Pollution Characteristics And Temporal Trends Of Polybrominated Diphenyl Ethers In Harbin Air

Polybrominated diphenyl ethers(PBDEs),as added brominated flame retardants,are easily dissipated into the environment during production,use,and waste disposal.PBDEs can be transported and spreaded through the atmosphere and other media.Due to their bioaccumulation,persistence and biotoxicity,PBDEs were listed as persistent organic pollutants(POPs)in the Stockholm Convention.China banned the production,use and import and export of commercial pentabromodiphenyl ether and commercial octabromodiphenyl ether in 2014.Since then,the research on PBDEs is frequently conducted.However,the long-term study on PBDEs in the atmospheric environment after the ban of PBDEs is limited,which prevents the assessment of temporal trends and banned effects of PBDEs.In this study,the pollution characteristics of PBDEs in Harbin air was the major research objective after five years sincethe ban of PBDEs.The concentration level,composition characteristics,seasonal variation characteristics were deeply studied.Furthermore,the sources of pollution were identified,and the health risks were evaluated.Temporal trends of PBDEs pollution was studied by comparing with the concentration before the ban.By comparing the simulation results of gas-particle models with the monitoring data,the prediction accuracy and universality of the models are deeply studied.A comparsion with gas-particle distribution characteristics of PBDEs in the atmosphere before and after the ban was conducted in order to study the temporal trends of gas-particle distribution of PBDEs.In this study,based on a long-term collection program,the air in the urban area of Harbin city was collected between January 2018 and May 2019.Totally,50 pairs of gas phase and particle phase samples were obtained.Pretreatment of air samples were performed by the Soxhlet extraction and concentration,silica gel column purification.PBDEs were qualitatively and quantitatively analyzed by gas chromatography-mass spectrometry.The results indicated that the average concentration of ?10PBDEs in the atmosphere of Harbin is 11.59±11.07 pg/m3.The most abundant congener is BDE-209,followed by BDE-28,BDE-153 and BDE-17.The seasonal variation of the concentration and composition of PBDEs in the atmosphere of Harbin are obvious.The concentration of ?10PBDEs was highest in spring,followed by summer and autumn,and lowest in winter.The temperature and Wind speed have a significant effect on the concentration of PBDEs.Compared with the concentration of PBDEs before the ban,except for BDE-153 and BDE-154,the concentration of other homologues has decreased significantly.The results indicated that the ban on commercial polybrominated diphenyl ethers can effectively reduce the pollution level of PBDEs in the atmosphere.The results of pollution sources identification of PBDEs in the atmosphere of Harbin indicated that there are strong correlations between BDE-28,BDE-47 and BDE-66.The principal component analysis method extracted three principal components.They related the pollution of commercial pentabromodiphenyl ether,the pollution of commercial decabromodiphenyl ether and the decomposition product of high brominated diphenyl ether.Commercial decabromobiphenyl ether has the highest contribution rate(77.38±13.03%)to the PBDEs in atmosphere.The exposure dose and risk of ?10PBDEs by the inhalation decreased along with age,and the health risks are within the acceptable range.The concentration of ?10PBDEs in the particle phase in the atmosphere of Harbin is higher than that in the gas phase.Compared with that before the ban,except for BDE-153 and BDE-154,the concentration of other homologues in the gas phase and particulate phase both decreased.Compared with that before the ban,in the temperature range above 0oC,all the particle phase mass fractions of BDE-17,BDE-28,BDE-47 and BDE-100 increased,and the gas/particle partitioning coefficients(Kp)of BDE-17 and BDE-100 had no obvious change.The average values of Kp with BDE-28 and BDE-47 increased.In the temperature range below 0 oC,the average values of particle phase mass fractions with BDE-28 and BDE-209 slightly decreased.The average value of Kp with BDE-28 did not change significantly,and that of BDE-209 obviously decreased.The equilibrium state model,steady-state model and empirical value were used to predict the particle phase mass fraction of PBDEs and the gas/particle partitioning coefficients.The results indicated that the predicted value of the steady-state model is much closer to the actual monitoring result.The result indicated that the steady-state model is much superior to be used for the study of gas/particle distribution of PBDEs in the atmosphere.