|Abstract Title:||Neglected mercury emission from local biomass combustion in Tibetan Plateau: Isotope evidence and implication|
|Presenter Name:||Deming Han|
|Session:||Atmospheric Hg cycling: Source and Emissions|
Abstract Information :
The mercury (Hg) in high-altitude Tibetan plateau (TP) area was recognized primarily originate from external regions via long range transportation. In this study, field biomass (yak dung and wood) combustion experiments were conducted in central TP area to investigate their emission characteristic. Results show that despite the total mercury content of yak dung (46.58 ñ 30.20 ?g/kg) was over 5 times higher than wood, their combustion product particle bound mercury (PBM) shared similar mean mercury concentrations (83.13-87.72 ng/m3). The PBM occupied relative high mass fractions (17.93-49.31%) of the total emitted mercury, and the mercury emission amount was preliminary estimated to be 1133-1356 kg/a for yak dung combustion. The positive shift of ë202Hg values (0.50-1.31?) of PBM relative to the feeding biomass, suggests the occurrence of equilibrium mass dependent fractionation (MDF). We propose this isotopic fractionation was mainly mediated by catalytic oxidation of Hg0 by chloride on fly ash particles. Binary mixing model of isotopes result indicate yak dung and wood combustion contribute 35.1% and 55.8% of TGM at central and eastern TP areas, respectively. Therefore, this study demonstrates that the biomass combustion contributes to mercury emission and deposition in TP, which may result in damaging influence on local fragile ecosystem under decreasing anthropogenic emission scenario.