| Taking heavy metals in road dust around Daye nonferrous metals smelter in Hubei province as the research object,a total of 62 samples were collected in the surrounding area of nonferrous smelter from December 8-12,2017,including 5 in smelting area,15in industrial zone,9 in cultural and educational district,28 in residential area and 5samples in business district.The contents of Hg,Pb,As,Cd,Ni,Cu,Zn,Tl,Sb,V,Cr,Co and Mn in road dust were determined by Inductively Coupled Plasma Mass Spectrometer,and content characteristics of Hg,Pb,As,Cd,Ni,Cu,Zn,Tl,Sb,V,Cr,Co and Mn in dust were analyzed by using pollution index,ground accumulation index and enrichment coefficient.The sources of heavy metals in road dust around Daye nonferrous smelter were analyzed by correlation analysis method,principal component analysis method,clustering method,positive definite matrix factor method and Kriging spatial interpolation method,and the health risk and ecological risk of the study area were estimated by means of health risk model and potential ecological risk model.According to the analysis,the mean content of Hg,Pb,As,Cd,Ni,Cu,Zn,Tl,Sb,V,Cr,Co and Mn in the road dust around Daye nonferrous smelter is 2.78,318.28,142.85,15.04,72.17,2678.34 and 505.96,0.97,26.03,102.42,321.42,47.05,965.20mg/kg,respectively,which showed that the degree of enrichment of Hg,Pb,As,Cd,Cu,Sb and Co.According to the comparison of heavy metal content of road dust in different functional areas,the content of heavy metals in road dust in smelting area and industrial area is significantly higher than that in cultural and educational districts,commercial areas and residential areas,and the content of Hg,V,Cr and Mn in industrial areas is significantly higher than that of other functional areas,while Pb,As,Cd,Ni,Sb have the highest content in the smelting area.According to the content of heavy metals in road dust in different study areas,the influence of smelting activities on the enrichment degree of heavy metals in road dust is obviously greater than that of traffic activities and tourism activities.From the combination of pollution index,enrichment factor and ground accumulation index,Hg,Pb,As,Cd,Ni,Cu,Zn,Sb,V,Cr,Co and Mn show different degree of enrichment in the research area,among which the enrichment level of Hg,Cd and Cu is higher.The correlation analysis,clustering analysis,factor analysis and positive definite matrix factor analysis of Hg,Pb,As,Cd,Ni,Cu,Zn,Tl,Sb,V,Cr,Co and Mn were analyzed,and 13 heavy metals mainly come from 4 sources.Factor 1 is the coal combustion source,and the main load element is Hg.The factor 2 is the machine manufacturing source,and the main load elements are Cr,V,Mn.Factor 3 is the transportation and smelting activity source,and the main load elements are Pb,As,Cd,Ni,Cu,Zn,Sb,Co;factor 4 is natural source,and the main load element is Tl.The contribution rates of coal combustion source,the machine manufacturing source,the transportation and smelting activity source and natural source in the study area were11.65%,24.59%,41.08%and 22.68%respectively.Therefore,transportation and smelting activities and machining manufacturing are the main sources of pollution in the research area.It can be seen from the function simulation that the smelting activity mainly affects the area within 3 km of the dominant wind direction.After analyzing comprehensive potential ecological risk of Pb,As,Cd,Cu,Hg,Ni,Cr and Zn,we know that the area is at high level of potential ecological risk and it is mainly because Hg,Cd and Cu have high potential ecological risk?high Toxic coefficient and high content level?.Besides,the peak value appears around smelting plant and industrial park,which indicates that smelting and industrial activities have impact on local ecological environment.From analysis of elements'potential ecological risk,we conclude that Pb,As,Cd,Cu and Hg have different degree of potential ecological risk.Hg,Cd and Cu are at higher level but Ni,Cr and Zn are at lower level.After analyzing comprehensive potential ecological risk of different functional zone,we know that smelting and industrial zone are at high level of comprehensive potential ecological risk and the peal value of major risk appears near smelting plant and industrial park,which indicates that smelting and industrial activities have impact on local ecological environment.After analyzing potential ecological risk of all elements in different functional zones,we conclude that Pb,As,Cd,Cu,Hg,Ni,Cr,and Zn had relatively high potential ecological risk in smelting and industrial zone.the elements having high potential ecological risk index in smelting zone are Zn,Cu,Cd,As and Pb;while the elements having high potential ecological risk index in industrial zone are Cr,Hg and Ni.Thereinto,Hg,Cd,and Cu are already at extremely high level of potential ecological risk,which verifies source analysis of Pb,As,Cd,Cu,Hg,Ni,Cr,Zn.It is indicated that after analyzing non-carcinogenic risk of As,Cr,Pb,Cu,Cd,Hg and Zn,adults exposed to heavy metals in road dust in the study area had no health risk,and the total non-carcinogenic risk was 5.75×10-2.Children have a non-carcinogenic risk with a risk value of 5.06,and been affected by non-carcinogenic risk brought by As,more sensitive than the adult,finger sucking finger as well as no protective measures,the child has higher non-carcinogenic risk than the adult.Non-carcinogenic risk of seven heavy metals can be ranked as follows:As>Cr>Pb>Cu>Cd>Hg>Zn.After computing exposure quantity of different heavy metal through all exposure pathways and non-carcinogenic risk,we know that digestive tract absorption is the main pathway for exposure of heavy metal in study dust area.The highest non-carcinogenic risk for children through digestive tract absorption is As,HQ>1.The non-carcinogenic risk of other elements through digestive tract absorption and skin exposure is below 1.Non-carcinogenic risk of adult in three pathways is below 1,which indicates that the adult has no health risk in three exposure routes and the child is affected by non-carcinogenic risk brought by As mainly through digestive tract absorption.After analyzing non-carcinogenic risk of children and adult in different functional zones,we know that high non-carcinogenic risk of both children and adult appear near smelting plant and industrial park.The non-carcinogenic risk of adult in 5 functional zones is below 1 but that of children in smelting zone is beyond 1,which is mainly because that As has high non-carcinogenic risk in smelting zone.Elements having high non-carcinogenic risk in smelting risk are Pb,As,Cd,Cu and Zn;while Hg and Cr appear relatively high non-carcinogenic risk in industrial zone,which further verifies the source analysis of Pb,As,Cd,Cu,Zn,Hg and Cr.After analyzing carcinogenic risk of As,Cr and Cd,we know that the total carcinogenic risk of the three elements is 1.43×10-6,and the carcinogenic risk can be neglected within the safe range(<1×10-4).The health risk should be minimal.Carcinogenic risk of Cr is higher than As,Cd,which is mainly caused by individual Cr with high carcinogenic risk around factory.We conclude from analysis of carcinogenic risk in different functional zone,among 5 functional zones,the industrial and smelting zone have relatively high carcinogenic risk.Thereinto,Cr is the element carrying greatest carcinogenic risk in industrial zone,commercial area,cultural and educational area as well as smelting zone and As is the one carrying greatest carcinogenic risk in residential area. |
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