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APPLICATIONS OF ENVIRONMENTAL ISOTOPES FOR WATERSHED INVESTIGATIONS
Citation:
Sidle, W. APPLICATIONS OF ENVIRONMENTAL ISOTOPES FOR WATERSHED INVESTIGATIONS. Presented at WSWRD Peer Review, Cincinnati, OH, September 27 - 29, 2004.
Impact/Purpose:
To inform the public.
Description:
Environmental isotopes include naturally-occurring nuclides that can be applied as tracers within watersheds (Sidle, 1998). Recent advances in mass spectroscopy may supplant many traditional and costly hydrometric techniques. It is now possible, for example, to utilize isotopes as conservative traces of groundwater flowpaths, for estimating solute exchange from one phase of a system to another, for determining extents of chemical reactions in the subsurface, for identifying source regions in watersheds, for identifying recharge areas of aquifers, and for estimating subsurface residence times.
Over the last 6 years the USEPA Isotope Hydrology Laboratory (IHL) has applied stable and radioactive isotope techniques
to resolving issues in:
- Wet-weather flows in urban watersheds
- Constructive wetland design
- Denitrification efficiency in agricultural riparian zones
- Non-point agricultural pollution
- Sources of Pb in sediments, waters, and air particulates
- Releases of As to drinking water wells
- Acidification of waterways
- Predicting sustainable groundwater to constructed wetlands
- Vulnerability of young recharge in watersheds
The emergent role of water and solute isotopes should prove to be more cost-effective than conventional watershed investigative methods when this technology transfer occurs.