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Full-Text Articles in Earth Sciences
Technical Note: On Uncertainties In Plant Water Isotopic Composition Following Extraction By Cryogenic Vacuum Distillation, Haoyu Diao, Philipp Schuler, Gregory R. Goldsmith, Rolf T. W. Siegwolf, Matthias Saurer, Marco M. Lehmann
Technical Note: On Uncertainties In Plant Water Isotopic Composition Following Extraction By Cryogenic Vacuum Distillation, Haoyu Diao, Philipp Schuler, Gregory R. Goldsmith, Rolf T. W. Siegwolf, Matthias Saurer, Marco M. Lehmann
Biology, Chemistry, and Environmental Sciences Faculty Articles and Research
Recent studies have challenged the interpretation of plant water isotopes obtained through cryogenic vacuum distillation (CVD) based on observations of a large 2H fractionation. These studies have hypothesized the existence of an H-atom exchange between water and organic tissue during CVD extraction with the magnitude of H exchange related to relative water content of the sample; however, clear evidence is lacking. Here, we systematically tested the uncertainties in the isotopic composition of CVD-extracted water by conducting a series of incubation and rehydration experiments using isotopically depleted water, water at natural isotope abundance, woody materials with exchangeable H, and organic materials …
Seasonal Origins Of Soil Water Used By Trees, Scott T. Allen, James W. Kirchner, Sabine Braun, Rolf T. W. Siegwolf, Gregory R. Goldsmith
Seasonal Origins Of Soil Water Used By Trees, Scott T. Allen, James W. Kirchner, Sabine Braun, Rolf T. W. Siegwolf, Gregory R. Goldsmith
Biology, Chemistry, and Environmental Sciences Faculty Articles and Research
Rain recharges soil water storages and either percolates downward into aquifers and streams or is returned to the atmosphere through evapotranspiration. Although it is commonly assumed that summer rainfall recharges plant-available water during the growing season, the seasonal origins of water used by plants have not been systematically explored. We characterize the seasonal origins of waters in soils and trees by comparing their midsummer isotopic signatures (δ2H) to seasonal isotopic cycles in precipitation, using a new seasonal origin index. Across 182 Swiss forest sites, xylem water isotopic signatures show that summer rain was not the predominant water source …
Optical Characterization And Distribution Of Chromophoric Dissolved Organic Matter (Cdom) In Soil Porewater From A Salt Marsh Ecosystem, Catherine D. Clark, Paige Aiona, Jason K. Keller, Warren J. De Bruyn
Optical Characterization And Distribution Of Chromophoric Dissolved Organic Matter (Cdom) In Soil Porewater From A Salt Marsh Ecosystem, Catherine D. Clark, Paige Aiona, Jason K. Keller, Warren J. De Bruyn
Biology, Chemistry, and Environmental Sciences Faculty Articles and Research
To characterize chromophoric dissolved organic matter (CDOM) in marsh porewaters and its contribution as a carbon source, optical properties (absorbance, fluorescence indices, 3-dimensional excitation-emission matrices [EEMs]) of soil porewater and surface water were measured in a southern Californian salt marsh. Absorption coefficients and fluorescence intensities were higher in porewater than in overlying surface waters, consistent with higher CDOM concentration at depth. Humic-type peaks A and C were observed in EEMs in all samples, and peak M was observed in surface waters and shallow porewater to -5 cm depth. Fluorescence:absorbance (flu:abs) ratios and spectral slopes (S) decreased across the surface interface, …