G01_P07

Abundance of Non-Fossil Carbon Content in the Tropical Indian Carbonaceous Aerosols

Pavuluri C^1,2, Uchida M³, Mantoku K³, Fu P^1,2, Kawamura K^1,4

¹Institute of Low Temperature Science, Hokkaido University, Sapporo, Japan, ²Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin, China, ³AMS Facility (NIES-TERRA), National Institute for Environmental Studies, Tsukuba, Japan, ⁴Chubu Institute for Advanced Studies, Chubu University, Kasugai, Japan

Carbonaceous aerosols that represent a large fraction of fine aerosol mass have serious impacts on the Earth’s climate system directly by scattering and absorbing solar radiation and indirectly by acting as cloud condensation nuclei. They also cause adverse effects on human health and play an important role in atmospheric chemistry. Although carbonaceous components have been studied well, their origins and atmospheric processing are not yet fully understood in the tropical Indian aerosols. To apportion the fossil and contemporary carbon content in the tropical carbonaceous aerosols from the Indian region, we collected atmospheric aerosols (PM₁₀) on day- (approximately 6:00–18:00 LT) and nighttime (18:00–6:00 LT) bases in winter (January 23 to February 6, n = 29) and summer (May 22–31, n = 20) 2007 from a mega‐city, Chennai (13.04°N; 80.17°E) located on the southeast coast of India. We measured the carbonaceous components, molecular composition and distributions of various organic classes of compounds and their stable carbon isotopic composition (δ¹³C), and radiocarbon (Δ¹⁴C), a unique tracer for distinct fossil and non-fossil carbon, isotope ratios of total carbon (TC) in the PM₁₀. Here we report the characteristics of Δ¹⁴C as percent of modern carbon (pMC) in TC, together with the comparison with the carbonaceous components and molecular marker species in PM₁₀. Based on the results obtained, we discuss the importance of contemporary sources and aging of the tropical carbonaceous aerosols, including their diurnal and seasonal changes, in the Indian region.