| Persistent organic pollutants(POPs)are a series of compounds which are extremely harmful to ecological environment and human health,the crude disposal of electronic waste is an important source of POPs.At present,28 POPs have been listed in the Stockholm Convention on Persistent Organic Pollutants,among which short chain chlorinated paraffins(SCCPs)were the latest POPs added in 2017.In addition,some pollutants with potential POP properties but haven't been controlled by the Convention,such as three alternative flame retardants(AFRs):dechlorane plus(DP),1,2-bis(2,4,6-tribromophenoxy)ethane(BTBPE),and decabromodiphenyl ethane(DBDPE),as well as polybrominated dibenzo-p-dioxins/dibenzofurans(PBDD/Fs),are typical pollutants released from electronic waste disposal,the above pollutants are collectively referred to as "new POPs" in this thesis.There are still some technical difficulties about the analysis of these new POPs in the environment,such as chromatographic co-eluting and mass overlapping interference for SCCP congeners,thermal degradation of octabromodibenzofuran(OBDF)and octabromodibenzo-p-dioxin(OBDD)during instrumental analysis.The studies on pollution characteristic and transformation principle of these new POPs in multi-environmental media combined with the disposal manner of electronic waste have not been reported.Firstly,an analytical method was developed for the simultaneous purification and separation of SCCPs,DP,BTBPE,DBDPE and PBDD/Fs in ambient air,soils and sediments.The samples were extracted by accelerated solvent extraction,purified by concentrated sulfuric acid partitioning,acid-base silica gel column separation,and active carbon-dispersed silica gel column reversal separation,the analytes were separated each other,and were separated from most interferences.SCCPs were determined using comprehensive two-dimensional gas chromatography-electron capture negative ionization-mass spectrometry(GC×GC-ECNI-MS).The problems of chromatographic co-eluting and mass overlapping interference for SCCPs caused by medium chain chlorinated paraffins and those interferences difficult to be removed by sample purification,including dichlorodiphenyldichloroethane,chlordane,and toxaphene,were solved.This method enabled 13C-1,5,5,6,6,10-C10H16Cl6 to be used as an extraction internal standard.The accuracy of SCCP analysis was greatly improved by GC×GC coupled with quadrupole mass spectrometry for determination and chlorine content-total response factor relationship calibration.Three AFRs and PBDD/Fs were accurately quantitated using gas chromatography-electron ionization-double focous high resolution mass spectrometry(GC-EI-HRMS),the thermal degradation of highly brominated compounds was reduced significantly at the inlet temperature of 280-290? operated in pulse injection mode for 1 min,the recoveries of 13C-OBDF and 13C-OBDD in environmental samples reached 22-76%and 29-85%(acceptance criteria of 17-157%),respectively.Based on the above developed analytical method,the levels of new POPs in multi-environmental media from a typical electronic waste dismantling area,Guiyu town in Guangdong province,China,were determined.The levels of new POPs in ambient air and sediments of Guiyu were high amoung the global reports,the levels of which in farmland soils of Guiyu were comparable to or slightly higher than the global average reports.The correlation analysis of new POP concentrations in samples showed that the concentrations of "feed-in"pollutants(SCCPs and three AFRs)in ambient air were significantly correlated,but were not correlated with those of "reaction-generated" pollutants(PBDD/Fs),perhaps the transformation characteristics of the two kinds of pollutants entering the atmosphere during the process of electronic waste disposal were inconsistent.The concentrations of all pollutants in farmland soils or sediments were significantly correlated with each other,it was possible that the transformation characteristics of the two kinds of pollutants between the air,soils and sediments were basically consistent after they entered the environment.By studying the influence of electronic waste disposal manner on the emission level of new POPs,it was found that the emission level of new POPs was positively correlated with the temperature of thermal disposal of electronic waste,the new POP pollution caused by open burning,roasting of circuit board,non-thermal manual disassembly and shredding were gradually decreased.The "reaction-generated" pollutants(PBDD/Fs)were mainly derived from the incineration of electronic waste in Guiyu,that was verified by the composition analysis of polycyclic aromatic hydrocarbons in environmental media,which were combustion indicators.The composition variation and transformation principle of new POPs in multi-environmental media were further identified.Based on the composition analysis of SCCP and DP technical products,the source patterns of SCCP congeners were classified into three categories,i.e.shorter,medium and longer carbon chain patterns,which were defined as CP-52-1,?,? type,respectively,all types were dominated by Cl6-9 congeners.DP technical product contained syn-and anti-isomers,and the proportion of anti-DP(fanti-DP)was close to 0.75.The investigation on formation mechanism of PBDD/Fs from brominated flame retardants(BFRs)showed that the source patterns of PBDD/F congeners were dominated by heptabromodibenzofuran(1,2,3,4,6,7,8-HpBDF)and OBDF.The relative content of SCCPs with different carbon chain lengths in the air of Guiyu was as follows:C10-CPs?C11-CPs>C12-CPs?C13-CPS,the abundance of medium and lowly chlorinated congeners were relatively high.The distribution patterns of carbon homologues of SCCPs in the soils were nearly same as those in the air,but the abundance of highly chlorinated congeners increased,indicating that highly chlorinated congeners were more easily enriched in the soils.The distribution characteristics of carbon homologues of SCCPs in the sediments were different from those in the air and soils,the relative content of which were C10-CPs?Cn-CPs>C11-CPs?C12-CPs,the abundance of medium and lowly chlorinated congeners were relatively high.POPs in the sediments were mainly derived from the dumping of disposed electronic waste residues in the rivers,the increase of C13-CPs content in the sediments might indicat that SCCP homologues with longer carbon chain mainly existed in these residues.The mass ratios of syn-DP and anti-DP in the air and soils were close to source ratio of two isomers in DP technical product,indicating that there was no significant selective degradation of two isomers in the air and soils.The fanti-DP values in the sediments varied greatly,ranging from 0.45 to 0.95,the values in the sediments at dumping sites of disposed electronic waste residues were relatively low,due to anti-DP was easier to thermal degradation than syn-DP.The distribution patterns of PBDD/F congeners in all environmental media were basically similar to the source pattern of PBDD/Fs generated by BFRs,lowly brominated congeners generated from thermal disposal of electronic waste tended to volatilize into the air,the relative contents of OBDF in the air and soils were slightly lower than source proportion,which might be due to partial photolysis of OBDF.However,the relative contents of OBDF in the sediments were close to source proportion.The studies on the partition of SCCP congeners between air and soils proved that the thermal disposal process of electronic waste resulted in the continuous emission of SCCPs to the atmosphere,which made the partition of them between air and soils in a dynamic state.However,the partition of SCCPs between air and soils in the areas engaged in non-thermal disposal and background sites tended to be balanced. |
PDF Full Text Request