| As persistent organic pollutants (POPs), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs),polychlorinated biphenyls(PCBs) and polybrominated diphenyl ethers(PBDEs) were widely concerned by various countries in the world, because of their carcinogenicity, mutagenicity and teratogenicity. These persistent organic pollutants in the atmosphere can be migrated with environmental media-air and enter the body through the food chain or by inhalation, resulting in human exposure.In this study, the concentration of the three catogaries of POPs in ambient air in a seaside city were analyzed by referencing to international standard methods and using isotope dilution high-resolution gas chromatography/high-resolution double-focusing magnetic mass spectrometer(HRGC/HRMS). The pollution levels of total 44 monomer, including 17 chlorinated dibenzodioxins/furans,18 polychlorinated biphenyls and 9 polybrominated diphenyls were studied in a city of China in rain and dry seasons, and the risk of human exposure to these three compounds was assessed preliminarily.The results showed that the levels of PCDD/Fs were in the range of 103.32～11882.95 fg/m3,with an average of 3426.84 fg/m3 and the median of 2950.35 fg/m3.The toxic equivalents were in the range of 11.45～370.12 fg I-TEQ/m3, with an average of 157.49 fg I-TEQ/m3 and the median of 151.24 fg I-TEQ/m3.The concentration of∑PCBs ranged from 9.16～126.60pg/m3,with an average of 52.72 pg/m3 and the median of 55.61 pg/m3. Six indicator PCBs concentration ranged from 8.34-122.67 pg/m3,with an average of 50.17 pg/m3 and the median of 52.81pg/m3;The concentration of the 12 DL-PCBs were 0.83-4.28 pg/m3,with an average of 2.55 pg/m3 and the median of 2.69pg/m3.∑TEQ-PCBs in the rang of 1.81～19.55fg WHO-TEQ/m3,the mean level was10.94fg WHO-TEQ/m3 and the median level was 12.82pg/m3.The concentration of∑8 PBDEs were 9.21～168.86 pg/m3,with an average of 34.23 pg/m3 and the median of 13.90pg/m3.Rain period in which the samples test BDE-209,the concentration range from 13.05～172.51 pg/m3,with an average of 49.67 pg/m3 and the median of 27.28 pg/m3.The average concentration of PCDD/Fs in air samples were 3837.59 pg/m3 in the dry season, 3016.10 pg/m3 in the rain season; the average TEQ of PCDD/Fs were 135.41 fg I-TEQ/m3 and 179.57 fg I-TEQ/m3, respectively.PCBs average concentration in the dry season was 44.97 pg/m3 and 60.48 pg/m3 in the rain season; the average TEQ of PCBs were 10.79 fg WHO-TEQ/m3 and 11.10 fg WHO-TEQ/m3,respectively.PBDEs average concentration in the dry season was 14.81 pg/m3 and 53.65 pg/m3 in the rain season. A clear trend was founded by the comparison of the concentration during two seasons, which the concentration of PCDD/Fs in the rain season is higher than that in the dry season, and on the contrary of PCBs and PBDEs.The abundance of different monomers has significant difference. OCDD was the biggest contributor to the total concentration (more than 20%).2,3,4,7,8-PeCDF was the dominant contributor to toxicity equivalent (TEQ).PCB-28 was the greatest contributor to the total concentration of indicator PCBs, and PCB-118 was the highest concentration of DL-PCBs. Similar to other studies, PCB-126 was the dominant contributor to toxicity equivalent (TEQ), accounted for over 94%, followed by PCB-169. The predominant PBDEs congeners (except BDE-209) measured in the two periods were BDE-47 and BDE-99, which declined in the dry season and other monomers(such as BDE-28, BDE-153, BDE-183) increased. The proportion of the monomer distribution tended to be equally.The PCDD/Fs concentration of this city was close to the average level of Sao Paulo of Brazil, higher than Taiwan, Hong Kong and the cities in Japan and European, lower than Korea's cities and Beijing, Guangzhou and Shanghai of China. The PCBs concentration was close to Yokohama and Manchester, lower than Gyeonggi-do of Korea and Taizhou of China. PBDEs concentration was similar to Chicago, higher than Osaka and Kyoto of Japan,the cities of Korea and Singapore, lower than Guangzhou, Beijing and Taizhou of China.Respiratory risk assessment found that adult and children daily exposure to PCDD/Fs was 0.0025～0.041pg I-TEQ/kg/day and 0.0058～0.094 pg I-TEQ/kg/day respectively. PCBs respiratory intake for adult and children was 0.0018 pg WHO-TEQ/kg/day and 0.0040 pg WHO-TEQ/kg/day (average) respectively. The city's residents daily intake of PCDD/Fs+DL-PCBs (including inhalation, dietary intake) was 1.39 pg WHO-TEQ/kg/day for adults and 5.52 pg WHO-TEQ /kg/day for children. Inhalation exposure to PCDD/Fs+DL-PCBs accounted for 2.09% and 1.21% of the total intake PCDD/Fs+DL-PCBs for adults and children, respectively. PBDEs in the daily average exposure was 5.56 pg/kg/day for adult and 12.66 pg/kg/day for children.
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