Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6338202 | Atmospheric Environment | 2015 | 9 Pages |
Abstract
NO3â concentration, nitrogen and oxygen isotopic compositions (δ15N and δ18O) of NO3â were measured in total suspended particulates (TSP) at Yongxing Island in the South China Sea (SCS) between Feb. 2013 and Jan. 2014, as well as on two cruises in the northern South China Sea (NSCS). Measurements aimed to identify NO3â sources, and possible chemical formation processes of NO3â. The δ15N and δ18O of NO3â in TSP at Yongxing Island ranged from â2.5 to +4.9â°, and +48.1 to +99.0â°, with annual weighted averages of +1.5â° and +83.2â°, respectively. Both δ15N and δ18O had higher values in cool months, indicating that NOx sources and oxidants were different between seasons. In cool months, NOx was mainly from anthropogenic sources, particularly from coal combustion in South China, resulting in high nitrogen deposition that was oxidized by O3 to NO3â. In warm months, natural emissions were an important source of NOx. TSP samples in the NSCS had higher NO3â concentrations, higher δ15N and lower δ18O values than samples from Yongxing Island over the same period. This suggests that atmospheric processes caused a decrease in NO3â concentrations and δ15N but increase in δ18O from coast to remote marine. Assuming to oxygen atoms were derived from O3 during transport in cool months, the mean ratio of NO3â formed by NOx to total NO3â was calculated to be 47.9%. This suggests the mean loss ratio of NOx was 89% while the loss ratio of NO3â was 87% during transport between Chinese coastal areas and Yongxing Island in Nov., 2013.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Atmospheric Science
Authors
Hong-Wei Xiao, Lu-Hua Xie, Ai-Min Long, Feng Ye, Yue-Peng Pan, Da-Ning Li, Zhen-Hua Long, Lin Chen, Hua-Yun Xiao, Cong-Qiang Liu,