气候变化领域集成服务门户(CCPortal): Observed changes in chronic and episodic acidification in Virginia mountain streams in response to the Clean Air Act and amendments

CCPortal

DOI	10.1016/j.atmosenv.2021.118279
	Observed changes in chronic and episodic acidification in Virginia mountain streams in response to the Clean Air Act and amendments
	Scanlon T.M.; Riscassi A.L.; Galloway J.N.
发表日期	2021
ISSN	1352-2310
卷号	252
英文摘要	Reductions in acidic deposition following the 1990 Amendments to the Clean Air Act have led to improvements in the acid/base status of many freshwater bodies in the eastern United States, but such recovery has not been as widespread in Virginia mountain streams. In the current analysis, water chemistry trends are determined for 63 streams within Shenandoah National Park, Virginia, and surrounding national forests, where water samples have been collected on a quarterly basis from 1987 to 2019. Over this timeframe, a majority of the most acid-sensitive streams – those with watersheds underlain by siliciclastic bedrock – have experienced reductions in acid neutralizing capacity (ANC). This outcome, which differs from the modest recovery predicted by earlier modeling studies, is likely due to further depletion of soil base cations and perhaps increases in organic acids. Meanwhile, stream water pH has increased for all watershed bedrock types, averaging between 0.05 and 0.10 pH units per decade. High-flow sampling was conducted at three sites from 1992 to 2019, revealing an assessment of episodic acidification that is more encouraging than that of chronic acidification. For two of these sites, pH during high-flow conditions increased much more rapidly than pH during low-flow conditions. Steep reductions in sulfur deposition over the three decades since the 1990 Amendments have led to a “flushing” of sulfate from shallow soils, which has contributed to the improved acid/base status during episodes of high flow. The findings suggest that continued low acidic deposition rates will lead to further improvements in stream water quality, with the timescales of recovery dependent upon bedrock geology of the watersheds. © 2021 Elsevier Ltd
关键词	Acid neutralizing capacity Clean air act pH Stream chemistry Trends
语种	英语
scopus关键词	Acidification; Chemical analysis; Deposition rates; Recovery; Rivers; Sulfur compounds; Water quality; Watersheds; % reductions; Acid neutralizing capacity; Acid-base status; Acidic deposition; Clean air act; Episodic acidification; Mountains streams; Stream chemistry; Trend; Virginia; pH; base; carboxylic acid; sulfate; sulfur; water; acidification; bedrock; soil remediation; stream; sulfate; sulfur; water chemistry; water quality; watershed; acidification; act; air quality control; Article; forest; geographic elevation; national park; priority journal; soil acidity; stream (river); Virginia; water sampling; watershed; Shenandoah National Park; United States; Virginia; Virginia
来源期刊	ATMOSPHERIC ENVIRONMENT
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/248520
作者单位	Department of Environmental Sciences, University of Virginia, 291 McCormick Road, Charlottesville, VA 22904, United States
推荐引用方式 GB/T 7714	Scanlon T.M.,Riscassi A.L.,Galloway J.N.. Observed changes in chronic and episodic acidification in Virginia mountain streams in response to the Clean Air Act and amendments[J],2021,252.
APA	Scanlon T.M.,Riscassi A.L.,&Galloway J.N..(2021).Observed changes in chronic and episodic acidification in Virginia mountain streams in response to the Clean Air Act and amendments.ATMOSPHERIC ENVIRONMENT,252.
MLA	Scanlon T.M.,et al."Observed changes in chronic and episodic acidification in Virginia mountain streams in response to the Clean Air Act and amendments".ATMOSPHERIC ENVIRONMENT 252(2021).