Reply on RC2

Abstract

<strong class="journal-contentHeaderColor">Abstract.</strong> Due to the intense release of reactive nitrogen (Nr) from anthropogenic activity, the source layout of atmospheric nitrogen aerosol has changed. The inorganic nitrogen (NH₄⁺ and NO₃^-) was essential part of atmospheric nitrogen aerosol and accounted for 69 %. To comprehensively clarify the level, sources, and environmental fate of NH₄⁺ and NO₃^-, their concentrations and stable isotopes (&delta;¹⁵N) in fine particulate matters (PM_2.5) were measured in a subtropical megacity of South China. N-NH₄⁺ and N-NO₃^- contributed 45.8 % and 23.2 % to total nitrogen (TN), respectively. The source contributions of NH₄⁺ and NO₃^- were estimated by &delta;¹⁵N, which suggested that anthropogenic combustion activities including coal combustion, biomass burning, and vehicles were dominant sources. Especially, biomass burning was the predominant source of NH₄⁺ (27.9 %). Whereas, coal combustion was the dominant source of NO₃^- (40.4 %). This study emphasized the substantial impacts of human activities on inorganic Nr. With the rapid development of industry and transportation, nitrogen emissions will be even higher. The promotion of clean energy and efficient use of biomass would help reduce nitrogen emissions and alleviate air pollution.