title: Atmospheric transport of urban-derived NH(x): Evidence from nitrogen concentration and delta(15)N in epilithic mosses at Guiyang, SW China.
abstract: Nitrogen concentration and delta15N in 175 epilithic moss samples were investigated along four directions from urban to rural sites in Guiyang, SW China. The spatial variations of moss N concentration and delta15N revealed that atmospheric N deposition is dominated by NHx-N from two major sources (urban sewage NH3 and agricultural NH3), the deposition of urban-derived NHx followed a point source pattern characterized by an exponential decline with distance from the urban center, while the agricultural-derived NHx was shown to be a non-point source. The relationship between moss N concentration and distance (y=1.5e(-0.13x)+1.26) indicated that the maximum transporting distance of urban-derived NHx averaged 41 km from the urban center, and it could be determined from the relationship between moss delta(15)N and distance [y=2.54ln(x)-12.227] that urban-derived NHx was proportionally lower than agricultural-derived NHx in N deposition at sites beyond 17.2 km from the urban center. Consequently, the variation of urban-derived NHx with distance from the urban center could be modeled as y=56.272e(-0.116x)-0.481 in the Guiyang area.
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: Hong-Wei
authors.initials: HW
authors.lastname: Xiao
mesh_terms: D000392:Air Movements; D000397:Air Pollution / Q000032:analysis*; D000641:Ammonia / Q000032:analysis*; D044002:Bryophyta / Q000737:chemistry*; D002681:China; D002947:Cities; D004784:Environmental Monitoring / Q000379:methods; D009584:Nitrogen / Q000032:analysis*; D009587:Nitrogen Isotopes / Q000032:analysis
chemical_list: D009587:Nitrogen Isotopes; D000641:Ammonia; D009584:Nitrogen