Main Sources Of Heavy Metals Research Articles

Assessment of health risks based on different populations and sources of heavy metals on agricultural lane in Tengzhou City by APCS-MLR models.

To identify the sources of heavy metals in local soils and their risks to human health. This study quantified the concentrations of eight heavy metals in 504 soil samples collected in Tengzhou, China. The ecological risks of a single heavy metal (EI), a comprehensive ecological risk index (RI), and a health risk assessment model were used to evaluate the level of contamination in the city. The results of the research study indicate that there are different levels of heavy metal pollution in rural and urban agricultural areas in Tengzhou. Moreover, the spatial variability of mercury (Hg) is considerable, reaching 0.96, indicating a significant impact of anthropogenic activities. For the ecological risk, the heavy metal element with the highest EI value was mercury with a mean value of 67.22 and a peak value of 776.00. The heavy metal with the lowest mean EI value was Zn with only 1.03. Meanwhile, the average RI is only 128.59, but some areas have an RI as high as 842.2. The sources of heavy metals were identified using principal component analysis, correlation analysis, and an absolute principal component score multiple linear regression model (APCS-MLR). The non-carcinogenic risk for children, the carcinogenic risk for children, and the carcinogenic risk for adults were 1.23, 2.42×10-4 and 1.00×10-4, respectively, and these values exceeded their respective recommended values, and As and Cr had some carcinogenic hazards. Heavy metals in the soil come from natural, industrial, traffic and agricultural sources and represent 39.59%, 29.48%, 25.17% and 5.77%, respectively. The main source of heavy metals in local agricultural soils is the geological background, and the government needs to strengthen the monitoring of As and Cr in drinking water resources, as well as reduce traffic pollution and factory waste emissions to reduce Hg in soils.

Source and Influencing Factor Analysis of Soil Heavy Metals Based on PMF Model and GeoDetector

In Lijiang City, as a typical example, 93 soil samples were collected from the study area, and soil pH； organic matter； and heavy metals arsenic （As）, mercury （Hg）, copper （Cu）, zinc （Zn）, lead （Pb）, cadmium （Cd）, and chromium （Cr） were determined. We explored the sources of heavy metals in the study area by means of Positive Definite Matrix Factorization （PMF） modeling and analyzed the impact of influencing factors by combining seven heavy metals with 13 influencing factors in a GeoDetector. The results showed that the mean values of soil heavy metals ω（As）, ω（Hg）, ω（Cu）, ω（Zn）, ω（Pb）, ω（Cd）, and ω（Cr） in the study area were 17.55, 0.19, 86.75, 164.84, 28.95, 0.39, and 167.87 mg·kg-1, respectively, which were greater than the background values of soils in Yunnan Province （except for As and Pb）. Regarding spatial distribution, the high values of Cu and Cr content were mainly concentrated in Yulong Naxi Autonomous County； the high value areas of As, Hg, Pb, and Cd were mainly concentrated in Ninglang Yi Autonomous County； and the high value of Zn content was mainly concentrated in Huaping County. Correlation analysis and PMF modeling revealed that the main sources of heavy metals As and Hg in the study area were industrial sources, Zn was from transportation pollution sources, Cr and Cu were from natural sources, and Cd and Pb were from agricultural sources. Further, the factor detector of the GeoDetector found that soil pH and organic matter （OC） had strong explanatory power for the content of seven heavy metals, and the interaction detector found that the results following the interaction of different influencing factors were nonlinear enhancement or two-factor enhancement, in which the interaction of OC and pH was the dominant factor for the spatial differentiation of heavy metals. This provides an important scientific basis for the protection of the soil environmental health and sustainable development in Lijiang City.

Determining priority control factors for heavy metal management in urban road dust based on source-oriented probabilistic ecological-health risk assessment: A study in Xi'an during peak pollution season

Urban road dust (URD) is essential for transporting heavy metals (HMs), which can be a major danger to both the environment and human health. Moreover, URD has the potential to be carried into bodies of water, leading to contamination of the aquatic ecosystem. A study was conducted in Xi'an, a city in northwestern China known for high air pollution levels, during January 2024 - a period characterized by peak pollution due to frequent low wind speeds and temperature inversions. The research investigated the presence of 10 types of HMs (Cu, Zn, Cd, Cr, Pb, As, Ni, Hg, Co, and Mn) in URD. Findings revealed elevated levels of Cu, Zn, Cd, Cr, Pb, As, and Hg in URD compared to background levels. Hg showed the most significant contamination (moderate to heavy), followed by moderate contamination of Cd, and lower levels of As, Zn, and Cu. The main sources of HMs were traffic (58.2%), mixed natural and industrial (30.3%), and industrial (11.5%). The ecological risk in the area was deemed to be very high, primarily because of Hg and Cd. Based on probabilistic health risk assessments, it was determined that non-carcinogenic risks were deemed acceptable for all groups. Nevertheless, the possibility of carcinogenic risks should not be disregarded. Strategies for controlling ecological-health risks prioritize mixed natural and industrial sources, with a focus on Hg, Cd, and As in URD. The results offer a foundation for policymakers to create specific control strategies.

Source Apportionment and Response to Landscape Pattern of Health Risk of Cultivated Soil Heavy Metals

Heavy metal pollution mainly caused by human activities is becoming increasingly prominent and threatening human health and ecosystem safety in soil, which is a non-renewable natural resource that humans rely on for survival and development. Assessment and analysis of soil heavy metal health risk is significant for protecting human health, preventing soil pollution, and maintaining ecosystem security. Based on the investigation of heavy metals, including Cr, Pb, Cd, As, and Hg, in cultivated soil in Liuhe District, the health risk assessment model was used to identify the health risk characteristics of heavy metals, and the spatial distribution, main sources, and responses to landscape patterns were explored by using inverse distance weight interpolation, positive definite matrix factorization, landscape pattern index, and redundancy analysis. The results showed that the coefficients of variation corresponding to Cr, Pb, Cd, As, and Hg in the study area were 0.19, 0.36, 0.23, 0.52, and 1.16, respectively, all of which belonged to moderate or high variability, indicating that they had high spatial heterogeneity and were susceptible to human factors. Cr, Pb, and As were the main health risk characteristic factors in the study area, with the carcinogenic risks to children ranging from 13.307×10-6 to 38.400×10-6, 0.839×10-6 to 3.250×10-6, and 4.548×10-6 to 16.680×10-6, respectively, which were higher than those in adults. Agricultural production activities, industrial production, and transportation activities were the main sources of heavy metals, with carcinogenic risks to children of 17.946×10-6 and 12.941×10-6, respectively. Furthermore, high-risk areas caused by agricultural production activities were mainly concentrated in the northern area of Liuhe District and showed an increasing trend from south to north and from the center to the periphery. The surrounding areas caused by industrial production activities and transportation were mainly concentrated in the chemical industry park and economic development zone of Liuhe District and showed a spatial agglomeration feature of decreasing from south to north and from the core to the periphery. The cumulative explanatory value of the landscape pattern index for the comprehensive carcinogenic risk to children was 0.463, and patch density, patch proportion in landscape area, patch aggregation degree, and maximum patch index had significant effects on the comprehensive carcinogenic risk in children, and the corresponding explanatory values were 0.422, 0.274, 0.351, and 0.232, respectively. This study had important theoretical and practical significance for expanding the perspective of environmental health research, promoting the transformation of soil heavy metal management methods and safeguarding regional population health.

Health Risk Assessment of Road-Dust-Bound Heavy Metals via Ingestion Exposure from One Typical Inland City of Northern China: Incorporation of Sources and Bioaccessibility

Heavy metals in road dust pose potential health risks to humans, while oral bioaccessibility and sources are all important factors influencing this health risk. However, few prior studies have combined them for health risk analysis. In this study, road dust samples were collected from different geographical locations of Jinan (west area, WA; central area, CA; and east area, EA) to analyze the source-specific and bioaccessibility-based health risks of heavy metals. The mean concentrations of heavy metals in the three areas were CA > EA > WA, with Cd, Cu, Mn, Pb, and Zn exceeding their corresponding background values. A source analysis using a Positive Matrix Factorization (PMF) model showed that traffic emissions were the main source of heavy metals in the WA and CA, while industrial activities were the main source in the EA. The mean bioaccessibility of heavy metals extracted using the Solubility Bioaccessibility Research Consortium (SBRC) method followed the order of Cd (75.5%) > Zn (42.2%) > Mn (42.1%) > Pb (42.0%) > Cu (32.9%) > As (23.6%) > Ni (20.1%) > V (16.8%) > Cr (13.3%). According to the combined source analysis, traffic was the primary risk factor in the WA (54.5 and 58.3% of NCR and CR, respectively) and CA (61.8 and 51.2%), with solid waste being the main risk factor in the EA (41.9 and 51.3%). In oral bioaccessibility testing, lower non-carcinogenic (<1.0) and carcinogenic risks (<1 × 10−6) of heavy metals were observed than those based on the total metal content. More importantly, As (43.4%) was replaced by V (29.7%) as the main contributor to NCR. Source-specific and bioaccessibility-based health risk assessments can accurately identify priority pollutants and heavy metals in urban road dust that need to be controlled. This provides more effective and accurate urban environmental risk management recommendations for sustainable urban development and population health.

Unveiling Heavy Metal Pollution in Soils and Rice Crops (Oryza sativa L.) Cultivation

The landscape changes through the increasing built-up areas (settlements and industrial) have a potential impact on reducing the quality of agricultural land. Waste from anthropogenic activities (industrial and domestic) is the main source of heavy metals that can affect rice production in the fields. This study examines the quality changes of paddy fields (Oryza sativa L.) polluted by wastewater in Muara Bakti Village, Bekasi Regency. Wastewater's impact on paddy fields is known through heavy metal contamination analysis in soil and rice plants. Chemical analysis of soil, water and plants was completed by the Balai Penelitian Tanaman Sayuran (Balitsa) Laboratory, West Bandung. The results showed that heavy metal levels such as lead (Pb) and cadmium (Cd) in the paddy soil samples were above the threshold in soil, respectively more than 25 mg/l and 0.01 mg/l. In contrast, the rice plant samples, it was identified as containing heavy metals such as Cd and chromium (Cr). Pb content was not detected in the rice plants. Soil in Muara Bakti Village contained optimal nutrients that are still suitable for agriculture. However, heavy metal content detected in soil samples and rice plants requires special handling to prevent endangering the agroecosystem and human health. Keywords: Agroecosystem, Heavy metals, Paddy fields, Soil pollution, Waste

Distribution Characteristics, Risk Assessment, and Source Analysis of Heavy Metals in Farmland Soil of a Karst Area in Southwest China

Soil environmental quality related to the residents’ life, health, and safety, has been the hotspot issues in science of ecological environment protection. Evaluating the distribution characteristics, ecological risk, and source of heavy metals in farmland is important for protecting soil resources. The agricultural area of Lianhua town, Gongcheng County, Guilin is a typical karst landform. In response to the problem of heavy metal pollution and complex sources in the soil of this area, the characteristics and sources of heavy metal pollution in the soil profiles from farmland, abandoned land, and forest were studied using the single-factor index method, the geoaccumulation index (Igeo) principal component analysis (PCA) and positive matrix factorization (PMF) model. The results showed that: (1) that the contents of cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) in the soil profile of the study area were higher than that of the soil elements background values in Guangxi. The total and available forms contents of all heavy metal elements exhibited the characteristics of accumulation in the surface profile; (2) among the six heavy elements, the contents of Cd were in a moderately to heavily polluted state. The contents of Cd in some soil profiles exceeded the control standard for agricultural land soil pollution. The contents of Zn and Ni were from slightly to moderately polluted in areas with frequent agricultural activities; (3) according to the PCA and PMF model, there were three main sources of heavy metals in the study area. Among them, Cd, Cu, Ni, and Zn are related to agricultural activities; the elements As, Cd, Cr, and Hg are closely related to geological background; Pb and Zn are mainly affected by atmospheric sedimentation of transportation. Agricultural activities and natural geological background are the main contribution sources of heavy metals in soil. Human activities are the main factors that cause the accumulation of heavy metals in soil. This research has theoretical guidance and practical significance for the prevention and control of soil heavy metal pollution and the protection of farmland environmental quality in the region.

Health Risk Assessment of Heavy Metals in Soils of a City in Guangdong Province Based on Source Oriented and Monte Carlo Models

Taking a city in Guangdong Province as the research area, the concentration and spatial distribution characteristics of heavy metals in the surface soil were studied to clarify the situation of soil heavy metal pollution and priority control factors, providing basic data for the prevention and control of soil heavy metal pollution in the city. The content characteristics of heavy metals in 221 soil samples in the city were analyzed, and the potential health risk assessment and source analysis were carried out through the Monte Carlo model, the potential health risk assessment (HRA) model, and the PMF receptor model. It was found that heavy metals ω(As), ω(Hg), ω(Cd), ω(Pb), ω(Cr), ω(Cu), ω(Ni), and ω(Zn) in the soil of the city were 18.16, 0.43, 1.46, 68.57, 98.34, 64.19, 26.53, and 257.32 mg·kg-1, respectively, with a moderate to high degree of variation. Except for Ni concentration, the soil concentrations of other heavy metal elements exceeded the background values of soil in Guangdong Province to a certain extent, and the concentrations of Cd and Zn exceeded the national secondary standards, resulting in severe heavy metal pollution; the main sources of heavy metals were industrial sources, and natural parent materials, lead battery manufacturing, transportation, artificial cultivation, and pesticide and fertilizer inputs also had an undeniable impact on the accumulation of heavy metals in the soil. Heavy metals in the soil had a certain degree of tolerable carcinogenic health risk for both children and adults, whereas non-carcinogenic risks could be ignored. The potential health risk of children was greater than that of adults, and the main exposure route was through oral intake. The input sources of pesticides and fertilizers and As should be the main controlling factors for the health risks of heavy metals in the city's soil, followed by mixed sources and Cr. There were differences in the spatial distribution characteristics and relative pollution levels of heavy metals, and it is necessary to deepen zoning monitoring and control, strengthen soil pollution prevention and control, and reduce human input of heavy metals in soil.

Source-specific probabilistic health risk assessment of heavy metals in surface water of the Yangtze River Basin

The detrimental effects of heavy metal accumulation on both ecosystems and public health have raised widespread concern. Source-specific risk assessment is crucial for developing effective strategies to prevent and control heavy metal contamination in surface water. This study aims to investigate the contamination characteristics of heavy metals in the Yangtze River Basin, identifying the pollution sources, assessing the risk levels, and further evaluating the health risks to humans. The results indicated that the average concentrations of heavy metals were ranked as follows: zinc (Zn) > arsenic (As) > copper (Cu) > chromium (Cr) > cadmium (Cd) > nickel (Ni) > lead (Pb), with average concentrations of 38.02 μg/L, 4.34 μg/L, 2.53 μg/L, 2.10 μg/L, 1.17 μg/L, 0.84 μg/L, and 0.32 μg/L, respectively, all below the WHO 2017 standards for safe drinking water. The distribution trend indicates higher concentrations in the upper and lower reaches and lower concentrations in the mid-reaches of the river. By integrating the Absolute Principal Component Scores-Multiple Linear Regression (APCS-MLR) receptor model and Positive Matrix Factorization (PMF) model, the main sources of heavy metals were identified as industrial activities (APCS-MLR: 41.3 %; PMF: 42.1 %), agricultural activities (APCS-MLR: 30.1 %; PMF: 27.4 %), and unknown mix sources (APCS-MLR: 29.1 %; PMF: 30.4 %). The calculation of the hazard index (HI) for both children and adults was <1, indicating no non-carcinogenic or carcinogenic risks. Based on the source-specific risk assessment, agricultural activities contribute the most to non-carcinogenic risks, while industrial activities pose the greatest contribution to carcinogenic risks. This study offers a reference for monitoring heavy metals and controlling health risks to residents, and provides crucial evidence for the utilization and protection of surface water in the Yangtze River Basin.

Characteristics and Identification Priority Source of Heavy Metals Pollution in Farmland Soils in the Yellow River Basin

Assessments of the soil environmental quality of farmland and pollution source apportionment are the foundation for ensuring national food security and agricultural sustainable development, as well as an important prerequisite for the pursuit to keep our lands clean. This study evaluated the characteristics of heavy metal pollution in farmland soils in the Yellow River Basin from 2000 to 2023, based on the data of heavy metal contents including As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn, using the geo-accumulation index method. Source apportionment was conducted by employing a positive matrix factorization (PMF) model. The probabilistic health risks were evaluated by coupling Monte Carlo simulation with a human health risk assessment model, and priority pollution sources and elements were identified. The results showed that:① the average content of all heavy metals in farmland soils within the study area was lower than the screening values specified in the soil environment quality risk control standard for soil contamination of agriculture land (GB 15618-2018) (pH>7.5). However, the contents of Cd, As, and Zn in the samples exceeded their screening values, with percentages of 21.69%, 5.56%, and 1.23%, respectively, with Cd having the highest rate of exceedance. ② Hg and Cd were moderately polluted, Cu and Pb were slightly polluted, and the other elements were not polluted. ③ The main sources of heavy metals in farmland soil were traffic-industrial sources, natural-agricultural sources, industrial-natural sources, and agricultural-industrial sources, with contribution rates of 37.04%, 26.69%, 21.72%, and 14.55%, respectively. ④ Heavy metals in farmland soil posed carcinogenic health risks to adults and children but did not have non-carcinogenic risks; As and Cd were priority control elements for human health risks, and industrial-natural sources and agricultural-industrial sources were priority control sources in the study area.

Risk assessment and source identification of soil heavy metals: a case study of farmland soil along a river in the southeast of a mining area in Southwest China.

To investigate the heavy metals (HMs) contamination of surface farmland soil along the river in the southeast of a mining area in southwest China and identify the contamination sources, 54 topsoil samples were collected and the concentrations of seven elements (Zn, Ni, Pb, Cu, Hg, Cr, and Co) were determined by inductively coupled plasma optical emission spectrometry (ICP-OES) and atomic fluorescence spectrometry (AFS). The geo-accumulation index ([Formula: see text]) and comprehensive potential ecological risk index ([Formula: see text]) were used for analysis to determine the pollution degree of HMs and the risk level of the study area. Meanwhile, the Positive Matrix Factorization (PMF) model was combined with a variety of statistical methods to determine the sources of HMs. To explore the influence of the river flowing through the mining area on the concentrations of HMs in the farmland soil, 15 water samples were collected and the concentrations of the above seven elements were determined. The results showed that the concentrations of Pb, Cu, and Zn in soil all exceeded the risk screening value, and Pb in soil of some sampling sites exceeded control value of "Agricultural Land Soil Pollution Risk Control Standard".[Formula: see text] showed that Pb was heavily contaminated, while Cu and Zn were moderately contaminated. RI showed that the study area was at moderate risk. PMF and various statistical methods showed that the main source of HMs was the industrial source. In the short term, the river flowing through the mine has no significant influence on the concentration of HMs in the soil. The results provide a reference for the local government to control contamination and identify the sources of HMs.

Road dust exposure and human corneal damage in a plateau high geological background provincial capital city: Spatial distribution, sources, bioaccessibility, and cytotoxicity of dust heavy metals

Ocular surface diseases are common in the plateau city, Kunming China, the continued daily exposure to heavy metals in dust may be an important inducement. In this study, the 150 road dust samples from five functional areas in Kunming were collected. The concentrations, distribution, possible sources, and bioaccessibility of heavy metals were analyzed. The adverse effects of dust extracts on human corneal epithelial cells and the underlying mechanisms were also assessed. The concentrations (mg·kg−1) of As (19.1), Cd (2.67), Cr (90.5), Cu (123), Pb (78.4), and Zn (389) in road dust were higher than the soil background, with commercial and residential areas showing the highest pollution. Their bioaccessibility in artificial tears was As (6.59 %) > Cu (5.11 %) > Ni (1.47 %) > Cr (1.17 %) > Mn (0.84 %) > Cd (0.76 %) > Zn (0.50 %) > Pb (0.31 %). The two main sources of heavy metals included tire and mechanical abrasion (24.5 %) and traffic exhaust (21.6 %). All dust extracts induced cytotoxicity, evidenced by stronger inhibition of cell viability, higher production of ROS, and altered mRNA expression of antioxidant enzymes and cell cycle-related genes, with commercial- areas-2 (CA2)-dust extract showing the greatest oxidative damage and cell cycle arrest. Our data may provide new evidence that dust exposure in high geological background cities could trigger human cornea damage.

Heavy Metal Content Characteristics and Pollution Source Analysis of Shallow Groundwater in Tengzhou Coal Mining Area

This study analyzed the sources of total metal elements using the positive matrix factorization (PMF) model and conducted human health risk assessment for adults and children using the health risk assessment model recommended by the United States Environmental Protection Agency (USEPA). According to the health risk assessment, As is the main contributor to the non-carcinogenic risk of groundwater in Tengzhou, with drinking water as the main exposure route. Regarding carcinogenic risks (CR), the values of As and Cr for adults and children were higher than 1 × 10−4, with drinking water as the main exposure route. Therefore, As is the largest contributor to the CR of groundwater for adults and children and drinking water is the main exposure route in the study area. The primary exposure pathways are oral intake and dermal contact, with oral intake presenting a significant risk. The carcinogenic risks according to principal component analysis (PCA) and PMF analysis showed that the main sources of heavy metals in shallow groundwater in Tengzhou City are agricultural, industrial, natural, and industrial deposition sources, with contribution rates of 21.7%, 27.2%, 31.0%, and 20.1%, respectively. In particular, natural sources are the largest contributor to the accumulation of heavy metals.

Spatial and Temporal Distribution and Source Analysis of Heavy Metals in Agricultural Soils of Ningxia, Northwest of China

The spatial and temporal dynamic monitoring of the heavy metal concentration in agricultural soils can help us to understand the extent and changes of regional soil heavy metal pollution, allowing us safeguard food safety and human health and provide basic data for the prevention and control of heavy metal pollution in agricultural soils. The heavy metals’ concentrations, including Cd, Cr, Cu, Hg, Ni, Pb, Zn, and As, were measured in surface (0–20 cm) soil samples collected in 2017 and 2021 from agriculture land to evaluate their pollution levels in the Ningxia Hui Autonomous Region (Hereinafter referred to as Ningxia), northwest of China. A correlation analysis, principal component analysis, and positive matrix factorization were used jointly to identify possible sources. The results showed that, for most soils, the concentrations of As, Cr, Cu, Ni, Pb, and Zn were lower than the contamination thresholds stipulated by the national guideline. The average concentrations of As, Cd, Zn, and Ni in 2021 were significantly lower than the levels in 2017 (p &lt; 0.05), but the average concentration of Cu was significantly higher in 2021 than in 2017 (p &lt; 0.05), and the average concentrations of Cr, Pb, and Hg did not change significantly during the last five years. According to the pollution assessment index (mean Igeo values), Cd and Hg were found to accumulate in the farmland environment and were the major pollutants in the region, and the hotspots with high concentrations of heavy metals were mainly located in the Yellow River irrigation area in Northern Ningxia. Four main sources of heavy metals in the soils were identified: As mainly originated from natural sources; Pb, Cd, and Ni from atmospheric deposition and industrial activities; Cr, Zn, and Cu from agricultural activities; and Hg from the coal-related industrial activities. The concentration of heavy metals from anthropogenic sources accounted for 77.10% in agricultural soils, indicating the strong influence of this source on soil heavy metal accumulation. These findings provide scientific evidence and valuable information to prevent heavy metal contamination and control of farmland.

Incorporating source apportionment and bioaccessibility into human health risk assessment of heavy metals in a soil-rice system in the Jiulong River basin, southeast China

A positive matrix factorization–bioaccessibility–Monte Carlo simulation–human health risk assessment (PMF–BA–MCS–HHRA) model was developed to accurately assess the cumulative probability distributions of carcinogenic and non-carcinogenic risks posed by heavy metals in the soil-rice system of the Jiulong River basin, and to quantify the sources of the health risks. The results showed that natural, agricultural, industrial, and coal combustion sources were the four main sources of heavy metals. The bioaccessibilities of heavy metals through grain ingestion were significantly higher than other exposure pathways. A non-carcinogenic risk was posed by arsenic (As) and a carcinogenic risk by cadmium (Cd). The non-carcinogenic risks of heavy metals were higher for children than for adults, while the opposite was true for carcinogenic risks. The grain ingestion pathway presented the greatest health risk from heavy metals in the soil-rice system. The non-carcinogenic risks were mainly derived from industrial sources, while the carcinogenic risks primarily came from agricultural sources. Arsenic derived from industrial sources and Cd derived from agricultural sources should be prioritized for control. Grain ingestion should be considered the priority exposure pathway for control. These results provide important theoretical and practical references for human health risk assessment and source management of heavy metals in soil-rice systems.

Source Analysis Based on the Positive Matrix Factorization Models and Risk Assessment of Heavy Metals in Agricultural Soil

Soil heavy metal pollution is a severe and growing problem, and it is crucial to assess the level of soil heavy metal contamination and determine the origins of pollutants. However, there is limited research on soil heavy metal source apportionment and its carcinogenic and non-carcinogenic hazards. Positive Matrix Factorization (PMF) is a powerful technique for source apportionment of pollutants in environmental matrices such as atmospheric particulate matter and soil, as it can handle missing and imprecise data to ensure data reliability, among other benefits. In order to explore the distribution characteristics and main sources of heavy metals in agricultural land, the contents of Cd, Cr, Cu, Pb, and Ni were collected and determined. The positive matrix factorization (PMF) model was used to analyze the source of heavy metals in the soil in the study area, and the human health risk evaluation was carried out. The results showed that (1) the coefficient of variation of Cd in the four areas was much higher than that of the other four heavy metals, which showed strong variability; (2) the content and distribution of heavy metals in different regions were different under the influence of different environments; (3) the PMF model analysis showed that the heavy metal pollution sources in the four areas were divided into two types: the soil parent material, which had industrial pollution, traffic pollution, and agricultural pollution; and the contribution rate of each pollution source; (4) the non-carcinogenic risks of heavy metals in children at all points in the study area were greater than those of adults, and the carcinogenic risks were the opposite of the carcinogenic risk in the study area. And the most serious carcinogenic risk in the study area was the harm caused by oral ingestion of heavy metal Cr into the adults’ bodies.

Distribution and Source Resolution of Heavy Metals in an Electroplating Site and Their Health Risk Assessment

It is very important to understand the distribution and sources of typical potentially toxic elements in industrial sites in order to provide essential information for risk assessment and the process of land reclamation selection. Here, around 29 soil column samples of 6 m depth were collected using a geoprobe drill rig from a typical electroplating site located in the Yangtze River Delta, which has been operating for more than 20 years. Analysis in the laboratory, including measurement of elemental concentrations using ICP-OES, was carried out. The distribution and sources of typical heavy metals were investigated, and correlated risks were assessed using positive matrix factorization. As, Pb, and Cr were the dominant heavy metal pollutants, with ranges of 3.20–154 mg/kg, 13.9–9271 mg/kg, and 27.2–2970 mg/kg, which were 1.28 times, 11.6 times, and 3.71 times higher than the Chinese national standard, respectively. Pb was found to be accumulated in the top 0–2 m and As in the top 0–3 m due to the presence of a typical clay and loamy soil. Additionally, Cr could be transferred into the groundwater, with a maximum concentration of 497 mg/kg, due to frequent interaction between the groundwater and soil. A PMF model showed that the dominant sources of pollution were the electroplating process section, the glass melting process section, the production process section, and the electroplating wastewater. Pb, As, and Cr were mainly generated from the industrial production process, glass melting process, and electroplating process. The pH and CEC appeared to influence the chemical speciation greatly, with higher content observed bound to carbonates as a result of exchange processes in the case of high CEC and low pH conditions. Both the Pb and As observed could contribute to non-carcinogenic and carcinogenic health risks, respectively, based on PMF-HRA analysis, which should receive greater attention in risk management strategies for polluted sites. Identification of the main sources of heavy metals in a site could provide a basis for potential land reclamation.

Enrichment Characteristics and Health Risk Assessment of Heavy Metals in Soil-Crop Systems

The effects of heavy metals in soil-crops systems, their enrichment characteristics, and health risks were investigated by analyzing the As, Cr, Cu, Pb, Cd, and Hg in 216 paired soil and crop samples from Yuyao, Zhejiang Province, China. Statistical analyses, enrichment characteristics, and health risks to adults were assessed using the health risk assessment model used by the U. S. Environmental Protection Agency. The results showed that the main sources of heavy metals were atmospheric pollution, water pollution, and pesticide spraying, that caused local pollution in bayberry soil, and that the Pb pollution source may be industrial waste and oil combustion release. They also indicated that the sources polluting bayberry soil with Cu and Hg were probably the same, the mustard-soil system had a relatively lower absorption capacity for heavy metals, and there was a significant correlation between heavy metals in the soil-rice system. The main carcinogenic risk factors associated with bayberry intake were As and Cr, but there were no non-carcinogenic and carcinogenic risks associated with rice intake. The non-carcinogenic and carcinogenic risks associated with bayberry could be reduced by planting on land not exposed to air and industrial pollution and to avoid spraying bayberry with pesticides.

Source Analysis and Pollution Assessment of Soil Heavy Metals in Typical Geological High Background Area in Southeastern Chongqing

In order to understand the pollution characteristics of soil heavy metals in typical geological high background areas in southeastern Chongqing, analyze its pollution sources, and put forward risk management and control suggestions, 211 topsoil samples (0-20 cm) were collected in Xinglong Town and Muye Township in the north of Youyang County, Chongqing City, and the contents of eight heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) and the soil pH value in the surface soil were analyzed. Additionally, mathematical statistics, pollution load index (P), potential ecological risk index (RI), correlation analysis, and the positive matrix factorization (PMF) model were used to study the content and spatial distribution characteristics of heavy metals in the topsoil, and pollution assessment and source analysis of heavy metals were carried out. The results showed that the average concentrations of heavy metals in the surface soil all exceeded the soil background value in Chongqing, showing different levels of enrichment. Among them, the proportion of Cd exceeding the screening value in the "soil environmental quality risk control standard for soil contamination of agricultural land" (GB 15618-2018) was as high as 83.41%, the proportion of exceeding the control value was 7.58%, and the potential risk was relatively high. The evaluation results of the pollution load index method showed that the study area was slightly polluted as a whole, and the evaluation results of the potential ecological risk index showed that the overall ecological risk of the study area was relatively high. Among them, the contribution rates of heavy metals Hg, Cd, and As were 50.27%, 28.63%, and 11.70%, respectively. The PMF results showed that there were three main sources of heavy metals in the soil in the study area:natural parent material sources, agricultural sources, and mixed sources of industrial activities and traffic emissions, accounting for 40.49%, 29.12%, and 30.39%, respectively. The quantitative source analysis results of soil heavy metals in the study area have important reference significance for soil heavy metal pollution control in geologically high background areas.

Analysis on the Distribution Characteristics and Influence Mechanism of Migration and Transformation of Heavy Metals in Mining Wasteland

In order to explore the distribution characteristics and the influence mechanism of migration and transformation of heavy metals in mining wasteland, soil and tailings samples were collected from the mining wasteland in the Dabaoshan Mining area, Guangdong Province, and the morphological characteristics of heavy metals were analyzed. At the same time, the pollution sources of the mining area were analyzed using Pb stable isotope analysis, and the characteristics and influencing factors of heavy metal migration and transformation in the mining area were expounded by combining X-ray diffraction analysis, transmission electron microscope-energy spectrum analysis (TEM-EDS), and Raman analysis of typical minerals in the mining area, as well as laboratory-simulated leaching experiments. Morphological analysis showed that the forms of Cd, Pb, and As in the soil and tailings samples in the mining area were mainly the residual phase, accounting for 85%-95% of the total, followed by the iron and manganese oxide-bound form (1%-15%). The main mineral types in the soil and tailings in the Dabaoshan Mining area were pyrite (FeS2), chalcopyrite (CuFeS2), and metal oxides, as well as a small amount of sphalerite (ZnS) and galena (PbS). Acidic conditions (pH=3.0) were beneficial to the release and migration of Cd and Pb from soil, tailings, and minerals (pyrite, chalcopyrite) and from the residual phase to the non-residual phase. Lead isotope analysis showed that the lead in the soil and tailings mainly came from the release of metal minerals in the mining area, and the contribution of diesel in the mining area was less than 30%. Multivariate statistical analysis showed that Pyrite, Chalcopyrite, Sphalerite, and Metal oxide were the main sources of heavy metals in the soil and tailings in the mining area, in which Cd, As, and Pb were mainly contributed by sphalerite and metal oxide. The form change in heavy metals in the mining wasteland was easily affected by environmental factors. The form characteristics and migration and transformation factors of heavy metals should be considered in the source control of heavy metal pollution in mining wasteland.