Study On Characteristic Of Persistent Organic Pollutants In Dry And Wet Atmospheric Deposition Of Xi’an

Dry and wet deposition is the main mechanism of removing persistent organic pollutants in the air, is the main source of persistent organic pollutants in the surface environment. Through this process, finished the process of the persistent organic pollutants(pops) in the atmospheric transport to the surface of the earth. It is the important factors for environmental fate and human exposure to it. So it is meaningful to study on the persistent organic compounds in atmospheric dry and wet deposition for protecting the environment and reducing the pollution of the environment.To investigate the characteristics of POPs in atmospheric deposition, and the contribution to the pollutant removal made by dry and wet deposition, we chose Xi’an City as the object. At the north, south, east and west of the first and second ring 302 atmospheric deposition samples were collected, included dry and wet deposition. Wet deposition were extracted using liquid-liquid extraction, dry deposition using ultrasonic extraction. 36 kinds of POPs were analyzed by gas chromatography, including Eight kinds of organochlorine pesticides(OCPs), 12 kinds of polychlorinated biphenyls(PCBS) and 16 kinds of polycyclic aromatic hydrocarbons(PAHs), only PCB157 was not detected. Through calculate deposition flux of pollutants we know pollution at different sampling. The sampling point is divided into five different functional areas, then analyzed the characteristics of the pollutants of the different functional areas and different environmental media, in addition to using the correlation analysis the correlation of pollutants and TOC, and the cumulative number of sunny days. Finally we made the ecological risk assessment of POPs in atmospheric moved by wet and dry deposition in Xi’an city.resultsshowedthat16kindsofpahsand8kindsofocpsdetectionrateis100%,pcb157 notdetected,pcb123andpcb118detectionratewere97.4%and92.5%respectively,other9kindsofpcbsdetectionrateis100%.theconcentrationsofpahs,pcbsandocpsmadeup47%to77%,16%to42%and5%to12%oftotalpops.intermsofdifferentfunctionalareas,industrialpark>trafficartery>campus>commercial>residentialareas,transportationandindustrializationpollutantscontentseverpollution.asthespatialdistributionofpopsisthesouth>north>east>west,andmainlycontributedbyfueloil.rainfallisthemainpathwayofpopsremoval,accordingtowetdeposition>drydeposition>run-off.therelationshipoftheantecedentdryweatherdays,tocandpopswerer>0.7,byusingspss,sotheyaremainfactorsofpopsdepositioninatmospheric.theeffectofintervalmethodisadopted,thepopsinatmosphericremovedbydryandwetdepositionsamplesweremadeanecologicalriskassessmentofxi’ancity,resultsshowedthatpopsinatmosphericofxi’anisveryserious,especiallypcbs,andfollowedbyocpsandpahsrespectively.