Assessment Of Heavy Metal Pollution Research Articles

Tissue distribution of cadmium and its effect on reproduction in Spodoptera exigua

Vegetable fields are often contaminated by heavy metals, and Spodoptera exigua is a major vegetable pest which is stressed by heavy metals mainly by feeding. In this study, cadmium accumulation in the tissues of S. exigua exposed to cadmium and its effects on the growth and development of the parents and the offspring were investigated. Under the stress of different concentrations of cadmium (0.2, 3.2, and 51.2 mg kg–1), the cadmium content in each tissue of S. exigua increased in a dose-dependent manner. At the larval stage, the highest cadmium accumulation was found in midgut in all three cadmium treatments, but at the adult stage, the highest cadmium content was found in fat body. In addition, the cadmium content in ovaries was much higher than in testes. When F1S. exigua was stressed by cadmium and the F2 generation was not fed a cadmium-containing diet, the larval survival, pupation rate, emergence rate and fecundity of the F2 generation were significantly reduced in the 51.2 mg kg–1 treatment compared to the corresponding F1 generation. Even in the F2 generation of the 3.2 mg kg–1 treatment, the fecundity was significantly lower than in the parental generation. The fecundity of the only-female stressed treatment was significantly lower than that of the only-male stressed treatment at the 3.2 and 51.2 mg kg–1 cadmium exposure levels. When only mothers were stressed at the larval stage, the fecundity of the F2 generation was significantly lower than that of the F1 generation in the 51.2 mg kg–1 treatment, and it was also significantly lower than in the 3.2 and 0.2 mg kg–1 treatments. The results of our study can provide useful information for forecasting the population increase trends under different heavy metal stress conditions and for the reliable environmental risk assessment of heavy metal pollution.

Pollution and health risk assessment of heavy metals in the surface sediments of Timsah Lake, Suez Canal, Egypt

Urbanization and industrial activities around Timsah Lake have led to discharging of pollutants into the lake. The heavy metals pollution level in the lake sediments and implications for living organisms and human health were estimated using several ecological indices. The spatial variations of metals (Cd, Cu, Pb, Mn, Zn, Ni, and Fe) and organic matter content demonstrate that most concentrations increase toward the western part of the lake. The geoaccumulation index (Igeo) arranged the metals as next; Cd > Pb > Zn > Cu > Mn > Fe > Ni, where the lake sediments are extended between moderately-to-extremely contaminated by Cd. Moreover, the contamination factor (CF) for Cd and Pb indicates very high contamination for 100 % of stations and moderate contamination for 58.3 % of the stations, respectively. Spatially, the degree of contamination (Cd) classified lake sediments into three categories; moderately, considerable and very highly contaminated, distributed in the lake's eastern, middle and western parts, respectively. Regarding ecological risk, the potential ecological risk factor (Eri) arranged the metals risks as follows: Cd > Pb > Cu > Ni > Zn, where Cd concentrations suggest high and very high risk for 16.7% and 83.3 % of stations, respectively. The potential ecological risk index (RI) divided lake sediments into moderate, considerable (most of the eastern part), and very high risk (most of the western part). According to sediment quality guidelines (SQGs), Cd values indicate that there have been negative effects on the biota ranging between occasional and frequent. A dermal exposure-based health risk evaluation revealed no non-carcinogenic impact on human health, while Cd indicated a tolerable risk of cancer for children. Moreover, 58.3 and 83.3 % of the stations indicated a tolerable risk of cancer by Ni for adults and children, respectively. The study recommended necessary proactive measures to monitor and manage heavy metal pollution, especially Cd, Pb, and Ni caused by human activities in the Lake.

Heavy metals pollution of soil in central plains urban agglomeration (CPUA), China: human health risk assessment based on Monte Carlo simulation.

The present study conducted the concentration evaluation, pollution assessment, source analysis, and risk assessment of heavy metals in the soil of the CPUA, China, to contribute to the smooth construction of urban agglomeration. Elevated levels of mean concentrations of cadmium (Cd), chromium (Cr), and copper (Cu) in the soils were shown compared to background values. Cu and zinc (Zn) and also lead (Pb) and Cd exhibited spatial similarity. Manganese (Mn) and Cr exhibited point source characteristics such as the concentrations at a point much higher than the surrounding area. The potential ecological risk in the northern region belonged to the moderate risk level category. Cd contributed over 90% to the potential ecological risk. The health risk among children was higher than that among adults. The major exposure pathways were different for adults and children. Exposure, as shown using Hazard Index (HI), to adults was mainly through the skin contact route, while to children was through both the skin contact and ingestion route. The primary CR (carcinogenic risk) to adults was through the inhalation route, while that to children was through the ingestion route. In both children and adults, Cr was the main contributor to HI and CR. According to the Monte Carlo simulation results, the cumulative probability of exceeding the critical value of HI for children was approximately 2.8-3.0 times that for adults. According to the sensitivity analysis results, non-carcinogenic risk prevention should begin mainly by reducing exposure duration and skin contact. The cancer risk may be reduced primarily by decreasing the exposure duration and controlling ingestion. The PMF (Positive Matrix Factorization) source analysis revealed that Pb mainly came from transportation sources. In addition, Cu, Pb, and Mn were derived mainly from agricultural sources. Cr was derived mostly from a natural source, and Cd originated mainly from an industrial source.

Risk assessment and source apportionment of heavy metals pollution from atmospheric deposition in Nanjing, China

Heavy metals (HMs) are the toxic pollutants in urban environment, and their sources are complex. Dust might be a good carrier of HMs into ecosystem and human. In this study, 48 dust samples were collected in Nanjing, an industrial city and transportation hub in the Yangtze River Delta, China. The concentrations, spatial distribution, sources and risks of heavy metals (Cr, Ni, Cu, Zn, Cd and Pb) in dust were determined and analyzed. The results showed that although the health risks of some HMs had decreased, Cr, Zn, and Cd had high concentrations and high risks on ecosystem/human. And thus, the total risks of the target HMs were higher than the threshold of non-risks. Especially, children may face the highest possible risks due to the frequent hand-oral ingestion when children play. The hot spot regions of the HMs were mainly in the industrial district in the north, urban, and rural region in south, relating with the industrial, traffic, and agricultural sources, respectively. The analysis for the risks of individual sources further confirmed these sources should be further controlled. The results in this study will provide information on the priority of HMs’ monitoring and source management.

Assessment of atmospheric heavy metal pollution in Qinghai-Tibet Plateau: Using mosses as biomonitor

Atmospheric heavy metal (HM) pollution may pose a significant threat to the fragile ecosystem of Qinghai-Tibet Plateau (QTP). To investigate potential atmospheric HM pollution within the QTP region of China, mosses, along with other higher plants and soil, were collected from 33 sites for heavy metal measurement. The concentration ranges of Zn, Pb, Cd, and Cu in mosses were 6.07–69.9, 5.36–23.9, 0.60–1.05, and 14.4–50.5 mg·kg−1 (dry weight), respectively, significantly higher than those in other higher plants, except for Zn. The spatial distribution of relative concentrations (RCs; moss to top soil) of HMs varied considerably, indicating distinct differences in atmospheric Zn and Cu pollution levels between the northern and southern QTP. This study first reported that moderate regional atmospheric Cu pollution, primarily due to large-scale mining in recent years, had occurred, particularly in southern QTP. Pb also presented slight pollution due to anthropogenic activities. However, Cd showed almost no atmospheric pollution, while Zn concentrations were relatively high in southern QTP. Although less severe than atmospheric pollution levels in Chinese inland or coastal cities, the atmospheric pollution of Pb and Cu in QTP indicated by mosses were far more severe than global background areas, or even worse than most European cities.

Historical trends and pollution assessment of heavy metals in core sediments from the Jiangsu offshore area, China

To assess the historical changes and pollution status of heavy metals, core sediments from the Jiangsu offshore area of China were systematically sampled and analyzed to determine the concentrations of Cu, Pb, Zn, Cr, Cd, As, Hg, Li, Ni, and Co. The stratigraphic framework of the SYS-1501 core was identified based on sedimentary structures, sedimentary facies, grain size, and comparison with seismic reflections and other well-studied cores from adjacent areas. The Pearson’s correlation coefficient, enrichment factor (EF), geoaccumulation index (Igeo), and principal component analysis (PCA) were used to distinguish the sources and assess the pollution risk of heavy metals. The results showed no elemental enrichment or contamination in the core sediments, and the high EF and Igeo values of Pb, As, Hg, and Li may be related to the selected background values of these metals. Except for Mn, all other metals and TOC exhibited similar vertical distribution patterns that were closely related to the mean grain size (Mz). Almost all the heavy metals were positively correlated with Al, Fe, and Mz, and all had high loadings on PC1, indicating that they are naturally sourced. Manganese (Mn) had a high loading on PC2, mainly representing the effect of marine authigenic elements on the sediments. Historical changes in the heavy metals in the core sediments were predominantly related to the sedimentary environment, sediment sources, and Mz.

Assessment of heavy metal pollution in the soil of a construction and demolition waste landfill

Construction industry has a significant effect on the environment and human health. In developing countries including Iran, the waste generated through construction and demolition is disposed in landfills, posing further harms to the environment by increasing the amounts of heavy metals (HMs). In order to tackle the mentioned issue, the first step is to assess the landfill soil’s contamination and risk. To date, no study has examined the status of heavy metal pollution and risk assessment of construction and demolition waste (CDW) landfills in Shiraz, Iran, although a large amount of CDW is disposed in this city. In order to fulfil the mentioned gap within the body of knowledge, a novel study was conducted in which a case study CDW landfill within Shiraz, Iran, was investigated carefully. 420 samples were collected, which was followed by various types of assessment techniques including geo-accumulation index, pollution load index, enrichment factor, and potential ecological risk assessment. The results obtained from pollution assessment methods illustrated considerable levels of contamination within the landfill, with Cd as the main contaminant (PLI value of 14.15, and significant enrichment for 92.7% of the collected samples). Risk assessment also showed a high-level risk of HMs for 84.16% of the samples extracted from the landfill soil, and the most prominent contributors were Cd and Pb with average ecological risks of 712.2 and 57, respectively. The results of this study can have a great impact on future policies and strategies regarding the disposal of CDW in Shiraz, Iran.

Assessment of Soil Heavy Metal Pollution in the Dump of a Western Inner Mongolian Coal Mine

Assessment of Soil Heavy Metal Pollution in the Dump of a Western Inner Mongolian Coal Mine

Heavy metals distribution characteristics, source analysis, and risk evaluation of soils around mines, quarries, and other special areas in a region of northwestern Yunnan, China

In this study, based on the assessment of soil heavy metals (HMs) pollution using relevant indices, a comprehensive approach combined network environ analysis (NEA), human health risk assessment (HHRA) method and positive definite matrix factor (PMF) model to quantify the risks among ecological communities in a special environment around mining area in northwest Yunnan, calculated the risk to human health caused by HMs in soil, and analyzed the pollution sources of HMs. The integrated risks for soil microorganisms, vegetations, herbivores, and carnivores were 2.336, 0.876, 0.114, and 0.082, respectively, indicating that soil microorganisms were the largest risk receptors. The total hazard indexes (HIT) for males, females, and children were 0.542, 0.591, and 1.970, respectively, revealing a relatively high and non-negligible non-carcinogenic risks (NCR) for children. The total cancer risks (TCR) for both females and children exceeded 1.00E-04, indicating that soil HMs posed carcinogenic risks (CR) to them. Comparatively, Pb was the high-risk metal, accounting for 53.76%, 57.90%, and 68.09% of HIT in males, females, and children, respectively. PMF analysis yielded five sources of pollution, F1 (industry), F2 (agriculture), F3 (domesticity), F4 (nature), and F5 (traffic).

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.

Source analysis and health risk assessment of heavy metals in agricultural land of multi-mineral mining and smelting area in the Karst region – a case study of Jichangpo Town, Southwest China

In the Karst region of Southwest China, the content of soil heavy metals is generally high because of the geological background. Moreover, Southwest China is rich in mineral resources. A large number of mining and smelting activities discharge heavy metals into surrounding soil and cause superimposed pollution, which has drawn widespread concern. Due to the large variation coefficients of soil heavy metals in the Karst region, it is particularly essential to select appropriate analysis methods. In this paper, Jichangpo in Puding County, a Karst area with multi-mineral mining and smelting, is selected as the research object. A total of 368 pieces of agricultural topsoil in the study area are collected. The pollution level of heavy metals in agricultural soil is evaluated by the geological accumulation index (Igeo) and enrichment factor (EF). Absolute Factor Score/Multiple Linear Regression (APCS/MLR), geographic information system (GIS), self-organizing mapping (SOM), and random forest (RF) are used for the source allocation of soil heavy metals. Finally, the combination of APCS/MLR and health risk assessment model is adopted to evaluate the risks of heavy metal sources and determine the priority-control source. The results show that the average values of soil heavy metals in the study area (Cd, Hg, As, Pb, Cr, Cu, Zn, and Ni) exceed the background values of corresponding elements in Guizhou Province. Three sources of heavy metals are identified by combining APCS/MLR, GIS, SOM, and RF. Zn (63.47%), Pb (55.77%), Cd (58.98%), Hg (32.17%), Cu (14.41%), and As (5.99%) are related to lead-zinc mining and smelting; Cr (98.14%), Ni (90.64%), Cu (76.93%), Pb (43.02%), Zn (35.22%), Cd (28.97%), Hg (22.44%), and As (5.84%) are mixed sources (natural and agricultural sources); As (88.17%), Hg (45.39%), Cd (12.04%), Cu (8.66%), and Ni (6.72%) are related to the mining and smelting of coal and iron. The results of health risk assessment show that only As poses a non-carcinogenic risk to human health. 3.31% of the sampling points of As have non-carcinogenic risks to adults and 10.22% to children. In terms of carcinogenic risks, As, Pb, and Cr pose carcinogenic risks to adults and children. Combined with APCS/MLR and the health risk assessment model, the mining and smelting of coal and iron is the priority-control pollution source. This paper provides a comprehensive method for studying the distribution of heavy metal sources in areas with large variation coefficients of soil heavy metals in the Karst region. Furthermore, it offers a theoretical basis for the management and assessment of heavy metal pollution in agricultural land in the study area, which is helpful for researchers to make strategic decisions on food security when selecting agricultural land.

Heavy metal concentration profiles and pollution assessment in the Jiangsu offshore area, China

The concentration profiles of various major and trace heavy metals (Cu, Pb, Zn, Cr, Cd, As, Hg, Ni, Li, and Co) were investigated along a 40.1-m-long sediment core in the offshore Jiangsu area of China, to assess their depositional trends and contamination levels. All metals, except Cd, exhibited similar profiles with high average concentrations during the Marine Isotope Stage 2–4 period. The sediment trace-metal concentrations were primarily related to grain size and sediment sources, with almost all heavy metals (except Cd) being positively correlated. Enrichment factors, geoaccumulation indices, and principal component analysis indicated no elemental enrichment or contamination. The high EF and Igeo values of As, Hg, and Li may be related to their background values.

Seasonal Variation Characteristics and Pollution Assessment of Heavy Metals in Water and Sediment of Taipu River

Taipu River is a river spanning two provinces and one city in a demonstration area in the Yangtze River Delta on an ecologically friendly developmentand an important water source in the upper reaches of the Huangpu River in Shanghai. To understand the multi-media distribution characteristics, pollution status, and ecological risk of heavy metals in the Taipu River, the contents of heavy metals (As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sb, and Zn) in the sediments of Taipu River were analyzed, and the pollution status and potential ecological risk were evaluated using the Nemerow comprehensive pollution index, geo-accumulation index, and potential ecological risk index methods. In addition, the health risk assessment model was used to assess the health risk of heavy metals in surface water of Taipu River. The results showed that the concentrations of Cd, Cr, Mn, and Ni in the surface water of Taipu River exceeded the class Ⅲ water limit at the upstream point in spring; the concentrations of Sb exceeded the class Ⅲ water limit at all points in winter; the average value of As exceeded the class Ⅲ water limit in overlying water during the wet season; and the average values of As and Cd exceeded the class Ⅲ water limit in pore water during the wet season. The health risk assessment of surface water implied that both adults and children had higher health risk in spring and lower health risk in other seasons. The health risk of children was significantly higher than that of adults, and it mainly came from chemical carcinogenic heavy metal elements As, Cd, and Cr. The average contents of Co, Mn, Sb, and Zn in Taipu River sediments in the four seasons all exceeded the Shanghai soil baseline; the average contents of As, Cr, and Cu in summer, autumn, and winter exceeded the Shanghai soil baseline; and the average contents of Cd, Ni, and Pb in summer and winter exceeded the Shanghai soil baseline. The evaluation results of the Nemerow comprehensive pollution index and geo-accumulation index showed that the pollution degree of the middle reaches of Taipu River was higher than that of the upper and lower reaches, and the Sb pollution was more serious. The potential ecological risk index method revealed that the Taipu River sediment was at a low risk. Cd had a high contribution in both the wet and dry seasons and could be regarded as the main heavy metal of potential ecological risk in the Taipu River sediment.

Source Apportionment and Pollution Assessment of Soil Heavy Metal Pollution Using PMF and RF Model: A Case Study of a Typical Industrial Park in Northwest China

Based on the concentration data of seven heavy metal elements[As, Cd, Cu, Pb, Hg, Ni, and Cr(Ⅵ)] in the surface soil of a typical industrial park in northwest China, the characteristics of heavy metal pollution in the industrial park were analyzed, and the ecological risk and pollution were evaluated using the potential ecological risk index and the index of geo-accumulation. The positive matrix factorization (PMF) model and random forest (RF) model were used for quantitative source analysis, and the emission data of sampling enterprises and empirical data of the source emission component spectrum were combined to identify the characteristic elements and determine the emission source category. The results showed that the heavy metals at all sampling points in the park did not exceed the second-class screening value of construction land in the soil pollution risk control standard for construction land (GB 36600-2018). However, compared with the local soil background values, five elements, excluding As and Cr, were enriched in different degrees, presenting slight pollution and moderate ecological risk (RI=250.04). Cd and Hg were the main risk elements of the park. The results of source analysis showed that the five main sources of pollution were fossil fuel combustion and chemical production sources (33.73%, 9.71%, total source contribution rate of PMF and RF, respectively; the same below), natural sources and waste residue landfill (32.40%, 40.80%), traffic emissions (24.49%, 48.08%), coal burning and non-ferrous metal smelting (5.43%, 0.11%), and electroplating and ore smelting (3.95%, 1.30%). The simulation R2 of the total variable of the two models were above 0.96, indicating that the models could predict heavy metals well. However, considering the actual situation of the number of enterprises in the park and roading density, the main pollution sources of soil heavy metals in the park should be industrial sources, and the simulation results of the PMF model were closer to the actual situation in the park.

Pollution Assessment and Source Analysis of Heavy Metals in Atmospheric Deposition in a Lead-zinc Smelting City Based on PMF Model

To explore the pollution characteristics and sources of heavy metals in atmospheric deposition in a typical lead-zinc smelting city, 511 effective atmospheric deposition samples from 22 points in different functional areas of a city in Henan Province were collected monthly during 2021. The concentrations and spatial-temporal distribution of heavy metals were analyzed. The geo-accumulation index method and health risk assessment model were utilized to evaluate the heavy metal pollution degree. The sources of heavy metals were quantitatively analyzed using a positive matrix factorization (PMF) model. The results showed that the average concentrations of ω(Pb), ω(Cd), ω(As), ω(Cr), ω(Cu), ω(Mn), ω(Ni), and ω(Zn) in atmospheric deposition samples were 3185.77, 78.18, 273.67, 149.50, 453.60, 810.37, 54.38, and 2397.38 mg·kg-1, respectively, which were all higher than the soil background values of Henan Province. All heavy metals except Mn had significant seasonal variation characteristics. The concentrations of Pb, Cd, As, and Cu in the industrial area with lead-zinc smelting were significantly higher than those in other functional areas, and the concentration of Zn was the highest in the residential mixed area. The results of the geo-accumulation index showed that the pollution of Cd and Pb were the most serious, followed by that of Zn, Cu, and As, which belonged to the serious-extreme pollution category. The main exposure route of non-carcinogenic risk was hand-mouth intake. Pb and As posed the greatest non-carcinogenic risk to children in all functional areas. The carcinogenic risks of Cr, As, Cd, and Ni through the respiratory system to humans were all below the threshold values. The analysis of the PMF model showed that the main sources of heavy metals in atmospheric deposition were industrial pollution sources (39.7%), transportation sources (28.9%), secondary dust sources (14.4%), incineration and coal combustion sources (9.3%), and natural sources (7.8%).

Heavy Metal Concentration, Source, and Pollution Assessment in Topsoil of Chuzhou City

In order to understand the pollution level and ecological risk of heavy metals in topsoil of Chuzhou City, a total of 4360 soil samples in Chuzhou City were collected, and the concentrations of eight heavy metals including Cr, Zn, Pb, Cu, Ni, Cd, As, and Hg were measured. Correlation analysis, cluster analysis, and principal component analysis were used to analyze the sources of the heavy metals, and the enrichment factor index, single-factor pollution index, pollution load index, geo-accumulation index method, and potential ecological risk index were selected to assess the environmental risk of the eight heavy metals in the topsoil. The results showed that the average values of Cr, Zn, Pb, Cu, Ni, Cd, As, and Hg contents in the surface soil of Chuzhou City were higher than the background value of that in the soil of Yangtze-Huaihe River Basin of Anhui, and Cd, Ni, As, and Hg were significantly different in space and influenced by external disturbance. The eight types of heavy metals could be divided into four categories based on correlation analysis, cluster analysis, and principal component analysis. Cr, Zn, Cu, and Ni were from natural background sources; As and Hg mainly came from sources of industrial and agricultural pollution; Pb mainly came from the sources of transportation pollution and industrial and agricultural pollution; and Cd came from the sources of transportation pollution, natural background, and industrial and agricultural pollution. The overall pollution degree of Chuzhou City was low, and the ecological risk level was at a slight level based on the pollution load index and the potential ecological risk index; however, the ecological risk of Cd and Hg was generally serious, and these two heavy metals should be taken as the objects of priority control. The results provided a scientific basis for soil safety utilization and classification control in Chuzhou City.

Soil heavy metal(loid) pollution and health risk assessment of farmlands developed on two different terrains on the Tibetan Plateau, China

The quality of farmland soils on the Tibetan Plateau is important because of the region's ecological vulnerability and their close link with local food security. Investigation on the pollution status of heavy metal (loid)s (HMs) in the farmlands of Lhasa and Nyingchi on the Tibetan Plateau, China revealed that Cu, As, Cd, Tl, and Pb were apparently enriched, with the soil parent materials being the primary sources of the soil HMs. Overall, the farmlands in Lhasa had higher contents of HMs compared to those in Nyingchi, which could be attributed to the fact that the former were mainly developed on river terraces while the latter were mainly developed on the alluvial fans in mountainous areas. As displayed the most apparent enrichment, with the average contents in the vegetable field soils and grain field soils of Lhasa being 2.5 and 2.2 times higher compared to those of Nyingchi. The soils of vegetable fields were more heavily polluted than those of grain fields, probably due to the more intensive input of agrochemicals, particularly the use of commercial organic fertilizers. The overall ecological risk of the HMs in the Tibetan farmlands was low, while Cd posed medium ecological risk. Results of health risk assessment show that ingestion of the vegetable field soils could pose elevated health risk, with children facing greater risk than adults. Among all the HMs targeted, Cd had relatively high bioavailability of up to 36.2% and 24.9% in the vegetable field soils of Lhasa and Nyingchi, respectively. Cd also showed the most significant ecological and human health risk. Thus, attention should be paid to minimize further anthropogenic input of Cd to the farmland soils on the Tibetan Plateau.

Assessment of heavy metal pollution and quality in lake water and sediment by various index methods and GIS: A case study in Beyşehir Lake, Turkey

Beyşehir Lake, Turkey's largest freshwater lake, is also a “Drinking Water Reserve”. In the study, heavy metal (As, Cr, Cu, Ni, Zn, Pb, Cd, Hg, Fe, Al, Mn) concentrations of seasonal lake water and bottom sediment samples were determined to evaluate the heavy metal pollution. Several index methods were applied, and pollution assessments were made using the obtained analysis results of lake water and sediment samples. The average concentrations of the heavy metals in the lake waters are observed as Fe > Al > Mn > As>Zn > Ni > Pb > Cr > Cu > Hg > Cd. When the lake waters were compared with the TS 266 (2005) and WHO (2017) limit values, it was determined that lake waters are below the limit values in terms of the heavy metals. According to index results, all of the lake samples are suitable for use as drinking water in accordance with the heavy metal pollution index (HPI) value, all of the samples are in the “low pollution” class in accordance with the heavy metal evaluation index (HEI) and degree of contamination (Cd) values. In addition, the water average concentrations of the heavy metals in the lake sediments are observed as Fe > Al > Mn > Cr > Ni > Zn > Cu > As>Pb > Cd > Hg. The contamination factor (CF) and enrichment factor (EF) revealed that sediments were considerably and moderately polluted by As, Cr, Cu, Ni, Cd, Fe and Mn and low polluted and/or unpolluted by other metals. The calculated pollution load index (PLI) and Igeo values indicate that lake sediments do not carry a risk of heavy metal contamination.

Spatial Distribution and Associated Risk Assessment of Heavy Metal Pollution in Farmland Soil Surrounding the Ganhe Industrial Park in Qinghai Province, China

The farmland around the industrial areas in the Upper Yellow River is crucial for agricultural production but is vulnerable to contamination from the surrounding industries. This research focused on analyzing the spatial distribution and environmental risks of heavy metal pollution in the farmland around the Ganhe Industrial Park in the Qinghai–Tibet Plateau. A total of 138 surface soil samples were collected, and the concentration of seven heavy metals (Cd, As, Pb, Cr, Cu, Ni, and Zn) was analyzed using the random forest (RF) model. Pollution indicators, including the pollution index and Nemero index, were used to evaluate the pollution levels of soil heavy metals. The human health and ecological risks were estimated using the hazard index (HI) and the potential ecological risk index (RI). Cd and Zn were identified as the primary soil pollutants in the study area, with Cd being more concentrated than other heavy metals. Heavy metal contamination was most severe in the central–eastern region of the study area, with a ring-shaped distribution, which correlated with the presence of zinc smelting and chemical plants. Furthermore, the study revealed that soil heavy metal contamination posed a health threat to the local population, with children being particularly vulnerable to non-carcinogenic risks when the HI was 1.21 and to potential carcinogenic risks when the CR was 2.27 × 10−5. Additionally, heavy metal pollution caused a moderate to high ecological risk in 56.4% of the samples. The results highlighted the severe impact of soil heavy metal pollution on the delicate ecosystem of the Upper Yellow River and Qinghai–Tibet Plateau. The government should take action to improve soil environment management and prevent heavy metal pollution to protect the health of the local population and the ecological environment.

Assessment of heavy metal pollution and preschool children health risk in urban street dusts from different functional areas in a typical industrial and mining city, NW China.

To assess the pollution characteristics and health risks associated with street dust exposure among preschool children in typical industrial and mining areas, we analyzed heavy metal concentrations of 20 urban street dusts in commercial area (CA), residential area (RA), scientific and educational area (SEA) and industrial and mining area (IMA) from Baiyin, NW China. The average concentrations of Cr, Mn, Ni, Cu, Zn, Cd, Pb, As and Hg were 614.96, 484.25, 1757.74, 6868.86, 893.19, 77.62, 1473.99, 15.01 and 0.59mg·kg-1, respectively. The ecological risk indexes for Cd, Cu and Hg were found as 20,075.20, 1425.07 and 1174.86, respectively, and the ecological risk was extremely high. The pollution load indexes (PLI) were > 1 for all four functional areas. The total hazard index (THI) for different functional areas were more than 1, and the main exposure pathway for children was ingestion route. Heavy metals in street dust of the IMA had the highest THI for children (43.88), and HI of Pb was being most significant (17.38). In addition, the carcinogenic risk to children via the respiratory route was acceptable. Furthermore, factor analysis and cluster analysis classified heavy metals into two groups, indicating common anthropogenic sources for Cr, Ni, Cu, Zn, Cd, Pb, As and Hg. In conclusion, urban street dusts from industrial and mining area of Baiyin, NW China were found polluted by heavy metals and the pollution would pose an obvious non-carcinogenic risk to preschool children.