Wet deposition of atmospheric inorganic nitrogen at five remote sites in the Tibetan Plateau

• Published in: Atmospheric Chemistry and Physics
• Main Authors: Liu, Y. W., Xu-Ri, Wang, Y. S., Pan, Y. P., Piao, S. L.
• Other Authors: Xu-Ri (reprint author), Chinese Acad Sci, Inst Tibetan Plateau Res, Key Lab Alpine Ecol & Biodivers, Beijing 100101, Peoples R China., Chinese Acad Sci, Inst Tibetan Plateau Res, Key Lab Alpine Ecol & Biodivers, Beijing 100101, Peoples R China., CAS Ctr Excellence Tibetan Plateau Earth Sci, Beijing 100101, Peoples R China., Peking Univ, Coll Urban & Environm Sci, Sino French Inst Earth Syst Sci, Beijing 100871, Peoples R China., Chinese Acad Sci, Inst Atmospher Phys, State Key Lab Atmospher Boundary Layer Phys & Atm, Beijing 100029, Peoples R China.
• Format: Journal/Newspaper
• Language: Chinese
• Published: ATMOSPHERIC CHEMISTRY AND PHYSICS 2015
• Subjects: REGIONAL ENVIRONMENTAL ASSESSMENTS; LONG-TERM TRENDS; EVEREST ICE CORE; CHEMICAL-COMPOSITION; PRECIPITATION CHEMISTRY; REACTIVE NITROGEN; CLIMATE-CHANGE; QOMOLANGMA EVEREST; IONIC COMPOSITION; URBAN SITE; Indian; ice core
• Online Access: https://hdl.handle.net/20.500.11897/439548; https://doi.org/10.5194/acp-15-11683-2015

Since the mid-20th century, nitrogen (N) deposition has shown an increasing trend in the Tibetan Plateau (TP), where alpine ecosystems are sensitive to elevated N deposition. However, the quantitative characterization of N deposition in the TP remains unclear, due in most part to the lack of in situ measurement. Using the Tibetan Observation and Research Platform network, we conducted shortterm in situ measurements of major ions (NO3-, Cl-, SO42-,NH4+,Na+, K+, Ca2+, and Mg2+)wet deposition at five remote sites in the TP during 2011-2013. At Southeast Tibet Station, Nam Co Station, Qomolangma Station, Ngari Station, and Muztagh Ata Station, the NH4+-N wet deposition was 0.63, 0.68, 0.92, 0.36, and 1.25 kgNha(-1) yr(-1), respectively; the NO3--N wet deposition was 0.28, 0.24, 0.03, 0.08, and 0.30 kgNha(-1) yr(-1), respectively; and the inorganic N wet deposition was 0.91, 0.92, 0.94, 0.44, and 1.55 kgNha(-1) yr(-1), respectively. The inorganic N wet deposition mainly occurred in the form of NH4+-N during summer at all sites. Results of enrichment factor analysis and principal component analysis demonstrated that both NH4+-N and NO3--N wet deposition in the TP were mainly influenced by anthropogenic activities. Backward trajectory analysis showed that the inorganic N deposition at Muztagh Ata Station was mainly transported from central Asia and the Middle East through westerlies. At Southeast Tibet Station, Nam Co Station, Qomolangma Station, and Ngari Station, the inorganic N deposition was mainly contributed by anthro- pogenic sources in south Asia, and was mainly transported by the Indian monsoon. Combining site-scale in situ measurements of inorganic N wet deposition in this and previous studies, the average wet deposition of atmospheric NH4+-N, NO3--N, and inorganic N in the TP was estimated to be 1.06, 0.51, and 1.58 kgNha(-1) yr(-1), respectively. The average NH4+-N : NO3--N ratio in precipitation in the TP was approximately 2 : 1. Results from the present study suggest that earlier estimations based on chemical transport model simulations and/or limited field measurements likely overestimated substantially the regional inorganic N wet deposition in the TP. To clarify the total N deposition in the TP more clearly, it is essential to conduct long-term monitoring of both wet and dry deposition of atmospheric N in various climate zones in the TP in the future. Strategic Priority Research Program - Climate Change: Carbon Budget and Related Issues, of the Chinese Academy of Sciences [XDA05050404-3-2, XDA05020402]; National Natural Science Foundation of China [40605032, 40975096, 41175128] SCI(E) ARTICLE [e-mail] 20 11683-11700 15