The Correlation Of Mercury And Bromine In Atmospheric Particulate Matter And Its Enlightenment

As mercury is a global environmental pollutant,atmospheric mercury has become a research hot topic.The total gaseous mercury(TGM)and total particulate mercury(TPM)in ambient air were sampled and measured in the East China University of Science&Technology(ECUST)for one year.Gold amalgamation-thermal decomposition and wet digestion followed by atomic fluorescence spectrometry(AFS)method were adopted to determine TGM,TPM and specaited mercury,respectively.ICP-MS was applied to determine the bromine content in particulate matters.The results showed that the mean concentration of TGM was 5.57±4.81 ng·m-3 during sampling period and it presented apparent seasonal variation:autumn>spring>summer>winter;the average concentration of TPM in particulate matters was 2.58±3.80 ug·g-1,of which average volume concentration was 163±230 pg m-3 with obvious seasonal variation:autumn>winter>spring>summer.The distribution of speciated mercury in particulate matters was hydrochloric soluble particle-phase mercury(HPM)>residual soluble particle-phase mercury(RPM)>element soluble particle-phase mercury(EPM).No significant correlation were found between TGM and TPM and meteorological factors.Particulate matters mass,mercury and carbon in particulate matters had a good correlation between each others.The transformation of mercury f-rom the gas phase to the particle phase might result from not only individually physical adsorption but also chemisorption.The mean concentration of bromine in particulate matters was 30.65±18.93 ng·m-3,which presents the seasonal variation:winter>autumn>spring>summer and meteorological factors(wind speedr the average temperature and relative humidity)had no significant effect on the concentration of bromine in particulate matter,the volume concentration of which was primarily concerned with the PM2.5.Bromine in particulate matters had the same trend with TPM,but the mean of TGM/Br molar ratio was 0.027,which may result from the form of combination of mercury with bromine in particulate matter.In different seasons,bromine content and mercury species in particulate matters showed a good correlation,but we still need further research on the components of mercury species in particulate matters to identify the effects between bromine and the transformation of mercury from thegas phase to the particle phase.The simulation in the laboratory showed that among activated carbon,bamboo charcoal and biomass carbon,either of them once contains bromine could accelerate the transformation of gaseous mercury to mercury particulate matter.The mercury content in the soil samples collected in Western China was far less than that in the atmospheric particulate matters of Shanghai while there were great differences between the distribution of mercury in soil and that of the atmospheric particulate matters of Shanghai.It showed that during either long-range or short-range transport of northern dust,the adsorption of mercury with the aerosol aging contributes more than that in the original particulate matters.