Stable carbon and nitrogen isotopic composition of fine mode aerosols (PM2.5) over the Bay of Bengal: impact of continental sources. Issue 1 (1st December 2016)

• Record Type: Journal Article
• Authors: Bikkina, Srinivas; Kawamura, Kimitaka; Sarin, Manmohan
• Is Part Of: Tellus. Volume 68:Issue 1(2016)
• Publication Date: 2016-12-01
• Subjects: stable C- and N-isotopes -- Bay of Bengal -- aerosols -- biomass burning -- fossil-fuel combustion -- South Asia -- South-east Asia -- Indo-Gangetic Plain; Atmospheric chemistry -- Periodicals; Atmospheric physics -- Periodicals; Meteorology -- Periodicals; Air -- Pollution -- Meteorological aspects -- Periodicals; Chimie de l'atmosphère -- Périodiques; Météorologie physique -- Périodiques; Météorologie -- Périodiques; Air -- Pollution -- Meteorological aspects; Atmospheric chemistry; Atmospheric physics; Meteorology; Meteorologie; Chimie de l'atmosphère; Météorologie physique; Météorologie; Meteorology; Electronic journals; Computer network resources; Periodicals; Ressource Internet (Descripteur de forme); Périodique électronique (Descripteur de forme); 551.505
• DOI: 10.3402/tellusb.v68.31518
• Languages: English
• ISSNs: 0280-6509

Abstract

Abstract : This study reports on stable carbon (δ 13 CTC ) and nitrogen (δ 15 NTN ) isotopic composition of total carbon and nitrogen (TC and TN) in the fine mode aerosols (PM2.5 ; N =31) collected over the Bay of Bengal (BoB). The samples represent two distinct wind regimes during the cruise (27 December 2008–28 January 2009); one from the Indo-Gangetic Plain (referred as IGP-outflow) and another from Southeast Asia (SEA-outflow). The PM2.5 samples from the IGP-outflow show higher δ 13 CTC (−25.0 to −22.8 ‰; −23.8±0.6 ‰) than those from the SEA-outflow (−27.4 to −24.7 ‰; −25.3±0.9 ‰). Similarly, δ 15 NTN varied from +11.8 to +30.6 ‰ (+20.4±5.4 ‰) and +10.4 to +31.7 ‰ (+19.4±6.1 ‰) for IGP- and SEA-outflows, respectively. Based on the literature data, MODIS-derived fire hotspots and back trajectories, we infer that higher δ 13 CTC in the IGP-outflow is predominantly associated with fossil fuel and biofuel combustion. In contrast, contribution of primary organic aerosols from the combustion of C3 plants or secondary organic aerosol (SOA) formation from biomass/biofuel-burning emissions (BBEs) can explain the lower δ 13 CTC values in the SEA-outflow. This inference is based on the significant linear correlations among δ 13 CTC, water-soluble organic carbon and non-sea-salt potassium (nss-K +, a proxy for BBEs) in the SEA-outflow. A significant linear relationship of δ 15 N with and equivalent mass ratio of / is evident in both the continental outflows. Since abundance dominates the TN over the BoB (>90 %), atmospheric processes affecting its concentration in fine mode aerosols can explain the observed large variability of δ 15 NTN .