Pollution Characteristics And Health-risk Assessment Of Polycyclic Aromatic Hydrocarbons In PM_2.5 In Two Primary Schools Of Lanzhou

A field observation between Jan to Dec was carried out with a medium-volume PM_2.5 sampler to collect PM_2.5 samples of Lanzhou city in 2015.We used HPLC to analyze sixteen kinds of optimal control PAHs and the concentrations,composition,sources and toxicity of atmospheric PM_2.5-bound PAHs in different seasons were studied.The results of this study are important for atmospheric organic pollution control and environment management of Lanzhou city.The main conclusions were as follows:?1?Based on the experimental data,the concentrations of PM_2.5-bound PAHs in Changjiaxiang Primary School and Yumen Streest Primary School were obtained.The concentrations of total PAHs ranged from 3.64 to 268.23 ng/m³ and the average concentrations is 38.46 ng/m³ in Changjiaxiang Primary School,while the concentrations of total PAHs in Yumen Street Primary School ranged from4.94-468.08 ng/m³ with the average concentration 39.66 ng/m³.Both of two districts followed the descending order:winter>autumn>spring>summer.In different seasons,the three to five rings PAHs occupied large proportion,the proportion of high rings and low rings were lower,in addition,the increasing proportion of 4–5 rings PAHs can be observed in winter.?2?The results obtained from diagnostic ratios associated and PCA revealed that combustion,traffic emission is predominant source in Chengguan,accompanied by biomass combustion.While coal combustion,traffic emission are main source of PAHs in Xigu,followed are biomass combustion.?3?The assessment of the risk of human health exposure to PAHs was performed by using the BaP concentration of cancer risk.The highest concentration was found in winter,autumn and spring followed,the lowest concentration was in summer.The concentration in winter is 8.3 times over than summer,and Xigu is 9.8 times,which indicates that the carcinogenic equivalent concentration in winter is still high,and its harm cannot be ignored.Health risk assessment showed that the risk of cancer for adults in the two districts was the highest,exceeding the acceptable risk value.The life expectancy loss showed that the life expectancy loss of adults were higher,three times that of children,indicating the health risks of PAHs in Lanzhou were at high levels..