某市秋冬季大气PM2.5中6种有毒元素的生态风险评价

目的 对某市秋冬季大气PM2.5中镉(Cd)、铬(Cr)、汞(Hg)、铅(Pb)、镍(Ni)、砷(As)的污染特征进行分析,并对其生态风险进行评价,为政府制定防治对策提供科学依据。方法 以该市光明实小、钓鱼台小学为采样点,分别在秋季冬季对PM25进行采样。测定Cd、Cr、Hg、Pb、Ni、As的含量,并利用富集因子(EF)法和潜在生态危害指数法对其生态风险进行评价。结果 除Ni外,其他元素的浓度均为冬季均高于秋季。秋季细颗粒物中As、Cd、Cr、Ni的超标率分别为2619%、2619%、10000%、238%;冬季细颗粒物中As、Cd、Cr的超标率分别为4091%、2728%、10000%。Hg的富集因子大于2,其他元素的富集因子均小于1。所有元素均属于低生态风险。结论 该市大气PM2.5中秋季Cr、Ni、Cd、As浓度超标,冬季Cr、As、Cd超标。除Ni外,其他元素的浓度冬季均高于秋季。Hg为中度富集,而其他元素则没有富集。该市秋冬季大气PM2.5中6种有毒元素均属于低生态风险。

Ecological risk assessment of six toxic elements in the atmospheric PM2.5 in autumn and winter of a city

Objective To analyze the characteristics of PM2.5 pollution in autumn and winter of the city based on six chemical elements including Cd,Cr,Hg,Pb,Ni and As,and to evaluate the ecological risk,in order to provide the scientific basis for the government to formulate feasible preventive measures.Methods Two sampling points were set in Guangming experimental primary school and Diaoyutai primary school in this city and PM2.5 samples in autumn and in winter were collected respectively.The contents of Cd,Cr,Hg,Pb,Ni and As in PM2.5 samples were analyzed,and the ecological risks of the six elements were evaluated with the method of enrichment factor(EF)and potential ecological risk assessment(Eir).Results Except for Ni,the contents of other elements were higher in winter than those in autumn and 26.19%,26.19%,100% and 2.38% of the autumn PM2.5 samples exceeded the air quality standard for As,Cd,Cr and Ni,respectively.And in winter the exceeded percentages were 40.91%,27.28% and 100.0% for As,Cd and Cr,respectively.The enrichment factor of Hg was higher than 2,and it was less than 1 of all the other elements.All elements belonged to low ecological risk.Conclusion The contents of Cr,Ni,Cd and As in PM2.5 in autumn of the city are in excess of the national standard,in winter the contents of Cr,As and Cd was in excess of the standard.Except for Ni,the contents of other elements are higher in winter than those in autumn.The EF of elements indicates that Hg is medium-enriched,while other elements are not enriched.The ecological risk assessment(Eir)of Cd,Cr,Hg,Pb,Ni and As of PM2.5 in autumn and winter of the city belongs to low ecological risk.