The Research Of Persistent Organic Pollutants In The Urban Rainwater And Soil

In recent years, researches have shown that persistent organic pollutants (POPs)are widespread present in all kinds of environmental media. Due to the persistentorganic pollutants are highly toxic, POPs play havoc with the ecological environment,therefore, scholars have become increasing concerned about the pollution of persistentorganic pollutants in the environment.With the purpose of analysis the pollution status of POPs in the urbanenvironment, the research took Xi’an city as a target, set up a total of10representativesampling points according to the urban planning layout. Between March2013toJanuary2014, the experimenter collected the early rainwater and the soil within10cmto the surface in each sample point, the research utilized gas chromatography (GC) tomeasure the content of three categories of persistent organic pollutants in samples,which are OCPs,PCBs and PAHs.The research discussed the distribution of all kinds ofpollutants in Xi’an rainwater and surface soil,the content changes of all kinds ofpollutants in heating and non-heating period,and the correlation of all kinds ofpollutants between rainwater and surface soil.The research used fugacity businessprinciple to determine the source and migration trend of POPs,and given the ecologicalrisk assessment of POPs in Xi’an rainwater and surface soil.The urban rainwater and soil in Xi’an city all contain OCPs,PCBs and PAHs.Theaequally content of OCPs,PCBs and PAHs in the rainwater were respectively0.150g/L-41.127g/L,0.011g/L-5.378g/L,99.836g/L-1134.335g/L, the averagecontent of OCPs, PCBs and PAHs in the surface soil were separately0.519g/kg-67.502g/kg,0.055g/kg-24.691g/kg,142.759g/kg-1507.080g/kg. Whatever in the rainwater or the soil, the POPs are mainly opˊ-DDT、ppˊ-DDT、-HCH、PCB169、PCB189、PCB126、PCB77、Pyr、Chr. The content of POPs in heating seasonis higher than that of non-heating season while the climate changes, moreover, thecontent of POPs have a good correlation between the rain and soil.DDT and PCBs in Xi’an urban rainwater have been more than the Environmentalquality standard for surface water, which the average concentration of opˊ-DDT andPCB169in the rainwater are respectively more than28times and200times of thestandard concentration according to the Environmental quality standard for soil, whilethe average content of HCH and DDT in the soil are below the Primary Standardbasing on the Chinese Standard of Soil Environment Quality (GB15618-1995).The calculation results of fugacity quotient (fs/fa) show that fs/fa value of OCPs,PCBs as well as PAHs are further less than1, which indicating that the generalmigration trend of Xi’an urban POPs is from the rainwater to the surface soil, in otherwords, these pollutants is from the atmosphere and the soil is the ultimate gatheringplant.The ecological risk assessment shows that OCPs have certain risks to rainwaterand soil, while PCBs and PAHs have greater risks to rainwater and soil.