| Heavy metals in atmospheric particulate matter are harmful to human health.In this study,five typical locations in Xi'an city were selected as sample sites to collect PM2.5 and PM10 samples,and 256 effective samples were collected.Six stormwater runoff samples were collected and inductive coupling was used.Plasma-mass spectrometer?ICP-MS?measures the concentration of six heavy metal elements such as Mn,Fe,Pb,Zn,Cd,and Cu contained in the sample.The pollution levels of atmospheric PM2.5 and PM10 and their heavy metal elements,the pollution distribution at different sampling points,and the characteristics of rainfall migration were analyzed.The enrichment factor and correlation analysis were used to determine the pollution sources of heavy metals.Using the improved estimation model to estimate human exposure and risk assessment,the following main conclusions were obtained:The average annual PM2.5 and PM10 concentration in Xi'an is 114.8?g/m3 and206.8?g/m3,respectively,which were 1.53 and 1.38 times with the secondary standard limit of the“Ambient Air Quality Standard GB 3095-2012”.The range of fluctuations in the four seasons in spring,summer,autumn and winter were relatively large,and the maximum concentration of PM10 was the lowest more than ten times.The average mass concentration ratios of PM2.5 and PM10 in the four seasons of spring,summer,autumn and winter,were 0.49,0.45,0.55,and 0.61,while indicating that PM10 was the main pollutant in the spring and summer,and PM2.5 was dominant in the winter and autumn.The annual average concentrations of six heavy metal elements as Fe,Mn,Cu,Zn,Cd,and Pb in PM2.5 and PM10 were:1580ng/m3,77.30ng/m3,23.52ng/m3,1327ng/m32.066ng/m3,163.1ng/m3and 2544ng/m3,156.3ng/m3,37.00ng/m3,1781ng/m3,2.99ng/m3,225.4ng/m3,and seasonal variations,Pb,Cd,Mn,Zn,Cu The winter concentration was the lowest in summer and Fe was the highest in spring.The contents of five heavy metals Fe,Cu,Zn,Cd,and Pb in PM2.5 are larger than those in PM10,and the ratio of heavy metals in PM2.5 to PM10 in PM2 fluctuates greatly,but most At 60%or more,the proportion of Pb in autumn even reached 80%,indicating that most of the heavy metals are more easily adsorbed on particles with smaller particle sizes.Through correlation analysis and enrichment factor analysis,it can be concluded that Cd and Pb come from the same pollution source,mainly represented by human factors such as traffic,coal combustion and chemical electronics production;the sources of pollution of Zn and Cu are relatively complex,The sources of Zn and Cu pollution are relatively complex,both from the natural source of the soil and the role of human factors,while Fe and Mn are mainly affected by natural sources.The mass concentration of Fe,Zn,and Pb in atmospheric particulate matter PM10on the first day was significantly lower than that of PM10,and it also showed that the larger the frequency of rainfall was,the smaller the PM10 was in early sunny days.The change of the concentration of heavy metals in the rainfall runoff shows a clear initial flushing effect,and the initial concentration is several times or even several times of the concentration when the concentration is stable.The average concentration of Cu and Cd in the rainfall runoff is higher than the Class I limit of the surface water environmental quality standard,and the Pb is higher than the Class II limit of the surface water environmental quality standard.Health evaluation results show:The order of exposure of heavy metal elements was hand intake>skin contact>respiratory intake,and the health risk of children exposed to heavy metals in PM2.5 and PM10 is greater.The non-carcinogenic health risks of heavy metals of Pb,Cd and Mn in PM2.5 and PM10 were at a high level?1.207.36>1?,posing a threat to human health.The non-carcinogenic health risks of elements Fe,Cu and Zn in PM2.5 and PM10 and the carcinogens of Cd in PM2.5 and PM10 Health risks(1.65×10-66 and 2.38×10-6<10-4)were low but the combined effects of various carcinogenic heavy metals and the long-term accumulation of environmental hazards to human health were unignorable. |
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