Assessing the Chemical and Biological Resilience of Lakes in the Cascade Range to Acidic Deposition

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• 作者：Joseph Eilers ; Kellie Vache ; Benn Eilers ; Roger Sweets…
• 关键词：Lake acidification ; Lake formation ; CE ; QUAL ; W2 ; Atmospheric deposition ; Paleolimnology
• 刊名：Water, Air, and Soil Pollution
• 出版年：2016
• 出版时间：December 2016
• 年：2016
• 卷：227
• 期：12
• 全文大小：1,419 KB
• 刊物类别：Earth and Environmental Science
• 刊物主题：Environment
  Environment
  Atmospheric Protection, Air Quality Control and Air Pollution
  Waste Water Technology, Water Pollution Control, Water Management and Aquatic Pollution
  Terrestrial Pollution
  Hydrogeology
  
• 出版者：Springer Netherlands
• ISSN：1573-2932
• 卷排序：227

文摘

The potential for atmospheric deposition of sulfur and nitrogen to affect lakes in the Northwestern USA to cause lake acidification was assessed by examining four lakes extending from southern Oregon into the central Washington Cascades. The four lakes were dilute (conductivity 2.2 to 3.6 μS/cm), low ANC (−3 to 11 μeq/L) systems, located in subalpine to alpine settings in designated wilderness areas. The four lakes were cored, dated with 210Pb and 14C, and analyzed for sediment nutrients and diatom remains. Diatom-inferred changes in chemistry were made possible through an earlier project to create a diatom calibration set for the Cascades. The three southern lakes exhibited volcanic inputs of ash or tephra, but diatom stratigraphy generally showed only modest responses to these events. None of the lakes exhibited any recent trends in diatom-inferred pH. The most significant finding with respect to paleolimnology was that Foehn Lake, WA, was formed in the twentieth century (1930 ± 7 years), likely as a result of melting of an adjacent snowfield. Current deposition was estimated using the AIRPACT-3 system, and lake chemistry was simulated using the CE-QUAL-W2 hydrodynamic model that had been modified to represent acid-base chemistry. The model simulations showed that the three southern lakes in the transect were insensitive to increases of nitrogen and sulfur until simulated increases reached 300% of current levels. Foehn Lake showed simulated declines of pH and ANC beginning at 50% increases over current deposition of S and N. The three southern lakes are resistant to changes from atmospheric deposition and other disturbances because of long hydraulic residence times, allowing internal processes to neutralize acidic inputs.