title: [Nitrogen concentration and nitrogen isotope in epilithic mosses for indicating the spatial variation and sources of atmospheric nitrogen deposition at Guiyang area].
abstract: Tissue N concentration and delta15 N signature in epilithic mosses were investigated along 4 directions from urban area to rural area at Guiyang city. Mosses N concentration ranged from 0.85% to 2.97% and showed significant decrease from urban area (2.24% +/- 0.32%) to suburb (1.27% +/- 0.13%), reflecting the level of atmospheric N deposition decreased away from urban. While slightly higher tissue N re-emerged at rural area beyond 25km (mean = 1.33%-1.75%), suggesting increased N deposition occurred in the rural area. Mosses delta15 N values varied from - 12.50 per thousand to - 1.39 per thousand characterized with getting less negative from urban to rural area. More negative delta15 N signatures of urban mosses (mean= - 8.87 per thousand(-) - 8.59 per thousand) mainly indicated the extensive NH3 sources released from excretory wastes and sewage, while mosses growing at farther suburb or rural area had less depleted delta15 N values (mean = - 3.83 per thousand(-) - 2.48 per thousand), indicating the large sources of agricultural NH3 emission connected with fertilizer application. Moreover, the pattern of mosses delta15 N variation in this study was opposite to areas where N deposition was dominated by oxidized form N (NO(x)) with generally positive mosses delta15 N. Accordingly, we concluded that reduced NH, was the dominant N form in atmospheric deposition at Guiyang area, which would be of great value for understanding the spatial variation and sources of atmospheric N deposition.
authors.affiliation: State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China. liuxueyan@vip.skleg.cn
authors.forename: Xue-Yan
authors.initials: XY
authors.lastname: Liu
authors.forename: Hua-Yun
authors.initials: HY
authors.lastname: Xiao
authors.forename: Cong-Qiang
authors.initials: CQ
authors.lastname: Liu
authors.forename: You-Yi
authors.initials: YY
authors.lastname: Li
authors.forename: Lin
authors.initials: L
authors.lastname: Li
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D000641:Ammonia / Q000737:chemistry; D001272:Atmosphere / Q000032:analysis*; D044002:Bryophyta / Q000737:chemistry*; D002681:China; D005843:Geography; D009584:Nitrogen / Q000032:analysis*; D009587:Nitrogen Isotopes / Q000032:analysis
chemical_list: D000393:Air Pollutants; D009587:Nitrogen Isotopes; D000641:Ammonia; D009584:Nitrogen