109 research outputs found
Heavy metal concentrations and their possible sources in paddy soils of a modern agricultural zone, southeastern China
No full textIn a typical modern agricultural Zone of southeastern China, Haining City, 224 topsoil samples were collected from paddy fields to measure the total concentrations of copper (Cu), lead (Pb), zinc (Zn), cadmium (Cd), chromium (Cr), mercury (Hg), arsenic (As) and cobalt (Co). The total concentrations ranged from 15.30 to 78.40 mg kg(-1) for Cu, 20.10 to 41.40 mg kg(-1) for Pb, 54.98 to 224.4 mg kg(-1) for Zn, 0.04 to 0.24 mg kg(-1) for Cd, 54.90 to 197.1 mg kg(-1) for Cr, 0.03 to 0.61 mg kg(-1) for Hg, 3.44 to 15.28 mg kg(-1) for As, and 7.17 to 19.00 mg kg(-1) for Co. Chemometric techniques and geostatistics were utilized to quantify their spatial characteristics and define their possible sources. All eight metals had a moderate spatial dependency except that Pb had a strong spatial dependency. Both factor analysis and cluster analysis successfully classified the eight metals into three groups or subgroups, the first group included Cu, Zn and Cr, the second group included Cd, As and Co, and the last group included Pb and Hg. The Cu, Zn and Cr concentrations in majority samples were higher than their local background concentrations and they were highly correlated (r > 0.80), indicating that they had similar pollution source and anthropic factor controlled their spatial distribution; the Cd, As and Co concentrations in majority samples were lower than their local background concentrations, indicating that the source of these elements was mainly controlled by natural factors; the mean concentration of Pb exhibited generally low level, close to its local background concentration, the Hg concentration in about half of samples was higher than its local background concentration, and they were poor correlated with the other metals, indicating that the source of Pb and Hg was common controlled by natural factor and anthropic factor.In a typical modern agricultural Zone of southeastern China, Haining City, 224 topsoil samples were collected from paddy fields to measure the total concentrations of copper (Cu), lead (Pb), zinc (Zn), cadmium (Cd), chromium (Cr), mercury (Hg), arsenic (As) and cobalt (Co). The total concentrations ranged from 15.30 to 78.40 mg kg(-1) for Cu, 20.10 to 41.40 mg kg(-1) for Pb, 54.98 to 224.4 mg kg(-1) for Zn, 0.04 to 0.24 mg kg(-1) for Cd, 54.90 to 197.1 mg kg(-1) for Cr, 0.03 to 0.61 mg kg(-1) for Hg, 3.44 to 15.28 mg kg(-1) for As, and 7.17 to 19.00 mg kg(-1) for Co. Chemometric techniques and geostatistics were utilized to quantify their spatial characteristics and define their possible sources. All eight metals had a moderate spatial dependency except that Pb had a strong spatial dependency. Both factor analysis and cluster analysis successfully classified the eight metals into three groups or subgroups, the first group included Cu, Zn and Cr, the second group included Cd, As and Co, and the last group included Pb and Hg. The Cu, Zn and Cr concentrations in majority samples were higher than their local background concentrations and they were highly correlated (r > 0.80), indicating that they had similar pollution source and anthropic factor controlled their spatial distribution; the Cd, As and Co concentrations in majority samples were lower than their local background concentrations, indicating that the source of these elements was mainly controlled by natural factors; the mean concentration of Pb exhibited generally low level, close to its local background concentration, the Hg concentration in about half of samples was higher than its local background concentration, and they were poor correlated with the other metals, indicating that the source of Pb and Hg was common controlled by natural factor and anthropic factor
Variability of copper availability in paddy fields in relation to selected soil properties in southeast China
No full textCopper (Cu) is an essential nutrient element for plant growth and is a toxic heavy metal in excess concentrations. As such, its concentration and availability in soils are of great agricultural and environmental concern. Availability and spatial pattern of copper in relation to selected soil properties in surface soils were evaluated for an agricultural region in southeastern China. A total of 224 topsoil samples (0-15 cm) were collected from paddy fields in a study area of 731 km2. We measured total Cu and DTPA-extractable Cu (available Cu) concentrations, soil pH, soil organic matter content (SOM), total nitrogen, available phosphorus, available potassium, and cation exchange capacity (CEC). We estimated Cu availability by calculating the ratio of available Cu to total Cu concentration. The results of our chemical analyses indicated that both total Cu and available Cu concentrations had a wide range throughout the study area. In addition, we measured slight Cu accumulation in paddy fields of the study area in comparison to background levels at Zhejiang Province scale. Correlation analysis revealed that available Cu concentration was positively correlated with total Cu concentration, CEC and SOM as indicated by moderate to high correlation coefficients (r = 0.64-0.82), and Cu availability was directly correlated with SOM, pH and Cu concentration with moderate to high positive correlation (r = 0.47-0.82) at 0.01 level of significance. Spatial distribution maps illustrated that total Cu concentration and available Cu concentration had similar distribution trends with the highest concentrations in the northeast region and low concentrations in the southwest region of the study area. Copper availability ratio had a spatial distribution trend with high ratios in the northeast region and low ratios in the central region of the study area. Soil properties influencing the spatial distribution of Cu availability were SOM and pH, in addition to the concentration of available Cu.Copper (Cu) is an essential nutrient element for plant growth and is a toxic heavy metal in excess concentrations. As such, its concentration and availability in soils are of great agricultural and environmental concern. Availability and spatial pattern of copper in relation to selected soil properties in surface soils were evaluated for an agricultural region in southeastern China. A total of 224 topsoil samples (0-15 cm) were collected from paddy fields in a study area of 731 km(2). We measured total Cu and DTPA-extractable Cu (available Cu) concentrations, soil pH, soil organic matter content (SOM), total nitrogen, available phosphorus, available potassium, and cation exchange capacity (CEC). We estimated Cu availability by calculating the ratio of available Cu to total Cu concentration. The results of our chemical analyses indicated that both total Cu and available Cu concentrations had a wide range throughout the study area. In addition, we measured slight Cu accumulation in paddy fields of the study area in comparison to background levels at Zhejiang Province scale. Correlation analysis revealed that available Cu concentration was positively correlated with total Cu concentration, CEC and SOM as indicated by moderate to high correlation coefficients (r = 0.64-0.82), and Cu availability was directly correlated with SOM, pH and Cu concentration with moderate to high positive correlation (r = 0.47-0.82) at 0.01 level of significance. Spatial distribution maps illustrated that total Cu concentration and available Cu concentration had similar distribution trends with the highest concentrations in the northeast region and low concentrations in the southwest region of the study area. Copper availability ratio had a spatial distribution trend with high ratios in the northeast region and low ratios in the central region of the study area. Soil properties influencing the spatial distribution of Cu availability were SOM and pH, in addition to the concentration of available (C) 2010 Elsevier B.V. All rights reserved
Concentrations and potential health hazards of organochlorine pesticides in (shallow) groundwater of Taihu Lake region, China
No full textA total of 27 shallow groundwater samples were collected from the Taihu Lake region (TLR), to determine the concentrations of 14 organochlorine pesticide (OCP) species, identify their possible sources, and estimate health risk of drinking the shallow groundwater. All OCP species occurred in the shallow groundwater of TLR with high detection frequency except p, p'-dichlorodiphenyldichlorothane (p, p'-DDD) and p, p'-dichlorodiphenyltrichloroethane (p, p'-DDT). DDTs and hexachlorocyclohexanes (HCHs) were the dominant OCP contaminants in the shallow groundwater of TLR, and they account for 44.2% total OCPs. The low alpha-HCH/gamma-HCH ratio, high beta-HCH/(alpha + gamma)-HCH ratio and beta-HCH being the dominant HCH isomers for the majority of samples suggest that the HCHs were mainly from the historical use of lindane after a period of degradation. p, p'-DDE being the dominant DDT metabolite for all the samples indicated that the DDTs were mainly from the historical residues. Compositional analysis also suggested that there were fresh input sources of heptachlors, aldrins and endrins in addition to the historical residues. Correlation analysis indicated the hexachlorobenzene (HCB) impurity in the shallow groundwater of TLR was likely from the historical application of lindane and technical HCH (a mixture of HCH isomers that is produced by photochlorination of benzene). Carcinogenic risk values for alpha-HCH, heptachlor, heptachlor epoxide, aldrins and dieldrin in the shallow groundwater in majority area of TLR were found to be >10(-6), posing a potentially serious cancer risk to those dependant on shallow groundwater for drinking water. (C) 2013 Elsevier B.V. All rights reserved.A total of 27 shallow groundwater samples were collected from the Taihu Lake region (TLR), to determine the concentrations of 14 organochlorine pesticide (OCP) species, identify their possible sources, and estimate health risk of drinking the shallow groundwater. All OCP species occurred in the shallow groundwater of TLR with high detection frequency except p, p'-dichlorodiphenyldichlorothane (p, p'-DDD) and p, p'-dichlorodiphenyltrichloroethane (p, p'-DDT). DDTs and hexachlorocyclohexanes (HCHs) were the dominant OCP contaminants in the shallow groundwater of TLR, and they account for 44.2% total OCPs. The low alpha-HCH/gamma-HCH ratio, high beta-HCH/(alpha + gamma)-HCH ratio and beta-HCH being the dominant HCH isomers for the majority of samples suggest that the HCHs were mainly from the historical use of lindane after a period of degradation. p, p'-DDE being the dominant DDT metabolite for all the samples indicated that the DDTs were mainly from the historical residues. Compositional analysis also suggested that there were fresh input sources of heptachlors, aldrins and endrins in addition to the historical residues. Correlation analysis indicated the hexachlorobenzene (HCB) impurity in the shallow groundwater of TLR was likely from the historical application of lindane and technical HCH (a mixture of HCH isomers that is produced by photochlorination of benzene). Carcinogenic risk values for alpha-HCH, heptachlor, heptachlor epoxide, aldrins and dieldrin in the shallow groundwater in majority area of TLR were found to be >10(-6), posing a potentially serious cancer risk to those dependant on shallow groundwater for drinking water. (C) 2013 Elsevier B.V. All rights reserved
Spatial Prediction of Soil Organic Matter Content Using Cokriging with Remotely Sensed Data
No full textAccurately measuring soil organic matter content (SOM) in paddy fields is important because SOM is one of the key soil properties controlling nutrient budgets in agricultural production systems. Estimation of this soil property at an acceptable level of accuracy is important; especially in the case when SOM exhibits strong spatial dependence and its measurement is a time- and labor-consuming procedure. This study was conducted to evaluate and compare spatial estimation by kriging and cokriging with remotely sensed data to predict SOM using limited available data for a 367-km(2) study area in Haining City, Zhejiang Province, China. Measured SOM ranged from 5.7 to 40.4 g kg(-1), with a mean of 19.5 g kg(-1). Correlation analysis between the SOM content of 131 soil samples and the corresponding digital number (DN) of six bands (Band 1-5 and Band 7) of Landsat Enhanced Thematic Mapper (ETM) imagery showed that correlation between SOM and DN of Band 1 was the highest (r= -0.587). We used the DN of Band I as auxiliary data for the SOM prediction, and used descriptive statistics and the kriging standard deviation (STD) to compare the reliabilities of the predictions. We also used cross-validation to validate the SOM prediction. Results indicate that cokriging with remotely sensed data was superior to kriging in the case of limited available data and the moderately strong linear relationship between remotely sensed data and SOM content. Remotely sensed data such as Landsat ETM imagery have the potential as useful auxiliary variables for improving the precision and reliability of SOM prediction
Spatial Estimation of Soil Total Nitrogen Using Cokriging with Predicted Soil Organic Matter Content
No full textAccurate measurement of soil total N (TN) content in agricultural fields is important to guide reasonable application of nitrogenous fertilizer. Estimation of soil TN content with limited in situ data at an acceptable level of accuracy is important because laboratory measurement of N is a time- and labor-consuming procedure. This study was conducted to evaluate cokriging of soil TN with predicted soil organic matter (SOM) content as auxiliary data. The SOM content was predicted by cokriging with a digital number (DN) of Band I of Landsat Enhanced Thematic Mapper (ETM) imagery. Soil TN content was estimated by using 88 soil samples for prediction and 43 soil samples for validation in a study area of 367 km(2) in Haining City, China. Field-measured soil TN content ranged from 0.47 to 2.48 g kg(-1), with a mean of 1.25 g kg(-1). Soil TN content of all 131 soil samples including samples for prediction and validation was highly correlated with measured (r = 0.81, p < 0.01) and predicted (r = 0.81,p < 0.01) SOM content in paddy fields. Then, the predicted SOM content was used as auxiliary variable for the prediction of soil TN content. By using the 43 samples for validation, we had a mean error (ME) of 0.03 g kg(-1) and a root mean square error (RMSE) of 0.31 g kg(-1) for kriging, and a mean error of 0.00 g kg(-1) and a root mean square error of 0.25 g kg(-1) for cokriging, respectively. Our results indicate cokriging with predicted SOM content data was superior to kriging. In addition, predicted data of the auxiliary variable have the potential to be useful for cokriging when the predicted auxiliary data have high prediction accuracy.Accurate measurement of soil total N (TN) content in agricultural fields is important to guide reasonable application of nitrogenous fertilizer. Estimation of soil TN content with limited in situ data at an acceptable level of accuracy is important because laboratory measurement of N is a time- and labor-consuming procedure. This study was conducted to evaluate cokriging of soil TN with predicted soil organic matter (SOM) content as auxiliary data. The SOM content was predicted by cokriging with a digital number (DN) of Band I of Landsat Enhanced Thematic Mapper (ETM) imagery. Soil TN content was estimated by using 88 soil samples for prediction and 43 soil samples for validation in a study area of 367 km(2) in Haining City, China. Field-measured soil TN content ranged from 0.47 to 2.48 g kg(-1), with a mean of 1.25 g kg(-1). Soil TN content of all 131 soil samples including samples for prediction and validation was highly correlated with measured (r = 0.81, p < 0.01) and predicted (r = 0.81,p < 0.01) SOM content in paddy fields. Then, the predicted SOM content was used as auxiliary variable for the prediction of soil TN content. By using the 43 samples for validation, we had a mean error (ME) of 0.03 g kg(-1) and a root mean square error (RMSE) of 0.31 g kg(-1) for kriging, and a mean error of 0.00 g kg(-1) and a root mean square error of 0.25 g kg(-1) for cokriging, respectively. Our results indicate cokriging with predicted SOM content data was superior to kriging. In addition, predicted data of the auxiliary variable have the potential to be useful for cokriging when the predicted auxiliary data have high prediction accuracy
Empirical estimation of total phosphorus concentration in the mainstream of the Qiantang River in China using Landsat TM data
No full textEutrophication is a serious environmental problem in Qiantang River, the largest river in the Zhejiang Province of southeast China. Increased phosphorus concentration is thought to be the major cause of water eutrophication. The objective of this study was to develop an empirical remote sensing model using Landsat Thematic Mapper (TM) data to estimate phosphorus concentration and characterize the spatial variability of the phosphorus concentration in the mainstream of Qiantang River. Field water quality data were collected across a spatial gradient along the river and geospatially overlaid with Landsat satellite images. Various statistical regression models were tested to correlate phosphorus concentration with a combination of other water quality indicators and remotely sensed spectral reflectance, including Secchi depth (SD) and chlorophyll-a (Chl-a) concentration. The optimal regression model was subsequently used to map and characterize the spatial variability of the total phosphorus (TP) concentration in the mainstream of Qiantang River. The results suggest that spectral reflectance from the Landsat satellite is spatially and implicitly correlated with phosphorus concentration (R-2 = 0.77). The approach proved to be effective and has the potential to be applied over large areas for water quality monitoring.Eutrophication is a serious environmental problem in Qiantang River, the largest river in the Zhejiang Province of southeast China. Increased phosphorus concentration is thought to be the major cause of water eutrophication. The objective of this study was to develop an empirical remote sensing model using Landsat Thematic Mapper (TM) data to estimate phosphorus concentration and characterize the spatial variability of the phosphorus concentration in the mainstream of Qiantang River. Field water quality data were collected across a spatial gradient along the river and geospatially overlaid with Landsat satellite images. Various statistical regression models were tested to correlate phosphorus concentration with a combination of other water quality indicators and remotely sensed spectral reflectance, including Secchi depth (SD) and chlorophyll-a (Chl-a) concentration. The optimal regression model was subsequently used to map and characterize the spatial variability of the total phosphorus (TP) concentration in the mainstream of Qiantang River. The results suggest that spectral reflectance from the Landsat satellite is spatially and implicitly correlated with phosphorus concentration (R(2) = 0.77). The approach proved to be effective and has the potential to be applied over large areas for water quality monitoring
Studies on the chromium concentrations in topsoils and subsoils of two rapidly industrialized cities in the Yangtze River Delta in east China
No full textA total of 782 topsoil samples (0-20 cm) and 371 subsoil samples (20-40 cm) were collected from agricultural land in two rapidly industrialized areas with a large number of small rural industries in southeast China, Zhangjiagang City (ZJG) and Changshu City (CS), to measure soil chromium (Cr) concentrations. Kriging and cokriging were used to predict the spatial distribution of Cr in the topsoils and subsoils. Paired-samples t test and spatial distribution maps were used to compare the Cr concentrations in topsoils and subsoils. The mean Cr concentration in ZJG topsoils was significantly higher than that in ZJG subsoils and the mean Cr concentration in CS topsoils showed no significant difference from that in CS subsoils. The Cr concentrations in topsoils were higher than those in subsoils over most of the area of ZJG and part of CS, suggesting that Cr accumulation had occurred in these areas and extrinsic factors have an important role controlling the distribution of Cr in topsoils. Semivariogram/cross-semivariogram was used to evaluate soil Cr spatial variability. The Cr in ZJG topsoils, ZJG subsoils, and CS topsoils had moderate spatial dependence and the Cr in CS subsoils had strong spatial dependence. Cr in ZJG subsoils had longer effective range than Cr in ZJG topsoils, suggesting that the anthropogenic factors affecting Cr distribution in ZJG topsoils; and Cr in CS topsoils had longer effective range than Cr in CS subsoils, indicating that soil formation may be the major explanation for the decrease in the variation of Cr in topsoils. A significant correlation was found between the Cr in topsoils and Cr in subsoils, indicating that natural factors also play an important role as extrinsic factors that control the distribution of Cr in topsoils.A total of 782 topsoil samples (0-20 cm) and 371 subsoil samples (20-40 cm) were collected from agricultural land in two rapidly industrialized areas with a large number of small rural industries in southeast China, Zhangjiagang City (ZJG) and Changshu City (CS), to measure soil chromium (Cr) concentrations. Kriging and cokriging were used to predict the spatial distribution of Cr in the topsoils and subsoils. Paired-samples t test and spatial distribution maps were used to compare the Cr concentrations in topsoils and subsoils. The mean Cr concentration in ZJG topsoils was significantly higher than that in ZJG subsoils and the mean Cr concentration in CS topsoils showed no significant difference from that in CS subsoils. The Cr concentrations in topsoils were higher than those in subsoils over most of the area of ZJG and part of CS, suggesting that Cr accumulation had occurred in these areas and extrinsic factors have an important role controlling the distribution of Cr in topsoils. Semivariogram/cross-semivariogram was used to evaluate soil Cr spatial variability. The Cr in ZJG topsoils, ZJG subsoils, and CS topsoils had moderate spatial dependence and the Cr in CS subsoils had strong spatial dependence. Cr in ZJG subsoils had longer effective range than Cr in ZJG topsoils, suggesting that the anthropogenic factors affecting Cr distribution in ZJG topsoils; and Cr in CS topsoils had longer effective range than Cr in CS subsoils, indicating that soil formation may be the major explanation for the decrease in the variation of Cr in topsoils. A significant correlation was found between the Cr in topsoils and Cr in subsoils, indicating that natural factors also play an important role as extrinsic factors that control the distribution of Cr in topsoils
Spatial characteristics of cadmium in topsoils in a typical e-waste recycling area in southeast China and its potential threat to shallow groundwater
No full textInformal electrical and electronic waste (e-waste) recycling often creates secondary sources of cadmium (Cd) pollution. To characterize the total Cd concentration (Cd-total) in topsoil and evaluate the threat of Cd in topsoils to shallow groundwater, 187 topsoil samples and 12 shallow groundwater samples were collected in a typical e-waste recycling area in southeast China. Soil organic matter content, soil pH and Cd-total in topsoil, pH and dissolved Cd concentration in shallow groundwater were measured. Cd-total in the topsoils showed an inverse distribution trend with soil pH in that high Cd concentrations (and low pH values) were found in the surrounding area of the metal recycling industrial park where there were many family-operated e-waste recycling facilities before the industrial park was established and with low concentrations (and high pH values) in other areas, and they had similar spatial correlation structures. Cd accumulation and acidification were synchronous in topsoils, and soil pH was significantly correlated with Cd-total in topsoils with low to moderate negative correlation coefficient (r = -024), indicating that both of them maybe correlated with informal recycling. The shallow groundwater in the surrounding area of the metal recycling industrial park was seriously contaminated by Cd, and topsoil Cd accumulation and acidification in the surrounding area of e-waste recycling sites significantly increase the risk of shallow groundwater contaminated by Cd. Action is urgently required to control Cd accumulation and acidification by improving the recycling operations of e-wastes in order to reduce the risk of Cd leaching from topsoils and shallow groundwater contamination. (C) 2013 Published by Elsevier B.V.Informal electrical and electronic waste (e-waste) recycling often creates secondary sources of cadmium (Cd) pollution. To characterize the total Cd concentration (Cd-total) in topsoil and evaluate the threat of Cd in topsoils to shallow groundwater, 187 topsoil samples and 12 shallow groundwater samples were collected in a typical e-waste recycling area in southeast China. Soil organic matter content, soil pH and Cd-total in topsoil, pH and dissolved Cd concentration in shallow groundwater were measured. Cd-total in the topsoils showed an inverse distribution trend with soil pH in that high Cd concentrations (and low pH values) were found in the surrounding area of the metal recycling industrial park where there were many family-operated e-waste recycling facilities before the industrial park was established and with low concentrations (and high pH values) in other areas, and they had similar spatial correlation structures. Cd accumulation and acidification were synchronous in topsoils, and soil pH was significantly correlated with Cd-total in topsoils with low to moderate negative correlation coefficient (r = -024), indicating that both of them maybe correlated with informal recycling. The shallow groundwater in the surrounding area of the metal recycling industrial park was seriously contaminated by Cd, and topsoil Cd accumulation and acidification in the surrounding area of e-waste recycling sites significantly increase the risk of shallow groundwater contaminated by Cd. Action is urgently required to control Cd accumulation and acidification by improving the recycling operations of e-wastes in order to reduce the risk of Cd leaching from topsoils and shallow groundwater contamination. (C) 2013 Published by Elsevier B.V
Calibration for discrete element modelling of railway ballast: A review
No full textThe discrete element method (DEM) has been confirmed as an effective numerical method for modelling railway ballast, and successfully used to analyse a wide range of ballast-related applications (e.g. geomaterials). However, there still exists some aspects under development. Among them, the model calibration can be the most significant one (morphology, degradation and contact model). Because reliable and accurate results can be obtained only when the parameters are carefully selected. Therefore, diverse DEM applications and developments in railway ballast are critically reviewed. Furthermore, the model calibration methods are discussed. This is able to help future researchers improve the existing calibration methods, further, build more accurate, standardised and validated DEM models for ballast-related studies. Additionally, this paper can assist researchers to choose an appropriate model for specific applications.Accepted author manuscriptRailway Engineerin
Empirical estimation of pollution load and contamination levels of phthalate esters in agricultural soils from plastic film mulching in China
No full textPollution load and contamination levels of phthalate esters (PAEs) in agricultural soils throughout China were studied in this work. The usage amount and residual rates of plastic film were the main factors explaining the variation among regions and leading to higher pollution load and contamination levels in agricultural big provinces. However, higher pollution loads and contamination levels frequently occurred under non-recycling than recycling scenarios during calculation. Extremely high loads (more than 10 kg/ha/year) of PAEs were estimated in five areas including Beijing city, Tibet, Liaoning Province, Jilin Province and Fujian Province and the high contamination levels in agricultural soil were presented in these places with more than 4.0 mg/kg under non-recycling scenarios. The predicted concentrations of PAEs in soils exceed the target value for soils from Netherlands (I PAEs pound = 0.1 mg/kg), indicating very high contamination of most Chinese agricultural soils. Significant differences in estimation results after plastic film utilization suggest that decreasing plastic film residue after application is an effective measure to control PAE pollution in soils. However, the comparison between contamination levels of PAEs estimated by the model and the previous detections of PAEs pollution levels in agricultural soils showed that there were presented wide range of PAE sources indicated to agricultural soils.Pollution load and contamination levels of phthalate esters (PAEs) in agricultural soils throughout China were studied in this work. The usage amount and residual rates of plastic film were the main factors explaining the variation among regions and leading to higher pollution load and contamination levels in agricultural big provinces. However, higher pollution loads and contamination levels frequently occurred under non-recycling than recycling scenarios during calculation. Extremely high loads (more than 10 kg/ha/year) of PAEs were estimated in five areas including Beijing city, Tibet, Liaoning Province, Jilin Province and Fujian Province and the high contamination levels in agricultural soil were presented in these places with more than 4.0 mg/kg under non-recycling scenarios. The predicted concentrations of PAEs in soils exceed the target value for soils from Netherlands (I PAEs pound = 0.1 mg/kg), indicating very high contamination of most Chinese agricultural soils. Significant differences in estimation results after plastic film utilization suggest that decreasing plastic film residue after application is an effective measure to control PAE pollution in soils. However, the comparison between contamination levels of PAEs estimated by the model and the previous detections of PAEs pollution levels in agricultural soils showed that there were presented wide range of PAE sources indicated to agricultural soils
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