[Wet deposition of atmospheric nitrogen in Jiulong River Watershed].
Spatio-temporal distributions and sources of atmospheric nitrogen (N) in precipitation were examined for Jiulong River Watershed (JRW), an agricultural-dominated watershed located in southeastern China with a drainage area of 1.47 x 10(4) km2. During 2004-2005, 847 rain samples were collected in seventeen sites and analyzed for ammonium N, nitrate N and dissolved total N (DTN) followed by filtration through 0.45 microm nucleopore membranes. Atmospheric N deposition flux was calculated using GIS interpolation technique (Universal Kriging method for precipitation, Inverse distance weighted technique for N) based on measured N value and precipitation data from eight weather stations located in the JRW. ArcView GIS 3.2 was used for surface analysis, interpolation and statistical work. It was found that mean DTN concentration in all sites ranged between 2.20 +/- 1.69 and 3.26 +/- 1.37 mg x L(-1). Ammonium, nitrate and dissolved organic N formed 39%, 25% and 36% of DTN, respectively. N concentration decreased with precipitation intensity as a result of dilution, and showed a significant difference between dry season and wet season. The low isotope value of nitrate delta 15N ranging between -7.48 per thousand and -0.27 per thousand (mean: -3.61 per thousand) indicated that the increasing agricultural and soil emissions together with fossil combustions contributed to atmospheric nitrate sources. The annual wet deposition of atmospheric N flux amounted to 9.9 kg x hm(-2), which accounts for 66% of total atmospheric N deposition flux (14.9 kg x hm(-2)). About 91% of wet atmospheric deposition occurred in spring and summer. The spatio-temporal variation of atmospheric N deposition indicated that intensive precipitation, higher ammonia volatilization from fertilizer application in the growing season, and livestock productions together provided the larger N source.
Chen
Neng-Wang
NW
State Key Laboratory of Marine Environmental Science, Environmental Science Research Center, Xiamen University, Xiamen 361005, China. nwchen@zju.edu.cn
Hong
Hua-Sheng
HS
Zhang
Luo-Ping
LP
D000393:Air Pollutants / Q000032:analysis*; D002681:China; D004784:Environmental Monitoring / Q000379:methods; D005618:Fresh Water / Q000032:analysis* / Q000737:chemistry; D005843:Geography; D009584:Nitrogen / Q000032:analysis*; D011891:Rain; D045483:Rivers / Q000737:chemistry*
D000393:Air Pollutants; D009584:Nitrogen