Health Risk Assessment Of Heavy Metals In The Site

With the adjustment of industrial structure and the"retreat into three"the gradual implementation of the strategy.Many of polluting enterprises were relocated from the city center area or shut down,such as electroplating,petroleum and chemical industry,causing the contaminated site to be left behind.The degree of pollution and health harm to human have prompted great concern.Human health risk based on specific site has been carried out.Not only can analyze different site activities of people affected by pollutants health risks and potential hazards,but also can provide a reliable basis for further utilization of legacy planning site.The pollution degree and human health risk of heavy metals in soil of a left electroplating factory were investigated in this study.Soil samples were collected according to the function area,to measure eight heavy metals?As?Cd?Pb?Cr?Cu?Ni?Zn and Hg?in one electroplating factories,located in Jiangsu district.The principle component analysis,nemerow index,geoaccumulation index and health risk assessment model were respectively carried out.To study the pollution source,pollution level and spatial distribution of health risk to heavy metals in soil.Moreover,a method based on chemical equilibrium simulation software?Visual MINTEQ?was developed to evaluate the health risk of heavy metals species in groundwater and was applied to electroplating plant.The main substance and results as following:?1?In all the sampling points,more than 5 heavy metals concents were above the background value in the surface soil.Pb,Cr,Cu,Ni and Zn exceeded the standard in100%,which have large area accumulation and serious pollution.The variation coefficient of surface soil was analyzed:Pb>Cu>Cr>Zn>Ni>Hg>Cd>36%>As>15%,all of which were strong variations.The contents of 5 kinds of heavy metals in the soil of each layer were different.The contents of 1.0m,1.5m and 3.0m were all higher than the background values,indicating that the heavy metals were mainly accumulated in the 0³.0m soil.The coefficient of variation of the average content of5 kinds heavy metals in soil,As>Ni>Cr>Cu>36%>Zn>15%were also highly variable,which were multi point or surface source pollution.?2?The SPSS factor was used to analyze the heavy metals in the surface soil,and4 main components were extracted.The first components include Cu,Ni and Zn,which may come from electroplating works.The second components were composed of Cr and Pb,which may be complex source of natural source and human source;Cd and Hg constituted third components and fourth components,respectively,which may be natural sources.The analysis of the total amount of heavy metals in each soil layer,only2 principal components were proposed.The first principal components included Cd,Cr,Cu,Ni,Pb and Zn,indicating that they had a similar source of pollution.As and Hg constituted second components.Thus,the content of Cd,Cr,Cu,Ni,Pb,and Zn in soil were mainly influenced by human activities,and Hg may be a natural source.?3?The Nemero comprehensive index showed that As,Hg and Cd of 8 heavy metals were all clean of all sampling points in the topsoil.Pb was moderately polluted,and Cr,Cu,Ni and Zn were heavily polluted in the topsoil.The 5 kinds of heavy metals As,Cr,Cu,Ni and Zn in all soil layers were polluted,especially in soil 1.0m,1.5m and3.0m depth.All samples of As were clean in each soil depth.?4?The index of geo accumulation showed that the order of heavy metal pollution in surface soil was Zn>Ni>Pb>Cu>Cr>Hg>Cd>As.As and Cd were not polluted.Most of the samples were polluted by Pb,Cr,Cu,Ni,Zn and Hg,which reached mild to moderate pollution.The results of geological accumulation index for As,Cr,Cu,Ni and Zn in soil from 1.5 to 12m shown that besides the slight increase of As and Ni in the 7.5m sampling layer,the rest metals decreased gradually with the increase of soil depth.The soil was mainly polluted by Cu,Ni,Cr and Zn in 0³.0m soil,especially in the soil 1.5m pollution was the most serious that all reached the serious pollution level.?5?Based on the ordinary Kriging interpolation method of Surfer software to draw the surface of health risk distribution map for 8 kinds of heavy metals in topsoil.The results showed that the carcinogenic and non-carcinogenic risks of Cr was all over accepted level,which were the main heavy metal pollutants.The risks of the electroplating workshop and landfill area for 8 heavy metals in topsoil were relatively high,which were the main pollution area.Maping the vertical spatial health risk of 5kinds of heavy metals of 95%value in the soil.The results show that only the non-carcinogenesis of Cr exceeded the acceptable level in soil 1.5m.The carcinogenesis risk of both As and Cr exceeded the acceptable level,especially at the depth of 1.5m in the soil,and the carcinogenesis risk of Cr reached 10^-4.?6?A method was proposed to assess heavy metal speciation in groundwater based on Visual MINTEQ model,analytic hierarchy process?AHP?and groundwater health risk model,which was applied to the electroplating factory.The results show that the non-carcinogenic risk of Cu,Pb and Zn in the electroplating plant were less than 1,which were not harmful to human health.The non-carcinogenic risks of Cu,Pb and Zn species were also less than acceptable level.The sum non-carcinogenic risk of each species was less than Cu,Pb and Zn based on total concentration.It Indicated that the health risk of heavy metals depends on their species,rather than the total concentration.In summary,the left electroplating site soil has been polluted by 8 heavy metals,especially Cr,Cu,Ni and Zn.It was most likely that plating operation was pollution source.The pollution and health risk of heavy metal of soil were more serious in 1.5m depth,and mainly contaminated space was in 0³.0m soil depth.The health risk values of Cr were greater than the acceptable level,which was the major heavy metal harm to human.It could help to provide decision-making and management information for soil control and remediation.The methodology presented in this study and its application proved that heavy metals species play an important role in determining health effects in groundwater,which improved health risk assessment system of heavy metals.