Pollution Risk Control Research Articles

Characterizing multi-source heavy metal contaminated sites at the Hun River basin: An integrated deep learning and data assimilation approach

In real-world scenarios involving groundwater contamination, the environmental complexity substantially complicates the tasks of tracing pollution sources and characterizing the features of affected sites. To address these challenges, this study presents an integrated framework that combines deep learning (AR-Net-DA) with data assimilation (ES-MDA). This approach effectively traces pollution sources and characterizes site features using sparse data from complex contamination scenarios. The paper introduces a case study involving multisource heavy metal (manganese) pollution in the Hun River basin, Liaoning Province, China. A high-fidelity model for groundwater flow and solute transport was developed. Subsequently, the innovative convolutional neural network model, AR-Net-DA, was employed to replace traditional process-based groundwater models by dynamically optimizing weights in proximity to various pollution sources. This model was then integrated into the ES-MDA inversion framework to concurrently determine pollution source parameters and the spatial distribution of aquifer permeability fields. The results demonstrate that this coupled inversion framework can accurately pinpoint pollution source locations and their release histories using limited observational data, while also mapping the spatial distribution of hydraulic conductivity fields with enhanced computational efficiency. These findings have significant implications for groundwater resource management, pollution risk control, and the remediation of contaminated sites.

Identification Priority Source of Heavy Metals in Urban Soils Based on Source-specific Ecological Risk Analysis in a Typical Tourist City

To understand the pollution status, distribution characteristics, and pollution sources of soil heavy metals in tourist cities in northwest China, the soil content of heavy metals As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn in the main areas of Dunhuang City was collected and analyzed. The soil heavy metal pollution level was quantitatively evaluated by the methods of the geo-accumulation index and improved Nemerow pollution index, and the sources of heavy metal pollution were quantitatively analyzed using cluster analysis and the positive matrix factorization （PMF） model. The contribution rate of each pollution source to ecological risk was determined by combining the PMF model and comprehensive ecological risk index. The results showed that except for the mean contents of As and Ni, the mean contents of Cd, Cr, Cu, Hg, Pb, and Zn were all higher than the background values in Gansu Province. However, the average content of the eight elements was lower than the screening value of construction land in the Standard for Soil Pollution Risk Control of Soil Environmental Quality Construction Land （trial） （GB 36600-2018）. Among them, the enrichment of Cd, Pb, and Hg was more serious, and the exceedance rate was higher than 90%. The results of the geo-accumulation index indicated that urban soils were mainly polluted by Hg in the study area, and Cd, Cr, Cu, Pb, and Zn pollution also existed in different degrees. The improved Nemerow pollution index illustrated that the comprehensive pollution degree of the soil was clean to moderate pollution, and the overall pollution was light pollution. Based on the PMF model, we could conclude that soil heavy metals in the study area were affected by natural sources, industrial deposition sources, industrial sources, traffic sources, and comprehensive sources, and the contribution rates were 29.28%, 25.86%, 20.13%, 16.5%, and 8.23%, respectively. The specific source-integrated ecological risk assessment model found that the industrial deposition source contributed the most to the ecological risk in the study area and could be regarded as the priority control pollution source, and Hg was considered to be the priority control pollution element for ecological risk.

Spatial Heterogeneity Analysis and Risk Assessment of Potentially Toxic Elements in Soils of Typical Green Tea Plantations

The spatial heterogeneity of potentially toxic elements (PTEs) in a typical green tea-producing area in Zhejiang was investigated with application of geostatistics. The positive matrix factorization (PMF) was conducted for analysis of pollution sources and risk assessment of the soil of the tea garden. The results revealed that 93.52% of the study area did not exceed the PTEs risk screening value in the soil pollution risk control standard of agricultural land. The results of the spatial heterogeneity analysis showed that Cd and Pb had moderate spatial auto-correlation, exhibiting similar spatial distribution patterns. The high-value locations were distributed in the southeast of the study area, while low-value locations were distributed in the southwest of the study area. The Cr, As, and Hg had strong spatial auto-correlation, while Cr and As had similar spatial distribution patterns whose high-value areas and low-value areas were concentrated in the west and center of the study area, respectively. The Cd, Pb, and As originated from the agricultural source, transportation source, and industrial source, respectively, while Cr and Hg were from the natural source on the basis of the results of the PMF model. The results of a potential ecological risk assessment revealed that five PTEs in the study area were of low potential risk. The single-factor ecological risk ranking was Cd > As > Hg > Cr > Pb. The overall ecological risk in the study area was slight. The human health risk model indicates that there was a non-carcinogenic risk for children in the study area, and the high-value area was concentrated in the northwest of the study area. It is concluded that emphasis shall be given to excessive Cd caused by agricultural sources in the southeast of the study area, and control and monitoring will be strengthened in the northwestern part of the study area. The relevant measures for prevention of soil pollution must be conducted.

Heavy Metal Pollution Status and Potential Ecological Risk Assessment in Farmland Surface Soil Along River in Jiaozuo Area

A total of 41 surface soil samples were collected from the farmlands along Guangliji River and Jianggou River in Jiaozuo area, and 7 heavy metals such As Cr, Cu, Zn, AS, Cd, Pb and Ni were determined by ICP-MS (Varian-820).The soil accumulation index method, single factor pollution index method, Nemerow comprehensive pollution index method and potential ecological risk index method were used to evaluate the pollution status and potential ecological risk of heavy metals in the study area. The results showed that compared with the risk screening value (pH>7.5) given in the "Soil Quality Standard for Soil Pollution Risk Control of Agricultural Land" (GB15618-2018), Cd in farmland soil along the two rivers exceeded the screening value by 5.7 times and 1.5 times, respectively, and was the main local pollutant. The Nemero comprehensive pollution index of the farmland along Guangliji River and Jianggou River was 9.71 and 1.88, respectively, which were in the level of heavy pollution and light pollution. The comprehensive potential ecological risk index of farmland along the two rivers is 417.65 and 85.79, with strong ecological risk and slight ecological risk respectively. The comprehensive evaluation shows that there is a certain degree of heavy metal pollution in the farmland soil along the river in Jiaozuo area, especially Cd pollution, and the ecological risk in some areas has exceeded the acceptable level, which should arouse the attention of the local government and relevant departments.

Risk assessment and source identification of soil heavy metals: a case study of farmland soil along a river in the southeast of a mining area in Southwest China.

To investigate the heavy metals (HMs) contamination of surface farmland soil along the river in the southeast of a mining area in southwest China and identify the contamination sources, 54 topsoil samples were collected and the concentrations of seven elements (Zn, Ni, Pb, Cu, Hg, Cr, and Co) were determined by inductively coupled plasma optical emission spectrometry (ICP-OES) and atomic fluorescence spectrometry (AFS). The geo-accumulation index ([Formula: see text]) and comprehensive potential ecological risk index ([Formula: see text]) were used for analysis to determine the pollution degree of HMs and the risk level of the study area. Meanwhile, the Positive Matrix Factorization (PMF) model was combined with a variety of statistical methods to determine the sources of HMs. To explore the influence of the river flowing through the mining area on the concentrations of HMs in the farmland soil, 15 water samples were collected and the concentrations of the above seven elements were determined. The results showed that the concentrations of Pb, Cu, and Zn in soil all exceeded the risk screening value, and Pb in soil of some sampling sites exceeded control value of "Agricultural Land Soil Pollution Risk Control Standard".[Formula: see text] showed that Pb was heavily contaminated, while Cu and Zn were moderately contaminated. RI showed that the study area was at moderate risk. PMF and various statistical methods showed that the main source of HMs was the industrial source. In the short term, the river flowing through the mine has no significant influence on the concentration of HMs in the soil. The results provide a reference for the local government to control contamination and identify the sources of HMs.

The effect of soil pollution information disclosure on housing prices

By utilizing the “Construction Land Soil Pollution Risk Control and Remediation Directory” released by various provincial governments in China as an exogenous shock, this paper explores the impact of disclosing soil pollution information on housing prices around contaminated sites. Our findings demonstrate that the release of soil pollution information led to an average reduction of 3.3% in secondhand housing prices, indicating a market premium for houses located farther from contaminated sites. Mechanism analysis reveals that the public release of pollution information motivates sellers to expedite transactions by strategically lowering listed prices, contributing to an overall decrease in housing prices. This paper provides causal identification evidence regarding the real estate market's responsiveness to soil pollution information, offering insights from China.

Experimental Study on key technologies for risk prevention and control of thallium pollution in A lead-zinc mine wastewater

In order to reduce the environmental risk of thallium pollution by enterprises and determine key technologies for thallium pollution prevention and control, the researcher conducted a deep exploration experiment on thallium removal in the inflow water of a certain lead-zinc mine. The experimental results showed that both sulfide precipitation method and catalytic oxidation & resin adsorption can achieve good thallium removal effect. Based on the actual characteristics of the lead-zinc industry, The author recommends a thallium pollution risk control technology scheme that combines terminal sulfide precipitation and source resin adsorption for thallium removal.

Assessment of soil quality in hanzhong city based on risk management of heavy metal pollution

In the present study, Hanzhong City was taken as an example, and the classification of soil heavy metal pollution risks was performed based on the evaluation of soil fertility status with soil physical and chemical properties as the main indicators. Results showed that the coefficients of variation of soil physical and chemical indicators in the study area were in the descending order: the soil fertility status showed a trend of increasing with decreasing terrain and increasing rivers. The high fertility areas were mainly distributed in the northwest and northeast of the plain area, while the low fertility areas were mainly distributed in the southeastern hilly and mountainous areas and in the western low-lying areas, and the transitional areas surrounded the low-fertility areas. At least 88.89% of the Cd samples and 98.61% of the Cr samples out of the eight heavy metals, Cd, Hg, As, Pb, Cr, Ni, Cu, and Zn, belonged to the priority protection class, while 11.11% of the Cd samples and 1.39% of the Cr samples belonged to the safe use class. The overall distribution of soil quality was similar to that of soil fertility status, while the distribution range of low-quality soil in the southeastern part was smaller and more concentrated. The above research results indicate that the introduction of the classification results of soil pollution risk control types generally reduces the soil fertility status correction and changes the spatial distribution pattern of the original soil fertility status to some extent. Bangladesh J. Bot. 52(2): 659-669, 2023 (June) Special

Assessment of soil quality in hanzhong city based on risk management of heavy metal pollution

In the present study, Hanzhong City was taken as an example, and the classification of soil heavy metal pollution risks was performed based on the evaluation of soil fertility status with soil physical and chemical properties as the main indicators. Results showed that the coefficients of variation of soil physical and chemical indicators in the study area were in the descending order: the soil fertility status showed a trend of increasing with decreasing terrain and increasing rivers. The high fertility areas were mainly distributed in the northwest and northeast of the plain area, while the low fertility areas were mainly distributed in the southeastern hilly and mountainous areas and in the western low-lying areas, and the transitional areas surrounded the low-fertility areas. At least 88.89% of the Cd samples and 98.61% of the Cr samples out of the eight heavy metals, Cd, Hg, As, Pb, Cr, Ni, Cu, and Zn, belonged to the priority protection class, while 11.11% of the Cd samples and 1.39% of the Cr samples belonged to the safe use class. The overall distribution of soil quality was similar to that of soil fertility status, while the distribution range of low-quality soil in the southeastern part was smaller and more concentrated. The above research results indicate that the introduction of the classification results of soil pollution risk control types generally reduces the soil fertility status correction and changes the spatial distribution pattern of the original soil fertility status to some extent. Bangladesh J. Bot. 52(2): 659-669, 2023 (June) Special

Dynamics of multiple stakeholders’ benefits due to mining area environmental remediation based on risk reduction and ecosystem services

Environmental remediation of heavy metal-mining sites can improve human well-being through pollution risk control and improved ecosystem services. A cost-benefit dynamic analysis for the multiple stakeholders involved in the project can better explain the overall efficiency and provide guidance for further mine remediation. Taking Asia's largest monomeric realgar mine environmental remediation project (MER) as a case, we conducted, for the first time, a dynamic cost–benefit analysis for multiple stakeholders over a 60-year period regarding environmental risks, health risks and ecosystem services. The results show that by improving the environment and ecosystem, the payback period is expected to begin 5 years after the end of the project, with a benefit‒cost ratio of 2.71 by 2050. Local residents, the direct beneficiaries, receive 13.2% of the benefits, which come from agricultural soil remediation projects (66.6%) and health risk reduction (33.4%). The government, as an investor, receives 3.3% of the benefits. Downstream water users are the main beneficiaries, receiving 76.5% of the total benefits, mainly from the benefit of As-contaminated water purification (97.9%). Compensation from downstream beneficiaries for improved water might be channeled into sharing the burden of MER implementation. Notably, the intercropping remediation of hyperaccumulators and low-accumulation crops for agricultural soils in MER provides employment and sustainable agricultural income during and after remediation, respectively. This green and sustainable remediation model improves both the environment and the livelihood of residents and should be recommended for nearly one million mining sites worldwide.

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

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

Health Risk Assessment of Heavy Metals in Soil and Wheat Grain in the Typical Sewage Irrigated Area of Shandong Province

Sewage irrigation is a common alternative to make up for the shortage of agricultural irrigation in intensive agricultural areas. Abundant organic matter and nutrients in sewage can improve soil fertility and crop yield, but hazardous materials, such as heavy metals, will damage the soil environmental quality and threaten human health. To better understand the characteristics of heavy metal enrichment and potential health risk in a sewage irrigated soil-wheat system, a total of sixty-three pairs of topsoil and wheat grain samples were collected from the sewage irrigated area of Longkou City in Shandong Province. The contents of Cr, Cu, Ni, Pb, Zn, As, Cd, and Hg were determined to analyze heavy metal contamination and calculate bio-accumulation factor (BAF), estimated daily absorption (EDA), as well as hazard quotient (HQ). The results showed that the average contents of the eight heavy metals were 61.647, 30.439, 29.769, 36.538, 63.716, 8.058, 0.328, and 0.028 mg·kg-1, respectively, which all exceeded the background values of corresponding heavy metals in the eastern Shandong Province. Especially, the average content of Cd was higher than the current standard value of soil environmental quality of agricultural land soil pollution risk control, indicating the apparent soil contamination. However, the correlations between the heavy metal contents in soil and wheat grains were not significant, suggesting that it is difficult to conclude the enrichment degree of heavy metals in wheat grains merely by the heavy metal contents in soil. The results of BAF showed that the high enrichment capacity of wheat grain was primarily obtained with Zn, Hg, Cd, and Cu. According to the national food safety limit standard, the over-limit ratios of Ni (100%) and Pb (96.8%) in wheat grains were the most serious. As a result, under the current consumption of local wheat flour, the EDAs of Ni and Pb were high, accounting for 28.278% and 1.955% of the acceptable daily intakes (ADI) for adults and 131.980% and 9.124% of the ADIs for children. The results of the health risk assessment exhibited that As and Pb were the main sources causing health risks, accounting for approximately 80% of the total risk. Although the sums of the HQ of the eight heavy metals for adults and children were below 10, the total HQ of children was 1.245 times higher than that of adults. The food safety of children should receive more attention. When considering spatial characteristics, the health risk in the southern study area was higher than that in the northern part of the study area. The prevention and control of heavy metal contamination in the southern area should be strengthened in the future.

Spatial Distribution, Source Apportionment, and Ecological Risk Assessment of Soil Heavy Metals in Jianghugongmi Producing Area, Shandong Province

Taking the Jianghugongmi producing area as the research object, As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn in the soil of the study area were sampled and determined. The correlation of heavy metals was discussed using the multivariate statistical method, the spatial distribution interpolation analysis of heavy metals was carried out using ArcGIS 10.2, the quantitative source analysis of heavy metal pollution was carried out using the enrichment factor (EF) and PMF methods, and the potential ecological risk was evaluated. The results showed that the contents of the soil heavy metals As, Cd, Cu, Hg, Pb, and Zn were lower than the screening values specified in the standard for soil pollution risk control of agricultural land (GB 15618-2018), and the soil ecological environment risk was low; the maximum values of Cr and Ni exceeded the risk screening values, but the risk was low. The main distribution range of pH in the study area was 6.05-6.69, which was suitable for rice growth. The Mohe River indicated the spatial distribution of pH and heavy metals, which was closely related to the supergene geochemical characteristics of the elements. However, Hg and Cd showed different spatial distribution characteristics under human influence. Hg was distributed in the middle and high value distribution area along the west side of the river, and the spatial distribution of Cd was significantly different from north to south. The quantitative source analysis results based on the EF method and PMF showed that the main sources of heavy metals in the study area were agricultural sources, mixed sources, coal sources, and natural sources. The contribution rates of various sources accounted for 24.2%, 35.4%, 9.5%, and 30.9%, respectively. The medium strong ecological risk points of Hg in the study area were distributed along the west side of the Mohe River, whereas the moderate potential ecological risk points of Cd were concentrated in the cultivated land on both sides of the Mohe River, and the potential ecological risk index (Er) of the other elements was<40. Cd and Hg were the main potential ecological risk elements in the study area, whereas Cd was still the main potential pollution element in the cultivated land soil in the study area.

Accumulation Effects and Health Risks of Heavy Metals in Rice in Location-based Cadmium Anomaly Area in Liuzhou

In order to explore the migration and transformation characteristics of soil heavy metals in rice in an area of ground source cadmium anomaly and to evaluate the safe planting of rice, a total of 91 pairs of soil and rice samples were collected from paddy fields in the typical area of Liuzhou city, Guangxi province, and the contents of heavy metals such as Cd, soil pH, and organic matter were tested. The results showed that:① Cd, Cu, Ni, and Zn in the paddy field exceeded the background values of 92.31%, 34.07%, 36.26%, and 90.11%, respectively. Compared with the screening values in the Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard, Cd and Zn exceeded 30.53% and 25.26%, respectively. Super standard points were mainly distributed in Fushi Town. ② Cd and Ni exceeded 35.16% and 3.30%, respectively, and Daliang town had the highest Cd enrichment coefficient and Cd exceeded rate. ③ Correlation analysis showed that soil pH was the main influencing factor of heavy metals in rice, and Cd and Ni had similar pollution sources in rice. ④ The results of rice health risk assessment showed that the THQ value of rice Cd in Daliang town was greater than 1.0, indicating the potential health risk of rice Cd in this area. The TTHQ values were all greater than 1.0, indicating that the risks to children were higher than those to adult women, which were higher than those of adult men, showing that reasonable dietary structure is crucial to prevent heavy metal intake in different ages and genders. Therefore, there are certain risks in rice planting in the Liuzhou area of ground source cadmium anomaly, which need to be controlled using different safety utilization measures.

Remediation Potential of Taraxacum kok-saghyz Rodin on Lead and Cadmium Contaminated Farmland Soil

Taraxacum kok-saghyz Rodin (TSK) is an energy plant that can be used as a raw material for natural rubber. The aim of this study was to examine the remediation potential of TSK to lead (Pb)- and cadmium (Cd)-contaminated farmland soil. In this study, a pot experiment was conducted, and the "Soil Environmental Quality and Agricultural Land Soil Pollution Risk Control Standard (GB 15618-2018)" was used as reference. We set up four different concentrations of Pb and Cd pollution treatment to study the characteristics of the accumulation and tolerance of TSK to Pb and Cd. The results showed that as the content of Pb and Cd in the soil increased, the chlorophyll content and biomass of TSK gradually decreased, and the SOD, POD, and CAT enzyme activities gradually increased. The BCF and TF of Cd were between 1.20 and 1.50, indicating that TSK presented some characteristics of a Cd hyperaccumulator. The BCF and TF of Pb were between 0.71 and 1.11. Thus, TSK was a good Pb enrichment plant and possessed the potential to repair soil with ω(Pb) below 400 mg·kg-1. The accumulation of Pb and Cd gradually increased, and the maximum accumulation of Cd and Pb in the shoots was 9.832 μg·plant-1 and 1091.185 μg·plant-1, respectively. However, in lower concentrations of Pb- and Cd-contaminated soil, the removal rate was greater, and the remediation efficiency was better. Overall, using TSK to repair Pb- and Cd-contaminated farmland soil has good application prospects and economic value.

Development of a new methodology for multifaceted assessment, analysis, and characterization of soil contamination

It is important to identify key performance and core progress features of soil contamination management practices. Traditional research currently focuses on numerical statistics of contaminated sites but exhibits structural limitations regarding cross-assessment and in-depth analysis of published findings. Herein, we report a multidimensional perspective to assess the environmental management performance of soil contamination via systematic and historical development of construction land risk control and remediation lists (RCRLs). The considered contaminated sites are mainly concentrated in Northern China, Yangtze River Delta, Pearl River Delta, and Sichuan-Chongqing regions. Monthly historical overviews indicate that most lists are updated 4–5 times within 32 months. Direct chemical-related industrial production results in the largest number of contaminated sites. Arsenic and lead are the most common heavy metals of concern in soil contamination. The fiscal revenue index exhibits the best positive performance in terms of the number of contaminated sites. By employing the site number, update frequency, and published contents of different calculation proportions, ten types of integrated assessment indicators (IAIs) are established to evaluate the environmental achievements in various provincial regions in regard to soil contamination protection. This multifaceted strategy can provide advanced guidance for Chinese environmental management and expand the application of soil pollution risk control and remediation in a wide range of countries.

Spatial distribution and human health risk assessment of soil heavy metals based on sequential Gaussian simulation and positive matrix factorization model: A case study in irrigation area of the Yellow River

The content of Cd, Cu, Pb, Zn, Cr, Ni and As from 250 soil samples was measured in agricultural soil of Ningxia section of the Yellow River. Positive matrix factorization (PMF) was to identify the main sources of these heavy metals; Sequential Gaussian Simulation (SGS) was to identify their spatial distribution and high-risk areas; and Human Health risk (HHR) model was to measure the health risk. Results showed that the average content of Cd and As exceeds the risk screening value of "Soil Environmental Quality-Agricultural Land Soil Pollution Risk Control Standard" (GB 15618-2018), which belongs to slight-level pollution. Although the content of other types of HMs (Cu, Pb, Zn, Cr, Ni) is below the risk screening value, they are still included heavily in the soil (except Cr). PMF indicated that mixed sources of agriculture and industry accounted for 27.06%, natural sources accounted for 14.12%, industrial sources accounted for 23.04%, traffic sources accounted for 21.50%, and Yellow River sedimentary sources accounted for 14.28%. PMF-HHR showed that the mixed sources of agriculture and industry are the most important factor causing non-carcinogenic risk (HI) to children (accounting for 55.75%). Industrial sources and traffic sources were the two main factors that cause HI to adults (industrial sources accounted for 25.16%, and traffic sources accounted for 28.78%). Mixed sources of agriculture and industry and natural sources were the two main factors that cause carcinogenic risk (CR) (mixed sources of agriculture and industry account for 35.34%, and natural sources account for 33.23%). SGS indicated that 0.64% and 9.32% of the total areas were posing as higher HI areas to children and adults respectively; in particular, 0.68% and 1.12% of the areas were identified as higher HI of As and Cr areas at a critical probability of 0.9.

Screening of cadmium resistant bacteria and their effects on plant growth promotion and remediation in soil

In order to investigate the remediation effect of the microbial-plant joint system on soil heavy metal Cd pollution, we carry out strain screening and pot experiment to explore the effects of plant growth-promoting bacteria on the accumulation capacity of ryegrass, soil physical and chemical properties and heavy metal speciation. The results show that the microscopic morphology of Burkholderia sp.YXL1 is pale yellow, rod-shaped and smooth edge with an average length of 5 μm, and it possesses strong growth-promoting ability and can tolerate cadmium content about 250 mg/L. The capacity of IAA production, siderophore and phosphate-solubilizing substances are 31.56 mg/L, 0.89 and 46.18 mg/L, respectively. In the <italic>YXL</italic>1-ryegrass joint remediation system, the organic matter and available phosphorus content in the soil are significantly increased by 4.08 g/kg and 2.54 mg/kg, respectively. The contents of weak acid extractable Cd and reducible Cd in the soil reach 16.25% and 12.53%, respectively. Compared with the control group, the ability of ryegrass to extract Cd from the soil is 2.76 times higher than that of the ryegrass treatment. The results also show that the Cd content of the cultivated layer soil is below the risk screening value (<0.3 mg/kg) in the Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard (GB 15618—2018) to realize the safe use of agricultural land in the <italic>YXL</italic>1- ryegrass joint remediation system after 4 years.

Pollution and health risk assessment of arsenic in street dust and soil from an industrial zone

Taking an industrial area in Wuhan as the research object, single factor index, Geoaccumulation index and EPA health risk model are utilized to evaluate the pollution pattern and health risk of arsenic (As) in street dust with different particle fractions and soil. The results showed that the content of As in street dust increased with the decrease of particle size. The average content of As in street dust with fine particle fraction and soil exceeded the soil background value of Hubei Province, but did not exceed the screening value of “Soil Environmental Quality Construction Site Soil Pollution Risk Control Standards (Trial)”. The content of As in soil had a high correlation with that of dust with < 63 particle fraction at the corresponding point, with high fit degree (R2=0.6012). There was moderate to heavy pollution of As in areas surrounding industrial enterprises like Wuhan Iron and Steel, cement plants, and areas with high traffic flow and construction sites. The As of street dust and soil at some points posed a non-carcinogenic risk to children, but no carcinogenic risk. The ingestion pathway was the largest non-carcinogenic exposure route of As in street dust and soil from the research area.

A novel method to analyze the spatial distribution and potential sources of pollutant combinations in the soil of Beijing urban parks

Organic and inorganic pollutants are often co-sedimentary in soils and have the same sources in the urban environment. The identification of the sources and distribution of combined pollutants is a basic step in risk management. In this study, the levels of polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) were measured in urban park soils in Beijing. Bivariate local Moran’s I and positive matrix factorization (PMF) source apportionment were used to identify the spatial clustering patterns and potential sources of PAHs and HMs, as well as to ultimately define a pollution risk control area. The results revealed an obvious clustered distribution of PAHs and HMs in the park soils. High-high areas were defined as sites containing a complex mixture of pollutants, which were mainly located in the center and north of Beijing. High-low and low-high areas were located outside the city center but had the potential for combined pollution, and therefore require continuous attention. Bivariate local indicators of spatial association (LISA) enabled a more accurate analyses of the mechanism controlling the spatial distribution of PAH and HM combinations in urban parks. The source apportionment indicated that industrial and traffic emissions were the most important sources of the pollutant combinations in urban parks, with traffic emissions accounting for most of the pollution.