological risk in these areas. The positive matrix factorization results implied that industrial, agricultural, and transportation activities were the main sources of heavy metals. The heavy metal pollution pattern exhibited three distinct stages: low contamination, rapid pollution, and pollution control. This pattern explains the heavy metal pollution process in the sediments and will provide scientific guidance for realizing the green and sustainable operation and development of the reservoir.

Heavy Metal in River Sediments of Huanghua City in Water Diversion Area from Yellow River, China: Contamination, Ecological Risks, and Sources

Determination of heavy metal (HM) contamination, ecological risks, and sources in river sediments are important to preventing and controlling environmental pollution. This study investigated the spatial distribution, potential ecological risks, and biological toxicity of five heavy metals in river sediments of Huanghua City in the water diversion area from the Yellow River, China. GIS, redundancy analysis (RDA), and the positive matrix factorization (PMF) model were used to accurately quantify the pollution sources and the spatial distribution of pollution sources. The results revealed that Cu had the highest degree of natural pollution, and the source mainly comes from traffic. Residential land (RL), population density (PD), GDP, and industrial construction (IC) make high contributions to traffic pollution; the highest level of potential ecological risk was Hg, and the source mainly comes from industrial wastewater discharges. IC makes a high contribution to industrial wastewater discharges pollution; the highest effect of bio-toxic risk was As, and the source mainly comes from farmland drainage water. Agricultural production potential (APP) and water area (WA) make high contributions to farmland drainage water pollution; Zn might be of natural origin, and woodlands (WLs) make high contribution to natural origin. This result provided a new idea for the system control of sediment heavy metal pollution in Huanghua City.

In Situ Remediation Technology for Heavy Metal Contaminated Sediment: A Review.

Sediment is an important part of the aquatic ecosystem, which involves material storage and energy exchange. However, heavy metal pollution in sediment is on the increase, becoming an important concern for the world. In this paper, the state-of-art in situ remediation technology for contaminated sediment was elaborated, including water diversion, capping, electrokinetic remediation, chemical amendments, bioremediation and combined remediation. The mechanisms for these techniques to reduce/immobilize heavy metals include physical, electrical, chemical and biological processes. Furthermore, application principle, efficiency and scope, advantages and disadvantages, as well as the latest research progress for each restoration technology, are systematically reviewed. This information will benefit in selecting appropriate and effective remediation techniques for heavy metal-contaminated sediment in specific scenarios.

A new method for identifying potential hazardous areas of heavy metal pollution in sediments

The combined effect of pollution source discharge and sediment adsorption leads to the rapid enrichment of heavy metals and other pollutants in lake sediments, which poses a serious threat to the lake ecosystem. Accurately identifying the risk areas of heavy metals in sediments is the key to lake sediment pollution control. Taking Taihu Lake as the study area, combined with the ecological risk status of heavy metals in sediments, the spatial clustering characteristics of pollution sources and the clustering information of sediment attributes, a potential toxic risk area identification method based on sediment source aggregation class (SLISA-SCA) was established. Through the source analysis of heavy metals in sediments, heavy metals such as Cr, Mn, Cu and Zn in Taihu Lake sediments were identified to have originated from natural sources and were subsequently disturbed by human activities to a certain extent. Cd was found to be strongly affected by human activities, and almost all Taihu Lake sediments were affected to varying degrees. In addition, the anthropogenic sources of heavy metals show high concentration clustering characteristics in the lake bay. By K-means cluster analysis of sediment attributes, three significant differences were obtained, which were determined as potential high pollution risk areas, potential medium risk areas and potential low risk areas, and the proportions were 5.6%, 27.6% and 66.8%, respectively. The SLISA-SCA model established in this study, from the perspective of source sinks, comprehensively considers the risks caused by pollution sources and sediment attributes to sediments and divides Taihu Lake into five different risk control areas (high-risk control area, potential high-risk control area, potential risk control area, potential low-risk control area and low-risk control area). This study identified areas with different levels of heavy metal pollution in Taihu Lake sediments, proposes corresponding treatment measures, and provides a scientific and systematic method and technology for the pollution management of other river and lake sediments in the world.

Determining heavy metal pollution in sediments from the largest impounded lake in the eastern route of China's South-to-North Water Diversion Project: Ecological risks, sources, and implications for lake management

The eastern route of the South-to-North Water Diversion Project (ER-SNWDP) is a major human health project designed to alleviate the water scarcity in the Beijing-Tianjin-Hebei region in China. Impounded lake water security is directly related to the water diversion project effectiveness. At present, there is not a thorough understanding of the sediment heavy metals in Lake Hongze, the largest impounded lake of the ER-SNWDP. Consequently, this study reports a distribution analysis of Cu, Zn, Pb, Cr, Cd, As, Hg, and Ni in 101 sediment samples from Lake Hongze; we, utilized the enrichment factor, geoaccumulation index, and potential ecological risk index for the are to determine the ecological risk of heavy metals. The heavy metal source was examined with correlation analysis and principal component analysis–multiple linear regressions. The results showed that the average heavy metal content (Cu, Zn, Pb, Cr, Cd, As, Hg, Ni) were 0.03–1.57 times greater than the Jiangsu Province background values. Cd, As, and Hg were the main contributors to the Lake Hongze ecological risk. Spatially, the open water area was the most polluted among the four lake parts, and most of the flushing area had a low ecological risk. Chengzi bay and the western lake area have similar risk profiles, but are lower than the open water area risk. Source analysis showed that nonpoint-source agricultural pollution and industrial production were important pollution sources, while a considerable portion of the heavy metal content came from atmospheric deposition and natural sources. This study identified the main contamination areas and revealed the possible sources of each heavy metal; as such, this study can serve as a reference for the remediation and management of Lake Hongze to ensure the water safety of the ER-SNWDP.

Evaluation and Source Analysis of Heavy Metal Pollution in Sediments of the Yellow River Basin Based on Monte Carlo Simulation and PMF Model

As sediment is an essential component of rivers, the enrichment of heavy metals in sediment presents a serious threat to the aquatic environment. Many industrial cities are located along the Yellow River, and heavy metal pollution is a prominent problem in these areas. Thus, the study of heavy metal pollution in sediments of the Yellow River basin is of vital significance to the safety of the Yellow River basin ecosystem. In this study, we collected data on the concentrations of heavy metals (Pb, Cd, Cr, As, Zn, Cu, Ni, and Hg) in the sediments of the Yellow River basin from 2000 to 2020. We first analyzed the spatial distribution characteristics of heavy metals based on descriptive statistics and geostatistics and then used the Monte Carlo method to evaluate the probability of the ground accumulation index(Igeo), potential ecological risk, and toxicity units. Finally, the number of pollution sources and their contribution rates were determined by combining the positive definite matrix factor (PMF) decomposition model and Pearson correlation analysis. It was found that the mean values of ω(Pb), ω(As), ω(Zn), ω(Ni), ω(Cu), ω(Hg), ω(Cr), and ω(Cd) in the Yellow River basin sediments were 26.92, 11.78, 87.17, 31.13, 24.96, 0.07, 73.36, and 0.58 mg·kg-1, which exceeded the mean soil background values in the Yellow River basin provinces by 1.27, 1.08, 1.26, 1.05, 1.09, 2.32, 1.14, and 5.95 times, respectively, among which Cd exceeded the standard by the largest factor and should be taken seriously. The Igeo was ranked as Cd>Hg>Cr>Cu>Pb>Zn>As>Ni, and Cd and Hg showed medium-severe pollution. The proportions of heavy ecological risk in sediments in the upper, middle, and lower reaches of the Yellow River basin were 18.6%, 15.7%, and 7.1%, respectively, with a decreasing trend. Heavy metals in the sediments of the Yellow River basin were in a low-toxicity state. The PMF-Pearson correlation analysis showed that the four sources of heavy metals in the Yellow River basin sediments were mining sources (42.2%), natural activities (38.3%), agricultural activities (11.6%), and electroplating wastewater (7.9%). The results of this study can provide a basis for developing relevant pollution prevention and control measures in the Yellow River basin.