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Department of Forest Resources – University of Idaho, Moscow USA. Isotope mass balance – Mica Creek. Paul Koeniger, Tim Link, John Marshall. 03/28/2006 – Mica Creek Group Meeting. What we plan to do …. . . . . . .
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Department of Forest Resources – University of Idaho, Moscow USA Isotope mass balance – Mica Creek Paul Koeniger, Tim Link, John Marshall 03/28/2006 – Mica Creek Group Meeting
What we plan to do … Combination of watershed hydrology and isotope techniques for an isotopic mass balance in forested watersheds - Snow sampling / spring snowmelt - Base flow sampling - Water vapour - evaporation vs. transpiration (- Isotopes as applied tracers: soil water-xylem-transpiration) Isotope hydrological mass balance (Mica creek): P*CP = (E*CE + T*CSW) + R*CR + GWr*CSW {+/-DSW*CSW} C: Isotope concentration P: precipitation R: runoff E: evaporation T: transpiration GWr: groundwater (recharge) SW: soil water
Isotopes inprecipitation: available data IAEA (2001). GNIP Maps and Animations, Accessible at http://isohis.iaea.org Bowen (2003). Accessible at http://www.waterisotopes.org
Isotopes in precipitation • Three to 5 sampling points • in monthly resolution (altitude effect) • - Reference station in Moscow (weekly) • Snow sampling campaign in winter • Event sampling
Isotopes in snow • Altitude effect in snow • Spatial variability • Snow profiles • Spring snowmelt event
Clearwater River / Spalding Stream flow Isotopes in stream flow:available data? (Coplen and Kendall 2000: U.S. Geological Survey Open-File Report 00-160)
Stream flow • Continuous (monthly) sampling at 3 to 5 locations • (control site, partial-, clear cut) • Event sampling – residence time distributions • Base flow • “ Isotope hydrological and hydro chemical characterization of base flow at Mica creek” – best in Sept. / Oct. 2006 • - Salt dilution discharge measurements • - 18O, 2H (and 3H/3He or 3H) • - Conductivity, pH, chloride, water chemistry
Evaporation – transpiration – water vapor isotopes • Soil water • Continuously - should represent transpiration • Transpiration • Xylem • Water labeling of sap flow: • with 18O possibilities for in situ equilibration techniques ?? • with 2H – sugar exchange?? • Evaporation • Water vapor collecting techniques
Conclusions • Water balance components are crucial for isotope mass balance • Isotopes in precipitation: reference station in Moscow -> regionalization • Isotopes in stream flow, soil water, xylem: sampling is ongoing • Isotopes in snow: results are soon to come … • Evaporation / transpiration component is probably the biggest challenge