Deciphering atmospheric sulfate formation pathways using triple-oxygen and quadruple-sulfur isotope compositions:knowns,unknowns,and mysteries
Fine particulate matter that has a diameter less than 2.5 micrometers(PM2.5) has becoming a persistent airpollution problem in many developing nations.The problem is particularly severe in the North China Plains(NCP) inwinter seasons where coal is burnt by a higher quantity and air is more stagnant than in other seasons.A majorcomponent of the PM2.5 is sulfate,among which most are of secondary origin,i.e.,formed via SO2 oxidation in theatmosphere.There are three major reaction phases,1) gas phase;2) aqueous phase,and 3) heterogeneous phase(catalyzed by surfaces or interfaces).In each of the phases,there are competing oxidants and catalysts in play.Most ofthe reaction steps and kinetic parameters have been obtained over the years and have been incorporated into climate orair quality models such as Community Multi-scale Air Quality(CMAQ) and GEOS-Chem modeling systems.With flux,concentration,meteorological data,these models can predict the relative contribution of each of the reaction phases andpathways via different oxidants in the atmosphere.These models are tested by comparing predicted and observed fluxes,concentrations,and their changes over certain meteorological conditions.When the two did not match,adjustment ofmodel parameters or major revision to chemistry pathways were attempted.For example,during severe NCP haze events,all existing air quality models failed to reproduce the observed extremely high sulfate contents.Heterogeneouschemistry or enhanced NO2 pathway has recently been suggested to compensate for the deficits.However,theseattempts are probably one of the many possible solutions to the discrepancies.Independent tests of the atmosphericsulfate chemistry models are imperative.
Huiming Bao
Peking University;Louisiana State University
国际会议
The 11th International Symposium on Geochemistry of the Earths Surface(GES-11)(第十一届地球表层地球化学国际研讨会)
贵阳
英文
1-1
2017-06-11（万方平台首次上网日期，不代表论文的发表时间）