We conducted a comprehensive analysis of soil heavy metals and the structure of the microbial community in various cultivated land types in an area with naturally high heavy metal content. 96 Topsoil and 20 soil profile samples were collected from agricultural soils: bare land (CK), corn (COR), paddy (RIC), and vegetable (VEG). The primary purpose of this investigation was to elucidate the underlying assembly mechanisms and key driving factors that influence dynamic changes in bacterial community composition across different cultivated land environments. Across all regions, substantial disparities were observed in bacterial diversity and levels of heavy metal contamination. The results of this study reveal that the average Cd and Cr levels in the four soil types were relatively high, with the greatest Cd contamination observed in the COR soil type. Notably, COR soils had the highest available As, Cd, Cr, Pb, and Zn levels compared to the other three types. Concerning bacterial diversity, the RIC soil type exhibited the highest levels, as demonstrated by high Shannon, Chao1, and ACE indices, compared to other land use types. Principal coordinate analysis (PCoA) and nonmetric multidimensional scaling (NMDS) results indicated that bacterial communities in RIC, VEG, and CK, COR soils showed a similar pattern. A deeper analysis of the microbial community revealed that Proteobacteria were the dominant phylum in agricultural soils, with Acidobacteria, Actinobacteria, and Planctomycetes closely behind. The study also revealed that pH, organic matter (OM), and heavy metals such as Cd, Pb, and Zn were the primary drivers behind the observed shifts in bacterial communities. Through the study of cultivated land use, it has been found that it changes the migration of heavy metals and the composition of soil bacterial communities, thus affecting soil health. These results have provided valuable insights into soil management to an area with naturally high heavy metal content.

Diet is the principal source of individual Pb exposure; it contributes more than 80

IntroductionThis study aimed to determine the status of soil mercury (Hg) contamination and to understand the associated soil microbial community structure and function, along with their relationships with environmental factors, in farmlands surrounding mercury mining regions.MethodsSoil samples were collected from farmland surrounding a mercury mining region (Chuandong town, CD, Huaqiao town, DP, Bahuang town, BG, and Shuangjiang town, LT) in Tong Ren, south-western China. We analyzed soil physicochemical properties, Hg pollution indices, and bacterial community structure and function. The interactions among soil environmental factors and bacterial community structure and function were determined using correlation analysis and redundancy analysis.ResultsThe soils exhibited varying degrees of Hg contamination: CD and LT soils were categorized by “light” Hg contamination, whereas DP and BG soils exhibited “moderate” Hg contamination. The potential ecological risk was “moderate” for CD soils, “considerable” for BG and LT soils, and “high” for DP soils. Long-term Hg contamination significantly increased soil bacterial community diversity and decreased bacterial community richness. Bacterial communities underwent adaptive restructuring, with Acidobacteria (16.90% relative abundance) dominating the acidic, high-Hg soils at the DP site and Proteobacteria (29.71% relative abundance) thriving in nutrient-rich conditions at the LT site. Key metal-resistant genera (Rokubacteriales, Gaiella) emerged as potential biomarkers of contamination. PICRUSt2 analysis revealed maintained metabolism potential under Hg stress, with carbohydrate metabolism and amino acid metabolism pathways collectively accounting for 26.43% of all predicted functions. Redundancy analysis identified soil pH, THg, and Gaiella were the key the factors driving the soil bacterial community function, with their independent contributions contributions to the variance being 72.83, 84.64, and 81.97%, respectively.DiscussionThese findings provide a mechanistic understanding of microbial resilience in Hg-contaminated ecosystems and identify critical leverage points for remediation strategies targeting both metal toxicity and the functional restoration of agricultural soils.

This study aimed to clarify the effect of long-term continuous cropping of pepper on soil fungal community structure, reveal the mechanism of continuous cropping obstacles, and provide a theoretical basis for the ecological safety and sustainable development of pepper industry. We took the pepper continuous cropping soil in the vegetable greenhouse planting base of Tongren City as the research object. The diversity and community structure of fungi in farmland soil were analyzed using Illumina MiSeq high-throughput sequencing, the responses of soil physio-chemical properties and fungal community characteristics to long-term continuous pepper cropping were discussed, and the relationships between the characteristics of fungal community structure and environmental factors were determined using CCA and correlation network analysis. The results showed that with the extension of pepper continuous cropping years, the soil pH value and organic matter (OM) content decreased, total phosphorus (TP) and available phosphorus (AP) contents increased, hydrolyzed nitrogen (AN) and available potassium (AK) contents decreased first and then increased, and total nitrogen (TN) and total potassium (TK) contents did not change significantly. Long-term continuous cropping decreased the Chao1 index and observed species index and decreased the Shannon index and Simpson index. The change in continuous cropping years had a significant effect on the relative abundance of soil fungal dominant flora. At the phylum level, the relative abundance of Mortierellomycota decreased with the extension of pepper continuous cropping years, the relative abundance of Ascomycota increased first and then decreased, and the relative abundance of Basidiomycota decreased first and then increased. At the genus level, with the increasing of pepper continuous cropping years, the relative abundance of Fusarium increased, and the relative abundance of Mortierella and Penicillium decreased. In addition, long-term continuous cropping simplified the soil fungal symbiosis network. CCA analysis indicated that pH, OM, TN, AN, AP, and AK were the driving factors of soil fungal community structure, and correlation network analysis showed that pH, OM, TN, TP, TK, AN, AP, and AK were the driving factors of soil fungal community structure, including Fusarium, Lophotrichus, Penicillium, Mortierella, Botryotrichum, Staphylotrichum, Plectosphaerella, and Acremonium. In conclusion, continuous cropping changed the soil physical and chemical properties, affected the diversity and community structure of the soil fungal community, changed the interaction between microorganisms, and destroyed the microecological balance of the soil, which might explain obstacles associated with continuous cropped pepper.

To investigate the intrinsic driving mechanism of citrus yield and quality enhancement under different fertilizer applications, a field experiment was conducted to study the effects of biochar （SW）, organic fertilizer （YJ）, farmyard manure （NJ）, chemical fertilizer （HF）, and no fertilizer as the control （CK） on soil physical and chemical properties, bacterial community characteristics, and citrus quality of citrus orchards in the yellow soil area of the Yunnan-Guizhou Plateau. The results showed that compared with those in the CK treatment, the yield, single fruit weight, edible rate, juice rate, vitamin C content, and soluble solids of citrus increased under the different fertilization treatments. In contrast, the titratable acid content of citrus decreased, resulting in an increase in the solid-acid ratio of citrus. Among the different fertilization treatments, the most significant effective treatment was SW. The SW and YJ treatments significantly increased the soil pH value, while the HF treatment decreased soil pH. Different fertilization treatments could increase the contents of soil organic matter, hydrolyzable nitrogen, available phosphorus, and available potassium. The SW treatment exhibited the most obvious effect on the contents of soil hydrolyzable nitrogen, available phosphorus, and available potassium. The YJ treatment exhibited the most obvious effect on the soil organic matter content. The different fertilization treatments significantly affected soil bacterial community diversity and community structure, among which the SW treatment significantly increased the soil Chao1 index, observed species index, and Shannon index； optimized soil bacterial community structure； and made the bacterial symbiotic network simple and stable. By contrast, the HF treatment significantly decreased the soil Chao1 index, observed species index, and Simpson index and had less effect on bacterial community structure. Redundancy analysis showed that soil available potassium （96.47%）, Chao1 index （73.80%）, and Chujaibacter （55.92%） were the key factors in improving citrus yield and quality. Variance decomposition analysis indicated that the soil bacterial community structure was the largest contributor （17.00%） to the improvement in citrus yield and quality. In conclusion, fertilization can effectively improve soil physical and chemical properties, increase soil nutrient supply level, optimize bacterial community structure, and improve citrus yield and quality. Of these, biochar can be used as a priority for the fertilization and improvement of the soil in citrus orchards in the yellow soil area of the Yunnan-Guizhou Plateau.

In order to understand the status of heavy metal pollution and the resulting ecological risk of farmland soil surrounding the manganese mining area, 174 soil samples were collected, and the heavy metals(Cu, Zn, Pb, Cr, Ni, Mn, As, and Hg) were analyzed. Principal component analysis (PCA) and the positive matrix factorization (PMF) model were used to determine the source of heavy metals in the soils. The single-factor pollution index method, geo-accumulation index method, potential ecological risk assessment method, and US EPA health risk assessment model were used to evaluate the ecological environment risk of heavy metals. The results showed that the average values of Cu, Zn, Cr, Ni, Mn, and Hg exceeded the background value of Guizhou. 100% of Zn samples and 38.86% of Cu samples exceeded the risk screening value for agricultural land soil pollution. Source analysis revealed that the main sources of soil heavy metals were mining emission, mixed agricultural activity and transportation, nature, and agricultural activities. The risk evaluation showed that Ni, Cr, Pb, and As belonged to the clean level, Hg and Cu were in a light pollution stage, Zn fell into the category of moderate contamination, and Mn reached the heavy pollution level. Cu, Zn, Pb, Cr, Ni, Mn, As, and Cd posed low potential ecological risk, while Hg caused a considerable potential ecological risk. In total, the integrated potential ecological risk of heavy metals was ranked "strong", eight types of heavy metals had carcinogenic risks and non-carcinogenic risks for children aged 0-5 years, and the main contributing factors were Cr and Mn, respectively.

In order to investigate the characteristics of soil microbial community structure and their relationships with environmental factors in the surrounding farmlands of a mercury mining region, we analyzed soil physical and chemical properties, Hg pollution, enzyme activity, and microbial community structure characteristics in the surrounding farmlands of a mercury mining region in Tong Ren (Bahuang Town, Bijiang District; Huaqiao Town, Shiqian County; Kaide Town, Jiangkou County; and Chuantong town, Bijiang District; referred to as BJ, SQ, JK, and TR, respectively). The relationships between the characteristics of soil microbial community structure and environmental factors were determined using redundancy analysis (RDA) and correlation network analysis. The results showed that the degree of soil Hg contamination varied depending on the sampling locations in the study region. The soils in JK and TR were categorized as having light-level Hg contamination, whereas those in SQ and BJ were at moderate-level Hg contamination. The potential ecological risk indicated that the soil suffered different degrees of Hg contamination (TR was at a medium level, BJ and JK were at a serious level, and SQ was at a high severe level of pollution). The dominant bacteria flora were Proteobacteria, Actinobacteria, Acidobacteria, and Chloroflexi, whereas the dominant flora of fungi included Ascomycota, Basidiomycota, and Mortierellomycota. RDA analysis showed that pH, sucrase (SC), and catalase (CAT) activities were the key environmental factors of soil bacterial community structure. Soil pH, available nitrogen (AN), available potassium (AK), HCl-Hg, acid phosphatase (ACP), and urease (URE) activities were the key environmental factors that affected soil fungal community structure. Correlation network analysis indicated that pH, available phosphorus (AP), HCl-Hg, SC, ACP, and CAT were the key environmental factors affecting soil bacterial community structure, including Proteobacteria, Acidobacteria, Actinobacteria, Chloroflexi, Firmicutes, Rokubacteria, and Planctomycetes. AK, pH, total nitrogen (TN), AP, AN, ACP, URE, and SC activities were the key environmental factors affecting soil fungal community structure, such as Ascomycota, Basidiomycota, Mortierellomycota, Glomeromycota, Chytridiomycota, Rozellomycota, Kickxellomycota, and Mucoromycota.

Systematic understanding of the status of potentially toxic metals (PTMs) in soil, dust and plant is of great need for their negative impacts on human and environmental health. Characterization and screening of PTMs will play an important role in health risk assessment and pollution control. In this study, a comprehensive investigation is conducted to explore the spatial occurrences, pollution status and health risks of 19 PTMs and 6 major elements (As, Ba, Ce, Co, Cr, Cu, Ga, La, Mn, Ni, Pb, Rb, Sr, Th, U, V, Y, Zn, Zr, Al, Ca, Fe, K, Mg, Na) in urban soil, street dust and plants in the City of Lanzhou in northwest China. Most PTMs in urban soil, dust and plant have similar spatial patterns and pose pollution to some extent. The priority metals Pb, Cu, Zn from traffic sources have similar tendency transferring among soil-dust-plant environment in comparison to other metals which prefer to accumulate in dust. PMF analyses confirm that coal combustion and industrial emission are important origins for metals in addition to traffic sources. Total carcinogenic risk of toxic metals in dust and soil for children are unacceptable compared to adults. Site-specific blood lead levels (BLLs) are predicted according to the occurrences of priority contaminant Pb in the urban environment. Children of less than three years old have higher BLLs than those of 4–6 years old. The highest BLL for children of 1–2 years old is up to 90 μg·L −1 , which is almost twice the US CDC Acceptable Threshold (50 μg·L −1 ) even though it is still below the China Acceptable Limit (100 μg·L −1 ). Therefore, attention to Pb contaminant prevention and measurement including complete environmental cleaning and screening of BLLs periodically for children 0–6 years old.

Due to various human activities, soil quality under different land use patterns is deteriorating all over the world. This deterioration is very complex in the river irrigation area and is caused by multi-point and non-point source pollution and seasonal variation. Therefore, the characteristics and sources of soil metal pollution in river irrigation area of Baoji city were analyzed. The contents of 8 metals were given by ICP-MS, in the soil samples. Statistical methods, geo-accumulation index ( I geo ) and potential ecological risk index ( RI ) were conducted to evaluate the spatial distribution features, sources and ecological risks of metal contamination from the study area soil. Principal component analysis and cluster analysis were used to analyze the pollution sources of metal. The analysis showed that Cd is the most polluted, and human activities represented a great impact on the contents of Zn, Ni, Cu and Cd in soil, Cd post moderate-strong pollution and strong risk, Cd has a maximum Igeo value of 3.17. All rivers were at risk of moderate pollution levels in study . Among them, some rivers had even reached strong pollution level. Pollution caused by human activities was the most significant pollution source of metal in the research area soil.

A new integrated source-specific risk model and site-specific blood lead levels (BLLs) of 0-6 children were introduced to comprehensive understand the status of the toxic metals in soil-dust-plant total environment from a Coal-Gas industrial city, NW China. 144 samples were collected and ten toxic metals (As, Ba, Co, Cr, Cu, Mn, Ni, Sr, Pb, and Zn) were screened by XRF and ICP-MS. It was found that the occurrences of toxic metals deferred in the different medium, such as Co, Cu, Pb, and Zn observed the trend of accumulating in soil and plant compared to clustered distributions of Cr, Mn and Ni preferred to accumulate in dust. However, few bioaccumulations observed in Ulmus pumila L. Toxic metals distributions in majority of sites influenced by coal combustion mixed sources and industrial activities posed the high integrated ecological risks and caused significant non-carcinogenic and carcinogenic integrated risks for local 0-6 children identified by new integrated source-specific risk model, especially observed in the priority contaminants Co and Pb. The site-specific BLLs confirmed that younger children fewer than 4 lived in the north region were more vulnerable to priority Pb pollution as their BLLs above 50 μg/L, almost up to 80 μg/L. Although proportions of source-specific risks to toxic metals changed in soil and dust, the critical sources from coal combustions and industrial activities posed the most important contribution to the local risks. Therefore, effective strategies targeting at critical sources on coal industries should be conducted to reduce risks, and mostly emphasize on the north hotspot areas.

通过采集兰州市和延安市主城区的土壤灰尘样品,测量了其粒径组成,界定了土壤和灰尘不同粒径的空间分布,分析了环境影响.结果表明:兰州市和延安市城市土壤灰尘粒径组成有明显的分布特征,主要集中在小于100μm的部分,整体粒径分布情况为:粉黏粒(<50μm)>极细砂(50～100μm)>细砂(100～250μm)>中砂(250～500μm)>粗砂(500～1000μm).其中兰州市小于100μm灰尘颗粒物粒径所占比例(69.17％)大于延安市(53.49％),极易在外动力条件下再次扬起成为扬尘污染的潜在污染源.从2个城市土壤和灰尘

ABSTRACT Mining of minerals in Guizhou, China, where it is enriched with reserves, may lead to soil contamination with heavy metals. We assessed the risk of eight typical heavy metals in Guizhou soils by collecting province-wide data available in the literature and using the geo-accumulation index method, the ecological risk assessment method, and the USEPA health risk assessment model. The concentrations of eight heavy metals, except for Pb and Cr, were above the background levels. Soil heavy metal pollution evaluation results showed that As, Cu, Zn, Pb, Cr, Cd, and Ni reached the pollution levels, while Hg fell into the category of moderate contamination. As, Cu, Zn, Pb, Cr, and Ni posed low potential ecological risk, while Cd and Hg demonstrated a considerable or a very high potential ecological risk. Totally, the integrated potential ecological risk was ranked “very high” . Regarding to health risk, the non-carcinogenic risks caused by heavy metals were insignificant, but the carcinogenic risk caused by As was significant. Consequently, there appeared serious soil contamination of Hg and As, with the latter also being the greatest potential risk to human health. Both Hg and As should stay at the highest priory for remediation efforts in Guizhou soils.

Environmental contaminations by potentially toxic metals (PTMs) are associated with energy exploitation and present a significant problem in urban areas due to their impacts on human health. The PTMs status in Urumqi total environment inevitably impacted by extensive development of coal and oil industries has been lack of understanding comprehensively. A series of PTMs (As, Ba, Ce, Co, Cr, Cu, Ga, La, Mn, Ni, Pb, Rb, Sr, Th, U, V, Y, Zn, Zr) in the soil-dust-plant (foliage of Ulmus pumila L.) system of Urumqi (NW China) were screened by XRF and ICPMS. Multivariate statistics, risk models, GIS-based geostatistics, Positive Matrix Factorization (PMF) receptor modelling and blood lead levels of 0-6 aged children evaluated by IEUBK model are used to determine the priority pollutants, sources and health effects of the investigated elements. The spatial distribution of PTMs in soil-dust-plant system significantly coincides with coal combustion, traffic emission, and industrial activity. Although all PTM toxicants in soil, dust and tree foliage show some effects, the priority contaminants are observed for Cu, Pb and Zn as single element. The total carcinogenic and non-carcinogenic risks from PTMs are beyond the tolerance range of 0-6 year's old children, and the dust (TCR = 1.07E-04) PTMs pose approximatively equivalent carcinogenic risk to soil PTMs (TCT = 1.09E-04). The predicted BLLs (75-83 mu g.L-1) of 1-2 years children are most strongly influenced by Pb in soil and dust, and therefore more attention should be focused on sources of Pb to support the primary health care of the toddlers in Urumqi. (C) 2020 Elsevier Ltd. All rights reserved.

In the face of increasing influences of coal industries on the water environment and water security, a deeper understanding of the chemistry of water and the eco-environmental health risks to human is needed to contribute. One of largest coal capital city of Yulin (NW of China) was chosen a scenario and case for further investigation. The distribution levels of multi-ions (F−, Cl−, HCO3−, NO3−, SO42−, Li+, K+, Ca2+, Na+, Mg2+, NH4+) and potentially toxic metals (PTMs) (Cd, Co, Cr, Cu, Mn, Ni, Pb, Sb and Zn) in drinking water, lake water and river water at the river catchment scale collected from study areas were determined by using ion chromatography and inductively coupled plasma mass spectrometer (ICP-MS). The water chemistry, health risks, sources and anthropogenic inputs were explored. The dominant ions in drinking, lake and river waters decreased as HCO3− > SO42− > Cl− in anions, and cations as Ca2+ > Na+ > Mg2+. The strong correlation between Na+ and Cl−, K+ and Cl−, Na+ and K+, Mg2+ and SO42− in surface waters (lake and river water) was controlled by rock weathering and with the hydrochemical type of SO42−·Cl−—Ca2+·Mg2+ illustrated by the Gibbs diagram. The concentrations of Cd, Co, Cr, Cu, Mn, Ni, Pb, Sb and Zn in drinking and surface waters were varied significantly, which was associated with coal mining and coal combustion activities. Although the non-carcinogenic risk of Cu, Mn, Ni, Pb, Sb and Zn in drinking water, lake and river water were acceptable, the carcinogenic risk caused by Cr in both drinking water and surface waters exceeded the values of 5.00E-05 and 1.00E-06 recommended by three international health organizations, respectively, which should be paid more attention to and monitored continuously in order to significantly understand the pollutants and the anthropogenic impact on water security and ecosystems, and also to ensure the sustainable clean energy and ecological coal exploitation in Yulin city.

Potentially toxic metals (PTMs), associated with different size particles in soil, may play an important role in adverse health effect and risk for human. The objective is to evaluate the lung and gastrointestinal bioaccessibility and risk of PTMs in Pb-contaminated alkaline urban soil depending on the particle size fractions. The size fractions of 50-250 mu m, 5-50 mu m, 1-5 mu m, < 1 mu m in Pb-contaminated alkaline urban soil from Baoji Heavy Industrial Base City, NW China, were screened by Sequential Wet Sieving Separation Procedure (SWSSP) based on Stokes' Law. The concentrations of 9 potentially toxic metals (As, Ba, Co, Cr, Cu, Mn, Ni, Pb and Zn) in each particle size fractions were characterized by ICP-OES and ICP-MS, and the in vitro bioaccessibility dependent of size fractions were evaluated by the simulation fluids of Artificial Lysosomal Fluid (ALF) and Gamble for lung, PBET, SBET, IVG, SBRC, UBM for gastric and intestinal, respectively. Health risks were assessed considering simulated external exposure using intestinal and lung bioaccessibility. The lung and gastrointestinal bioaccessibility and exposure risks of PTMs in fine particle size (i.e. < 1 mu m) was higher than larger particle size fractions (i.e. 50-250 mu m, 5-50 mu m, 1-5 mu m), however, some different variations of bioaccessibility observed the simulation fluids and time dependent. In case of single PTMs, the lung bioaccessibilities of PTMs in ALF were higher than those in Gamble fluids, most prominent in Co, Cu, Mn and Zn, while the gastrointestinal [G + I] bioaccessibility of PTMs was less than those in gastric [G], like Cu, Mn, Pb and Zn mostly. The non-carcinogenic risks of these PTMs to children via inhalation were acceptable and higher than those of adults, but reverse for carcinogenic risk. Comparatively, the non-carcinogenic and carcinogenic risks of PTMs via ingestion pathway were both higher than those for adults. Although the risks from ingestion were in acceptable range, the total carcinogenic risks for children were more than 10(-4), which would bring carcinogenic risks and should be paid attention to. It was noted that the toxic metal, Co in all size fractions was the most important contributor for noncarcinogenic risks and Cr mostly for carcinogenic risks via inhalation pathway for adults and children in local areas. However, Pb was the most important contributor for noncarcinogenic risk both for adults and children via ingestion pathway relative to Co and Cr for carcinogenic risks through hand-to-mouth ingestion. Those observations demonstrated the important role that the smaller particle fractionations in Pb-contaminated alkaline soil played in both bioaccessibility and the refinement of human health-risk assessments for the inhalation and ingestion pathway.

Snack foods are common and highly advertised to children and serve their natural predispositions for sweet and salty tastes. However, the risk issues of low-cost snacks eaten by 0-6 aged children are lack of more concern. To better understand the issue of low-cost snacks this study considered potentially toxic metals (PTMs) impact on children's health risk, measured PTMs in a collection of 570 collected low-cost snacks contributed by 1342 voluntary participants children aged 0-6 years involved in Xi'an city are conducted. Nine priority PTMs and amounts ranked as Mn > Zn > Cu > Cr > Sb > Pb > Ni > Cd > Co. The Estimated Weekly Intake of PTMs in snacks for children accounted for a proportion of the Provisional Tolerance Weekly Intake. Children's daily snack ingestion of Cr, Cd and Pb were especially concerning. It was noted that all PTMs in flour products contribute to the total Target Hazard Quotient (THQ>1) were observed having a non-carcinogenic risk compared to the single metals Cr, Co and Cd with carcinogenic risk. The correlations between Cu, Pb, Zn in low-cost snacks and children's bloods reflected PTMs especially for Pb that transfers into children's bodies mostly through low-cost foodstuffs ingestion. Also, the elevated blood lead levels (BLLs) depended on readily available, low-quality snacks accessible for children. Therefore, multi-initiatives aimed at improving the quality, increasing awareness, and a PTM monitoring program for low-cost snack food market to young children should be undertaken. (C) 2020 Elsevier Ltd. All rights reserved.

Coal is a primary energy source in the world. Potentially toxic metals (PTMs) emission from coal mining and combustion are posing a serious public health concern. In order to quantify and evaluate the effect of PTMs on children’s health, the concentrations of 12 PTMs (As, Co, Cr, Cu, Mn, Ni, Pb, Sr, Zn, Ca, Fe, and Mg) bound in urban soil and street dust are determined and blood lead levels of these PTMs in 229 children (0–6 years old) are collected from the coal mining city of Yulin, China. In vitro pulmonary bioaccessibilities of PTMs are evaluated by artificial lysosomal fluid and Gamble’s solution, and gastrointestinal bioaccessibilities by the unified BAGRE method (UBM); correlations between chemical speciation of PTMs and their bioaccessibility are examined, and children’s (0–6 years old) health risks are systematically studied. Similar distribution levels of PTMs are found in soils and dusts, with the most polluted metals being Co, Sr, Ca and Pb. All PTMs (except Cr, Fe) are from the considerable artificial lysosomal fluid extraction both in soil and dust, while Ca and Co are favorably extracted in gastro and intestinal phases than others. Significant correlations are observed between the bioaccessibilities (lung and gastrointestinal) and Fe/Mn hydroxide-bound and carbonate-bound phases, which are key factors influencing and determining PTMs’ bioaccessibility. Blood lead levels for children (0–6 years old) are 27.47 (21.65, 33.30) for 0–1 year olds, 32.29 (26.39, 38.19) for 1–2 year olds, 36.99 (28.16, 45.81) for 2–3 year olds, 30.79 (22.56, 39.01) for 3–4 year olds, 27.12 (17.31, 36.93) for 4–5 year olds, 34.59 (24.22, 44.97) for 5–6 year olds and 37.83 (24.15, 51.51) μg/L for 6–7 year olds, respectively, with 3.93%, 3.49%, 4.80%, 2.62%, 1.31%, 1.75% and 1.31% exceeding 50 μg/L, respectively. This indicates that the blood lead levels elevate for 1–2 year and 5–6 year old groups, which should be paid more attention. Although the non-carcinogenic and carcinogenic risks of most PTMs are under the acceptable level, the higher carcinogenic risk of Ni and non-carcinogenic risk of Pb should be monitored continuously. We suggest that further actions will be taken to reduce PTMs exposure for children through sustainable clean and ecological energy technology for coal mining, especially for those infants of 1–2 years old.

A total of 155 urban soil and 157 dust samples were collected from Xining city (NW, China) with the objective to systematically investigate the spatial occurrences, sources, and health risk status of potential toxic metals (PTMs) bound in urban soil and street dust. Results established by Geographic Information System tools with inverse distance weighted interpolation technique indicated that the spatial status of 24 multi-PTMs varied with their concentration levels in urban soils and street dusts in monitored local areas. However, they had the similar sources in soil and dust. It was found that Bi, Ga, Nb, Ni, Rb, Sr, Th, U, Y, Zr, As, Mn, Nb, Ti, and V would be possibly predominated by nature material, whereas contamination of Ba, Cr, Cu, Pb, and Zn was clearly related to traffic-related sources. Peculiar associations among Sb, Sn, Ce, and Co were possibly enriched in soil and dust very close to the industrial activities. It was noted that PTMs in urban soil was an important contributor to them in dust. Compared with the potential ecological risk index of all PTMs, Sb posed very high risk. The calculated hazard index and cancer risk of all PTMs suggested the acceptable range both to noncarcinogenic and carcinogenic risk to children and adults except for the case of Cr. However, the noncarcinogenic risk for children was usually higher compared with adults. Although the noncarcinogenic and carcinogenic risk were not significant, the risk of Cr above the threshold for children and adults were observed in most local sites, which should be given more attention.

Utilization of microbes is one of the most promising methods to remediate potentially toxic metals (PTMs) from soil. In this study, a systematic investigation was conducted to study the influence of Bacillus subtilis on PTMs occurrence, fractionation, translocation, and accumulation in the rhizosphere soil of Maize (Zea mays L.) in pot experiments. B. subtilis showed strong effects on the fate and mobility of Pb, Sb, Ni, Zn, Cu, and Cr, and it also affected PTMs' distribution in the rhizosphere soil, maize growth, and microbial community structure. Results showed that it was easier for Zn to accumulate in maize roots than other PTMs. According to chemical fractionation, B. subtilis tended to immobilize Pb, Sb, Ni, Zn, and Cu in the rhizosphere soil. Compared with other PTMs, Cr tended to be more available and more mobile, which indicated a higher health risk to the eco-environment. These findings suggested that B. subtilis could be used as a geomicrobiological stabilizer to immobilize PTMs (Pb, Sb, Ni, Cu, Zn) in alkaline soils and decrease their uptake by plants, thus reducing the risks of a potential transfer into the food chain.

In order to better understand both the conceptual and operational aspects of bioaccessibility and phytobioavailability of PTMs (Co, Cr, Cu, Li, Mn, Ni, Pb, Zn) in different urban soils, a total of 30 soil samples from agricultural region, entertainment district, education area, traffic area, residential area and industrial area (IA) in Baoji urban city (NW China) were collected and the bioaccessibility and phytobioavailability were measured by multi-in vitro models of PBET, SBET, citric acid leaching and Tessier sequential extraction procedure, respectively. The suitable in vitro measurement of bioaccessibility and phytobioavailability for each PTM was selected and would be reliably applied for health risk assessment. The results indicated that the bioaccessibility and phytobioavailability for each PTM evaluated by in vitro models depended on PTM total concentration and anthropologic activity influence. The health risks associated with bioaccessibility of PTMs exposure showed that the carcinogenic and non-carcinogenic risks in all areas for children and adults were below the threshold or acceptable risk levels except lead exposure on children in IA, indicating there were more health risks to the children in than that in other functional areas. It was worth that the highest observation of Pb in IA would strongly correlate with lead–acid battery industries, which the emissions would influence on the occurrences of Pb distributing in the other functional areas, which were supported from the analysis results of XPS. Therefore, the continuous monitoring and attention to the health risk of inhabitants in different functional areas should be paid.