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Tracing nitrates and sulphates in river basins using isotope techniques
1Department of Geology and Geophysics, University of Calgary, 2500 University Drive NW, Calgary, Alberta, T2N-1N4, Canada. Irock@ucalgary.ca
Summary
Stable isotope techniques reveal pyrite oxidation as a key source of riverine sulfate and manure as a significant contributor to nitrate pollution in the Oldman River Basin. Hydrology influences nutrient levels and isotopic signatures.
Area of Science:
- Environmental Science
- Geochemistry
- Hydrology
Background:
- Riverine nitrate and sulfate pose environmental challenges in watershed studies.
- Understanding pollutant sources is crucial for effective river basin management.
Purpose of the Study:
- To demonstrate the utility of stable isotope techniques in identifying sources and fates of riverine nitrate and sulfate.
- To analyze the Oldman River Basin (OMRB) in southern Alberta, Canada as a case study.
Main Methods:
- Utilized stable isotope analysis (delta(34)S) for sulfate.
- Employed chemical and isotopic analyses for nitrogen.
- Integrated hydrometric data to assess solute fluxes.
Main Results:
- Increasing sulfate and decreasing delta(34)S values indicate pyrite oxidation in tills as a major sulfate source.
- Manure-derived nitrogen significantly contributes to elevated nitrate levels in agricultural areas.
- Hydrological conditions drive seasonal variations in nitrate concentration and isotopic composition.
Conclusions:
- Stable isotope techniques effectively elucidate nutrient and pollutant sources in river systems.
- The findings support the use of isotopic measurements for informed river basin management.
- Pyrite oxidation and agricultural return flows are key drivers of water quality in the OMRB.