Premium
Surface water acidification responses and critical loads of sulfur and nitrogen deposition in Loch Vale watershed, Colorado
Author(s) -
Sullivan T. J.,
Cosby B. J.,
Tonnessen K. A.,
Clow D. W.
Publication year - 2005
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2004wr003414
Subject(s) - deposition (geology) , acid neutralizing capacity , hydrology (agriculture) , surface water , watershed , tributary , environmental science , throughfall , nitrogen , groundwater , acid rain , environmental chemistry , acid deposition , geology , soil water , chemistry , soil science , environmental engineering , geography , geomorphology , sediment , geotechnical engineering , cartography , organic chemistry , machine learning , computer science
We evaluated the sensitivity of The Loch, a subalpine lake in Rocky Mountain National Park in Colorado, to acidification in response to increased atmospheric loading of sulfur (S) and nitrogen (N) using the Model of Acidification of Groundwater in Catchments (MAGIC). Lake water acid‐base chemistry was moderately sensitive to changes in both S and N deposition. However, the loads of S deposition that would drive chronic lake water acid neutralizing capacity (ANC) to below 0 or 20 μeq L −1 were estimated to be 11 and 8 kg S ha −1 yr −1 , respectively, assuming constant future N deposition at current levels. Comparable loads for N deposition, assuming constant future S deposition, were estimated to be 21 and 12 kg N ha −1 yr −1 , respectively. Modeling results for Andrews Creek, an alpine tributary to The Loch, suggested critical loads for surface water acidification that averaged about one third lower. Surface water ANC = 50 μeq L −1 was projected to occur in 50 years in The Loch if S or N deposition increased by a moderate amount (<40%) but could not be achieved in Andrews Creek by reducing either S or N deposition to zero. On the basis of the results of synoptic surveys of lake water chemistry, about one fifth of the wilderness lakes in the Colorado Front Range are more acid‐sensitive than The Loch. This modeling exercise suggests the need for a regional analysis of critical loads for the larger population of acid‐sensitive aquatic resources in order to provide part of the scientific foundation for federally mandated land management decisions.