Significant Contribution of Emissions from Asian Religious and Cultural Activities to Atmospheric Brown Clouds

摘要

"Brown Clouds" are caused by a mixture primary and secondary particulate matter (PM) generated from engine exhaust, biomass burning, and industrial processes. Atmospheric elemental carbon (EC) and organic carbon (OC) are the major primary PM constituents emitted by inefficient combustion of fossil fuels and biomass. EC and OC occur together in PM as soot, and their combination is important for climate change because EC absorbs solar radiation, potentially contributing to global warming. However, EC/OC soot also scatters solar radiation back into space, which may counteract the warming effect. Water-soluble OC may take up liquid water, thereby modifying its optical properties and affecting the formation and surface tension of cloud droplets. In India, large amounts of EC and OC are emitted from agricultural crop residue burning, fossil fuel combustion in residential and industrial sectors transportation, forest fires and other activities. EC and OC emission factors from religious and ritual burning activities have not been adequately characterized, nor have the amounts of material burned each year been estimated. This study measures these emissions factors, quantifies the activity levels, and estimates contributions to brown cloud formation for several types of Indian religious rituals.