Atmospheric Nitrogen Deposition at Two Sites in an Arid Environment of Central Asia

Arid areas play a significant role in the global nitrogen cycle. Dry and wet deposition of inorganic nitrogen (N) species were monitored at one urban (SDS) and one suburban (TFS) site at Urumqi in a semi-arid region of central Asia. Atmospheric concentrations of NH(3), NO(2), HNO(3), particulate ammonium and nitrate (pNH(4) (+) and pNO(3) (−)) concentrations and NH(4)-N and NO(3)-N concentrations in precipitation showed large monthly variations and averaged 7.1, 26.6, 2.4, 6.6, 2.7 µg N m(−3) and 1.3, 1.0 mg N L(−1) at both SDS and TFS. Nitrogen dry deposition fluxes were 40.7 and 36.0 kg N ha(−1) yr(−1) while wet deposition of N fluxes were 6.0 and 8.8 kg N ha(−1) yr(−1) at SDS and TFS, respectively. Total N deposition averaged 45.8 kg N ha(−1) yr(−1)at both sites. Our results indicate that N dry deposition has been a major part of total N deposition (83.8% on average) in an arid region of central Asia. Such high N deposition implies heavy environmental pollution and an important nutrient resource in arid regions.