Atmospheric reactive nitrogen concentrations at ten sites with contrasting land use in an arid region of central Asia

Abstract. Atmospheric concentrations of reactive nitrogen (N_r) species from 2009 to 2011 are reported for ten sites in Xinjiang, China, an arid region of central Asia. Concentrations of NH₃, NO₂, particulate ammonium and nitrate (pNH₄⁺ and pNO₃⁻) showed large spatial and seasonal variation and averaged 7.71, 9.68, 1.81 and 1.13 μg N m⁻³, and PM₁₀ concentrations averaged 249.2 μg m⁻³ across all sites. Lower NH₃ concentrations and higher NO₂, pNH₄⁺ and pNO₃⁻ concentrations were found in winter, reflecting serious air pollution due to domestic heating in winter and other anthropogenic sources such as increased emissions from motor traffic and industry. The increasing order of total concentrations of N_r species was alpine grassland; desert, desert-oasis ecotone; desert in an oasis; farmland; suburban and urban ecosystems. Lower ratios of secondary particles (NH₄⁺ and NO₃⁻) were found in the desert and desert-oasis ecotone, while urban and suburban areas had higher ratios, which implied that anthropogenic activities have greatly influenced local air quality and must be controlled.