Distribution,Sources And Air-soil Exchange Of Polycyclic Aromatic Hydrocarbons And Polychlorinated Biphenyls In Ny-(?)lesund

Polycyclic aromatic hydrocarbons（PAHs）and polychlorinated biphenyls（PCBs）are recognized as persistent toxic substances（PTS）in the world.As common by-products of human activities,most of PAHs and PCBs are generated in middle and low latitudes,and can be transported to the Arctic with the atmosphere currents and ocean currents.PAHs and PCBs have been detected in a variety of environmental compartments in Svalbard,and the concentration of pollutants is at a high level.In order to understand the distribution,migration and transformation pattern of local pollutants,to probe into the impact of human activities on remote districts with low temperature,the distribution,health risk,main sources,interannual variation and air-soil exchange of PAHs and PCBs in Svalbard have been studied.The gas phase,particle phase,soil and animal feces in Ny-（?）lesund have been taken as the research object,and the concentration,composition and distribution of 16 priority PAHs and 27 PCBs were analyzed,and the toxicity risks of local PAHs and PCBs were evaluated.The sources of PAHs in the gas phase,particulate phase and soil phase in Ny-（?）lesund have been analyzed by diagnostic ratios and positive matrix factor method（PMF model）,and the source of PCBs has been studied by PMF model.Finally,the air-soil exchange of PAHs and PCBs under the situation of global climate change has been studied by fugacity model.The main conclusions are as follows:（1）The average concentrations ofΣ₁₆PAH in the gas phase and particle phase are2.7-37.8 ng·m^-3 and 0.05-2.9 ng·m^-3,respectively.The toxic equivalence quantity（TEQ）of the atmosphere is 0.6-266.9 pg·m^-3,and the toxicity risk is low.The concentration of PAHs in the atmosphere is significantly lower than that in the middle and low latitude areas,but slightly higher than that in other Arctic and some remote areas.The high concentration ofΣ₁₆PAH appears not only in the soil near the coal mine and the scientific research station,but also in the areas with less human activities such as the glacier front and the lakeside,but the toxic equivalence quantity of PAHs in most of the soil samples is lower than the safe value(600 pg·g^-1 dw).The incremental lifetime cancer risk of the soil is generally acceptable.The concentrations ofΣ₁₆PAH in most of the animal feces ranged from 65.0 to 939.5 ng·g^-1 dw.Only one sample near the coal mine in 2018 has a concentration of 2818.3 ng·g^-1 dw.From 2015 to 2019,the proportion of high molecular weight PAHs in the above four compartments increases significantly.The PMF model has been used to analyze the source of PAHs in the atmosphere and soil,and it is speculated that the variation of components is related to the local combustion source.（2）The rates of detected PCBs in Ny-（?）lesund area are low.The average concentrations ofΣ₂₇PCB in the gas phase and particle phase are lower than 10 pg·m^-3and 8 pg·m^-3,respectively.In 2015,the TEQ of atmosphere in Ny-（?）lesund has been over the acceptable level in some period,but the toxicity risk is generally low.The average concentration ofΣ₂₇PCB in the soil was lower than 3 ng·g^-1 dw,and the higher concentration(>8 ng·g^-1 dw)appears in the soil around the scientific research station and glacier front.In 2015,the highest concentration of PCB congener in the soil is PCB-169,which becomes PCB-157 in 2016,and the proportion of low chlorinated PCBs increases significantly.The toxic equivalence quantity of PCBs in the soil is lower than that in urban areas in middle and low latitudes,but higher than that in some remote areas.The incremental lifetime cancer risk is neglectable.The concentration ofΣ₂₇PCB in animal feces ranges from 0.1 to 2.2 ng·g^-1 dw.In 2015,the concentration of hexachlorobiphenyl accounted for the largest proportion,followed by heptachlorobiphenyl and PCB-206;in 2016,only four congeners have been detected.It is speculated by PMF model that traffic and industries are the main sources for local PCBs.（3）When the air temperature is 0℃,3-rings PAHs mainly tends to volatize and 4–6 rings PAHs mainly tends to deposit.At the temperature of 5℃,the volatilization flux of 3-rings PAHs will increase by 40%-70%,the volatilization trend of 4-rings PAHs will be stronger,and the deposition flux of 5-6 rings PAHs will be basically unchanged.When the air temperature is 0℃,most of the PCBs tend to deposit,but difference among sampling points is obvious.At the temperature of 5℃,the volatilization flux of low chlorinated PCBs will increase by 20%-60%,and the deposition flux of high chlorinated PCBs has no obvious change.