The Study Of Atmosphere Wet And Dry Deposition Of Pahs In Harbin

Polycyclic aromatic hydrocarbons?PAHs?are a persistent organic pollutant in the atmosphere with a"triad"effect and characterized by sustained diffusion.Dry deposition has a scavenging effect on PAHs in the atmosphere.Similarly,wet deposition has a scavenging effect on PAHs in the atmosphere too.Dry and wet sedimentation plays an important role in atmospheric PAHs.For dry deposition of PAHs,a lack of this part in the northeast of data research,for the PAHs wet deposition research,many areas only studied the characteristics of rainfall and snowfall research rarely.Therefore,this paper studies the characteristics of atmospheric dry and wet deposition of PAHs collected from atmospheric,dry deposition,rainfall and snowfall samples in 2017-2018.In this study,samples of atmospheric,dry deposition,rainfall and snowfall were collected meanwhile samples of atmospheric particulate phase deposition were pretreated.The content of PAHs in samples was determined by gas chromatography-mass spectrometry?GC-MS?.The average concentrations of?₁₆PAHs in atmosphere,dry deposition,rainfall and snow are 93.02±94.83 ng·m^-3,5244.73±6066.18 ng·g^-1,15732.14±9233.67 ng·L^-1 and 35373.52±23032.12 ng·L^-1 respectively.Compared with the results reported at home and abroad,the pollution level in this study is in the middle rank in the world,the mean concentration of?₁₆PAHs in the atmosphere,dry deposition,rainfall and snowfall is significant difference between heating and non-heating periods.In the study of the characteristics of dry and wet deposition,the atmospheric coherent deposition flux is:1068.15±1252.77 ng·m^-2·d^-1,coherent deposition flux of atmospheric particles is 1666.03±2029.49 ng·m^-2·h^-1.The coherent deposition flux of atmospheric gas phase and particle has obvious difference in heating period and non-heating period.The removal rates of PAHs by rainfall and snowfall are 10⁸and 10⁷ orders of magnitude,respectively,and is two orders of magnitude higher than the rule of thumb.The average precipitation flux of?₁₆PAHs during precipitation and snow deposition is 2406.95 ng·m^-2·d^-1 and 3520.71 ng·m^-2·d^-1,respectively.Compared with the results reported at home and abroad,the wet deposition flux of PAHs in Harbin is at a high pollution level,which is in the middle of the world.Through the application of characteristic molecule ratio method and principal component analysis method,it is found that coal combustion in heating period has the greatest impact on Harbin,and the influence of various factors in non-heating period is more complex,the influence of automobile exhaust is more obvious,according to the sources of PAHs in Harbin,we should mainly control coal burning in winter,use clean coal burning and improve energy utilization.