Differences in the risk assessment of soil heavy metals between newly built and original parks in Jiaozuo, Henan Province, China

Source-specific ecological and human health risk analysis of topsoil heavy metals in urban greenspace: a case study from Tianshui City, northwest China

Soil contamination of heavy metals in urban greenspaces can exert detrimental impacts on ecological biodiversity and the health of inhabitants through cross-media migration-induced risks. Here, a total of 72 topsoil samples were collected from greenspaces in the popular tourist city of Tianshui, ranging from areas with parks, residential, road, industrial and educational soils. The study aimed to evaluate an integrated source-specific ecological and human health risk assessment of heavy metals. Among the analyzed heavy metals, except Cr (mean), all exceeded the local background values by 1.30-5.67-fold, and Hg, Cd, Pb and As were the metals with large CV values. The Igeo and CF results showed Hg, Cd, As and Pb exhibited significantly high pollution levels and were the primary pollution factors. The mean PLI values indicated moderate pollution in educational (2.21), industrial (2.07), and road (2.02) soils but slight pollution in park (1.84) and residential (1.39) greenspaces. The Igeo, CF, and PLI results also revealing that these heavy metals are more likely to be affected by human activity. Four primary source factors were identified based on PMF model: coal combustion (25.57%), agricultural sources (14.49%), atmospheric deposition (20.44%) and mixed sources (39.50%). In terms of ecological risk, the mean IRI values showed considerable risks in educational soils (287.52) and moderate risks in road (215.09), park (151.27) and residential (136.71) soils. And the contribution ratio of atmospheric deposition for park, residential, road, industrial and educational greenspaces were 57.72%, 65.41%, 67.69%, 59.60% and 75.76%, respectively. In terms of human health risk, the HI (below 1) and CR (below 1.00E-04) for adults from soils of all land use types was negligible. However, children have more significant non-carcinogenic and carcinogenic hazards especially in residential soils, the HI (above 1) and CR (above 1.00E-04) revealed the significance of regarding legacy As contamination from coal combustion when formulating risk mitigation strategies in this area. The proposed method for source and risk identification makes the multifaceted concerns of pollution and the different relevant risks into a concrete decision-making process, providing robust support for soil contamination control.

Assessing bioavailability risks of heavy metals in polymetallic mining regions: a comprehensive analysis of soils with varied land uses

To accurately assess the bioavailability risk of heavy metals (HMs) in a representative polymetallic mining region, we undertook an exhaustive analysis of Cu, Pb, Ni, Co, Cd, Zn, Mn, and Cr in soils from diverse land-use types, encompassing agricultural, forest, residential, and mining areas. We employed speciation analysis methods and a modified risk assessment approach to ascertain potential ecological threats posed by the HMs. Our findings reveal that both the total potential ecological risk and the modified bioavailability risks are most pronounced in the soil of the mining area. The modified bioavailability threats are primarily caused by Pb, Ni, Cd, and Co. Although the total potential ecological risk of Cu is high in the local soil, the predominance of its stable forms reduces its mobility, thereby mitigating its detrimental impact on the ecosystem. Additionally, medium modified bioavailability risks were identified in the peripheries of agricultural and forest areas, potentially attributable to geological processes and agricultural activities. Within the urban district, medium risks were observed in residential and mining areas, likely resulting from mining, metallurgy, industrial operations, and traffic-related activities. This study provides critical insights that can assist governmental authorities in devising targeted policies to alleviate health hazards associated with soils in polymetallic mining regions.

Potentially Toxic Elements Uptake and Distribution in Betula middendorffii T. and Duschekia fruticosa R. Growing on Diamond Mining Area (Yakutia, Russia)

This study was conducted in the territory of the industrial site of the Udachny Mining and Processing Division (Yakutia, Russia). The objects of study were permafrost soils and two species of shrubs (Betula middendorffii T. and Duschekia fruticose R.). Soil and plant samples were analyzed by atomic absorption spectrometry for the presence of potentially toxic elements (Pb, Ni, Mn, Cd, Co, Co, Cr, Zn, Cu, and As). The bioaccumulation factor for each element was also calculated. In the studied plants, the investigated elements were arranged in the following descending row in terms of their content: Mn > Zn > Cr > Ni > Cu > Pb > As > Co > Cd, but in terms of bioaccumulation degree, they decrease in the following row: Cr > Zn > Ni > Mn > Pb > Cu > Cd > Co-for Betula middendorffii, Cr > Zn > Ni > Pb > Cu > Mn > Mn > Cd > Co-for Duschekia fruticose. The bioaccumulation factor results confirmed that Betula middendorffiii and Duschekia fruticosa are resistant to high concentrations of Cr, Ni, Co, Cu, Mn, and Zn elements coherent to kimberlites.

Health Risk Assessment of Heavy Metals in Agricultural Soils Based on Multi-Receptor Modeling Combined with Monte Carlo Simulation

The spatial characteristics, pollution sources, and risks of soil heavy metals were analyzed on Hainan Island. The results showed that the heavily polluted points accounted for 0.56%, and the number of mildly and above polluted points accounted for 15.27%, respectively, which were mainly distributed in the northern part of the study area. The principal component analysis-absolute principal component score-multiple linear regression (APCS-MLR) and the positive matrix factorization (PMF) revealed four sources of heavy metals: agricultural pollution sources for cadmium, (Cd), industrial and mining pollution sources for arsenic, (As), transportation pollution sources for zinc and lead (Zn and Pb), and natural pollution sources for chromium, nickel, and copper (Cr, Ni, and Cu). The human health risk assessment indicated that the average non-carcinogenic risk (HI) for both adults and children was within the safe threshold (<1), whereas Cr and Ni posed a carcinogenic risk (CR) to human health. In addition, the total non-carcinogenic risk (THI) indicated that heavy metals posed a potential non-carcinogenic risk to children, while the total carcinogenic risk (TCR) remained relatively high, mainly in the northern part of the study area. The results of the Monte Carlo simulation showed that the non-carcinogenic risk (HI) for all heavy metals was <1, but the total non-carcinogenic risk index (THI) for children was >1, indicating a potential health risk above the safe threshold. Meanwhile, nearly 100% and 99.94% of the TCR values exceeded 1 × 10-4 for children and adults, indicating that Cr and Ni are priority heavy metals for control. The research results provide the necessary scientific basis for the prevention and control of heavy metals in agricultural soils.

PFOA-contaminated soil remediation: a comprehensive review

Soil and groundwater contamination has been raised as a concern due to the capability of posing a risk to human health and ecology, especially in facing highly toxic and emerging pollutants. Because of the prevalent usage of perfluorooctanoic acid (PFOA), in industrial and production processes, and subsequently the extent of sites contaminated with these pollutants, cleaning up PFOA polluted sites is paramount. This research provides a review of remediation approaches that have been used, and nine remediation techniques were reviewed under physical, chemical, and biological approaches categorization. As the pollutant specifications, environmental implications, and adverse ecological effects of remediation procedures should be considered in the analysis and evaluation of remediation approaches, unlike previous research that considered a couple of PFAS pollutants and generally dealt with technical issues, in this study, the benefits, drawbacks, and possible environmental and ecological adverse effects of PFOA-contaminated site remediation also were discussed. In the end, in addition to providing sufficient and applicable understanding by comprehensively considering all aspects and field-scale challenges and obstacles, knowledge gaps have been found and discussed.

Evaluation of the prediction effectiveness for geochemical mapping using machine learning methods: A case study from northern Guangdong Province in China

This study compares seven machine learning models to investigate whether they improve the accuracy of geochemical mapping compared to ordinary kriging (OK). Arsenic is widely present in soil due to human activities and soil parent material, posing significant toxicity. Predicting the spatial distribution of elements in soil has become a current research hotspot. Lianzhou City in northern Guangdong Province, China, was chosen as the study area, collecting a total of 2908 surface soil samples from 0 to 20 cm depth. Seven machine learning models were chosen: Random Forest (RF), Support Vector Machine (SVM), Ridge Regression (Ridge), Gradient Boosting Decision Tree (GBDT), Artificial Neural Network (ANN), K-Nearest Neighbors (KNN), and Gaussian Process Regression (GPR). Exploring the advantages and disadvantages of machine learning and traditional geological statistical models in predicting the spatial distribution of heavy metal elements, this study also analyzes factors affecting the accuracy of element prediction. The two best-performing models in the original model, RF (R2 = 0.445) and GBDT (R2 = 0.414), did not outperform OK (R2 = 0.459) in terms of prediction accuracy. Ridge and GPR, the worst-performing methods, have R2 values of only 0.201 and 0.248, respectively. To improve the models' prediction accuracy, a spatial regionalized (SR) covariate index was added. Improvements varied among different methods, with RF and GBDT increasing their R2 values from 0.4 to 0.78 after enhancement. In contrast, the GPR model showed the least significant improvement, with its R2 value only reaching 0.25 in the improved method. This study concluded that choosing the right machine learning model and considering factors that influence prediction accuracy, such as regional variations, the number of sampling points, and their distribution, are crucial for ensuring the accuracy of predictions. This provides valuable insights for future research in this area.

Spatial variability of heavy metals concentrations in soil of auto-mechanic workshop clusters in Nsukka, Nigeria

The indiscriminate disposal of spent engine oils and other hazardous waste at auto mechanic workshops clusters in Nsukka, Enugu State, Nigeria is an environmental concern. This study examines the concentration of heavy metals in the soil inside the workshop cluster and in the unpolluted soil outside the workshop cluster at approximately 100 m. Ten sampling points were randomly selected from within the cluster and another ten from outside the cluster. Using a hand-held Global Positioning System, the coordinates of the selected points were established and used to create a digital map. Soil samples at depths of 0-30 cm and 30-60 cm, were analyzed for Cu, Fe, Zn, Pb, As and Cd using Spectrophotometer. Moisture content determination and particle size analysis were also done on the samples. Spatial variability of heavy metals concentrations of the studied site was also mapped with ArcGIS 10.2.2 using interpolation methods. Results showed that the soil ranged from sandy loam to sandy clay loam. Cadmium and Zinc had the lowest and highest concentration, respectively, in the studied area. Comparing the concentrations of heavy metals in soils within and outside the auto mechanic cluster revealed notable differences across various depths (0-30 cm and 30-60 cm). The analysis results for soil samples within the cluster exhibited concentration levels (mg/kg) ranging from 0.716-0.751 (Cu), 2.981-3.327 (Fe), 23.464-30.113 (Zn), 1.115-1.21 (Pb), 2.6-2.912 (As), and 0.133-0.365 (Cd) demonstrating a variation pattern in the order of Zn > Fe > As > Pb > Cu > Cd. Conversely, for soil samples outside the cluster, concentration levels (mg/kg) ranged from 0.611-0.618 (Cu), 2.233-2.516 (Fe), 12.841-15.736 (Zn), 0.887-0.903 (Pb), 1.669-1.911 (As), and 0.091-0.091 (Cd). To assess the disparity in heavy metal concentration levels between samples collected within and outside the clusters, ANOVA test was performed. The test showed significant difference in heavy metal concentrations between samples within and outside the auto mechanic cluster (p < 0.05), implying auto mechanic activities significantly impact heavy metal levels within the cluster compared to outside areas. The assessment of soil pollution utilized indices including the Geo-accumulation Index (Igeo), Contamination factor (Cf), and anthropogenic metal concentration (QoC). Zinc, Cadmium, and Arsenic showed the highest contamination factors, indicating significant soil contamination likely due to anthropogenic activities. The concentrations of the metals analyzed were within WHO permissible limits while the metals concentrations were also observed to decrease as depth was increased. Using ArcGIS 10.2.2, spatial maps showing heavy metal distribution were developed, with the Kriging method proving superior. This study suggests that heavy metal levels in the soil at the area be monitored on a regular basis.

Ecological pollution features and health risk exposure to heavy metals via street dust and topsoil from Nkpor and Onitsha in Anambra, Nigeria

The manuscript presents the investigation results on the pollution and risk of metal mines, and it is considered an important report on environmental pollution near mines in Nigeria, with archival value. The research involved soil sampling and heavy metal analysis for about 12 months in three metal mines. Based on these results, the paper provides information on pollution levels and hazards using well-known methods like pollution and ecological risk indexes. The increasing population in urban communities attracted by various industrial, economic and social activities causes contamination of atmospheric environment that can affect human health. We investigated heavy metal distributions, correlation coefficient among elements, ecological indices and probable health risk assessment in street dust and topsoil from Nkpor and Onitsha urban suburb, Nigeria. The mean concentration of heavy metals in car dust from Onitsha and Nkpor suburb follows thus: Fe > Mn > Cu > As > Pb > Ni > Cr. The decreasing trend of heavy metal in rooftop dust from both area: Fe > Mn > Cu > Pb > As > Ni > Cr whereas metal contents in topsoil were: Fe > Mn > Cu > Pb > Ni > Cr > As for both areas. The degree of pollution indices was characterized by contamination factor (CF), geo-accumulation factor (I-geo), pollution load index (PLI), Nemerow (PN), ecological and potential ecological risk index (ER and PERI) which indicated low pollution in the urban street environment. The results of Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) showed that the estimated heavy metals displayed sources from atmospheric deposition, natural origin and anthropogenic sources. Risk assessment revealed that ingestion of dust and soil was the significant route for heavy metals exposure to the populace followed by inhalation, then dermal contact. Considering all factors, non-cancer risk was more prominent in children than adults and no significant health hazard could be attributed to both aged groups as of the period of study except for As and Ni that needs constant monitoring to avoid exceeding organ damaging threshold limit of 1 × 10-4.

Characteristics and evaluation of heavy metal pollution in a soil-wheat system of an arid oasis city in northwest China

In this paper, the Cu and Ni accumulation and contamination levels in agricultural soils and wheat around a smelter in Jinchang City in northwest China were investigated with a combination of field investigations and indoor analytical tests, using a soil-wheat system as the study area. The average Cu and Ni contents in the soil were 119.50 mg kg-1 and 123.40 mg kg-1, respectively, both of which exceeded the local soil background values. The Cu and Ni contents in 46.15% o and 26.92% of sampling sites, respectively, exceeded the screening values for soil contamination risk in agricultural land in China. The average Cu content in different parts of wheat was in the order of roots (24.22 mg kg-1) > leaves (20.11 mg kg-1) > husks (5.51 mg kg-1) > grains (4.05 mg kg-1) > stalks (3.74 mg kg-1). Furthermore, the average Ni content ranked as leaves (24.64 mg kg-1) > roots (21.12 mg kg-1) > husks (6.95 mg kg-1) > stalks (1.75 mg kg-1) > grains (0.38 mg kg-1). The health risk evaluation showed that with average hazard index values of 0.88 for adults and 1.04 for children for Cu and Ni in wheat grain, wheat in this region is unlikely to pose a health risk to adults but may pose a lesser health risk to children. The Ni bio-concentration and translocation factors in the husk and leaves of wheat were greater than those of Cu and smaller than those of Cu in the other parts of wheat. The results of this study provide basic data for the remediation of heavy metal contamination in local agricultural soils.

A comprehensive health risk assessment associated with bioaccumulation of heavy metals and nutrients in selected macrophytes of Loktak Lake, Manipur, India

The Loktak Lake, a Ramsar site in Northeast India, is known for its rich biodiversity that includes a variety of macrophyte species, most of which have not been studied for their phytoremediation capacities and potential toxicity via consumption of the edible species. Therefore, a comprehensive assessment was conducted to evaluate the accumulation of selected heavy metals and nutrients in 10 dominant macrophyte species growing in Loktak Lake and to assess the potential health risks associated with consumption of the edible plants. The concentrations of nutrients such as total phosphorus (TP), total nitrogen (TN), potassium (K), calcium (Ca), magnesium (Mg), and heavy metals such as copper (Cu), manganese (Mn), zinc (Zn), and iron (Fe) were found to be in the order of plant > sediment > water. The bioaccumulation factors (BAFs) revealed high efficiency of most plants to accumulate heavy metals and nutrients in their tissues from the lake water and sediments, indicating their potential to be used as phytoremediators. Translocation factors (TFs) were also estimated to determine the efficiency of the plants to translocate elements from root to shoot. Colocasia esculenta and Polygonum perfoliatum exhibited the highest BAF values, whereas Colocasia esculenta, Hedychium flavum, Phragmites karka, and Oenanthe javanica exhibited the highest TF values for most elements. Target hazard quotients (THQs) revealed potential health risks associated with one or more heavy metals in the plants, except for Zn, whose THQ values were below the level of concern in all the edible plant species. The hazard index (HI) signifying potential non-carcinogenic health risk from the combined effects of all the heavy metals was highest for Polygonum perfoliatum, indicating a potentially higher risk to health if this edible macrophyte is regularly consumed in higher quantities and may pose long-term health effects to the exposed population.

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.

Arsenic and heavy metals at Japanese abandoned chemical weapons site in China: distribution characterization, source identification and contamination risk assessment

As-containing chemical weapons (CWs) and their degraded products pose a great threat to the environment and to human health. In this study, concentration and distribution characteristics, source identification, and health risk assessments were determined for As, Cr, Ni, Cu, Zn, Cd and Pb in environmental samples from Lianhuapao (LHP), a typical site of Japanese abandoned chemical weapons (JACWs) in China. The results show that the concentration levels of As, Cr and Ni in the LHP soils are abnormally high, with 69.57%, 83.33% and 91.67%, respectively, of the total sample exceeding the risk screening values for soil contamination of agricultural land. As levels in water samples were generally within safety limits, with the exception of perched water in the core contamination area. In the study area, none of the dominant plant species were enriched with As, except for the Pteris vittata L. Pentavalent arsenic was found to be the predominant arsenic species in the topsoil and water samples. Source identification using statistical approaches indicated that the concentrations of As, Pb, Cu, Cd and Zn are likely influenced by JACWs, while Cr and Ni levels may be related to the natural weathering process. The total concentrations of As, Cr and Ni showed a significant degree of contamination, but only As displayed high potential ecological risk. The calculated indexes of health risk evaluation strongly indicate an unacceptable carcinogenic risk (1E-04) to children, and higher non-carcinogenic risk, relative to that of adults. Our data indicate that the health risk from the resulting As contamination is still a cause for concern, although the JACWs were excavated decades ago from these soils.

Source apportionment and potential ecological risk assessment of heavy metals in soils on a large scale in China

The properties and sources of soil heavy metals (Pb, Zn, Cu, Cd, As, Hg, Cr, and Ni) need to be comprehensively analyzed to take effective steps to control and reduce soil pollutants. In this research, 416 soil samples were collected on a large scale in China. Two receptor models (PCA/MLR and PMF) were utilized to identify pollutant sources and quantify the contributions. The means of soil heavy metals (Zn, Cu, As, Hg, Cr, and Ni) were lower than the corresponding screening values and intervention values. Cd was greater than the intervention value, while Pb was between the screening value and the intervention value. Source apportionments suggested that mine sources were the most polluted (64.28%), followed by traffic sources (38.98%), natural sources (11.41-39.58%), industrial sources (9.8-18.65%), and agricultural sources (2.79-14.51%). Compared to the PCA/MLR model, the PMF model had a better effect in evaluating soil heavy metal pollution. It gave corresponding weights according to the data concentration and its uncertainty, which made the result reasonable. The ecological risk assessment indicated that Cd posed a significant risk, while Hg caused a mild risk and the other six heavy metals posed a low risk. The spatial distribution of ecological risk suggested that severe risk points were mainly distributed in the central area, while high-risk points were distributed in the southern region. The SRI method was developed to link pollution sources and their potential ecological risks and indicated better applicability to the PMF model. The study findings could provide guidelines for monitoring the main sources and reducing the pollution of soil heavy metals.

An integrated approach for quantifying source apportionment and source-oriented health risk of heavy metals in soils near an old industrial area

Soil contamination of heavy metals (HMs) caused by the long-term industrial activities has become a major environmental issue due to its adverse effects on human health and ecosystem. In this paper, 50 soil samples were analyzed to evaluate the contamination characteristics, source apportionment and source-oriented health risk of HMs in soils near an old industrial area in NE China by applying an integrated approach of Pearson correlation analysis, Positive matrix factorization (PMF) model and Monte Carlo simulation. The results showed that the mean concentrations of all HMs greatly exceeded the soil background values (SBV), and the surface soils in the study area were heavily polluted with HMs, displaying a very high ecological risk. The toxic HMs emitted from the bullet production were identified as the primary source of HMs contamination in soils, with a contribution rate of 33.3%. The human health risk assessment (HHRA) suggested that the Hazard quotient (HQ) values of all HMs for children and adults are within the acceptable risk level (HQ < 1). The carcinogenic risk (CR) values of HMs for children and adults significantly exceeded the acceptable threshold of 1E-6 with a basic trend: As > Pb > Cr > Co > Ni, indicating a high cancer risk. For source-oriented health risk, the CR of four pollution sources for children and adults shows a same trend: Factor 4 > Factor 3 > Factor 2 > Factor 1. Among those, the source of HMs pollution from bullet production is the largest contributor to cancer risk, and As and Pb are the most important HMs pollutants that cause cancer risk to humans. The present study sheds some light on the contamination characteristics, source apportionment and source-health risk assessment of HMs in industrially contaminated soils, which helps improve the management of environmental risk control, prevention and remediation.

Variation in pollution status, sources, and risks of soil heavy metals in regions with different levels of urbanization

Soil heavy metal (HM) pollution is an increasing threat to ecosystem integrity and human health with rapid urbanization. Nevertheless, how soil HMs vary with the process of urbanization remains unclear. Here we used index evaluation, spatial analysis, and a positive matrix factorization (PMF) model to determine the pollution characteristics and sources of eight soil HMs (Mn, Cr, Cu, Zn, As, Cd, Pb, and Ni) among regions with different urbanization levels (urban area, suburb, and ecoregion) in Baoding City, Northern China. We also assessed the risks posed to the ecosystem and human health using risk assessment models. The results indicated that the mean levels of Cu, Zn, As, Cd, and Pb in the study area exceeded the soil environmental quality standards by 10.7 %, 10.7 %, 12.5 %, 23.2 %, and 3.57 %, respectively. A pronounced regional spatial distribution was discovered with high levels in suburban areas. Both the geo-accumulation index and potential ecological risk index revealed significantly higher HM contamination in suburban areas than in urban or ecoregion areas. Source apportionment based on the PMF model and correlation analysis showed that soil HMs in suburban areas primarily originated from agricultural activity, industrial sources, and natural sources. Those in urban soils originated from industrial sources, urban traffic, and natural sources, whereas those in ecoregions derived from natural sources and agricultural activity. The complex sources of soil HMs in suburban areas resulted in the highest carcinogenic risks to children health, followed by the ecoregion, but not in urban areas. This study identified the differences in pollution levels, sources, and risks of soil HMs among regions with different urbanization levels and can guide future efforts to mitigate and manage soil HM pollution during urbanization.

Characteristics of Soil Heavy Metal Pollution and Health Risk Assessment in Urban Parks at a Megacity of Central China

In this study, we compared the concentrations of the heavy metals Cd, Cr, Cu, Zn, Ni, and Pb in the surface soils of urban parks in Wuhan, Hubei Province, with those in the surface soils of urban parks worldwide. The soil contamination data were assessed using enrichment factors and spatial analysis of heavy metals using inverse distance weighting and quantitative analysis of heavy metal sources with a positive definite matrix factor (PMF) receptor model. Further, a probabilistic health risk assessment of children and adults using Monte Carlo simulation was performed. The average Cd, Cr, Cu, Zn, Ni, and Pb concentrations in the surface soils of urban parks were 2.52, 58.74, 31.39, 186.28, 27.00, and 34.89 mg·kg^-1, respectively, which exceeded the average soil background values in Hubei. From the inverse distance spatial interpolation map, heavy metal contamination was primarily observed to be present to the southwest of the main urban area. The PMF model resolved four sources: mixed traffic and industrial emission, natural, agricultural, and traffic sources, with relative contributions of 23.9%, 19.3%, 23.4%, and 33.4%, respectively. The Monte Carlo health risk evaluation model demonstrated negligible noncancer risks for both adult and child populations, whereas the health effects of Cd and Cr on children were a concern for cancer risks.

Source, environmental behavior and potential health risk of rare earth elements in Beijing urban park soils

Rare earth elements (REEs) have been increasingly diffused to the environment due to their extensive use and application in industries, agriculture, and high-tech devices, which have been regarded as emerge pollutants. However, the study concerning REEs in urban soils is still limited. Therefore, the objectives of this study were to investigate the potential source and risk of REEs in urban environment. We analyzed the concentration and distribution of REEs in urban park soils, and performed a combination of micro geochemical method and random forest method to characterize the pollution sources of REEs. The results showed that the ΣREE concentrations in Beijing urban park soils ranged from 117.19 to 198.09 mg/kg. Spatial distribution indicated that the high concentrations of REEs were mainly concentrated in the west of Beijing near an industrial area. The geochemical parameters, micro spherules and random forest results confirmed the anthropogenic pollution sources from industry and traffic. Risk assessment showed that the average daily doses of total REEs for children and adults were far below the reference threshold with values of 0.08 and 0.02 µg/kg/day, respectively. Our study has exhibited that though the reconstruction of parks from abandoned industrial sites showed an accumulation of REEs, the health risk of REEs for human beings are negligible.

Contamination Assessment and Potential Human Health Risks of Heavy Metals in Urban Soils from Grand Forks, North Dakota, USA

Heavy metal (HM) pollution of soil is an increasingly serious problem worldwide. The current study assessed the metal levels and ecological and human health risk associated with HMs in Grand Forks urban soils. A total 40 composite surface soil samples were investigated for Mn, Fe, Co, Ni, Cu, Zn, As, Pb, Hg, Cr, Cd and Tl using microwave-assisted HNO3-HCl acid digestion and inductively coupled plasma mass spectrometry (ICP-MS) analysis. The enrichment factor (EF), contamination factor (CF), geoaccumulation index (Igeo), ecological risk and potential ecological risk index were used for ecological risk assessment. The park soils revealed the following decreasing trend for metal levels: Fe > Mn > Zn > Cr > Ni > Cu > Pb > As > Co > Cd > Tl > Hg. Based on mean levels, all the studied HMs except As and Cr were lower than guideline limits set by international agencies. Principal component analysis (PCA) indicated that Mn, Fe, Co, Ni, Cu, Zn, As, Cd, Pb, Cr and Tl may originate from natural sources, while Hg, Pb, As and Cd may come from anthropogenic/mixed sources. The Igeo results showed that the soil was moderately polluted by As and Cd and, based on EF results, As and Cd exhibited significant enrichment. The contamination factor analysis revealed that Zn and Pb showed moderate contamination, Hg exhibited low to moderate contamination and As and Cd showed high contamination in the soil. Comparatively higher risk was noted for children over adults and, overall, As was the major contributor (>50%), followed by Cr (>13%), in the non-carcinogenic risk assessment. Carcinogenic risk assessment revealed that As and Cr pose significant risks to the populations associated with this urban soil. Lastly, this study showed that the soil was moderately contaminated by As, Cd, Pb and Hg and should be regularly monitored for metal contamination.

Integrated Insights into Source Apportionment and Source-Specific Health Risks of Potential Pollutants in Urban Park Soils on the Karst Plateau, SW China

Polycyclic aromatic hydrocarbons (PAHs) and heavy metal(loid)s (HMs) pose risks to environmental and human health. Identification of priority control contaminants is important in guiding the management and control of these synchronous pollutants. A total of 247 soil samples were collected from 64 urban parks in the karst plateau city of Guiyang in SW China to determine the concentrations, spatial distributions, and health risks of PAHs and HMs. The results indicate that dibenz(ah)anthracene and benzo(a)pyrene are the main PAHs species of high ecological risk, and Cr, Mn, and Ni pose elevated ecological risk among the HMs. Four sources were identified for PAHs (biomass burning, coke oven, traffic sources, and coal burning) and HMs (traffic sources, coal burning, industrial sources, and natural sources). The non-carcinogenic risk (NCR) and total carcinogenic risk (TCR) of PAHs were all determined to be negligible and at acceptable levels, several orders of magnitude below those of HMs. The NCR and TCR values of HMs were relatively high, especially for children (11.9% of NCR > 1; 79.1% of TCR > 10-4). Coal burning and natural sources make the greatest contributions to the NCR and TCR values from karst park soils in Guiyang. Considering HMs bioavailability, NCR and TCR values were rather low, due to the high residual HM fractions. Integrated insights into source specific ecological and human health risk indicate future directions for management and control of synchronous PAH and HM pollution, particularly for karst plateau areas.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12403-023-00534-3.

Towards an integrated health risk assessment framework of soil heavy metals pollution: Theoretical basis, conceptual model, and perspectives

The health risk of soil heavy metals pollution has been gaining increasing public concern. However, many countries have not set their own health risk assessment (HRA) framework and most of the existing studies directly referred to the USEPA risk assessment model and parameters. For those countries that do not propose an original HRA framework, the experience of developed countries is crucial for advancing their own HRA system. This study systematically reviewed the development of HRA framework in some representative developed countries. The theoretical basis, conceptual model, progress, and challenges of HRA researches concerning soil heavy metals pollution were summarized. By recalling and comparing the health risk-related laws and guidance in the USA, UK, and Japan, results showed that the construction of HRA framework varied between these countries, but HRA has become the main method for deriving their soil environmental criteria. We further summarized the evaluation scales, land use types, exposure pathways, and sensitive receptors of HRA studies, and highlighted the key parameters affecting health risk outputs. There has been a shift toward the incorporation of probabilistic modeling, metals bioavailability, and sources emission characteristics into recent HRA studies. Nonetheless, challenges remained on how to minimize the uncertainty of generating probability distribution and detecting metal bioavailability. To facilitate the development of HRA framework, it was advised that developing countries should strengthen the theoretical researches of health risk and localization researches of exposure factors. Future directions are suggested to tend to: 1) promote sensitive analysis to quantify the impact of distribution assumptions on health risk outputs, 2) derive reasonable risk threshold and consistent evaluation protocol for bioavailability-based health risk assessment method, and 3) strive to explore the combined health effect of exposure to heavy metals in soil through source-media-receptor integrated studies.

Contamination, sources and health risks of toxic elements in soils of karstic urban parks based on Monte Carlo simulation combined with a receptor model

Understanding the health risks of toxic elements (TEs) in urban park soils and determining their priority control factors are crucial for public health and pollution management. Soil samples were collected from 33 urban parks in Guiyang, a typical karstic city. For each park, 15-45 topsoil samples were collected according to the area and then thoroughly mixed to obtain a representative sample. The results showed that the mean concentrations of TEs in park soils (22.5, 0.37, 88.6, 43.7, 0.26, 39.9, 44.7, and 101.0 mg/kg for As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn, respectively) were higher than their background values. Approximately 54.5% and 33.3% of enrichment factor (EF) values reached moderately enriched to significantly enriched levels for Cd and Hg, respectively. Moreover, 54.5% and 42.4% of monomial potential ecological index (EI) values were at considerable to high risk levels for Cd and Hg, respectively. These results illustrate that Cd and Hg pose high ecological risks. According to the potential ecological risk index (RI) values, 21.2% of the parks were exposed to considerable ecological risk and 48.5% were at moderate risk. Based on the positive matrix factorization (PMF) model, four sources governing TE contamination (including coal combustion, natural sources, traffic emissions, and industrial activities) were identified, with contribution rates of 32.3%, 31.0%, 19.6%, and 17.1%, respectively. A probabilistic health risk assessment showed acceptable non-carcinogenic risks and high levels of carcinogenic risk in all populations. Based on the source-specific health risk assessment, arsenic from coal combustion was determined to be a major contributor to human health risks. Although several efforts have been made by the local government to eliminate coal-borne arsenicosis, our results revealed that the accumulation of arsenic in the soil due to coal combustion poses a potential threat to human health.

Spatial Distribution of Soil Heavy Metals and Associated Environmental Risks near Major Roads in Southern Tibet, China

Soil heavy metal pollution is becoming an increasingly serious environmental problem. This study was performed to investigate the contents of surface soil heavy metals (Cu, Zn, Pb, Cd) near six roads in the southern part of the Tibetan Plateau. Multivariate statistics, geoaccumulation index, potential ecological risk, and a human health assessment model were used to study the spatial pollution pattern and identify the main pollutants and regions of concern. The mean Igeo was ranked in the order Cd > Cu > Zn > Pb, with the average concentrations of Cd, Zn, and Cu exceeding their corresponding background levels 4.36-, 1.00-, and 1.8-fold, respectively. Soil Cd level was classified as posing a considerable potential risk near national highways and a high potential risk near non-national highways, whereas soil Cu, Zn, and Pb were associated with a low potential ecological risk for each class of roads. Furthermore, the non-carcinogenic risk due to soil heavy metals for each class of roads was within the acceptable risk level for three exposure pathways for both adults and children, but the carcinogenic risk attributable to soil Pb exceeded the threshold for children near highways G318, G562, and G219 and for adults near highway G318. Our work not only underscores the importance of assessing potential threats to ecological and human health due to soil heavy metal pollution on road surfaces but also provides quantitative guidance for remediation actions.

Heavy-Metal Speciation Distribution and Adsorption Characteristics of Cr (VI) in the Soil within Sewage Irrigation Areas

While sewage irrigation relieves water shortages in Northern China, its excessive application triggers a series of environmental problems, such as heavy-metal pollution. Soil profile and river sediment profile samples from the sewage irrigation area (SIA) were collected by selecting the farmlands in which sewage irrigation activity has been reported since the 1960s, around Huiji River (HJR) and Huafei River (HFR) in Kaifeng, Henan Province, China, as research areas. In this study, the total amount of heavy metals (Cr, Cd, Pb, Mn, Zn, and Ni) and the heavy-metal speciation analysis using the modified BCR sequential extraction method were used to evaluate the impacts of wastewater on agricultural soils and the potential risk. Furthermore, the least contaminated Cr (VI) was selected for the study of adsorption characteristics to determine the environmental capacity of soils for heavy metals when the composition of wastewater changes under long-term effluent irrigation conditions. The results show that: (1) the concentrations of heavy metals in soil continuously decreased with depth, while the opposite was observed in sediment, reflecting the continuous improvement in water quality over the historical period; (2) In the topsoil, the mean concentrations (mg·kg−1) in rank order are as follows: Mn (588.68) > Zn (284.21) > Pb (99.76) > Cr (76.84) > Ni (34.71) > Cd (3.25), where Cd exceeded the control value by 3.15 times around HFR, and sediment samples also showed higher heavy metal concentrations in HFR than in HJR; (3) Speciation distribution and risk assessment code (RAC) indicate that Mn and Cd were at medium risk and that Cd warrants attention due to its being a non-essential toxic element in humans; (4) The adsorption rates of soil in various layers in different profiles within SIAs for Cr (VI) gradually increased with the increasing initial content of Cr (VI). Among the three isothermal adsorption models, the fit result obtained by the Langmuir equation was superior to those obtained by the Freundlich equation and the linear equation.

Seasonal changes of heavy metals and health risk assessment based on Monte Carlo simulation in alternate water sources of the Xinbian River in Suzhou City, Huaibei Plain, China

The urban alternate water source (AWS) is of great significance to the sustainable development of the city, the pollution degree, and source of heavy metals (HMs) in AWS, and whether it will adversely affect human health has received widespread attention. In this study, the urban AWS of Xinbian River in Suzhou City, Huaibei Plain, China, was used as the research object to study the seasonal changes of HMs (As, Cr, Cu, Cd, Pb, and Zn), quantitative identification of pollution sources, and human health risks (HHR). Research results show that the contents of those HMs, except As, are less than the drinking standards limit set by the World Health Organization (WHO), and the contents of As, Cr, and Zn are the largest in summer. The multivariate statistical analysis combined with positive matrix factorization (PMF) model analysis revealed that industrial sources accounted for 44.83%, and agricultural sources accounted for 55.17%. HHR assessment based on Monte Carlo simulation shows that the noncarcinogenic risks of adults and children are in the acceptable range (hazardous ingestion (HI) < 1), and the probability of carcinogenic risk values of children and adults are 95.03% and 38.96%, respectively, which are exceed the acceptable range (1 × 10^-4) recommended by the United States Environment Protection Agency (USEPA). Approximately 30.75% of the carcinogenic risk value of agricultural source HMs to children exceeds the acceptable range (1 × 10^-4). The above research results indicate that the effect of agricultural non-point source pollution on AWS should be prevented.

Correlative distribution of DOM and heavy metals in the soils of the Zhangxi watershed in Ningbo city, East of China

In peri-urban critical zones, soil ecosystems are highly affected by increasing urbanization, causing probably an intense interaction between dissolved organic matter (DOM) and heavy metals in soil. Such interaction is critical for understanding the biogeochemical cycles of both organic matter and heavy metals in these zones. However, limited research has reported the correlative distribution of DOM and heavy metals at high seasonal and spatial resolutions in peri-urban critical zones. In this study, 160 soil samples were collected from the farmland and forestland of Zhangxi watershed, in Ningbo, eastern China during spring, summer, fall and winter four seasons. UV-visible absorption and fluorescent spectroscopy were used to explore the optical characteristics of DOM. The results indicated a mixture of exogenous and autogenous sources of DOM in the Zhangxi watershed, while DOM in farmland exhibited a higher degree of aromaticity and humification than that in forestland. Fluorescent results showed that humic acid-like, fulvic acid-like and microbial-derived humic-like fractions were mostly affected by seasons. The distribution of heavy metals was affected mainly by land-use changes and seasons. Correlation analysis between heavy metals and DOM characteristics and components suggested that aromatic and humic substances were more favorable in binding with EDTA extractable Ni, Cu, Zn and Cd. The bioavailable Cd and Pb decreased due to binding with humic fractions, indicating its great effects on the bioavailability of Cd and Pb. Overall, these findings provide an insight into the correlative distributions of DOM and heavy metals in peri-urban areas, thereby highlighting their biogeochemical cycling in the soil environment.

Determination of priority control factors for the management of soil trace metal(loid)s based on source-oriented health risk assessment

Trace metal(loid)s (TMs) in soils can seriously threaten the ecological environment and human health. With the limitation of resources and costs, determining priority control factor is critical for managing soil TM pollution. To explore the pollution characteristics, source apportionment, and human health risk of TMs, a total of 209 surface soil samples were collected from Anqing City, China. Results showed that all the average values of TM concentration, except for Cr, were higher than their corresponding background value. Using a Positive matrix factorization model coupled with Correlation analysis, four sources (including agricultural sources, atmospheric deposition sources, industrial sources, and natural sources) were identified as the determinants for the accumulation of soil TMs, with the contribution rates of 12.4%, 8.1%, 64.1%, and 15.4%, respectively. The assessment of probabilistic health risks revealed that Non- carcinogenic risks of all populations were acceptable (HI < 1), while Carcinogenic risks were all at a high level (TCR > 10E-04). Agricultural pollution and As were identified as priority control factors, according to the analysis results of the relationship among TMs, pollution sources and health risks. Our findings provide scientific support for decision-makers to formulate target control policies and reduce management costs of soil pollution.

Accumulation and partitioning of toxic trace metal(loid)s in phytoliths of wheat grown in a multi-element contaminated soil

Cropland contamination by toxic trace metal (loid)s (TTMs) has attracted increasing attention due to the serious consequential threat to crop quality and human health. Mitigation of plant TTM stress by silica amendment has been proposed recently. However, the relationship between the siliceous structure of phytoliths and TTMs in plants, and the environmental implications of phytolith-occluded trace metal (loid)s (PhytTMs) remain unclear. This study assessed the accumulation of five metal (loid)s, including lead (Pb), zinc (Zn), cadmium (Cd), copper (Cu) and arsenic (As), in the organic tissues and phytoliths of wheat grown in a mixed-TTM contaminated soil under both lightly and heavily contaminated conditions. The results show that the concentrations of plant TTMs and PhytTMs were significantly (p < 0.05) positively correlated, and higher in heavily contaminated wheats than those in lightly contaminated ones. The bio-enrichment factors between phytoliths and organic tissues were higher for As (1.83), Pb (0.27) and Zn (0.30) than for Cd (0.03) and Cu (0.14), implying that As, Pb and Zn were more readily co-precipitated with silicon (Si) in phytolith structures than Cd and Cu. Network analysis of the relationship between soil and plant elements with PhytTMs showed that severe contamination could impact the homeostasis of elements in plants by altering the translocation of TTMs between soils, plants, and phytoliths. The accumulation of TTMs in phytoliths was affected by the capacity of Si deposition in tissues and chelation of TTMs with silica, which could impact the role of PhytTMs in global biogeochemical TTM cycles.

Heavy Metals in Soil and Sand from Playgrounds of Çanakkale City (Turkey), and Related Health Risks for Children

Children spend most of their time in playgrounds and, in parallel, constitute the social group most sensitive to contaminants. Here, we present the results of a comparative study of heavy-metal contents between soils and sand from sandboxes obtained from playgrounds of Çanakkale city. Average contents of soils followed the order of iron (Fe) (12,901 mg kg−1) > manganese (Mn) (475 mg kg−1) > zinc (Zn) (58 mg kg−1) > copper (Cu) (28 mg kg−1) > nickel (Ni), chromium (Cr) (21 mg kg−1) > lead (Pb) (18 mg kg−1). Sand had lower contents, however, due to the reduction of particles size through prolonged use, and accumulation of Fe/Mn (oxyhydr)oxides on sand grains tended to diminish the differences between soils and sand. Through chemometric analysis, Cr and Ni were found to have a lithogenic origin, while the rest of metals were related to anthropogenic activities. Spatially, heavy-metal contents followed the pattern of the city’s sprawl. Risk estimates on children’s health showed that ingestion was the most important exposure route, followed by dermal contact and inhalation. Exposure of children to sand was of similar importance to that of soils. These findings are significant, as the contamination of sand has not yet received much attention compared to the soil of playgrounds.

Health risk assessment of heavy metal(loid)s in park soils of the largest megacity in China by using Monte Carlo simulation coupled with Positive matrix factorization model

Urban Parks are important places for residents to engage in outdoor activities, and whether heavy metal(loid)s (HMs) in park soils are harmful to human health has aroused people's concern. A total of 204 topsoil samples containing nine HMs were collected from 78 urban parks of Shanghai in China, and used to assess the health risks caused by HMs in soils. The results revealed that the Hg, Cd and Pb were the main enriched pollutants and posed higher ecological risks than the other HMs. Four HM sources (including natural sources, agricultural activities, industrial production and traffic emissions) were identified by combining the Positive matrix factorization model and Correlation analysis, with the contribution rate of 48.24%, 7.03%, 13.04% and 31.69%, respectively. The assessment of Probabilistic health risks indicated that the Non-carcinogenic risks for all populations were negligible. However, the Total carcinogenic risk cannot be negligible and children were more susceptible than adults. The assessment results of source-oriented health risks showed that industrial production and traffic emissions were estimated to be the most important anthropogenic sources of health risks for all populations. Our results provide scientific support needed for the prevention and control of HM pollution in urban parks.

Pollution Characteristics and Associated Risk Assessment of Heavy Metals in Farmland Soils From a Typical County of Hubei Province, Central China

Knowledge from the negative impacts of the counties' anthropogenic activities on soil pollution was of great significance in China, and valuable information was urgently needed for the control and remediation of soil pollution. The current pollution levels of heavy metals (Cu, Pb, Cd, Zn, Ni, and Cr) in farmland soils were investigated in Yangxin County, Hubei Province, central China. The comprehensive results of quantitative comparison and evaluation in this study showed that Cu (144.9 ± 298.6 mg kg^-1), Cd (2.9 ± 1.6 mg kg^-1), and Ni (137.0 ± 111.0 mg kg^-1) posed higher pollution risks to public and ecosystem health, which were higher than the corresponding soil background values. The combined results of geostatistics, spatial and statistical analysis indicated that studied heavy metals were mainly attributed to agricultural, traffic and industrial induced pollution. Overall, urgent attention should be paid to the risk reduction and management of soil Cu, Cd, and Ni pollution in the study area.

Pollution effect assessment of industrial activities on potentially toxic metal distribution in windowsill dust and surface soil in central China

Boundaries between industrial and urban areas in developing countries are not clearly defined, but pollution effect assessment of industrial activities on potentially toxic metal (PTM) distribution in these areas has rarely been investigated. Fifteen villages and eight communities surrounding the industrial areas from Anyang, China, were chosen as research objects in this study. A total of 78 windowsill dust and 78 surface soil samples were collected to determine the pollution levels, spatial distribution and risk indices of nine PTMs. PTM concentrations (expect Cr, Mn and Ni in surface soil) in the surveyed region were higher than the local soil background values. Amongst these PTMs, serious Cd and As pollution was discovered, and Cd and As in windowsill dust and surface soil exceeded the background value by 73.00 and 9.59, 9.74 and 10.92 times, respectively. Compared with the I_geo in surface soil, a large degree of variation in I_geo for the different PTMs was found in windowsill dust. The interpolated spatial distribution of dust Cr, Zn, Pb, Cd and soil Mn, Ni and Cu had a gradually decreasing pollution trend from the south to the north due to the prevailing wind directions in winter in the study area. Results of multivariate statistics reflected that industrial production and traffic emission affected the concentration of PTMs in windowsill dust and surface soil. The non-carcinogenic risks for children (soil: 12.4; dust: 19.2) were larger than those for adults (soil: 1.02; dust: 1.51). This finding suggested that industrial activities caused serious harm to the residents around industrial areas.

Trace element contamination in urban topsoil in China during 2000-2009 and 2010-2019: Pollution assessment and spatiotemporal analysis

The Chinese government has launched a critical battle against soil pollution in recent years to establish an effective pollution prevention and control framework. This study sought to investigate the long-term pollution status of potentially toxic trace elements in urban topsoil nationwide, and to further investigate the effectiveness of pollution control over the past decade. The concentrations of 8 elements (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) in urban topsoil in China between 2000-2009 and 2010-2019 were separately collected for comparative analysis. Individual and comprehensive pollution levels of the elements were evaluated at the city, provincial, regional, and national scales, and further spatially mapped using GIS. Combined with PCA, the main factors influencing these elements in soil nationwide were identified. The results revealed a severe situation in terms of potentially toxic trace element accumulation in urban topsoil, where the NNIPIs surpassed 3 in both periods. The elements As, Cd, and Hg were closely associated with industrial activity and coal burning. Hg and, in particular, Cd pollution (NPI > 3) were found to be severe in most of the cities studied. For the elements As, Cu, Pb, and Zn, pollution ranged from slight to moderate (1.0 < NPI ≤ 3.0), and Cu, Pb, and Zn were related to a significant degree with vehicle use. Soil Cr and Ni were mainly controlled by parent materials of lithogenic origin, and slight pollution was identified (1.0 < NPI ≤ 2.0). Pollution patterns showed different characteristics across the regions, and those of the same region and the nation hardly changed over time. Mercury pollution was dominant in the northern regions (NW, MYeR, NE, and NC), while Cd pollution was more severe for the south (EC, MYaR, SC, and SW). Notably, the country's comprehensive pollution level was stable across the two periods, with momentum towards improvement observed over the past decade.

Response of ammonia-oxidizing archaea and bacteria to sulfadiazine and copper and their interaction in black soils

The large-scale development of animal husbandry and the wide agricultural application of livestock manure lead to more and more serious co-pollution of heavy metals and antibiotics in soil. In this study, two common feed additives, copper (Cu) and sulfadiazine (SDZ), were selected as target pollutants to evaluate the toxicity and interaction of antibiotics and heavy metals on ammonia oxidizers diversity, potential nitrification rate (PNR), and enzymatic activity in black soils. The results showed that soil enzyme activity was significantly inhibited by single Cu pollution, but the toxicity could be reduced by introducing low-concentration SDZ (5 mg · kg^-1), which showed an antagonistic effect between Cu and SDZ (5 mg · kg^-1), while the combined toxicity of high-concentration SDZ (10 mg · kg^-1) and Cu were strengthened compared with the single Cu contamination on soil enzymes. In contrast, soil PNR was more sensitive to single Cu pollution and its combined pollution with SDZ than the enzyme activity. Real-time fluorescence quota PCR and Illumina Hiseq/Miseq sequencing results showed that ammonia-oxidizing archaea (AOA) was decreased in C2 (200 mg · kg^-1 Cu treatment) and ammonia-oxidizing bacteria (AOB) was obviously stimulated in soil contaminated in C2, while in S5 (5 mg · kg^-1 SDZ treatment), AOB was decreased; both AOA and AOB were significantly decreased at gene level in soils with combined pollutants (C2S5, 200 mg · kg^-1 Cu combined with 5 mg · kg^-1 SDZ). So, it can be concluded that combined pollution can cause more serious toxicity on the enzymatic activity, PNR, and ammonia-oxidizing microorganisms in soil through the synergistic effect between heavy metals and antibiotics pollutants.

Policy adjustment impacts Cd, Cu, Ni, Pb and Zn contamination in soils around e-waste area: Concentrations, sources and health risks

Pollution control policies (PCP) have been implemented in some e-waste dismantling areas in China to curb metal contamination since 2012. We investigated the effects of policy intervention on the concentrations, sources and health risks of heavy metals in soils. Post-implementation, among Cd, Cu, Ni, Pb and Zn, Pb levels declined while the Cd, Cu, Ni and Zn concentrations in soils were not impacted. Changes in their pollution indices and health risks were also similar. After the PCP, the contribution of traffic emission significantly decreased, while natural and industrial contribution increased due to the heighten background input and relocation of small e-waste dismantling workshops. Risk assessment showed that total cancer risk of five metals also slightly increased. Thus, policy intervention might be effective in controlling the release of some metals from e-waste dismantling. However, the performance of control measures varied depending on both source emission and geochemical properties of the metals. This study reveal the ongoing need of stricter supervision, targeted emission reduction and more-effective soil remediation actions to alleviate soil contamination from e-waste dismantling.

Environmental Health and Ecological Risk Assessment of Soil Heavy Metal Pollution in the Coastal Cities of Estuarine Bay-A Case Study of Hangzhou Bay, China

Shanghai is the major city on the north shore of Hangzhou Bay, and the administrative regions adjacent to Hangzhou Bay are the Jinshan district, Fengxian district, and Pudong new area (Nanhui district), which are the main intersection areas of manufacturing, transportation, and agriculture in Shanghai. In this paper, we collected a total of 75 topsoil samples from six different functional areas (agricultural areas (19), roadside areas (10), industrial areas (19), residential areas (14), education areas (6), and woodland areas (7)) in these three administrative regions, and the presence of 10 heavy metals (manganese(Mn), zinc(Zn), chromium(Cr), nickel(Ni), lead(Pb), cobalt(Co), cadmium(Cd), mercury(Hg), copper(Cu), and arsenic(As)) was investigated in each sample. The Nemerow pollution index (NPI), pollution load index (PLI), and potential ecological risk index (PERI) were calculated to assess the soil pollution levels. The hazard quotient (HQ) and carcinogenic risk (CR) assessment models were used to assess the human health risks posed by the concentrations of the heavy metals. The CR and HQ for adults and children in different functional areas descended in the following order: industrial areas > roadside areas > woodland areas > residential areas > education areas > agricultural areas. The HQ of Mn for children in industrial areas was higher than 1, and the risk was within the acceptable range.

Heavy metal(loid)s in the topsoil of urban parks in Beijing, China: Concentrations, potential sources, and risk assessment

Urban parks play an important role in the urban ecosystem and are also used by residents for recreation. The environmental quality of urban park soils might influence human health following long-term exposure. To assess potential sources and pollution risks of heavy metal(loid)s in the topsoil of urban parks, we subjected metal concentrations in soil samples from 121 parks in the Beijing urban area to geostatistical analyses, conditional inference tree (CIT) analyses, ecological risk and human health risk assessment. CIT effectively explained the influence of human activity on the spatial variation and accumulation of soil metal(loid)s and identified the contributions of natural and anthropogenic inputs. The main factors influencing the accumulation of heavy metal(loid)s, including urbanization duration, park age, per capita GDP, industrial output, and coal consumption, were evaluated by CIT. Except for Cr and Ni, the average concentrations of the metal(loid)s tested (Cu, Pb, Zn, Hg, As, and Cd) were higher than the background values. In the urban parks, Ni and Cr derived mostly from soil parent materials. Concentrations of Cu, Zn, Pb, Cd, As, and Hg were strongly associated with human influences, including industrial, agricultural, and traffic activity. After assessing health and ecological risks, we conclude that heavy metal(loid)s in the soil of Beijing urban parks pose no obvious health risk to humans, and the ecological risk is also low.

Health risk assessment and bioaccessibilities of heavy metals for children in soil and dust from urban parks and schools of Jiaozuo, China

Urban parks and schools sever as the mainly activity areas for children, but risk assessment posed by heavy metals (HMs) from soil and dust in these area has rarely been investigated. In this study, six urban parks and seven schools in Jiaozuo, China, were taken as research objects to understand the contamination level and bioaccessibility of HMs from soil and dust in urban parks and schools. The results indicated that Zn, Cu, Pb, Cd, As, Ni and Co from soil and dust were above the background values, especially Zn and Cd in dust, and As and Cd in soil. Serious Cd pollution was discovered, and respective Cd concentrations in soil and dust were 17.83 and 7.52 times the background value. Additionally, the average concentration and bioaccessibility of Zn, Mn, Pb, Cd, Cr, Ni and Co in dust were both higher than in soil. High concentration and high bioaccessibility of HMs in dust suggested that HMs contamination were serious and universal in Jiaozuo. The concentrations of most HMs were higher in the gastric phase, except for Cu and Cd which remained higher in the intestinal phase. Both in the gastric phase and intestinal phase, Mn, As and Cd in soil and dust both have high bioaccessibility which all exceed 10%. The carcinogenic and non-carcinogenic risks base on the total HMs for children (soil: 7.93, 1.96E-05; dust: 6.44, 3.58E-05) were greater than those for adults (soil: 6.35E-01, 1.32E-05; dust: 5.06E-01, 2.42E-05), and urban parks and schools posed high potential risk for children. Therefore, assessment the risk posed by HMs contamination of soil and dust in urban parks and schools is vital and urgent for children.

Editorial of the VSI "Antibiotics and heavy metals in the environment: Facing the challenge"

The Virtual Special Issue (VSI) "Antibiotics and Heavy Metals in the Environment: Facing the Challenge" received more than 100 submissions from research teams around the world. Finally, more than 50 papers were accepted and published. These very interesting research papers allow going ahead in the knowledge of different aspects which determine the fate of antibiotics and heavy metals in the environmental. The success of the VSI, as well as reports from scientific databases, indicate that this field of research is clearly growing, which is expected to continue, especially considering emerging pollutants as a whole.