Source identification and health risk assessment of trace elements in atmospheric PM1 during foggy days in Qingdao
In order to understand pollution level and sources of metallic elements in PM1 on foggy days in Qingdao,and to assess the risk to human health,this study classified foggy days based on visibility and humidity data,and revealed the sources and health risks of metallic elements in PM1 on foggy days in Qingdao by combining the PMF and the health risk assessment model.The PM1 concentration on clean-foggy days was slightly higher than that on clean days,while the PM1 concentration on polluted-foggy days was 1.11 times as compared with hazy days and 3.07 times as compared with clean days.The metal elements in the autumn and winter foggy days were influenced by anthropogenic sources,with the highest content of Potassium.The main contributing elements in the summer foggy days were the typical crustal elements Ca,Fe,Al and sea salt Na.The PMF results showed that the metal elements in the PM1on the autumn and winter foggy days came from biomass/coal combustion,vehicle emissions,crustal dust,sea salt,ship emissions and industry,the metal elements in PM1 on foggy days in summer were biomass/coal combustion,vehicle/road dust sources,crustal dust,sea salt,ship emissions and industry.The sampling site is adjacent to the sea,where sea fog is frequent and sea salt sources are an important source of metal elements on foggy days in summer.The results of health risk assessment showed that the non-carcinogenic risk of PM1 for adults and children exposed to foggy days in Qingdao in autumn and winter was below the threshold value.The non-carcinogenic risk of Mn was the highest for adults and children,and the non-carcinogenic risk of hand-oral ingestion of As(HQAs=0.50)was the highest for children.The carcinogenic risks of As(3.1×10 6)and Cr(1.9×10 6)exceeded the thresholds for carcinogenic risk,and it is recommended to strengthen the control of the sources of emissions containing Mn,As,and Cr.
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