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Traditionally, the assessment of heavy metal concentrations using remote sensing technology is sample-intensive, with expensive model development. Using a mining area case study of Daxigou, China, we propose a cross-time-domain transfer learning model to monitor heavy metal pollution using samples collected from different time domains. Specifically, spectral indices derived from Landsat 8 multispectral images, terrain, and other auxiliary data correlative to soil heavy metals were prepared. A cross time-domain sample transfer learning model proposed in the paper based on the TrAdaBoost algorithm was used for the Cu content mapping in the topsoil by selective use of soil samples acquired in 2017 and 2019. We found that the proposed model accurately estimated the concentration of Cu in the topsoil of the mining area in 2019 and performed better than the traditional TrAdaBoost algorithms. The goodness of fit (R2) of the test set increased from 0.55 to 0.66; the relative prediction deviation (RPD) increased from 1.37 to 1.76; and finally, the root-mean-square deviation (RMSE), decreased from 8.33 to 7.24 mg·kg−1. The proposed model is potentially applicable to more accurate and inexpensive monitoring of heavy metals, facilitating remediation-related efforts. [ABSTRACT FROM AUTHOR]

The rapid growth of industrialization and urbanization in China has led to an increase in soil heavy metal pollution, which poses a serious threat to ecosystem safety and human health. The advancement of spectral technology offers a way to rapidly and non-destructively monitor soil heavy metal content. In order to explore the potential of rice leaf spectra to indirectly estimate soil heavy metal content. We collected farmland soil samples and measured rice leaf spectra in Xushe Town, Yixing City, Jiangsu Province, China. In the laboratory, the heavy metals Cd and As were determined. In order to establish an estimation model between the pre-processed spectra and the soil heavy metals Cd and As content, a genetic algorithm (GA) was used to optimise the partial least squares regression (PLSR). The model's accuracy was evaluated and the best estimation model was obtained. The results showed that spectral pre-processing techniques can extract hidden information from the spectra. The first-order derivative of absorbance was more effective in extracting spectral sensitive information from rice leaf spectra. The GA-PLSR model selects only about 10% of the bands and has better accuracy in spectral modeling than the PLSR model. The spectral reflectance of rice leaves has the capacity to estimate Cd content in the soil (relative percent difference [RPD] = 2.09) and a good capacity to estimate As content in the soil (RPD = 2.97). Therefore, the content of the heavy metals Cd and As in the soil can be estimated indirectly from the spectral data of rice leaves. This study provides a reference for future remote sensing monitoring of soil heavy metal pollution in farmland that is quantitative, dynamic, and non-destructive over a large area. [ABSTRACT FROM AUTHOR]

Farmland soil quality is a crucial determinant for agricultural productivity, food safety, and human well-being. Among the various contaminants, heavy metals have emerged as pervasive factors significantly impacting farmland quality, attracting widespread societal concern. In this study, we systematically applied multivariate statistical analysis, geostatistical methods, and the positive matrix factorization (PMF) source apportionment technique to elucidate the sources and contributions of eight heavy metals (Cd, Hg, As, Pb, Cr, Cu, Zn, Ni) in farmland soils within an industrialized town. Our findings reveal that Cd, Hg, Pb, and Zn exhibit pollution or enrichment in farmland soils compared to natural background levels, with Hg and Cd surpassing 164.3% and 50.2%, respectively. Notably, Zn demonstrates discernible point-source pollution. Source apportionment results highlight industrial point sources, coal combustion, and agriculture as the primary anthropogenic contributors to heavy metal contamination, with zinc-plating enterprises being the predominant industrial point sources. Addressing the specific issue of point-source pollution from Zn in industrial activities, further analysis establishes a correlation between soil Zn content and the distance from zinc-plating enterprises. Utilizing an atmospheric transport model, we observe that the impact of industrial activities on soil Zn is limited when the distance exceeds 1.5 km, emphasizing the importance of monitoring Zn pollution within areas less than 1.5 km. This study pioneers a progressive source apportionment approach, considering the origins of different heavy metals, pollution levels, distance factors, and the cost-effectiveness of environmental measures. The insights gained provide scientifically sound strategies for future decision making in environmental protection. [ABSTRACT FROM AUTHOR]

Heavy metal (HM) pollution nowadays is a hot issue concerning global ecological and food safety. As one of the most important woody bamboos for edible shoots in Southeast Asia and southwest China, Dendrocalamus brandisii usually occurs in red soil with a high HM geological background. However, the bioaccumulation process and possible risks of HMs in their cultivation area remain unclear. In this study, a comprehensive risk assessment of HM pollution was conducted in the main cultivation area of D. brandisii under two cultivation patterns in Yunnan, China. The results revealed that moderate to heavy HM pollution existed in the soil of the study area, while bamboo shoots displayed either no pollution or weak contamination. The "large-area intensive afforestation" cultivation pattern can better control HM pollution in soil and shoots than the "small-scale farmer management" pattern. Strong and complex correlations among HMs were unveiled in both soil and shoot samples. The Cr content of 39% of the shoot samples exceeded China's national standards. Cu and Zn were the two most easily accumulated HMs in shoots, with BCF of 0.1235 and 0.1101, respectively. Bioaccumulations of As and Cd were positively correlated with their concentrations in soil. Furthermore, the positive matrix factorization model (PMF) identified three main sources of soil HMs, i.e., Pb and Zn from traffic emissions accounting for 30%; Ni, Mn, and Cr from pedogenic parent material making up 35.4%; and As from mining and metallurgical activities accounting for 34.6%. Monte Carlo simulations suggested the probability of total noncarcinogenic risk for children from bamboo shoots was 24.82% and that As in the soil was the primary element of health risk to children (HQc = 13.94%). These findings emphasize the urgent need to control and mitigate HM pollution from the identified sources and may contribute to the sustainable cultivation of D. brandisii and food safety in Yunnan and similar tropical areas with high HM contents. [ABSTRACT FROM AUTHOR]

Metal beneficiation activities may cause soil pollution in the surrounding cropland, making it crucial to conduct heavy metal pollution assessment and source analysis of the cultivated land in mining areas for the protection of the ecological environment and human health. In this study, a total of 205 surface soil samples (0–20 cm) were collected on site from the Tianheba cropland near the lead–zinc concentrator in Xieping Village, Huixian County, Gansu Province, China; their pH values and their SOM, Zn, As, Cd, Cr, Hg, and Pb contents were determined. Based on the data, we used the Kriging spatial interpolation, the Nemero index, the index of geoaccumulation, and the PMF model to analyze the characteristics of the spatial distribution of soil heavy metals in the region, the degree of contamination, the sources, and the contribution rate. The results indicated that the heavy metals with contamination levels in the Tianheba cropland were Cd, Zn, Pb, Hg, As, and Cr in descending order, with the average concentrations of Cd (0.39 mg/kg), Zn (122 mg/kg), Pb (30.4 mg/kg), and Hg (0.07 mg/kg) being significantly higher than the background values of the Gansu soils. The soil in the region as a whole was heavily polluted; it was heavily polluted with Cd, moderately polluted with Zn, and mildly polluted with Pb. Hg had a larger value in the index of geoaccumulation. By analyzing the spatial distribution and sources of the soil metals, it was found that the cropland contaminated with heavy metals in Tianheba was distributed around the mineral processing plant and the infiltration area of the canal. The PMF model revealed three pollution sources: the industrial source related to mining activities, the fertilizer application source, and the natural source. This study provides a scientific basis for the precise management of heavy metal pollution in the area. [ABSTRACT FROM AUTHOR]

With the development of the economy and society, the environmental problems caused by heavy metals have always been the focus of attention. Strong concern has been recently shown for the heavy metal pollution of soils in southwestern China. The heavy metals of surface soils in the Xinping area of Yunnan province, China are surveyed along with some crop samples. There are 3312 surface soils and 95 crop samples collected in about 370 square kilometers. Heavy metals including As, Cd, Cr, Hg, and Pb and pH are analyzed. New single and integrated pollution indices of heavy metals for soils (PI and PIn) and crops (PIc and PInc) based on Chinese criteria (GB15618-2018 and GB2762-2022) are described and presented here and used to assess the pollution status of heavy metals. The results indicate that the background level of surface soils is about 62.1%, the screening level is about 33.4%, and the intervention level is about 4.5%, which is mainly a result from Cr and spatially coincides with the peridotite rock, indicating a geogenic pollution source. Most crop samples are not contaminated with heavy metals. Comparing the results of the two integrated pollution indices between soils and crops, two inconsistent assessments are observed. One is that some contaminated crops are growing in unpolluted areas (or Type I) and the other is that some uncontaminated crops are growing in polluted areas (or Type II). This indicates a new challenge between the assessment criteria on soils and crops. [ABSTRACT FROM AUTHOR]

With the rapid development of China's industrialization and urbanization, the problem of heavy metal pollution in soil has become increasingly prominent, seriously threatening the safety of the ecosystem and human health. The development of hyperspectral remote sensing technology provides the possibility to achieve the rapid and non-destructive monitoring of soil heavy metal contents. This study aimed to fully explore the potential of ground and satellite image spectra in estimating soil heavy metal contents. We chose Xushe Town, Yixing City, Jiangsu Province as the research area, collected soil samples from farmland over two different periods, and measured the contents of the heavy metals Cd and As in the laboratory. At the same time, under field conditions, we also measured the spectra of wheat leaves and obtained HuanJing-1A HyperSpectral Imager (HJ-1A HSI) satellite image data. We first performed various spectral transformation pre-processing techniques on the leaf and image spectral data. Then, we used genetic algorithm (GA) optimized partial least squares regression (PLSR) to establish an estimation model of the soil heavy metal Cd and As contents, while evaluating the accuracy of the model. Finally, we obtained the best ground and satellite remote sensing estimation models and drew spatial distribution maps of the soil Cd and As contents in the study area. The results showed the following: (1) spectral pre-processing techniques can highlight some hidden information in the spectra, including mathematical transformations such as differentiation; (2) in ground and satellite spectral modeling, the GA-PLSR model has higher accuracy than PLSR, and using a GA for spectral band selection can improve the model's accuracy and stability; (3) wheat leaf spectra provide a good ability to estimate soil Cd (relative percent difference (RPD) = 2.72) and excellent ability to estimate soil As (RPD = 3.25); HJ-1A HSI image spectra only provide the possibility of distinguishing high and low values of soil Cd and As (RPD = 1.87, RPD = 1.91). Therefore, it is possible to indirectly estimate soil heavy metal Cd and As contents using wheat leaf hyperspectral data, and HJ-1A HSI image spectra can also identify areas of key pollution. [ABSTRACT FROM AUTHOR]

In this study, the effects of pollution levels and heavy metal pollution on soil microbial diversity in karst tea plantations are reported. Four tea plantations from plateau hills, under forests, by lakesides and on steep slopes in the South China karst were used as research regions. Soil samples were taken from these tea plantations, the soil heavy metals Cd, Cr, Pb, Zn, Ni and Cu were tested using inductively coupled plasma-mass spectrometry, and Hg and As were tested via atomic fluorescence spectrometry. The soil microbes were analyzed via high-throughput sequencing technology. Heavy metal pollution was evaluated via the single factor index and pollution load index, and the correlation between soil heavy metals and the microbial community was analyzed via SPSS 18.0 and Canoco 5.0 software. The results showed that the studied tea plantation soils were greatly polluted by the heavy metals, Cd and Hg, to a low to moderate degree. The comprehensive pollution of multiple heavy metals occurred only in lakeside tea plantations, in which pollution reached a low degree. It is also suggested that Hg and Cd were the major contributors, followed by Cu. The soil microbial diversity in soil samples from lakeside tea plantations was the highest; however, the discrepancy in its dominant species composition was also the highest. When the pollution load index was close to 0.6, the microbial diversity decreased sharply. Afterward, the diversity and heterogeneity generally gently increased, and the dominant composition was more obvious. These results reveal that the impact of heavy metal pollution on soil microbial diversity was not very distinct, but the impact on the dominant microbial community composition was obvious. In addition, the heavy metals, Cd, Hg and Cu, were the key factors that impacted the soil microbial community composition. [ABSTRACT FROM AUTHOR]

Heavy metal(loid)s pollution in farmland soil is not only a serious environmental but also a human health-related issue. Accurate understanding and evaluation of heavy metal pollution levels in the soil are very important for sustainable agricultural development and food safety. Mountainous and hilly areas have the dual functions of industrial development and agricultural production, and the farmland soil in these areas is more susceptible to heavy metal pollution. In this study, the single factor index, Nemerow index, geo-accumulation index, enrichment factor index, and potential ecological risk indices, which are mainly used to assess the contamination and risk of heavy metals in farmland soils. The sources of heavy metals in agricultural soils of the study area were analyzed using correlation analysis and principal component analysis. Finally, geostatistical methods were used to map the heavy metal contamination of farmland soils. An average concentration of all heavy metals (except As) in farmland soils of the study area exceeded the corresponding background values, as indicated by the obtained results. The results of the principal component analysis showed that the heavy metal sources in the soils of the study area can be classified into two groups. The five pollutant index methods all showed the most serious Hg pollution in the study area. The integrated pollutant mapping results showed that the risk of heavy metal pollution in the study area was mostly moderate, except for the western and central parts of the region. This study enhances understanding of the pollution levers of heavy metals in Yiyuan farmland soils, and also can facilitate the monitoring of heavy metal contaminants at the primary stage of the food chain and assess the risk of the presence of heavy metal contaminants in food, thus improving the health of the residents. [ABSTRACT FROM AUTHOR]

The expected typical gley moist paddy soil was collected in Zhejiang Province, China, and conventional (XS 134 and JH 218) and varieties of hybrid (YY 538 and CY 84) rices were used for a pot experiment. The effects of exogenous heavy metals lead (Pb) and chromium (Cr) on rice growth and the accumulation of heavy metals in the grains were studied. The results show that heavy metal concentrations in soil and rice grains have significant correlations, and Pb and Cr significantly (p < 0.05) inhibited the rice growth (plant height and panicle weight). The potential ecological hazard index (RI) of heavy metals in the soil was 4.88–6.76, which belongs to the grade of "slight ecological hazard", and Pb provides a larger potential ecological hazard than Cr in the studied region. The thresholds for potential health risks and ecological risks for Pb and Cr were lower than the "Control Standards for Soil Pollution Risk of Agricultural Land (Trial)" (GB15618-2018, China). This work provides the basis for soil pollution control for Pb and Cr and the selection of rice cultivars from Pb and Cr accumulated soils. [ABSTRACT FROM AUTHOR]

This study collected 1135 topsoil samples of cultivated land in Laiyang County, eastern China, to analyze the distribution, pollution and health risks of heavy metals (As, Cd, Cu, Cr, Hg, Ni, Pb and Zn). The results show that: (1) the levels of eight heavy metals at some sites were higher than the risk screening values in China, and there was heavy metal pollution. (2) An improved geoaccumulation index was used to evaluate soil pollution. The average value of Igeo before and after improvement was 0.32 (Iml, no pollution to medium pollution) and −0.04 (Iol, no pollution), respectively. (3) Hg and Cd were identified as the main contributors to ecological risk in this study, with a cumulative ecological risk contribution percentage > 65%. The results of the potential ecological risk index (PERI) show that 9.3% of the sampling sites were considered to have moderate ecological risk. (4) As, Pb, Ni and Cu made a contribution of >95% in terms of non-carcinogenic risk to adults and children through different exposure routes, and different soil intake routes posed no non-carcinogenic risk to adults; there was a sampling site with HQChildren > 1, which was consistent with the non-carcinogenic risk site, indicating that children in this location and surrounding areas are more likely to face dual health risks. Therefore, it is necessary to promote the risk management of heavy metals in the study area in order to safely use soil resources. [ABSTRACT FROM AUTHOR]

In this study, the contents and associated soil properties of 6 metal elements (Pb, As, Cu, Zn, Ni, Cr) were measured in 63 topsoil samples in the affected areas of a typical non-ferrous metal slag field in Huili City, Sichuan Province, China. The associated soil properties of the 6 metals include Ammonium Nitrogen ( NH 4 + -N), Nitrate ( NO 3 − -N), Available Phosphorus (AP), Available Potassium (AK), Electrical Conductivity (EC), Cation Exchange Capacity (CEC), Soil Water Content (SWC), and pH. Multivariate statistics-spatial analysis-soil pollution comprehensive evaluation method was used to quantify the environmental pollution degree of heavy metals in the topsoil and divided (zone) the slag field based on the degree of pollution. Pearson correlation analysis and positive matrix factorization (PMF) were used to identify and quantitatively analyze pollution sources and their contributions. The results show that the average contents of Pb, As, Cu, Zn, Ni, and Cr were 13.27, 19.87, 6.91, 50.55, 25.06, and 77.71 mg·kg−1, respectively. Nemerow comprehensive evaluation results showed that the sites with Slight Pollution and Mild Pollution accounted for 26.98% and 3.17% of the total sampling sites, respectively. Approximately 70% of the sampling sites in the study area had no heavy metal pollution in the soil. Sites with No Pollution or Slight Pollution were mainly distributed in the forest areas with vegetation coverage, while sites with Moderate Pollution or Heavy Pollution were mainly distributed in crop planting areas and areas near slag fields. PMF model revealed four pollution sources: natural sources, mixed industrial and transportation sources, agricultural sources, and industrial river water. These results will provide theoretical references for the utilization and treatment of heavy metal-contaminated soil around the slag field in the dry-hot valley. [ABSTRACT FROM AUTHOR]

Heavy metal pollution of soil in agricultural areas is the most prominent environmental pollution problem in China, seriously affecting human health and food security. It has become one of the environmental problems to which all sectors of society attach great importance. Soil heavy metals in the weathering area of hazardous geological bodies in southwest China have naturally high background attributes. Therefore, ecological risk assessment and analysis of potential sources of soil heavy metals in southwest China is of great significance for soil health management, soil heavy metal pollution control and territorial spatial planning. In this study, we collected 787 soil samples (0–20 cm) in Xuanwei County in China and analyzed the concentrations of As, Cd, Cr, Cu, Hg, Ni, Pb and Zn in soils. Igeo, RI, HI and CR were used to calculate the pollution levels, ecological risks and human health risks. Additionally, the PMF model and one-way ANOVA were used to identify the potential sources and discuss the factors affecting the enrichment of heavy metals. The results showed that the mean contents of the surface soils were 1.190 (Cd), 139.4 (Cr), 96.74 (Cu), 0.081 (Hg), 56.97 (Ni), 46.66 (Pb) and 130.1 (Zn) mg/kg. All heavy metals exceeded the background values of the A layer soil in Yunnan Province. The Igeo showed that Cd was the most hazardous element in the study area, followed by Cu, Cr, As, Ni and Pb. The RI showed that low ecological risks, moderate ecological risks, considerable ecological risks and strong ecological risks accounted for 3.81%, 55.27%, 37.74% and 3.18%, respectively, of the total samples, and Cd was the main dominant element. The HI values of the As element in children were greater than 1, indicating a non-carcinogenic risk, and other elements' risks were acceptable. The CR values of Cr and Ni were higher than their limits (1 × 10−4), and both had carcinogenic risks in children and adults, as did As in children. According to the PMF model, four heavy metals sources were identified: geological sources (32%), sources from mining activities (19.38%), atmospheric deposition sources (17.57%) and agricultural sources (31.05%). Thereinto, As and Pb were mainly derived from agricultural sources, Cd and Cr were mainly associated with geological sources, Cu was largely from mining activity sources, Hg was mainly from atmospheric deposition sources and Ni and Zn were mainly from geological sources, mining activities and agricultural activities. The parent material has a significant influence on the enrichment of heavy metals in the soil, and the heavy metals are significantly enriched in the carbonate parent material and quaternary parent material. Topography also plays a role in heavy metal accumulation; Cd, Cr, Cu, Ni and Zn gradually decreased with the increase in altitude, and As and Pb increased with the increase in altitude. Mn-oxide played a crucial part in the enrichment of Cu and Zn, while SOC, K2O and pH had little influence on the accumulation of heavy metals. [ABSTRACT FROM AUTHOR]

The contaminated site is considered a high-risk pollution source due to the accumulation of industrial waste and wastewater, which affects the soil and groundwater environment. In this study, through soil and groundwater investigation, we outlined the characteristics of heavy metal contamination in the soil and groundwater of the contaminated site, assessed the health risk of the contaminated site to humans, and established a numerical model to predict the ecological and environmental risks of the site. The results of the study showed that the maximum contamination concentration of pollutants (lead, arsenic, cadmium) in the soil all exceeded the Chinese environmental standard (GB36600-2018, Grade II), that the maximum contamination concentration (cadmium, Cd) of the groundwater exceeded the Chinese environmental standard (GB14848–2017, Grade IV), and that the heavy metal pollution was mainly concentrated in the production area of the site and the waste-residue stockpiles. The total carcinogenic risk and non-carcinogenic hazard quotient of the site's soil heavy metal contaminants exceed the human acceptable limit, and there is a human health risk. However, the groundwater in the area where the site is located is prohibited from exploitation, and there is no volatility of the contaminants and no exposure pathway to the groundwater, so there is no risk to human health. The simulation prediction results show that, with the passage of time, the site groundwater pollutants as a whole migrate from south to north, affecting the northern surface water bodies after about 12 years, and there is a high ecological and environmental risk. The above findings provide a scientific basis for the study of the soil and groundwater at the riverside contaminated site. [ABSTRACT FROM AUTHOR]

This study examined the pollution status of potential toxic elements (PTEs) in cultivated soils throughout the Poyang Lake region, Jiangxi Province, China. A total of 251 topsoil samples were collected from the 0–20 cm depth to determine the concentrations of seven PTEs (Hg, As, Pb, Cd, Cu, Cr, and Zn). Based on the concentrations of PTEs, we constructed an improved matter–element extension model to evaluate the level of soil pollution by PTEs. We also applied Hakanson's toxic response factor to correct the weights of PTEs determined by a conventional weighting method. The mean concentrations of all seven PTEs in the soil samples exceeded their local background values in Jiangxi Province. The over-standard rates of different PTEs were ranked in the order of Cr > Cu > Cd > Hg > Zn > Pb > As (36.2–87.9%). These potentially harmful pollutants mainly came from the surrounding industrial and agricultural areas, and could enter cultivated soils through different pathways. Samples from Duchang County, Hukou County, and Gongqingcheng City were in a clean state, whereas samples from other areas was in a still clean state or at the warning limit. The evaluation results were consistent with those obtained using several conventional methods. The improved matter–element extension model can therefore be applied for the evaluation of soil pollution by PTEs and yield reliable results in cultivated land. [ABSTRACT FROM AUTHOR]

Soil contamination with heavy metals is a global problem, and these metals can reach the food chain through uptake by plants, endangering human health. Among the metal pollutants in soils, zinc (Zn) and lead (Pb) are common co-pollutants from anthropogenic activities. Thus, we sought to define the accumulation of Zn and Pb in agricultural soils and maize. Concentrations of Pb in agricultural soil (in Namibia) could reach 3015 mg/Kg, whereas concentrations of Zn in soil (in China) could reach 1140 mg/Kg. In addition, the maximum concentrations of Zn and Pb were 27,870 and 2020 mg/Kg in maize roots and 4180 and 6320 mg/Kg in shoots, respectively. Recent studies have shown that soil properties (such as organic matter content, pH, cation exchange capacity (CEC), texture, and clay content) can play important roles in the bioavailability of Zn and Pb. We also investigated some of the genes and proteins involved in the uptake and transport of Zn and Pb by maize. Among several amendment methods to reduce the bioavailability of Zn and Pb in soils, the use of biochar, bioremediation, and the application of gypsum and lime have been widely reported as effective methods for reducing the accumulation of metals in soils and plants. [ABSTRACT FROM AUTHOR]

Unconventional water is an important water resource for agricultural utilization in the drought and water shortage of Northeast China. Additionally, exploration in making full use of it is an important way to alleviate water shortage in China. This paper analyzed the effects of unconventional water through field trials on the accumulation of heavy metals in both cucumbers and the typical black clay soil (expressed as black soil) around the Anshan metallic ore. By exploring the effects of unconventional water after secondary treatment on the accumulation characteristics of heavy metals in cucumbers and the heavy metal balance in the soil–crop system under different conditions, the study shows that there are no significant differences in the heavy metal content when the quantity of unconventional water for irrigation varies. Unconventional water for short-term irrigation does not cause pollution to either the soil environment or the crops. Nor will it cause the accumulation of heavy metals, and the index for the heavy metal content is far below the critical value of the trade standard and national standard, which indicates that the crops irrigated with unconventional water during their growth turn out to be free of pollutants. Unconventional water brings less heavy metals into the black soil than crops. The input and output quantities have only small effects on the heavy metal balance in the black soil. This paper provides a reference for the safety control and evaluation of unconventional agricultural utilization. [ABSTRACT FROM AUTHOR]

Heavy metal(loid)s (HMs) contamination in agricultural soil and crops is related to the quality and safety of agricultural products and public health and has attracted worldwide attention. This study systematically investigated the bioaccumulation of HMs including Cd, Pb, Cr, Hg, As and Se in soil and associated crops (Tea, Plum and Corn) in Guizhou Province, China, and assessed the health risks of the edible part of the crops using the bioconcentration factor (BCF), geoaccumulation index (Igeo), and target hazard quotient (THQ). The results indicate that the mean concentrations of Pb (39.54 ± 16.56 mg/kg), Cr (122.50 ± 33.36 mg/kg), Hg (0.26 ± 0.33 mg/kg), As (25.40 ± 21.34 mg/kg), and Se (0.90 ± 0.46 mg/kg) in cultivated soil exceed the background values of Guizhou Province by 1.12, 1.28, 2.36, 1.27, and 2.4 times, respectively. However, the average concentration of Cd is 0.49 ± 0.49 mg/kg, which is lower than the corresponding background value. The average Igeo values of Pb, Cd, Cr, and As in the soil samples were lower than 1, indicating a relatively low degree of enrichment, whereas the enrichment of Hg was relatively obvious, as approximately 32.9% of the samples were at moderate and above enrichment levels. The contents of HMs in samples of corn, plum, and tea were lower than the corresponding pollutant limit. The BCF values of Cd, Hg, and Se in the three crops were relatively high, indicating a strong migration ability, and the average BCF values of tea in the soil-crop system were higher than those of corn and plum. Correlation analysis showed that the soil pH and concentrations of K2O, Fe2O3, and Al2O3 were negatively correlated with the BCF of Pb, Cr, and Hg in the soil-crop system, indicating that they were affected by macro-oxidation in the soil, whereas Cd and As were basically not affected. The human health risk assessment of THQ values demonstrated that the health risks to local residents from eating corn and drinking tea were low. [ABSTRACT FROM AUTHOR]

Soil-heavy metal pollution in mining areas is one of the problems in the comprehensive treatment of soil environmental pollution. To explore the degree of soil-heavy metal pollution and the human health risk in mining areas, the contents of soil As, Cd, Cu, Cr, Hg, Ni, Pb, and Cr(VI) in an abandoned gold mining area were determined. The geoaccumulation index (Igeo), single-factor pollution index (SPI), Nemerow comprehensive pollution index (NCPI), potential ecological risk index (PERI), and the human health risk assessment model were used to assess the pollution degree and the risk of soil-heavy metal pollution. Finally, the assessment results were used to provide remediation guidance. The results showed that (1) the average contents of As, Cd, Cr, Cu, Hg, and Ni in the mining area exceeded the background values of the soil elements. (2) The mining area was polluted by heavy metals to different degrees and had strong potential ecological hazards. (3) The total carcinogenic risk of heavy metals exceeded the health risk standard. The main components of pollution in the mining area were As, Cd, Cr, and Hg. Results from this study are expected to play a positive role in pollution treatment and the balance between humans and ecology. [ABSTRACT FROM AUTHOR]

To fulfill sustainability principles, a three-site field experiment was conducted to screen suitably mixed passivators from lime + biochar (L + C, 9000 kgha−1 with a rate of 1:1) and lime + biochar + sepiolite (L + C + S, 9000 kg ha−1 with a rate of 1:1:1), in Yuecheng (YC), Zhuji (ZJ), and Fuyang (FY), where there are typical contaminated soils, in South China. Treated with passivators in soil, DTPA-extractable Cd, Cr and Pb in soil were decreased by 9.87–26.3%, 37.2–67.5%, and 19.0–54.2%, respectively; Cd, Cr, and Pb in rice were decreased by 85.9–91.5%, 40.0–76.5%, and 16.4–45.4%, respectively; and these were followed by slightly higher efficacy of L + C + S than L + C. The differences between L + C and L + C + S mainly lie in soil microbial communities, enzymes, and fertility. In YC, treatment with L + C + S increased microbial carbon and activities of urease (EC3.5.1.5) and phosphatase (EC3.1.3.1) by 21.0%, 85.5%, and 22.3%; while treatment with L + C decreased microbial carbon and activities of phosphatase and sucrose (EC3.2.1.26) by 1.31%, 34.9%, and 43.4%, respectively. Moreover, the treatment of FY soils with L + C + S increased microbial carbon and activities of urease, phosphatase, and sucrase by 35.4%, 41.6%, 27.9%, and 7.37%; and L + C treatment only increased the microbial carbon and the activity of phosphatase by 3.14% and 30.3%, respectively. Furthermore, the organic matter and available nitrogen were also increased by 8.8–19.0% and 7.4–14.6% with L + C + S treatments, respectively. These suggested that the combination of L + C + S stimulated the growth of soil microbial communities and increased the activity of soil enzymes. Therefore, the L + C + S strategy can be a practical and effective measure for safe rice production as it was more suitable for the remediation of heavy metals in our experimental sites. [ABSTRACT FROM AUTHOR]

Contamination by heavy metals is a significant issue worldwide. In recent decades, soil heavy metals pollutants in China had adverse impacts on soil quality and threatened food security and human health. Anthropogenic inputs mainly generate heavy metal contamination in China. In this review, the approaches were used in these investigations, focusing on geochemical strategies and metal isotope methods, particularly useful for determining the pathway of mining and smelting derived pollution in the soil. Our findings indicate that heavy metal distribution substantially impacts topsoils around mining and smelting sites, which release massive amounts of heavy metals into the environment. Furthermore, heavy metal contamination and related hazards posed by Pb, Cd, As, and Hg are more severe to plants, soil organisms, and humans. It's worth observing that kids are particularly vulnerable to Pb toxicity. And this review also provides novel approaches to control and reduce the impacts of heavy metal pollution. Hydrometallurgy offers a potential method for extracting metals and removing potentially harmful heavy metals from waste to reduce pollution. However, environmentally friendly remediation of contaminated sites is a significant challenge. This paper also evaluates current technological advancements in the remediation of polluted soil, such as stabilization/solidification, natural attenuation, electrokinetic remediation, soil washing, and phytoremediation. The ability of biological approaches, especially phytoremediation, is cost-effective and favorable to the environment. [ABSTRACT FROM AUTHOR]

Nonferrous metallurgy is an important source of heavy metal in the environment and consequently poses potential risks to ecosystems. The impact of smelting on the surrounding envi-ronment is a concern. In this work, the content levels of selected heavy metals—chromium (Cr), nickel (Ni), copper (Cu), zinc (Zn), lead (Pb), cadmium (Cd), and arsenic (As)—were investigated separately in soil samples collected around two nonferrous metal smelteries using inductively coupled plasma mass spectrometry (ICP-MS). The spatial distribution characteristics of soil metal pollutants was studied by ArcGIS methods and the potential ecological risks were assessed by the Hakanson potential eco-logical hazard index. The results show that soils were heavily polluted by Cr, Ni, Cu, Zn, Cd, Pb, and As. Their mean contents in soil around Smeltery A were 88, 62, 103, 1200, 1.4, 146, and 69 mg/kg, respectively, and those around Smeltery B were 86, 59, 83, 117, 0.53, 57, and 65 mg/kg, respectively. Their contents were obviously higher than the background values of soil Cr (68 mg/kg), Ni (31 mg/kg), Cu (22 mg/kg), Zn (78 mg/kg), Cd (0.09 mg/kg), Pb (22 mg/kg), and As (14 mg/kg). The distribution pattern in soil and risk assessment results show that the pollution surrounding the two smelteries reached intense and moderate ecological hazard and that the contribution of Cd and As was up to 87.05% and 82.59%, respectively. These results suggest that metal smelting makes a considerable contribution to soil pollution. [ABSTRACT FROM AUTHOR]

Various human production activities have caused tremendous damage to the soil ecological environment of cultivated land. Regional ecological risk assessments and the safe use of cultivated land have received widespread attention. The ecological risk assessment of heavy metals based on soil geochemical zoning has not been reported in the past. Using 14,389 topsoil samples, considering comprehensive geological background information, Yishui County in northern China was divided into three soil geochemical areas and 14 soil geochemical sub-regions by means of principal component factor superposition. The results of environmental quality and risk assessments of eight heavy metals based on soil geochemical zoning show that the single pollution index was greater than 1.0 and the Nemerow pollution index was greater than 0.7 for Ni in a sub-region, indicating that Ni pollution had reached the early warning limit, which demonstrates that Ni has a certain enrichment trend. Meanwhile, the geoaccumulation index of Ni and Cr was greater than zero in some sub-regions, indicating a slight pollution level. In addition, the potential ecological risk factor of the measured heavy metals was greater than 40 in 9 sub-regions, indicating a moderate ecological hazard, and the risk index was greater than 150 in a sub-region, revealing moderate ecological intensity, in which Hg and Cd were leading contributors to potential ecological hazards with a contribution rate between 58% and 76%. This method is suitable for the evaluation of soil environmental quality and safety for medium and large scales, and can provide a scientific basis for further zoning and grading prevention and control of soil pollution in cultivated land. [ABSTRACT FROM AUTHOR]

With the rapid industrialization and urbanization, more attention is turning to heavy metal contamination in the soil environment. To assess the potential environmental risk on soil, a comprehensive geochemistry study on heavy metal was performed in Laizhou, eastern China, using 3834 surface soil samples (0–20 cm, regular grid of 1 × 1 km2) and 60 layered soil samples (0–200 cm) were analyzed. The average concentrations of As, Cd, Cr, Cu, Hg, Ni, Zn and Pb were 7.60 mg·kg−1, 0.15 mg·kg−1, 45.50 mg·kg−1, 19.10 mg·kg−1, 44.00μg·kg−1, 18.70 mg·kg−1, 51.40 mg·kg−1 and 29.00 mg·kg−1, which were lower than the threshold levels of the Grade II criteria of China national environment quality standard for soil, but the contents of As, Cd, Hg, and Pb were higher than background values of eastern Shandong Province surface soil. Fractionation analysis showed that the potential bioavailability in surface soils decreases in the order of Cd > As > Cu > Ni > Zn > Cr > Pb > Hg. Soil assessments with enrichment factor, contamination factor, Nemerow composite index, geo-accumulation index and potential ecological risk index, indicate the soil in Laizhou is contaminated strongly with As, Cd and Hg and a moderately Cr, Ni, Cu and Zn. The level of Pb pollution is between moderate to high. Multivariate analyses suggest that Cr and Ni were derived mainly from natural sources, and As, Cd, Pb, while Hg mostly came from anthropogenic sources. Cu and Zn were from a mixture of anthropogenic and natural sources. Our results demonstrate that more attention should be paid to monitoring soil quality in the heavily polluted site. [ABSTRACT FROM AUTHOR]

There exists serious heavy metal contamination of agricultural soils in China. It is not only time- and labor-intensive to monitor soil contamination, but it also has limited scope when using conventional chemical methods. However, the method of the heavy metal monitoring of soil based on vegetation hyperspectral technology can break through the vegetation barrier and obtain the heavy metal content quickly over large areas. This paper discusses a highly accurate method for predicting the soil heavy metal content using hyperspectral techniques. We collected leaf hyperspectral data outdoors, and also collected soil samples to obtain heavy metal content data using chemical analysis. The prediction model for heavy metal content was developed using a difference spectral index, which was not highly satisfactory. Subsequently, the five factors that have a strong influence on the content of heavy metals were analyzed to determine multiple regression models for the elements As, Pb, and Cd. The results showed that the multiple regression model could better estimate the heavy metal content with stable fitting that has high prediction accuracy compared with the linear model. The results of this research provide a scientific basis and technical support for the hyperspectral inversion of the soil heavy metal content. [ABSTRACT FROM AUTHOR]