Study On Pollution Characteristics And Risk Assessment Of Polychlorohydrocarbon In Fine Particulate Matter Of Typical Areas

In recent years,atmospheric fine particulate pollution has become a severe environmental problem in the world,especially in China.Previous studies have shown that there is a positive correlation between the death rate and PM_2.5 concentrations.Based on the characteristics of PM_2.5,atmospheric toxic pollutants are easily attached to PM_2.5.The combination exposure with PM_2.5 and pollutants will cause serious human health risks.Hexachlorobutadiene（HCBD）and pentachloroanisole（PCA）received increasing attention in recent years due to their inclusion in the Stockholm convention in 2017.The report regarding the occurrence of HCBD and PCA in PM_2.5is limited so that it is necessary to clarify their contamination profiles and human health risks.Chlorobenzenes（CBs）are chemically similar to HCBD and PCA.,and their polychlorinated substitution will affect the ecosystem.Hexachlorobenzene（HCB）and pentachlorobenzene（Pe CB）were therefore listed in the Stockholm Convention in sequence,while their analogs 1,2,4-trichlorobenzene（TCB）and1,2,4,5-tetrachlorobenzene（Te CB）were regulated as the priority pollutants in the European Union.Considering the simultaneous extraction and detection due to their similar structures,in this study,HCBD,PCA and CBs were selected as target analytes,so-called emerging polychlorinated pollutants（EPPs）.In this study,six emerging polychlorinated pollutants（EPPs）,including HCBD,PCA and CBs,in PM_2.5 samples were simultaneously determined by gas chromatography-triple quadrupole mass spectrometry（GC-MS/MS）combined with ultrasonic-assisted extraction and multi-column purification.We optimized the type of glass liner,injection method,the flow rate of carrier gas,injection volume,injection temperature,transfer line temperature,ion source temperature and the ionization method,and validated the best instrumental method for the analysis of target analytes in the complex environmental samples.The instrumental detection limits were0.32-14.6 ng/L,and the intra-day and inter-day reproducibility were 0.61%-9.10%and0.79%-8.52%,respectively,indicating the high sensitivity and reproducibility for the accurate analysis of the target analytes.Based on the developed method,the concentrations of EPPs in PM_2.5 of Taiyuan during 2017-2018 were analyzed.HCBD and PCA were reported to be found in PM_2.5 for the first time.Based on the results of statistical analysis,the potential sources of analytes in PM_2.5 were clarified.CBs were mainly related to agricultural activities and coal combustion.HCBD may be derived from the manufacture or incineration of chlorine-containing products.PCA probably originated from atmospheric chemical reactions.We also investigated the level of target analytes in PM_2.5 and dust samples from a plastic processing plant and electronic processing plant.The results showed that the total concentrations of all analytes in PM_2.5 and dust were 0.0011-4.42 pg m^-3 and 0.0011-517 ng g^-1.For dust samples,the concentrations of analytes in the plastic processing plant were much lower than those in thethe electronic processing plant,indicating the EPPs emission from these two manufacturing techniques.Finally,the results of preliminary human risk assessment showed that the estimated daily intakes of adults or children via inhalation of analyte-contained PM_2.5 were much lower than the reference dose values of the corresponding analyte,suggesting minimal human health risks from target analytes in PM_2.5.