Nitrogen inputs and isotopes in precipitation in the North China Plain

Publikations-Art

Zeitschriftenbeitrag (peer-reviewed)

Autoren

Zhang, Y., Liu, X., Fangmeier, A., Goulding, K., Zhang, F.

Erscheinungsjahr

2008

Veröffentlicht in

Atmospheric Environment

Band/Volume

42/

Seite (von - bis)

1436-1448

Nitrogen (N) deposition in the North China Plain (NCP), an intensive agricultural region undergoing rapid economic development in China, has not been well documented until now. In a 4-year study, using a deposition network (11 sites), we analyzed bulk and wet-only deposition, and the isotopic composition (d15N) of ammonium and nitrate in precipitation in the NCP. Annual bulk deposition of inorganic N averaged 27 kgNha_1 (ranging from 15 to 50 kgNha_1) across sites and years, but with very large variation in both space and time. Bulk and wet deposition of inorganic N were significantly higher at sites in the Beijing area compared with that at rural sites in the NCP, implying more air N pollution around Beijing. Although there was a wide seasonal variation of d15N for NH4-N (-12.7% to +12.9%) and NO3-N (-10.0% to +20.7%) in precipitation across the sites in the NCP, a significant difference in the mean isotopic composition of NH4-N and NO3-N was measured in precipitation samples from two suburban sites (Dongbeiwang, DBW; Campus experimental farm, CEF) in Beijing (+0.45+- 4.39% for NH4-N and +4.23 +- 4.34% for NO3-N on average) compared to two rural sites (Quzhou, QZ; Wuqiao, WQ) in Hebei (-2.8 +- 4.06% for NH4-N and -1.19 +- 3.74% for NO3-N on average). Both deposition flux and isotopic composition of inorganic N in precipitation suggest that N deposition is most probably influenced by multiple pollution sources in the urban area around Beijing area, while it is mainly derived from local agricultural sources of reactive N species at rural areas of the NCP.