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

Abstract

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 NH3, NO2, HNO3, particulate ammonium and nitrate (pNH4 + and pNO3 −) concentrations and NH4-N and NO3-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−1at 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.

Divergence in physiological responses between cyanobacterial and lichen crusts to a gradient of simulated nitrogen deposition

“…N deposition rate in dry lands is increasing rapidly (Fenn et al 2003;Li et al 2014), which has caused changes in plant growth, soil respiration, microbial activity, microbial composition, and nutrient transformation Alon and Steinberger 1999;Stursova et al 2006). Shifts in biomass and the physiological performance of biocrusts can also occur in response to increasing N deposition (Belnap et al 2008).…”

Comparative study of the growth and carbon sequestration potential of Bermuda grass in industrial and urban areas

“…The nitrate and ammonia major source of emission is vehicle, exhaust, coal combustion, fertilizer manufacturing, industrial process and burning of biomass (Li et al, 2013;Sutton et al, 2014). So deposition of both compounds were highest in industrial location.…”

“…Although lighter rain cleans the pollutants but heavy rainfall results in greater amount of deposit pollutants (Anderson et al, 2006). Significant increase of wet and dry deposition of nitrate was due to domestic heating, dry weather, low temperature and wind speed which led to more deposition of pollutants as these environmental condition does not allow the pollutants to transform into different compounds and diffuse (Li et al, 2013). Ammonium deposition was lower than nitrate, ammonia in atmosphere reacts with sulfate and nitrate to form ammonium sulfate and ammonium nitrate aerosols which were transported 500 km from the source before they were removed from atmosphere through rain or dry deposition (Berner and Berner, 2012).…”

Simulated seasonal variations in nitrogen wet deposition over East Asia

“…Nitrogen wet deposition (NH + 4 + NO − 3 ) in the summer and spring accounted for 71% of the annual total (3.9 Tg N yr −1 , and animal husbandry to nitrogen deposition (Li et al 2013). The values of NH + 4 ∕NO − 3 are usually much smaller than 1 in the U.S. and in European countries, and usually over 1 in China, indicating a relatively larger effect of agriculture activities.…”