| Taking heavy metals in the soil of a zinc plant as the research object,the contents of eight heavy metal elements such including Cu,Zn,Pb,Cd,Mn,Cr,As and Sb in soil were determined,distribution characteristics of heavy metals in the soil of this area was analyzed by virtue of multivariate statistical method and and ArcGIS.Besides,we adopt four ecological hazard index methods to evaluate the risk level of soil ecological pollution.The RAG-C and RAGS,two health risk assessment models,were used to evaluate the harm to human body casued by the As,Cd,Zn and Sb in soil.The main0 research conclusions are as follows:?1?The analysis of heavy metal content in the study area indicated that the average content of 8 heavy metal elements in the soil all exceeded the soil background value of Hunan Province,and the maximum value of Cd exceeded the background value by 1700 times;Compared with The Soil Pollution Risk Standard For Construction Land?trial?,the contents of Pb,Cd,As,Zn and Sb are more than 3 times of the standard value,and other elements are under the level.The variation coefficients of 8 heavy metals in soil are more than 54%,which is highly variable,indicating human activities have a big impact.?2?Multivariate statistical analysis showed that there was a significant correlation between heavy metals Cu,Mn and Zn in the soil of the study area,and the pollution contribution rate was 27.3%.The pollution source was mainly accumulated solid waste;Pb,Cr and Cd elements were clustered into one type,and the pollution contribution rate is 26.2%.The pollution source is mainly the wastewater generated during production.As and Sb are affected by the same pollution factor.The pollution contribution rate is 25.7%.The pollution source is the smoke emitted by the zinc plant.?3?According to the results of ecological risk assessment the single factor pollution index indicates that the pollution sites of Cd,Zn,Pb,As and Sb in the study area are more than 76%.The pollution degree is more serious,and Cu,Mn and Cr are not polluted;the results of the ground accumulation index and the single factor index are basically consistent,but the pollution level is more serious,Cd,Zn,Pb,As and Sb pollution points are more than 90%.Cu pollution area is more than 86%.Mn and Cr are also lightly polluted;Nemero index method shows pollution the points accounted for 97%of the study area,87%of the heavy pollution level,and the pollution range was heavy;the comprehensive potential ecological risk risk results were basically consistent with the Nemeruo index method,and the medium ecological risk risk points accounted for more than 97%.In conclusion,the overall ecological pollution risk of the study area is high.?4?The results of health risk assessment model evaluation showed that the contribution rate of As,Cd,Zn and Sb elements in the soil of the study area through mouth to human health risk was above 48%,which was the main contribution source;Before the RAG-C model was revised,the statistics are as below CRAss are 4.01×10-4.CRCdd is 7.63×10-4.total non-carcinogenic hazard quotient HIAss is 37.1.HICdd is 10.1,HISbb is 10.4;model corrected CRAss are 3.85×10-4.CRCdd is 7.63×10-4.total non The carcinogenic hazard quotient HIAss was 36.0.HICdd was 9.8.HISbb was 10.2.The carcinogenic risk value and hazard strategy after exposure model and parameter correction is less than before the correction,but within an order of magnitude,and much higher than the acceptable risk value.which was much higher than the acceptable risk value.When using the RAGS model,the total carcinogenic risk index CRT of children and adults exceeded 10-4,and the minimum of adult reached 10-5,The total non-carcinogenic hazard HIT children is 1.28 times than that of adults.The focus of the two models is different,but the results show that the study area has carcinogenic and non-carcinogenic risks to human health.Therefore,when studying the specific legacy site,the relevant model parameters are corrected according to the area where the site is located,and the result is closer to the actual situation of the site. |
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