| Polycyclic aromatic hydrocarbons(PAHs)is a kind of typical persistent organic pollutants(POPs)in the form of fused rings linked by two or more benzene rings,mainly from fossil fuels and biomass pyrolysis or incomplete combustion and exsit in the atmosphere,soil,water,food,dust and other media.It was concerned by reseachers because of its carcinogenic,teratogenic and mutagenic.Lanzhou is an important industrial base and comprehensive transportation hub in the northwest of China.Coal and oil are the main substance of energy consumption,thus the pollution level of PAHs can not be neglected.In order to investigate the pollution characteristics and influenced factors of PAHs in environmental media,samples of atmospheric fine particulate matter,water,food,soil and dust were collected and their PAHs were analyzed by GC-MS.Further more,environmental exposure level and health risk assessment of PAHs in different media were assessed by multi-media-multi-channel Human Exposure Model of US EPA in Lanzhou.The main results were obtained as follows:(1)The concentrations of ?PAHs in environmental media in different areas showed different pollution characteristics in Lanzhou.The concentrations of ?PAHs in airborne fine particles matter,food,soil and drinking water were 200.11ng/m3,8.67ng/g,39.11×105ng/kg and 14.5ng/L,respectively.There were the highest in Xigu District and the lowest in Yuzhong County.The concentrations of ?PAHs in the dust of indoor and outdoor were 9.84×105ng/kg and 11.55×105ng/kg,respectively.?PAHs in the indoor dust appeared as Yuzhong County>Xigu District>Chengguan District,and in the outdoor dust appeared as Xigu District>Chengguan District>Yuzhong County.The concentration of ?PAHs in the indoor dust was higher than outdoors in Yuzhong County,and the situation of Chengguan and Xigu District was on contary.The proportion of PAHs with 4~6 rings was higher and that of 2~3 rings was lower.Bb F was the most serious pollution in 16 kinds of PAHs monomer.(2)The concentrations of ?PAHs in heating period were much higher than that of non-heating period in Lanzhou.The concentrations of ?PAHs in atmospheric fine particles,food,soil and drinking water were 195.98ng/m3,312.16ng/g,39.11×105ng/kg and 14.5ng/L,respectively.The concentration of ?PAHs in outdoor dust(12.21×105ng/kg)was higher than that in indoor dust(8.95×105ng/kg).The proportion of PAHs with 4~6 rings was higher and that of 2~3 rings was lower.The pollution level of Bb F was the highest in all PAHs.(3)The pollution characteristics of Ba P equivalent concentration(Ba P-TEQ)in different environmental media were not same in Lanzhou.Ba P-TEQ in other environmental media were the highest in Xigu District except that it in food was the highest in Chengguan District,and it in all media during heating period was higher than non-heating period.Ba P daily exposure and carcinogenic health risk of female were higher than male,in addition to the Ba P daily exposure and carcinogenic health risk in other environmental media of 45 to 59 years were higher than those of 18 to 44 years except in food.(4)There were significant differences in carcinogenicity risk of PAHs through different exposure pathways in different populations in Lanzhou.Respiratory exposure was the most important pathway of PAHs,and its carcinogenic health risk in Xigu District was higher than that of Chengguan District and Yuzhong County.The carcinogenic health risks by oral exposure in male and 18 to 44 years were the highest in Xigu District,female in Yuzhong County and 45 to 59 years in Chengguan District had the same characteristic.Although the carcinogenic health risk through skin exposure was the highest in Yuzhong County.The total carcinogen risk through multi-channel exposure of PAHs was Xigu District> Yuzhong County> Chengguan District,heating period> non-heating period.(5)The ILCR exposed to different populations was different in different periods and different regions in Lanzhou.In addition to the highest ILCR of the environmental media in Xigu District except in Chengguan District exposed to dietary exposure,and in the heating period it was higher than that of non-heating period.ILCR of individual population appeared Xigu District> Chengguan District> Yuzhong County,heating period> non-heating period.The carcinogenic risks of PAHs through different exposure pathways exceeding the acceptable risk level(1 × 10-6)recommended by WHO,and it was highest by oral exposure.In summary,the PAHs in different environmental media were at high levels of pollution in Lanzhou.The carcinogenic risk of the population(different age and different gender)through different exposure pathways exceeding the acceptable risk level(1×10-6)recommended by WHO. |
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