| Non-standard e-waste dismantling can lead to the emission of large amounts of persistent toxic substances(PTS)derived from the e-waste dismantling into the environment.As one of the main components of medium oil in electronic products,PCBs are widely used,causing serious pollution and health risks.That the illegal e-waste dismantling of family workplace in Guiyu city,Guangzhou province and Taizhou city,Zhejiang province has caused serious problems to environment and local people health.Due to the Chinese government encouraged the processing industries including e-waste recycling industry relocating from the eastern regions to the western regions under China's Western Development Strategy(WDS)since 1999,the environmental pollutions and health risks derived from e-waste recycling dismantling have attracted attention.While little data is available on the ambient environment levels and occupational risks of PTS emission derived from the formal e-waste dismantling plant with standardization and scale production in northwest China.In this thesis,100 air samples including gaseous and particle phases(PM10,PM2.5 and PM1.0)were collected at three sampling sites including two different locations(indoor and outdoor of workplaces)of recycling plant and one farmyard far away 5 km from recycling plant area in 2016 winter to determine ambient ?31PCBs concentrations,we evaluated the exposure risks of occupational workers based on air PCBs concentration.The conclusions of this thesis are as follows:(1)The total concentration of 31 PCB congeners analyzed(termed as ?31PCBs hereafter)in air(gas phase + particle phase)of the study area was within the range of 62.39-1019.95 pg/m3,with the average concentration of 206.33 pg/m3.This was much lower than that reported in Guiyu city,Guangzhou province(?37PCBs:472.3±405.1 ng/m3),and was also lower than the maximum acceptable limit for occupational environment air regulated by Japan(0.1mg/m3),the former Soviet Union(1.0mg/m3),and Sweden(0.03mg/m3),and lower than the time-weighted average concentration of occupational environment air in Germany(20mg/m3).The concentration of ?3iPCBs was highest for indoor of the dismantling workplace(206.33 pg/m3),followed by the rural farmyard site(51.48 pg/m3)and then was outdoor of dismantling workplace(50.50 pg/m3).The concentration of ?3iPCBs in PM10(91.55pg/m3,52.87%)was the highest,followed by that in PMi.o(66.78pg/m3,38.57%)and then in PM2.5(14.83pg/m3,8.56%).(2)The gas phase concentration of PCBs was 33.16 pg/m3,21.78 pg/m3 and 43.65 pg/m3 for indoor of dismantling workplace and outdoor of dismantling workplace as well as the rural site,respectively.In contrast,the PCBs in particle phase exhibited the average concentration of 173.15 pg/m3,28.71 pg/m3 and 7.84 pg/m3 at the three locations.We can conclude that PCBs emissions from the E-waste dismantling in the workplace were mainly found in particulate phase.(3)The low-chlorinated PCBs dominated the most PCB components in which tetrachloro-PCBs were found to be the most abundant PCB congeners for both indoor and outdoor of the dismantling workplace,followed by the trichloro-PCBs.Samples collected at rural site had higher concentrations for low-chlorinated PCBs,which might relate to the long-distance transport of these species from other regions to the rural site.Overall,the low-chlorinated PCBs were more partitioned into gas phase,while the high-chlorinated PCBs were mostly presented in particle phase.(4)The dismantling of the e-waste was the main source of PCBs indoor and outdoor the e-waste dismantling workplace.However,PCBs at the rural site was likely originated from the long-range migration of the atmospheric PCBs beyond the study area.(5)Based on the measured PCBs,the US EPA health risk assessment model was utilized to preliminarily assess the exposure risk.The results show that the cancer risk of PCBs emitted by this e-waste dismantling workplace to the occupational workers was relatively low.To conclude,this study shows that the emission of PCBs from e-waste dismantling workplace built and operated meeting the national environmental protection requirements conforms to the standards for occupational environment air issued by Japan,the former Soviet Union,Sweden,and the Federal Republic of Germany.The detected concentrations of PCBs emitted by these kinds of plants were several magnitudes lower than those emitted from the traditional family workplace(like those in Guiyu city,Guangdong province).As a result,the exposure risk of PCBs to occupational workers is relatively low.This indicates that the large-scale electronic waste dismantling plants in China,which requires standardized dismantling operations and standardized managements in accordance with environmental protection requirements,is effective on protection of both atmospheric environment and the health of the occupational workers. |
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