The effects of acid precipitation-long term ecological measurements in loch vale watershed, Rocky Mountain National Park
✍ Scribed by Jill Baron; A. Scott Denning; Keith Schoepflin
- Publisher
- Springer
- Year
- 1989
- Tongue
- English
- Weight
- 50 KB
- Volume
- 12
- Category
- Article
- ISSN
- 0167-6369
No coin nor oath required. For personal study only.
✦ Synopsis
The high elevation Front Range ecosystems of Rocky Mountain National Park are extremely vulnerable to acidification from atmospheric deposition. Throughout the Rocky Mountain West increasing urbanization, development and combustion of fossil fuels, and mining and smelting of ores may combine to provide additional sources of acidification over the next twenty years. Although annual volume-weighted pH averages 5.0 from 1980 through 1985, summertime precipitation is acidic, averaging 4.7 for this same period. Nitrate is the anion most strongly correlated with acidity in dilute precipitation. A reconstruction of past lake history using diatoms as indicators of lake pH change and metals as indicators of changes in metal deposition showed no long-term trend that could be attributed to increasing emissions of industrially produced acid precursors. This leads us to conclude the summertime acidity either has no biological consequence or has occurred for few enough years that the method of detection, diatom community pH preference, is too coarse to discern recent community shifts. An instrumented watershed, Loch Vale, provided the study site where long-term hydrologic and biogeochemical budgets were determined. Four years of data collection strongly suggest snowmelt is a major influence on both the annual hydrologic cycle and elemental flux through the watershed. Between 60 and 70% of annual water input enters as snow, melting over a period of two months. Concurrently, 60-90% of the annual flux of SO4 and a comparable amount of the annual flux of NO3 occurs during the snowmelt period. Other important processes to surface water composition include freezing of lake surfaces during winter, weathering of base cations from primary and secondary minerals (cations increase 24 times in outflow over inputs), seasonal nutrient consumption and decomposition of phytoplankton, and terrestrial biological uptake and immobilization of N and S.