Occurrence,Sources And Fate Of Polycyclic Aromatic Hydrocarbons And Polychlorinated Biphenyls In The Pacific Sector Of The Arctic

Polycyclic aromatic hydrocarbons(PAHs)and polychlorinated biphenyls(PCBs)are two types of classic persistent toxic substances(PTS).16 PAHs are on the priority pollutant list of the United States Environmental Protection Agency(US EPA);PCBs were the first priority control organic pollutants listed in 2001 by Stockholm Convention.They exist in the environment for a long time and can migrate with water,organisms and atmosphere.In recent years,global climate change has led to the increase of water temperature and the melting of sea ice.The distribution and exchange balance of pollutants at the water-air interface is being disturbed,and the role of the Arctic seawater as"source"or"sink"is also changing.To research the environmental behavior characteristics of pollutants under the background of climate change and to identify the secondary sources and final fate of pollutants has become an urgent scientific problem.As an important area connecting the Arctic Ocean and the Pacific Ocean,the Pacific sector of the Arctic Ocean is an important channel for pollutants to enter the Arctic from the low latitude region.Based on the analysis of the occurrence characteristics,migration and transformation of PAHs and PCBs in the atmosphere,water and sediment of the sector,this paper discusses the migration behavior of PAHs and PCBs from the perspective of environmental multimedia and takes PAHs as an example to reveal the long-distance migration mechanism of typical PTS in the sector under the background of climate change.Based on the Chinese 9th Arctic Expedition(CHINARE 9),16 PAHs and 27 PCBs were analyzed by ultrasonic extraction gas chromatography mass spectrometry.The results show that the concentration of?PAHs in the gaseous phase and the atmospheric particle phase of CHIANRE 9 is 894.17?5658.53 pg/m~3 and 26.80?958.17 pg/m~3,respectively.The total concentration first decreases and then increases with the latitude increasing.The total concentrations of PAHs in seawater dissolved phase and particle phase are 1.79?12.76 ng/L and 34.69?338.28 ng/L,respectively.And the spatial distribution characteristics are very similar to those in the air gaseous phase.PCBs were not detected in the atmospheric particle phase,seawater particle phase and surface sediment;the total concentrations of PCBs in air gaseous phase are 1.23?2.39 pg/m~3;the total concentrations of PCBs in the seawater dissolved phase are 22.51?431.04pg/L.The isomer ratio method and principal component analysis show that PAHs sources in multimedia in different regions are different,and the sources of PAHs in dissolved phase and air gaseous phase are very similar,mainly due to incomplete combustion of coal and other biomass and combustion of chemical fuels such as petroleum;the sources of PAHs in atmospheric particle phase and seawater particle phase are complex,most of which are from leakage and combustion of liquid petroleum,etc.Complex hybrid sources.The total concentrations of PAHs in surface sediment are33.40?63.42 ng/g dw,and the potential source is petroleum leakage and combustion.As for the PCBs in air gaseous phase,there are different potential sources in different sea areas within CHINARE 9.The PCBs in seawater dissolved phase mainly come from the impregnation of power capacitors,while the PCBs in atmospheric gas phase present different potential sources in each sea area.By establishing a steady-state unbalanced level ? fugacity model,the environmental behavior and the fate of PAHs in the Pacific sector of the Arctic are simulated.The role Chukchi Sea played is"source"or"sink"for the global PAHs transmission process is discussed.It is found that the main migration process of LMW-PAHs is the diffusion from the seawater to the atmosphere in the study area.MMW-PAHs and HMW-PAHs tend to be transported downward,and finally buried in the surface sediments.The migration flux of seawater-air interface and seawater-sediment interface respectively accounted for 93%and 7%of the total flux,among which the upward migration flux of LMW-PAHs was the dominant,while the MMW-PAHs and HMW-PAHs mainly transported downward.PAHs degradation process in the study area occurred in seawater.In summer,the Chukchi Sea in the south is not the"sink"of all PAHs.Four kinds of low ring PAHs,including naphthalene,acenaphthylene,acenaphthene and fluorene,have begun to escape from the seawater to the atmosphere,and 12 kinds of PAHs,including active phenanthrene,are in a state of close dynamic equilibrium.The Pacific sector of the Arctic has evolved into the"source"of most LMW-PAHs.