A Comprehensive Evaluation of H2SO4 formation from OH and sCI pathways in high BVOC environments
Monday, 15 December 2014: 3:10 PM
The recently highlighted importance of stabilized Criegee intermediates (sCI) as an oxidant for atmospheric SO2 triggered a number of studies to assess the atmospheric implications of H2SO4 formation from the sCI reaction pathway. In addition, it has not been clear why new particle formation events are not observed in the Amazon rain forest. The mostly widely speculated reason has been a very low H2SO4 level. We will present quantitative assessments of SO2 oxidation by sCI leading to the H2SO4 production using a comprehensive observational dataset from a tropical rainforest study during the GOAmazon field campaign at the T3 site in Manacapuru, Amazonas, Brazil. To our best knowledge, this is the first observation of H2SO4 and OH in Amazon and is unique for all tropical sites due to the accompanying comprehensive gas and aerosol observations such as CO, NOX, SO2, VOCs, and physical and chemical characteristics of aerosols. We will discuss observed H2SO4 levels during the GOAmazon field campaigns to demonstrate 1) H2SO4 formation potential from OH and sCI oxidation pathways by contrasting extremely clean and relatively polluted air masses and 2) the Implications of the observed H2SO4 levels in new particle formation and particle growth events.