| Street dust is the“source”and“sink”of various pollutants in the urban environment.Under the external dynamic conditions,it is easy to form point-line-surface composite urban dust pollution.Urban street dust has not only great harm to the ecological environment and human health,but also the harmful effects caused by human activities.In 2011,the Hubei Provincial Environmental Protection Department issued a notice to list eight key areas,such as Wuhan Qingshan District,as the key prevention and control areas for heavy metal pollution.Therefore,it is of great research and practical significance to investigate and monitor the heavy metals in the street dust of Qingshan District,and carry out health risk assessment based on effective uncertainty control to provide comprehensive and detailed reference information for environmental health risk management.The street dust in Qingshan District was selected as the research object,and the basic physical and chemical properties,heavy metal contents?Cu,Cr,Zn,Pb and Cd?and heavy metal bioavailability of the three particle size segments of summer and winter street dust in27 sampling points were tested in Qingshan District.The land accumulation index method was used to quantitatively evaluate the pollution of heavy metals in street dust.The potential health risks of heavy metals in street dust were evaluated by improved health risk assessment method.The results were spatially characterized by ArcGIS,and priority control pollutants and priority risk control areas were identified.Finally,the multi-statistical method was used to analyze the pollution sources of heavy metals in street dust,and the countermeasures and suggestions for the prevention and control of heavy metal pollution and health risk management in the dust of street in Qingshan District were proposed.Research indicates:?1?The pH of the street dust in Qingshan District was alkaline.The average value of organic matter of the three particle size segments in summer dust was 2.32%?<62?m?,2.35%?62100?m?and 1.67%?100150?m?,respectively.The average value of organic matter of the three particle sizes in winter dust was 2.95%?<62?m?,2.92%?62100?m?and 2.41%?100150?m?,respectively.?2?The concentration of five heavy metals was Zn>Cr>Pb>Cu>Cd.Compared with the background value of each element,the dust enrichment ability in summer and winter were Zn>Pb>Cd>Cu>Cr and Cd>Zn>Pb>Cu>Cr,respectively.The content of Cd in winter dust was obviously higher than that in summer.The content of Cu in winter dust was slightly higher than that in summer.The content of Cr and Zn in winter dust was similar to that in summer.The content of Pb in summer small particle size dust was much higher than that in winter,but opposite in the larger particle size dust.The spatial distribution of heavy metals varied greatly.?3?The bioavailability of heavy metals in summer and winter dust were Zn>Cu>Pb>Cd>Cr and Cu>Cd>Zn>Pb>Cr,respectively.The accumulation index indicated that the heavy metals?except Cr?in the street dust of Qingshan District showed different degrees of pollution,and the degree of heavy metal pollution in winter dust was generally higher than that in summer.In addition,the smaller the street dust particle size,the more serious pollution of heavy metals.The heavy metal pollution level of street dust in Qingshan District in summer and winter were Zn>Pb>Cd>Cu>Cr and Cd>Zn>Pb>Cu>Cr,respectively.?4?The total non-carcinogenic risk of five heavy metals in all sampling points in Qingshan District was less than 1,indicating that there was no non-carcinogenic risk in street dust in Qingshan District.The total non-carcinogenic risk of each heavy metal exposure to children was higher than that to adults.The non-carcinogenic risk exposure of each heavy metal was expressed as intake>skin contact>breathing.Cr and Pb in the street dust of Qingshan District had greater impacts on the non-carcinogenicity of the human body.There was no cancer risk in Cd in the dust of Qingshan District.The cancer risk of Cr at S16(1.13×10-6)and S22(1.31×10-6)sampling points exceeds 10-6,which indicated acceptable cancer risks of Cr.?5?Priority control of heavy metals were Cr,Zn,Pb and Cd,and priority control of areas were concentrated in S16,S19,S21,S22 and S26.According to the comprehensive source analysis,Cu-Zn-Pb-Cd in the dust of Qingshan District mainly came from traffic and industrial composite pollution.Cr in the dust of Qingshan District was caused by natural source and pollution of steel industry.?6?Through the identification of the source of heavy metals in the dust of Qingshan District,combined with its health risk and spatial distribution,it put forward targeted risk control measures.First,strengthen the industrial transformation of Qingshan District and foster the introduction of clean,efficient and low-energy strategic emerging industry.Second,strengthen the control of source and pollutant emissions.Third,promote the construction of environmental health risk monitoring system in Qingshan District.Fourth,publicize environmental and health science knowledge,strengthen information disclosure,and increase public participation. |
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