title: Atmospheric S and N deposition relates to increasing riverine transport of S and N in southwest China: Implications for soil acidification.
abstract: Following Europe and North America, East Asia has become a global hotspot for acid deposition, with very high deposition of both sulfur (S) and nitrogen (N) occurring in large areas of southwest and southeast China. This study shows that the outflow flux of sulfate (SO42-) in three major tributaries of the Upper Yangtze River in the Sichuan Basin in southwest China has been increasing over the last three decades, which implies the regional soil acidification caused by increasing sulfur dioxide (SO2) emissions. Since 2005, the outflow of SO42-to the Upper Yangtze River from the Sichuan Basin has even reached the atmospheric SO2emission from the basin. In contrast to S emissions, the rapid increase in nitrogen (N) emissions, including nitrogen oxides (NOx) and ammonia (NH3), have resulted in only a slight increase in nitrate (NO3-) concentrations in surface waters, indicating a large retention of N in the basin. Although N deposition currently contributes much less than S to soil acidification in this area, it is possible that catchments receiving a high input of N may be unable to retain a large fraction of the N deposition over long periods.
authors: State Key Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China; Collaborative Innovation Centre for Regional Environmental Quality, Tsinghua University, Beijing 100084, China. Electronic address: lduan@tsinghua.edu.cn.
authors: Lei
authors: L
authors: Duan
authors: Air Environmental Modeling and Pollution Controlling Key Laboratory of Sichuan Education Institutes, College of Resources and Environment, Chengdu University of Information Technology, Chengdu 610225, China.
authors: Xiao
authors: X
authors: Chen
authors: State Grid Xingyuan Company Limited, Beijing 100761, China.
authors: Xiaoxiao
authors: X
authors: Ma
authors: State Key Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
authors: Bin
authors: B
authors: Zhao
authors: Norwegian Institute for Water Research, Gaustadalleen 21, Oslo 0349, Norway.
authors: Thorjørn
authors: T
authors: Larssen
authors: State Key Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China; Collaborative Innovation Centre for Regional Environmental Quality, Tsinghua University, Beijing 100084, China.
authors: Shuxiao
authors: S
authors: Wang
authors: Air Environmental Modeling and Pollution Controlling Key Laboratory of Sichuan Education Institutes, College of Resources and Environment, Chengdu University of Information Technology, Chengdu 610225, China.
authors: Zhixiang
authors: Z
authors: Ye
mesh_terms: D000641:Ammonia; D002681:China; D004784:Environmental Monitoring / Q000379:methods; D005060:Europe; D009566:Nitrates / Q000032:analysis; D009584:Nitrogen / Q000032:analysis*; D009656:North America; D045483:Rivers; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000737:chemistry*; D013455:Sulfur / Q000032:analysis*; D013458:Sulfur Dioxide / Q000032:analysis; D014873:Water Pollutants / Q000737:chemistry*
chemical_list: D009566:Nitrates; D012987:Soil; D012989:Soil Pollutants; D014873:Water Pollutants; D013458:Sulfur Dioxide; D013455:Sulfur; D000641:Ammonia; D009584:Nitrogen
keywords: Acidification; N saturation; Nitrogen budget; Sulfate adsorption; Sulfur budget