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HERO ID
3444905
Reference Type
Journal Article
Title
Critical loads and exceedances for nitrogen and sulfur atmospheric deposition in Great Smoky Mountains National Park, United States
Author(s)
Fakhraei, H; Driscoll, CT; Renfro, JR; Kulp, MA; Blett, TF; Brewer, PF; Schwartz, JS
Year
2016
Is Peer Reviewed?
0
Journal
Ecosphere
ISSN:
0046-1237
Volume
7
Issue
10
Page Numbers
1-28
DOI
10.1002/ecs2.1466
Web of Science Id
WOS:000387216300009
Abstract
Acid deposition has impacted sensitive streams, reducing the amount of habitat available for fish survival in the Great Smoky Mountains National Park (GRSM) and portions of the surrounding Southern Appalachian Mountains by decreasing pH and acid neutralizing capacity (ANC) and mobilizing aluminum dissolved from soil. Land managers need to understand whether streams can recover from the elevated acid deposition and sustain the healthy aquatic biota, and if so, how long it would take to achieve this condition. We used a dynamic biogeochemical model, PnET-BGC, to evaluate past, current, and potential future changes in soil and water chemistry of watersheds of the GRSM in response to the projected changes in acid deposition. The model was parameterized with soil, vegetation, and stream observations for 30 stream watersheds in the GRSM. Using model results, the level of atmospheric deposition (known as a “critical load”) above which harmful ecosystem effects (defined here as modeled stream ANC below a defined target) occur was determined for the 30 study watersheds. In spite of the recent marked decreases in atmospheric sulfur and nitrate deposition, our results suggest that stream recovery has been limited and delayed due to the high sulfate adsorption capacity of soils in the park resulting in a long lag time for recovery of soil chemistry to occur. Model simulations suggest that over the long term, increases in modeled stream ANC per unit decrease in NH4+ deposition are greater than unit decreases in SO42− or NO3− deposition, due to high SO42− adsorption capacity and the limited N retention of the watersheds. Watershed simulations were used to extrapolate the critical load results to 387 monitored stream sites throughout the park and depict the spatial pattern of atmospheric deposition exceedances. These types of model simulations inform park managers on the amount of air quality improvement needed to meet the stream restoration goals.
Keywords
303(d) listed streams; critical loads; Great Smoky Mountains National Park; forest watershed biogeochemical model; nitrogen and sulfur deposition; Southern Appalachian Mountains; Special Feature: Science for Our National Parks' Second Century; stream acidification; total maximum daily load
Tags
IRIS
•
Nitrate/Nitrite
Broad LitSearch 2016/1/1 - 2017/12/5
Refs found by LitSearch but not ATSDR/IARC
WoS
Refs found only by 2017 LitSearch or Citation Mapping
Ref Types 12/2017
Non-Peer-Reviewed
LitSearch Update 2016-2017
WoS
•
ISA NOxSOxPM Ecology (2018)
Cited in First Draft
Appendix C: Case Studies
Southeast US
Cited in the Second Draft
Chapter 1
Appendix 4
Appendix 7
Appendix 8
Appendix 16
16.3 Southeast
•
ISA NOxSOxPM Ecology (2020- Final Project Page)
Cited
Integrated Synthesis
Appendix 4
Appendix 7
Appendix 8
Appendix 16
16.3 Southeast
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