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Xie D, Zhao B, Kang R, Ma X, Larssen T, Jin Z, Duan L. Delayed recovery of surface water chemistry from acidification in subtropical forest region of China. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 912:169126. [PMID: 38070570 DOI: 10.1016/j.scitotenv.2023.169126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Revised: 11/20/2023] [Accepted: 12/03/2023] [Indexed: 01/18/2024]
Abstract
The three largest acid rain regions of current earth are located in northern and western Europe, eastern North America, and East Asia. Sulfur and nitrate concentrations in headwater streams in Europe and North America decreased as atmospheric sulfur and nitrogen deposition decreased, albeit with a considerable delay. However, how water chemistry responds to the declining sulfur and nitrogen deposition in China is unclear. The regional survey of surface water chemistry during 2010 and 2018 within the Sichuan Basin in southwestern China showed that the recovery of the surface water chemistry was delayed for at least 5 years owing to the release of previously deposited sulfur and nitrogen stored in the soil. After sulfur deposition declined from its peak value, the subregions of purplish soil with low sulfate adsorption capacity still exhibited a net sulfur release in 2010, but this release was no longer evident by 2018. The subregions with the red and yellow soils, which have a high sulfate adsorption capacity, operated as sulfur sinks during 2010 and 2018, indicating a continuous immobilization process through sulfate reduction despite a decrease in sulfur deposition. Additionally, this sulfate reduction countered the release of sulfate caused by sulfur desorption. There was a substantial nitrogen sink within the Sichuan Basin. Nitrogen leaching decreased slowly with the declined nitrogen deposition, except in regions where nitrogen deposition exceeded the critical threshold. Compared to temperate forest regions in Europe, the Sichuan Basin and its surrounding areas have experienced higher decline rates in the leaching of sulfur and nitrogen, highlighting that the subtropical forest region undergoes a faster restoration of surface water chemistry.
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Affiliation(s)
- Danni Xie
- School of Land Engineering, Chang'an University, Xi'an 710064, China; SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China
| | - Bin Zhao
- State Key Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China; State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, Beijing 100084, China
| | - Ronghua Kang
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China
| | - Xiaoxiao Ma
- State Grid Xinyuan Company Ltd., Beijing 100052, China
| | - Thorjørn Larssen
- Norwegian Institute for Water Research, Økernveien 94, Oslo 0579, Norway
| | - Zhangdong Jin
- School of Land Engineering, Chang'an University, Xi'an 710064, China; SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China.
| | - Lei Duan
- State Key Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China; State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, Beijing 100084, China.
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Lin J, Compton JE, Sabo RD, Herlihy AT, Hill RA, Weber MH, Brooks JR, Paulsen SG, Stoddard JL. The changing nitrogen landscape of United States streams: Declining deposition and increasing organic nitrogen. PNAS NEXUS 2024; 3:pgad362. [PMID: 38213613 PMCID: PMC10783649 DOI: 10.1093/pnasnexus/pgad362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 10/14/2023] [Accepted: 10/26/2023] [Indexed: 01/13/2024]
Abstract
Air quality regulations have led to decreased nitrogen (N) and sulfur deposition across the conterminous United States (CONUS) during the last several decades, particularly in the eastern parts. But it is unclear if declining deposition has altered stream N at large scales. We compared watershed N inputs with N chemistry from over 2,000 CONUS streams where deposition was the largest N input to the watershed. Weighted change analysis showed that deposition declined across most watersheds, especially in the Eastern CONUS. Nationally, declining N deposition was not associated with significant large-scale declines in stream nitrate concentration. Instead, significant increases in stream dissolved organic carbon (DOC) and total organic N (TON) were widespread across regions. Possible mechanisms behind these increases include declines in acidity and/or ionic strength drivers, changes in carbon availability, and/or climate variables. Our results also reveal a declining trend of DOC/TON ratio over the entire study period, primarily influenced by the trend in the Eastern region, suggesting the rate of increase in stream TON exceeded the rate of increase in DOC concentration during this period. Our results illustrate the complexity of nutrient cycling that links long-term atmospheric deposition to water quality. More research is needed to understand how increased dissolved organic N could affect aquatic ecosystems and downstream riverine nutrient export.
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Affiliation(s)
- Jiajia Lin
- Pacific Ecological Systems Division, Office of Research and Development, US Environmental Protection Agency, Corvallis, OR 97333, USA
- Oak Ridge Institute for Science and Education, Corvallis, OR 97333, USA
- Oregon Department of Environmental Quality, Water Quality Division, Portland, OR 97232, USA
| | - Jana E Compton
- Pacific Ecological Systems Division, Office of Research and Development, US Environmental Protection Agency, Corvallis, OR 97333, USA
| | - Robert D Sabo
- Center for Public Health and Environmental Assessment, Health and Environmental Effects Division, Office of Research and Development, US Environmental Protection Agency, Washington, DC 20004, USA
| | - Alan T Herlihy
- Pacific Ecological Systems Division, Office of Research and Development, US Environmental Protection Agency, Corvallis, OR 97333, USA
- Department of Fisheries, Wildlife, and Conservation Sciences, Oregon State University, Corvallis, OR 97331, USA
| | - Ryan A Hill
- Pacific Ecological Systems Division, Office of Research and Development, US Environmental Protection Agency, Corvallis, OR 97333, USA
| | - Marc H Weber
- Pacific Ecological Systems Division, Office of Research and Development, US Environmental Protection Agency, Corvallis, OR 97333, USA
| | - J Renée Brooks
- Pacific Ecological Systems Division, Office of Research and Development, US Environmental Protection Agency, Corvallis, OR 97333, USA
| | - Steve G Paulsen
- Pacific Ecological Systems Division, Office of Research and Development, US Environmental Protection Agency, Corvallis, OR 97333, USA
| | - John L Stoddard
- Pacific Ecological Systems Division, Office of Research and Development, US Environmental Protection Agency, Corvallis, OR 97333, USA
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