Abstract
The measurement of atmospheric NH3 was conducted by mean of passive samplers from September 2009 to December 2010 at Lin’an regional background station located in the economically blooming Yangtze River Delta (YRD) region in eastern China. NH4 + in fine particles was also measured in 2010 at this site. The NH3 concentration ranged from 0.1 to 41.8 ppb, with the annual average of 16.5 ± 11.2 ppb in 2010. The daily NH4 + concentrations ranged from 0.02 to 19.2 μg/m 3 , with an annual average of 4.3 ± 3.5 μg/m 3 . NH3 concentrations were highest in summer and lowest in winter, showing positive correlations with agricultural activities and temperature. The highest concentrations of NH4 + were in autumn coinciding with the period of active open burning of agricultural residues. The mean mass ratio of NH3/NHx is estimated to be 0.8 ± 0.1 during 2010, indicating that NHx was mainly influenced by local sources around Lin’an. The air mass back trajectory analysis suggests that both local sources and long-distance transport played important roles in the observed ammonium aerosol at Lin'an. High NHx deposition in this regional background station suggests the urgency of reducing NH3 emission in the YRD region.
Highlights
Gaseous ammonia (NH3) is the third most abundant nitrogen containing compounds and is the primary alkaline trace gas in the atmosphere
We present for the first time NH3 continuous measurement from September 2009 to December 2010 at Lin’an regional background station in Yangtze River Delta (YRD), characterizing the seasonal variation of ammonia and ammonium
The average concentration of NH3 with one standard deviation (SD) was 16.5 ± 11.2 ppb, which was higher than that (10.2 ppb) observed from June 2008 to December 2009 at Shangdianzi (40°39′N, 117°07′E, 293.3 m a.s.l.) regional background station in Northern China reported by Meng et al (2011) (Table 2)
Summary
Gaseous ammonia (NH3) is the third most abundant nitrogen containing compounds and is the primary alkaline trace gas in the atmosphere. The relatively high concentrations of NH3 observed at Lin’an in this study resulted from ongoing agricultural activity, including fertilizer use, vegetation and livestock as well as industrial processes in the region surrounding this site.
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