Size-separated aerosol chemical characterization over Ny-Ålesund during the Arctic summer of 2010

Abstract

Chemical composition of aerosols is of great concern in the Arctic because of its great influence on climate. In this communication, we report the physico-chemical properties of size-separated aerosol data archived at Gruvebadet lab in Ny-Ålesund (78.55°S, 11.55°E) as a part of the Indian Arctic Mission over the station "Himadri" in 2010. The results reveal that the mass-size distribution (MSD) of aerosol composition exhibits tri-modal distribution with coarse-mode (62%), fine-mode (32%) and weak nucleation-mode (6%) indicating dominance of natural sources over the study region. MSD of chemical components showed a significant contribution to coarse-mode particles for Ca²⁺, Mg²⁺, Na⁺ and Cl⁻; fine-mode particles for SO₄²⁻, NO₃⁻, NH₄⁺ and K⁺. The marine sources contributed maximum for SO₄²⁻ (89%) and Mg²⁺ (44%) in the coarse fraction, and in the fine fraction, 31% to SO₄²⁻ and 86% to Mg²⁺. Non-marine sources were major contributors (80 to 95%) in both mode fractions for Ca²⁺and K⁺. The estimated aerosol radiative forcing in the atmosphere of ∼3.21 W/m² could be attributed to the loading of black carbon aerosols (62%) over the site. The backward trajectories show air masses from Canada and Greenland travelling from 6000 m elevation, bringing the pollutants to Ny-Ålesund and lower altitudes; the oceanic region within Arctic circle contributes more.