Ecological security and health risk assessment of soil heavy metals on a village-level scale, based on different land use types

Different "nongrain" activities affect the accumulation of heavy metals and their source-oriented health risks on cultivated lands

"Nongrain" production on cultivated land is one of the primary environmental issues in China. Different "nongrain" activities may introduce different pollution sources to the local environment, leading to variations in heavy metal contents in soil, which can profoundly impact national food security. In this study, three typical "nongrain" regions (Nanxun (NX), Xiaoshan (XS) and Lin'an (LA)) with intensive aquaculture, tea planting and flower (seedling) growth on cultivated land around the Hangzhou metropolitan area were selected to address the spatial heterogeneity of accumulation levels, sources and source-oriented health risks of heavy metals in soil. The results showed that Hg was the main pollutant in NX and XS, while Cd and As were the major contaminants in LA. Aquiculture and sericultural industries (37.43%), natural sources (23.59%) and industrial activities (38.99%) were the major sources in NX; atmospheric deposition (37.73%), flower and seedling planting (23.49%) and metal-related industries (35.16%) were the major sources in XS; and atmospheric deposition (28.06%), excessive application of fertilizers and pesticides during tea planting (43.47%) and natural sources (28.47%) were the major sources in LA. The major risk population, area, exposure route and hazardous elements were children, LA, ingestion and As and Cr, respectively. From the perspective of source-based health risk assessment, in addition to natural sources that are difficult to intervene in, industrial activities, especially leather and wood process industries, metal-related industries and excessive fertilizer and pesticide application during tea planting contributed the most to the total health risk, which explained 67%, 41% and 42%, respectively, of the total risk in NX, XS and LA. High health risks are present in sources with heavy loadings of hazardous heavy metals (As and Cr); thus, to protect human health, the corresponding high-risk anthropogenic pollution sources in different "nongrain" areas need to be controlled.

Evaluation of sediment quality for heavy metal(loid)s contamination and health risk assessment in the Gulf of Suez, Egypt

The Gulf of Suez faces challenges related to contamination, primarily due to industrial, tourism, and shipping activities along its shores. This study aims to record the distribution, concentration, and potential environmental and health risk impacts of heavy metal(loid)s (HMs) in 30 surface sediment samples collected from Ras Sidr coastline, Gulf of Suez. Various contamination and health indices were employed for this study. The average concentrations of HMs (μg/g) were ranked as follows: Fe (3472), Mn (103.3), V (10.41), As (7.94), Cr (6.00), Zn (5.31), Ni (2.94). The spatial distribution of HMs indicated an increase in Mn, Zn, As, and V levels toward the southern part of the study area, potentially linked to the proximity of manganese quarries and their metal association at Abu Zenima. Contamination indices revealed moderately severe enrichment with As, minor enrichment with Mn, and no enrichment for the remaining HMs. Multivariate analysis suggested a natural origin for Cr, Fe, Mn, Ni, Zn, and V, while As were likely anthropogenic. Values of hazard index (HI) for HMs in both adults and children followed the descending order of As > Fe > Cr > V > Mn > Ni > Zn. However, all HI values were below 1.0, indicating no significant non-carcinogenic risk for individuals along the Ras Sidr coastline. 19 samples exhibited lifetime cancer risk (LCR) values exceeding 1 × 10-4 for As in children, suggesting potential carcinogenic risks. LCR values for As in adults and Cr in adults and children ranged from 1 × 10-5 to less than 1 × 10-6, indicating acceptable or tolerable levels of carcinogenic risk and no significant threats to health.

A comparative study of the risk assessment and heavy metal contamination of coastal sediments in the Red sea, Egypt, between the cities of El-Quseir and Safaga

This study aimed to assess the influence of pollution on the quality of sediments and the risks associated with El-Qusier and Safaga Cities, Red Sea, Egypt, during 2021, divided into four sectors, using multiple pollution indices. To achieve that, we evaluated the metal pollution index (MPI), contamination factor (Cf), pollution load index (PLI), contamination security index (CSI), and anthropogenicity (Anp%). Moreover, carcinogenic and non-carcinogenic risks are used for human health hazards. Results indicated that Mn and Fe recorded the highest concentrations, whereas Cd had the lowest. El-Quseir City sediments were found the following metal ions: Fe > Mn > Ni > Zn > Cu > Co > Pb > Cd, where the order in the Safaga City was: Fe > Mn > Zn > Ni > Cu > Pb > Co > Cd. MPI > 1, this is alarming in the study area due to heavy metal pollution. In addition, Cf < 1 in all metals except Cd with contamination degree CD ranged from low to considerable contamination in El-Qusier city. In contrast, contamination ranged from significant to very high in Safaga city. PLI < 1 is lower than the reference at all monitored stations. CSI values ranged from relatively low to moderate. Besides Cd, data reflect each element's low environmental danger (EriMe40). This study's risk index (RI) is low to moderate in Sector 1 and high to extremely high in Sector 2. HQ and HI index < 1 means it is safe for human health in order: HI ingestion > HI dermal. CSR for different pathways was recorded as dermal > ingestion, in which total CSR for all paths is considered harmful, and the cancer risk is troublesome and higher than the reference ranges of 1 × 10-6-1 × 10-4. In conclusion, the examined heavy metals provide environmental hazards across the assessed locations.

Microbial features with uranium pollution in artificial reservoir sediments at different depths under drought stress

The uranium (U) containing leachate from uranium tailings dam into the natural settings, may greatly affect the downstream environment. To reveal such relationship between uranium contamination and microbial communities in the most affected downstream environment under drought stress, a 180 cm downstream artificial reservoir depth sediment profile was collected, and the microbial communities and related genes were analyzed by 16S rDNA and metagenomics. Besides, the sequential extraction scheme was employed to shed light on the distinct role of U geochemical speciations in shaping microbial community structures. The results showed that U content ranged from 28.1 to 70.1 mg/kg, with an average content of 44.9 mg/kg, significantly exceeding the value of background sediments. Further, U in all the studied sediments was related to remarkably high portions of mobile fractions, and U was likely deposited layer by layer depending on the discharge/leachate inputs from uranium-involving anthoropogenic facilities/activities upstream. The nexus between U speciation, physico-chemical indicators and microbial composition showed that Fe, S, and N metabolism played a vital role in microbial adaptation to U-enriched environment; meanwhile, the fraction of Ureducible and the Fe and S contents had the most significant effects on microbial community composition in the sediments under drought stress.

Study on the relationship between regional soil desertification and salinization and groundwater based on remote sensing inversion: A case study of the windy beach area in Northern Shaanxi

Soil desertification and salinization are important environmental concerns in arid regions, and their relationship with groundwater change must be further clarified. However, the relationships among soil desertification, salinization, and groundwater are difficult to investigate on a large spatiotemporal scale using traditional ground surveys. In the windy beach area in Northern Shaanxi (WBANS), desertification and salinization problems coexist; therefore, this area was selected as the study area. The feasibility of implementing large-scale remote sensing inversions to identify the degree of desertification and salinization was verified based on measured data, and the degree of influence of groundwater burial depth (GBD) on desertification and salinization was quantified using the geodetector and residual trend analysis methods. The results showed that the GBD in the WBANS presented an increasing trend and the degree of salinization showed a decreasing trend. Moreover, the joint influence of the unique natural environment and anthropogenic activities has led to increases in fractional vegetation cover and considerable improvements in the ecological environment. The intensity of desertification explained by GBD in the WBANS increased significantly (p < 0.01) at a rate of change of 0.0190/year, with high q-values above 0.66 for both Yuyang and Shenmu. The contribution rate of potential evapotranspiration and precipitation to salinization in Yuyang and Shenmu was >97 %, and the contribution rate of GBD to salinization in Dingbian, Jingbian, and Hengshan was 34.78 %, 31.15 %, and 29.41 %, respectively. Overall, the suitable GBD in the WBANS is 2-4 m. The study results provide a reference for research on the inversion, monitoring, and prevention of desertification and salinization dynamics on a large spatiotemporal scale and offer a scientific basis for rationally determining GBD.

Assessment of human health risks of toxic elements in coastal area between Al-Khafji and Al-Jubail, Saudi Arabia

The present work aims to document the distribution of toxic elements (TEs) and assess the human health risk posed by the TEs in the marine sediment of the Arabian Gulf, Saudi Arabia. The descending order of TE averages (μg/g) was as follows: Ni > Cr > V > Zn > Pb > Cu > As > Co. Based on the enrichment factor values, only minor enrichment for Pb, As, Cr, and Ni was noted. The hazard index (HI) values for the non-carcinogenic risk of the TEs were less than 1.0, and the lifetime cancer risk values for carcinogenic Pb, Cr, and As ranged between 2.96 × 10-8 and 5.44 × 10-5, indicating no significant health hazards for the inhabitants of the study area.

Occurrence, sources and risk of heavy metals in soil from a typical antimony mining area in Guizhou Province, China

Antimony mining activities can result in serious contamination of soil by heavy metals, which represents a risk to human health. In this study, the contamination and sources of 14 heavy metals, and their risks to both ecosystem and public health from these metals at an antimony mining site in Guizhou Province in China were explored. The results showed that the mean concentrations of Hg, Cu, As, Se, Cd, Sn, Sb and Pb were 3.73, 2.49, 13.99, 38.32, 1.11, 1.61, 305.33, 1.59 times than their local background levels. Sb, Se, As and Hg presented the relatively heavy pollution, wherein Sb (EI = 2137.34 > 320), Hg (EI = 150.26 > 80) and As (EI = 139.92 > 80) also posed the strong ecological risk. The sources identification illustrated Hg, Pb, As, Bi, Cr, Sb, Cd and Zn were attributed to industrial activities, Ni, Co, Au and Cu (p < 0.01) were derived from a combination of a lithogeny origin and anthropogenic source, whereas Se was of natural origin. Health risk assessment demonstrated that Ni, Cr and As presented both the unacceptable noncarcinogenic and carcinogenic risk, and Sb (HI = 1.44E+03) and Cd (HI = 2.91E+00) posed unacceptable noncarcinogenic risk to the local resident. Furthermore, children in the 1-6 age group (HI = 7.83E+02) were more sensitive to noncarcinogenic risk, and the 6-18 age group (CRI = 2.39E-02) as more prone to carcinogenic risk. The dermal contact was the predominant exposure pathway of noncarcinogenic and carcinogenic risks with a contribution rate of over 97% for all age groups. Overall, this research provided the comprehensive information on heavy metals in an antimony mining sites, and the related heavy metals should be paid attention for ensuring soil safety and protecting local people's health.

Ecological and health risk assessment of heavy metals contamination in mangrove sediments, Red Sea coast

Due to the significance of mangroves for the diversity of marine and terrestrial life along the Red Sea coast, the present work aimed to evaluate the environmental and health risk of heavy metals in Wadi el-Gemal sediments. The findings of single and integrated indices demonstrated no significant pollution with Fe, Cu, Zn, Ni, Co, and Cd, while the sediments showed severe and minor enrichment with Mn and Cd, respectively, which might be attributed to the presence of some mining activities in the mountains near the study area. The possible carcinogenic and non-carcinogenic risks due to their dermal absorption from the sediments were analyzed and the findings demonstrated that the non-carcinogenic health hazards were within tolerable and safe limits. Moreover, the evaluation of chronic daily intake and the overall cancer risk (LCR) for adults and children for Pb and Cd both ruled out any current potential carcinogenic health risks.

Potentially Toxic Element Contamination in Soils Affected by the Antimony Mine Spill in Northwest China

This study provides a comprehensive assessment of the potential ecological and health risks in the area of the antimony mine spill in Longnan, Northwest China, and identifies the sources of potentially toxic elements (PTEs) in the soil as a result of the spill. The geo-accumulation index and enrichment factor show that the study area is highly contaminated with arsenic (As), mercury (Hg) and antimony (Sb). The ecological risk index in the tailings spill area ranged from 320.43 to 5820.46 (mean: 1489.82), indicating a very-high potential ecological risk, with mean values of 104.86, 1118.87 and 248.84 for As, Hg and Sb, respectively. The multivariate statistical analysis suggested that Sb and Hg come from tailings leakage, while copper (Cu), nickel (Ni) and zinc (Zn) may be imported from natural sources, and As and lead (Pb) originate from agricultural activities. In addition As and Sb pose a high health risk. With the exception of the non-carcinogenic risk in adults, all other risks are significantly exceeded in other populations, with children being the highest-risk group. These findings provide important quantitative information for the assessment and management of PTE contamination in other tailings spill areas.

Heavy metal pollution in surface sediments and human health assessment in southern Al-Khobar coast, Saudi Arabia

Surface sediment samples from twenty-nine stations in south Al-Khobar coastline, Arabian Gulf, have been examined to assess the heavy metal contamination and impact on human health through dermal contact. The content in Cu, Zn, Cd, Pb, Fe, Mn, Co, Hg and Ni, was evaluated. Pollution index, modified degree of contamination, and pollution load index agreed to exclude heavy metal pollution. Differently, soil pollution index and Nemerow integrated pollution index pointed out moderate and heavy pollution grade for Hg and Cu, respectively. The human health assessment, according to the low values of the hazard index ˂ 1.0 for both adults and children, excluded any significant impact on the human body. The chronic daily intake and the total lifetime cancer risk also were consistent in excluding any risk to human health. Similarly, the carcinogenic risks for Pb and Cd, and the total cancer risk ˂1 × 10^-6, did not imply significant health hazards.

Contamination and health risk assessment of arsenic and chromium in coastal sediments of Al-Khobar area, Arabian Gulf, Saudi Arabia

The contamination and health risks by arsenic and chromium in the Al-Khobar coastal area, Arabian Gulf, have been assessed by examining 29 samples of surface sediment. Several single and complex indices were accounted to assess contamination, while the chronic daily intake (CDI), the hazard index (HI) and the total lifetime cancer risk (LCR) were applied to assess human health. The studied sediments showed absence or low level of As and Cr contamination. Results of CDI suggested a greater intake of As and Cr in children than in adults, mainly by ingestion pathway, reaching >99.5 % from the total for both adults and children. The recorded values of HI indicated not significant non-carcinogenic effects on the human body. LCR was higher in children than in adults. However, the recorded values suggested that the present carcinogenic risk for As and Cr can be considered acceptable or tolerable.

The potential ecological risk assessment of soil heavy metals using self-organizing map

Heavy metal pollution control zoning aiming at the health maintenance of watershed soil ecosystem has become an important means of soil environmental protection and governance. Based on the self-organizing map (SOM), this study classifies the data sets of eight heavy metals such as Co, Cd, Zn, Cr, Cu, Pb, Ni, and Tl in 354 samples, calculates the potential ecological risk value of soil heavy metals in combination with the potential Hakansom Risk index (HRI), and uses the geographic information system (GIS) for visualization. In the research results, SOM has divided five soil ecological risk categories. The highest average ecological risk value of 85.95 is found in cluster IV, which is clustered and distributed in urban development areas in the upper reaches of the river. The average ecological risk values of cluster I and cluster V are relatively close at 79.64 and 79.19, respectively. Cluster I and cluster V are distributed in the north of the river in a linear and cluster manner, respectively, and are located on a concave bank with a relatively gentle slope. The average ecological risk of soil pollution in cluster II is 77.59, which is linearly distributed on both banks of the river. The ecological risk of soil pollution in cluster III is the lowest (74.39), mainly scattered in the south of rivers with less human activities. The study further identified the environmental factors that affect the soil ecological risk value in different cluster units and put forward the classified and differentiated management and control strategies for different cluster units. The research shows that SOM can cluster the data sets of heavy metals with high sensitivity and low threshold through competitive learning to effectively provide the distribution information of abnormal soil ecological risk areas. This information is helpful for urban environmental management departments and planning departments to take targeted management and recovery measures to avoid the health risks related to soil heavy metal pollution.

Characteristics, Health Risk Assessment, and Transfer Model of Heavy Metals in the Soil-Food Chain in Cultivated Land in Karst

Heavy metal(loid) contamination of farmland is a crucial agri−environmental problem that threatens food safety and human health. In this study, we examined the contamination levels of heavy metals (As, Pb, Cd, Hg, Cr) in farmland and foods (rice, maize, and cabbage) in the core of Asia’s largest karst region and assessed the potential health risks of consumption of these three foods. In addition, we developed a predictive transfer model of heavy metals in the soil−food chain through multiple regression equations. The results reveal that the soil heavy metals in the study area showed high accumulation characteristics, and the average concentration exceeded the national background value by 1.6−130 times, among which Cd pollution was the most serious. The order of contamination of the three soils in the study area was cabbage land > maize land > rice land. The order of potential risk of toxic elements in all three soils was Cd > Hg > As > Pb > Cr. The results of the risk assessment of agricultural consumption indicated a high carcinogenic and noncarcinogenic risk for the local population. The top contributor to carcinogenic risk was Cr, followed by As. Cd is the major noncarcinogenic contributor in maize and cabbage, and the noncarcinogenic contribution in rice is mainly caused by As. The risk was higher in children than in adults and was the highest for rice consumption. In addition, the predictive transfer model showed that the Cd levels in the three foods showed sufficient predictability and reasonable simulations of Cd concentrations in rice, maize, and cabbage throughout the study area. It could allow decision-making on the need for remediation strategies to reduce the risk of metal contamination of agricultural land in potentially high−risk areas of karst.

Heavy Metal Pollution and Health Risk Assessment of Vegetable-Soil Systems of Facilities Irrigated with Wastewater in Northern China

Soil pollution by heavy metals is a major concern in China and has received much attention in recent years. Aiming to investigate the status of heavy metal pollution and the safety of vegetables in the soil of wastewater-irrigated facilities, this study investigated the distribution and migration characteristics of heavy metals in vegetable−soil systems of facilities in a typical sewage irrigation area of the Xi River, Shenyang City, northern China. Health risks due to the fact of exposure to heavy metals in the vegetable soil of facilities and ingrown vegetables through different exposure pathways were evaluated. Spatial interpolation and a potential ecological risk assessment were applied to evaluate the soil quality. Bioaccumulation factors (BCFs) were used to analyze the absorption and transportation capacity of Cd, Cu, Pb, and Zn by different parts of different vegetables. The results showed that the average concentration of Cd exceeded the standard values by 1.82 times and accumulated by 11 times, suggesting that Cd poses the most severe pollution among the four metals in the soil of facilities in the Xi River sewage irrigation area. In the city, a significant accumulation of Cd in the soil was identified with different spatial distributions. Cd also contributed the most in terms of the estimated potential ecological risk index, while the impacts of the other three metals were relatively small. The concentrations of heavy metals were mostly lower than the limit set by the corresponding Chinese standards. Various BCFs were observed for the four metals in the order Cd > Zn > Cu > Pb. Vegetables also demonstrated different BCFs in the order of leaf vegetables > Rhizome vegetable > Solanaceae vegetable. The magnitude of the noncarcinogenic risk for all four heavy metals was less than one for all three exposure routes and did not cause significant noncarcinogenic health effects in humans. However, the carcinogenic risk of Cd from some vegetables via dietary intake was considered higher. Protection measures should be taken to implement better pollution control and land use planning.

High Ecological Health Risks of Potentially Toxic Metals in Polluted Drainage Sediments: Is There a Need for Public Concern during Flash Floods?

The present study aimed to investigate the concentrations of potentially toxic metals (PTMs) in the drainages, rivers, and coast of Malacca in Peninsular Malaysia. The ranges of total PTM concentrations (mg/kg dry weight) were 1.88–7.01 for Cd, 18.9–1689 for Cu, 26.0–850 for Ni, 56.5–307 for Pb, and 75.4–312 for Zn. Based on an ecological risk assessment and geochemical fractions, it was concluded that heavy metals pollute the drainages and the Malacca River. The potential ecological risk index (PERI) categorised the drainage and river sites as a “very high ecological risk”. Therefore, it was shown that elevated levels of PTMs in the drainages near Malacca Industrial Area and in the Malacca River sediment were most probably attributed to untreated (or incomplete treatment of) industrial effluents. The drainage sediments were found to have higher hazard quotient (HQ) values for the three pathways of the PTMs for children and adults. Although in general, the non-carcinogenic risks of the PTMs for children and adults indicated no significant detrimental health effects, the hazard index (HI) for Pb in children at drainage locations surpassed 1.0, suggesting a non-carcinogenic risk (NCR), which is a cause for worry. Consequently, the ecological health risk assessments offered critical information for PTM pollution reduction and environmental management in future sustainable development initiatives in Peninsular Malaysia’s drainages and rivers. The present findings on the ecological health risks of PTMs based on 2006 samples can serve as an important baseline for future reference and comparison. This work should encourage future investigations on the direct impact of the risks to the residents during floods in Malaysia, as part of mitigation and risk assessments of the contaminated drainage and river sediments in an attempt to lower the hazards for the surrounding residents.

Geochemical characteristics and source apportionment of toxic elements in the Tethys-Himalaya tectonic domain, Tibet, China

Toxic elements (TEs) in soil threaten the eco-environmental system and human health. The identification and prediction of sources and high-risk areas of TEs in soil are fundamental for regional pollution prevention and control. In this study, geostatistical methods and GIS-based approaches were used to quantitatively analyze the spatial distribution, geochemical characteristics, key driving factors, and their interactive effects of TEs in soil from a typical area of the Tethys-Himalaya tectonic domain in Tibet based on an integrated approach combining positive matrix factorization and GeoDetector models. The mean contents of chromium, arsenic (As), cadmium, mercury and lead in the soil exceeded the Tibetan background values, with 66.20% of As being higher than the screening values. The spatial distribution of TEs content in the soil was primarily affected by geogenic source factors (primarily geology types, soil parent materials, soil types, and soil pH), and environmental source factors (primarily precipitation and vegetation types) and anthropogenic source factors (primarily income of residents and land-use types) also had the same contribution approximately. Compared with that for individual driving factors, the interaction between most pairs of driving factors enhanced their explanatory power. The high-risk areas for soil As pollution were primarily distributed in the valley areas of the upper reaches of the Longzi River Basin. Therefore, to guarantee the health of residents and the security and sustainability of agricultural production in the study area, regular monitoring and soil remediation should be used to reduce the migration and transformation of As in the local biogeochemical cycle. This study provides new ideas for the regional prediction of high-risk areas for soil pollution, which has guiding importance and reference value for the control and management of large-scale soil pollution.

Ecological Impacts of Land Use Change in the Arid Tarim River Basin of China

Land use/cover change has become an indispensable part of global eco-environmental change research. The Tarim River Basin is the largest inland river basin in China. It is also one of the most ecologically fragile areas in the country, with greening and desertification processes coexisting. This paper analyzes the evolution of land-use/cover change in the Tarim River Basin over the past 30 years based on remote sensing data. The research also explores the contribution of conversion between different land types to the ecological environment by selecting methods, such as transfer matrix and ecological contribution rate. Results indicate that grassland and barren land are the main land types in the region, accounting for 72.46% and 18.87% of the basin area, respectively. From 1990 to 2019, cropland area increased from 33,585.89 km2 to 52,436.40 km2, an increase of 56.13%, while barren land areas decreased from 781,380.57 km2 to 760,783.29 km2. Most of the land-use conversion was grassland to other land types and other land types to barren land. Since 1990, the conversion of barren land to grassland and cropland in the basin has led to ecological improvement, whereas the conversion of grassland to cropland has caused deterioration, but with a generally improving trend. It is anticipated that, over the next decade, changes in land types will involve increases in grassland and woodland area, decreases in barren land and cropland, and an overall improvement in the ecological environment in the watershed. Since agriculture and animal husbandry are the main industries in the Tarim River Basin and the land-use structure is dominated by cropland and grassland, several key measures should be implemented. These include improving land use, rationalizing the use of water and soil resources, slowing down the expansion of cropland, and alleviating the contradiction between humans and land, with the ultimate aim of achieving sustainable development of the social economy and ecological environment.

Assessment of Contents and Health Impacts of Four Metals in Chongming Asparagus-Geographical and Seasonal Aspects

In this paper, the contents of four typical metals (Pb, Cd, Hg, and As) in asparagus, water, and soil from Chongming Island were quantitatively determined by inductively coupled plasma mass spectrometry (ICP-MS). The contents of these metals in asparagus showed a common rule of Pb > As > Cd > Hg in different harvest seasons and regions. Significant seasonal differences were found in the contents by difference analysis, but no obvious regional differences were observed. Furthermore, the asparagus did not accumulate these four metals from the soil in Chongming Island by the assessment of bio-concentration factor. The asparagus was proved safe by the analysis of single-factor pollution index and Nemerow pollution index. Through combining the analysis of the above indexes and the geological accumulation index, we found that 51.62% of soil samples were mildly polluted by cadmium. The results of health risk analysis showed that the risk value of children was higher than that of adults under oral exposure, but the four metals in asparagus possessed no obvious risk to health. The above assessments illustrate that the daily consumption of asparagus in Chongming Island will not cause potential health impacts. It is of benefit to ensure the quality and economic interests of asparagus planting in Chongming Island through the investigation of this study.

Prediction of high-risk areas of soil heavy metal pollution with multiple factors on a large scale in industrial agglomeration areas

Heavy metals in soil are a great threat to ecosystems and human health. The rapid development of industrialization has created a serious risk of heavy metal pollution in soil. The study took the industrial-intensive Dahetan subbasin as the typical area. The factors and interactions that affected the distribution of soil heavy metals (Cd, Hg, As, Pb and Cr) in the typical area were explored based on the Geodetector model. The analysis results were extended to predict high-risk areas of heavy metal pollution in the soil in the Xiangjiang River basin. The results showed that Cd, As and Pb were significantly affected by local industrial and mining activities, and Hg and Cr were primarily affected by natural factors, such as pH and soil type. Compared to a single factor, the interaction between factors had a greater impact on the concentration of heavy metals. The high-risk areas of soil heavy metal pollution in the Xiangjiang River basin were primarily concentrated in the upper reaches and middle reaches.Significant overlapping of high-risk areas of multiple heavy metals occurred in the west, middle and south of the basin. The spatial visualization of the high-risk areas was realized, and the influence of several factors was integrated via layer superposition. This study proposes a new idea to predict the high-risk areas of soil pollution in large-scale areas to provide a reference for the regional prevention and control of soil pollution.

Spatiotemporal Dynamics of Ecological Security Pattern of Urban Agglomerations in Yangtze River Delta Based on LUCC Simulation

Urbanization has not only promoted economic development, but also significantly changed land use and development strategy. The environmental problems brought by urbanization threaten ecological security directly. Therefore, it is necessary to introduce changes in land use when constructing an ecological security pattern. This study takes the Yangtze River Delta urban agglomeration, one of the most economically developed regions in China, as the research area. Based on its land use status, the Cellular Automata–Markov model was used to predict the quantitative change and transfer of land-use types in 2025, and three types of land-use patterns were simulated under different scenarios. Combined with the pressure–state–response model, the Entropy TOPSIS comprehensive evaluation model is used to evaluate the three phases in the years of 2005, 2010, and 2015, and the results indicated that the safety level dropped from 85.45% to 82.94%. Five spatial associations were obtained from the spatial autocorrelation analysis using GeoDA, and the clustering distribution of the three phases was roughly the same. Based on the requirements of “Natural Growth” scenario, “Urban Sprawl” scenario, and “Ecological Protection” scenario, the transfer matrix of the various land-use types were modified rationally. The results of scenario simulations illustrated that the level of urbanization was inversely proportional to the level of ecological security. The surrounding cities in the northern part of Taihu Lake were developing rapidly, with low levels of ecological security. The hilly cities in the southern part, in contrast, developed slowly and had a high level of ecological security. Based on the temporal and spatial changes in the ecosystem, an ecosystem optimization model was proposed to determine the ecological functional areas. The nature of each functional area provided the basis to formulate urban construction and management plans and achieve sustainable urban development.

Assessments of the Ecological and Health Risks of Potentially Toxic Metals in the Topsoils of Different Land Uses: A Case Study in Peninsular Malaysia

Simple Summary

This study reported the ecological risks and human health risk assessments of five potentially toxic metals in the topsoils of six land uses in Peninsular Malaysia. It was found that industry, landfill, rubbish heap, and mining areas were categorized as “very high ecological risk”. The land uses of industry, landfill and rubbish heap were found to have higher hazard quotient values for the three pathways of the five metals for children and adults, when compared to the mining, plantation, and residential areas. The values for both the non-carcinogenic (Cd, Cu, Ni, and Zn), and carcinogenic risks for inhalation (Cd and Ni) obtained for children and adults in this study showed no harmful health effects on their health. However, of public concern, the hazard index, for Pb of children at the landfill and the rubbish heap showed non-carcinogenic risk for children. Therefore, children need to be taken care from public standpoint. They should be advised not to play in the topsoils near industry, landfill and rubbish heap areas. The present findings are important for the environmental management of potentially toxic metals especially in the land uses of industry, landfill and rubbish heap in Peninsular Malaysia.

Abstract

Human activities due to different land uses are being studied widely in many countries. This study aimed to determine the ecological risks and human health risk assessments (HHRA) of Cd, Pb, Ni, Cu, and Zn in the topsoils of six land uses in Peninsular Malaysia. The ranges of the potentially toxic metals (PTMs) in the soils (mg/kg, dry weight) of this study were 0.24–12.43 for Cd (mean: 1.94), 4.66–2363 for Cu (mean: 228), 2576–116,344 for Fe (mean: 32,618), 2.38–75.67 for Ni (mean: 16.04), 7.22–969 for Pb (mean: 115) and 11.03–3820 for Zn (mean: 512). For the ecological risk assessments, the potential ecological risk index (PERI) for single metals indicated that the severity of pollution of the five metals decreased in the following sequence: Cd > Cu > Pb > Zn > Ni. It was found that industry, landfill, rubbish heap, and mining areas were categorized as “very high ecological risk”. For HHRA, the land uses of industry, landfill and rubbish heap were found to have higher hazard quotient (HQ) values for the three pathways (with the order: ingestion > dermal contact > inhalation ingestion) of the five metals for children and adults, when compared to the mining, plantation, and residential areas. The values for both the non-carcinogenic (Cd, Cu, Ni, and Zn), and carcinogenic risks (CR) for inhalation (Cd and Ni) obtained for children and adults in this study showed no serious adverse health impacts on their health. However, of public concern, the hazard index (HI), for Pb of children at the landfill (L-3) and the rubbish heap (RH-3) sites exceeded 1.0, indicating non-carcinogenic risk (NCR) for children. Therefore, these PERI and HHRA results provided fundamental data for PTMs pollution mitigation and environmental management in areas of different land uses in Peninsular Malaysia.

Soil properties mediate ecosystem intrinsic water use efficiency and stomatal conductance via taxonomic diversity and leaf economic spectrum

The interactions between plants and soils lead to complex feedbacks that regulate intrinsic water use efficiency (iWUE) and stomatal conductance (gs) at ecosystem level and reflect water constraints on plant productivity. However, the relationships among soil properties, biodiversity, and leaf functional traits contributing to the variability in ecosystem iWUE and gs remain largely unknown. To elucidate these relationships, we used principal component analysis to reduce soil properties to a fertility spectrum and a limiting-resource spectrum across grassland, and early-, mid- and late-successional forests in a karst catchment. Leaf functional traits at community level were calculated based on leaf biomass, and were reduced to an economic spectrum and a limiting-resource spectrum. Leaf carbon (δ¹³C) and oxygen (δ¹⁸O) stable isotopes at community levels were used as proxies for ecosystem iWUE and g_s. The effects of soil properties, biodiversity (taxonomic, functional and phylogenetic diversity) and leaf traits on δ¹³C and δ¹⁸O were evaluated using structural equation models. Our results showed that variability in ecosystem iWUE and gs was determined overwhelmingly by indirect effects of soil properties via two different pathways: the soil fertility spectrum, determining the number of coexisting species (taxonomic diversity) and turnover of species (leaf economic spectrum), and the soil limiting-resource spectrum, shaping the specific phylogenetic lineages (phylogenic diversity). In addition, δ¹³C and δ¹⁸O were constrained by the interactive effects of leaf economic spectrum, and taxonomic and phylogenic diversity; total effects of biodiversity on δ¹³C and δ¹⁸O were larger than those of leaf economic spectrum. Our study highlighted the critical role of the evaluating interaction relationships between leaf functional traits, biodiversity metrics and soil properties in understanding the mechanisms of ecosystem function responding to environmental change.

Spatial distribution and risk assessment of agricultural soil pollution by hazardous elements in a transboundary river basin

The present study aimed to evaluate the sources of pollution and the potential human and ecological risks of hazardous elements (HEs) in 40 hotspot sites of the agricultural soil around the Arvand River, Iran. The mean concentrations of As, Cd, Co, Cr, Ni, Pb, Zn, and Hg were measured to be 7.2, 0.8, 14.0, 67.9, 69.5, 63.0, 296, and 0.66 (mg kg^-1), respectively. With the exception of Ni, the mean concentrations of all the elements were found to be higher than those in the background. The spatial distribution of HEs in the study area indicated an increasing trend of contamination from the north to the south. Pb, Zn, and Hg were the most enriched elements, resulting in a high pollution load. Moreover, the agricultural soil of the study area was threatened by a very high ecological risk due to the contribution of Hg, Cd, and Pb. Multivariate statistical analyses determined that the pollution sources are specified by the oil refinery emissions and effluents, irrigation with polluted water, fertilizers, dust storms, and airport emissions. The carcinogenic risk of HEs in both adults and children revealed an acceptable level; however, children faced a great chance of non-carcinogenic risk. The results provide a scientific basis for monitoring HEs and managing health risks via effective methods in the agricultural areas of the Arvand River basin.

Evaluation of Ecological Environment Effect of Villages Land Use and Cover Change: A Case Study of Some Villages in Yudian Town, Guangshui City, Hubei Province

Rapid economic development has a significant negative impact on the rural ecological environment. Evaluating the ecological environmental effect of land use and its change trend at the village scale has important practical significance for maintaining ecological functions and ensuring ecological safety. Taking a typical village in Yudian Town as an example, we applied a land-use ecological environment effect evaluation and the CA-Markov change trend prediction model and constructed an index of ecological environmental effect status. Based on the land use, resource environment, and social economic data from 2014 and 2019, we evaluated the ecological environmental effects of land use in each village, simulated the land-use change in each village in two different scenarios, i.e., the developmental orientation (DO) and ecological orientation (EO), in 2030, and analyzed the corresponding change trend of the land-use effect. The ecological environmental effect of land use showed obvious characteristic differentiation in villages with different development levels. For example, villages with poor natural geographic background conditions and slower economic development had a good level of ecological environmental effect, whereas villages with better resource and environmental endowments but faster economic development had lower levels of ecological environmental effect. Village land-use management methods have had a certain effect on improving ecological security, but the effect has been slow. In conclusion, the research results portray the relationship between rural land use and ecological environmental effects in low hilly areas in northern Hubei at a small scale and have reference value for land resource allocation and spatial pattern optimization in similar regions.

Health Risk and Geochemical Assessment of Trace Elements in Surface Sediment along the Hooghly (Ganges) River Estuary (India)

This study investigated sediment spatial and seasonal distribution of trace elements (TEs) (n = 16) and human health effects along the Hooghly River Estuary (India). The index of geo-accumulation (Igeo), enrichment factor (EF), hazard quotient (HQ), modified hazard quotient (mHQ) and toxic risk unit (TRI) were calculated to estimate sediment pollution level, while hazard index (HI) and lifetime cancer risk (LCR) were used to assess TEs enrichment vs. human health. The concentrations (µg/g dry weight) of TEs were: Cd (0.01–1.58), Cr (41.98–105.49), Cu (16.41–51.09), Ni (28.37–63.90), Fe (22075–47919), Mn (423–630), Co (11.43–23.11), Zn (48.82–105.81), V (63.92–138.92), Pb (25.01–43.27) and Ti (0.18–3.50); As (2.92–16.26), B (59.34–98.78), Si (11.52–98.78); Be (1.71–4.81), Ba (95.23–293.72). From Igeo and EF, Cd was the major contaminant, while Ni presented moderate/high contamination (HQ and TRI). Children were more exposed to carcinogenic and non-carcinogenic risks compared to adults. For non-carcinogenic substances, no significant risk was found to both children and adults (HIs < 1). The LCR for Cr (3.924 × 10−4 for children) and As (1.379 × 10−4 for children) was higher than the threshold limit value (TLV, 10−4 and 10−6) indicating significant carcinogenic risks to be managed.