| With the adjustment of industrial structure and the acceleration of urbanization,a great number of various types of contaminated sites have emerged,among which the contaminated sites of non-ferrous heavy metal extraction and smelting,petrochemicals,electronic dismantling,printing and dyeing has been researched more sufficiently,but few focuses have been made on the agate industry site.In 2006,approved by the government of Fuxin Mongol Autonomous County,an industry concentration area with agate processing and dyeing as the leading role and culture,tourism and modern services as a whole was constructed in Nalishan village,Shijiazi Town.Agate processing and dyeing enterprises in the park are distributed in the form of small workshops near the farmland of Nalishan village,although the park was shut down in 2015 due to the impact of the market environment,the agate dyeing workshops in the park are still retained and produced.The raw materials for agate processing and dyeing are mainly various different speciation of heavy metals,and long-term agate processing and dyeing had led to heavy metal pollution of the groundwater in the region.However,there are also environmental problems of the heavy metal pollution in the site of this concentration area is not well characterised,and the sources,ecological and health risks are unknown.Consequently,in this paper,the distribution of heavy metals pollution in the Fuxin agate industry concentration area was characterised,the sources were apportionmented,the ecological and health risks were assessed,and the risk control measures of heavy metal risk in the Fuxin agate industry concentration area are proposed,which will provide a basis for the risk management of heavy metal risk in the agate processing and dyeing sites of workshop-style and distributed-type.The main results were as follows:（1）The pollution characteristics and spatial distribution of heavy metals in the agate industry concentration area site were studied by using the mathematical statistics and the Kriging spatial interpolation.The results showed that,in soil,Cd,Cr,Cu,Ni and Co concentrations were high,Ni and Co exceeded the corresponding screening values of the‘Soil environmental quality-Risk control standard for soil contamination of development land（Trial）’（GB 36600-2018）by a maximum of 1.69 and 3.33 times,and Cd,Cr,Cu and Ni exceeded the corresponding screening values of the‘Soil environmental quality-Risk control standard for soil contamination of agricultural land（Trial）’（GB 15618-2018）by a maximum of 2.45,2.39,15.45 and 2.74 times,respectively.Among them,the contaminated areas of Cr,Cu and Co were mostly located in Nalishan village,and their distribution areas were expanding from the soil surface to the deep layer;the contaminated areas of Cd and Ni were mainly located in the farmland,and the distribution area of Cd decreases with the increase of the depth of the soil,while Ni was the opposite of it.Groundwater Cr（Ⅵ）concentration was high,the exceeded rate compared with theⅢwater quality standard of‘Standard for groundwater quality’（GB/T 14848-2017）was81.82%,and the maximum exceedance multiplier was 41.2 times,the contaminated samplings were mainly located in Nalishan village.（2）The qualitatively analysis of the soil heavy metal sources in the agate industry concentration area were used by the correlation analysis and the factor analysis.The results showed that,Cr and Co were significantly correlated,mainly from the combined sources of agate dyeing and natural sources;Cu,Ni and Zn were significantly correlated,mainly from the industrial sources of agate processing;Pb,Hg and Cd were not correlated with other heavy metals,and originated from traffic emissions sources,atmospheric deposition sources and agricultural sources,respectively.The quantitatively analysis of the soil heavy metal sources in the agate industry concentration area were used by the positive matrix factorization（PMF model）and the random forest（RF model）.The results showed that,the RF model was more accurate and more realistic.Based on the results of the RF model,the contribution rates of agate dyeing and natural sources,industrial sources of agate processing,traffic emissions sources,atmospheric deposition sources and agricultural sources were determined to be 21.80%,30.21%,21.41%,11.60%,and 14.98%,respectively.（3）A probabilistic soil heavy metal risk assessment model based on different sources was constructed by combining the source apportionment model,Monte Carlo simulation,the potential ecological risk index method and the health risk assessment model.The ecological and health risks of heavy metals in the soil of the agate industry concentration area were accurately assessed and the priority control elements were screened by applying the model.The results showed that,soil heavy metals in agate industry concentration area were in medium ecological risk,agricultural sources and Cd should be the primary control elements affecting ecological risk.Soil heavy metals in agate industry concentration area posed carcinogenic risk for adults,carcinogenic risk and non-carcinogenic risk for children,children’s health risk were higher than adults,and the main exposure pathway was oral ingestion,combined sources of agate dyeing and natural sources and Cr,Co should be the primary control elements affecting.（4）A modified groundwater ion species health risk assessment model was constructed by combining the traditional and speciation-based health risk assessment model and employing a weighted analysis method to correct the concentrations of each heavy metal ion species.The health risk of Cr（Ⅵ）contamination of groundwater in agate industry concentration area was accurately assessed by applying the model.The results showed that,among the 10 chemical species of Cr（Ⅵ）simulated by chemical equilibrium,Cr O42-and Ca Cr O4（aq）posed a carcinogenic risk.After correction,the risk indices for Cr O42-and Ca Cr O4（aq）significantly increased,and Cr O42-also posed a non-carcinogenic risk for children.（5）The risk control principles of heavy metal pollution in the agate industry concentration area of workshop-style and distributed-type was concentrated.Based on the study results of soil and groundwater heavy metal pollution distribution characteristics,source apportionment,and risk assessment in the agate industry concentrated area,Nalishan village and surrounding farmland were designated as the key control area,the agricultural sources,as well as the combined sources of agate dyeing and natural sources were identified as the primary pollution sources,Cd,Cr and Co were selected as the priority control heavy metals,and institutional control,in-situ remediation,engineering control and monitoring of natural attenuation were used as the main control techniques,so some targeted control measures were proposed for controlling the risk of heavy metals in soil and groundwater in the control area. |
