DOI: 10.5194/hess-24-4045-2020
论文题名: A combination of soil water extraction methods quantifies the isotopic mixing of waters held at separate tensions in soil
作者: Bowers W.H. ; Mercer J.J. ; Pleasants M.S. ; Williams D.G.
刊名: Hydrology and Earth System Sciences
ISSN: 1027-5606
出版年: 2020
卷: 24, 期: 8 起始页码: 4045
结束页码: 4060
语种: 英语
Scopus关键词: Centrifugation
; Distillation
; Isotopes
; Mixing
; Soil moisture
; Textures
; Combination approaches
; Extraction of waters
; Isotope compositions
; Isotopic composition
; Physical and chemical properties
; Soil water extractions
; Unsaturated condition
; Water residence time
; Extraction
; quantitative analysis
; separation
; soil water
; tension
英文摘要: Measurements of the isotopic composition of separate and potentially interacting pools of soil water provide a powerful means to precisely resolve plant water sources and quantify water residence time and connectivity among soil water regions during recharge events. Here we present an approach for quantifying the time-dependent isotopic mixing of water recovered at separate suction pressures or tensions in soil over an entire moisture release curve. We wetted oven-dried, homogenized sandy loam soil first with isotopically "light"water (δ2H =-130 ‰; δ18O =-17.6 ‰) to represent antecedent moisture held at high matric tension. We then brought the soil to near saturation with "heavy"water (δ2H =-44 ‰; δ18O =-7.8 ‰) that represented new input water. Soil water samples were subsequently sequentially extracted at three tensions ("low-tension"centrifugation ≈ 0.016MPa; "mid-tension"centrifugation ≈ 1.14MPa; and "high-tension"cryogenic vacuum distillation at an estimated tension greater than 100MPa) after variable equilibration periods of 0 h, 8 h, 1 d, 3 d, and 7 d.We assessed the differences in the isotopic composition of extracted water over the 7 d equilibration period with a MANOVA and a model quantifying the time-dependent isotopic mixing of water towards equilibrium via self-diffusion. The simplified and homogenous soil structure and nearly saturated moisture conditions used in our experiment likely facilitated rapid isotope mixing and equilibration among antecedent and new input water. Despite this, the isotope composition of waters extracted at mid compared with high tension remained significantly different for up to 1 d, and waters extracted at low compared with high tension remained significantly different for longer than 3 d. Complete mixing (assuming no fractionation) for the pool of water extracted at high tension occurred after approximately 4.33 d. Our combination approach involving the extraction of water over different domains of the moisture release curve will be useful for assessing how soil texture and other physical and chemical properties influence isotope exchange and mixing times for studies aiming to properly characterize and interpret the isotopic composition of extracted soil and plant waters, especially under variably unsaturated conditions. © 2020 Author(s). Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/162617
Appears in Collections: 气候变化与战略
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作者单位: Bowers, W.H., Department of Botany, University of Wyoming, Laramie, 82070, United States; Mercer, J.J., Department of Botany, University of Wyoming, Laramie, 82070, United States; Pleasants, M.S., Department of Ecosystem Science and Management, University of Wyoming, Laramie, 82070, United States; Williams, D.G., Department of Botany, University of Wyoming, Laramie, 82070, United States, Department of Ecosystem Science and Management, University of Wyoming, Laramie, 82070, United States
Recommended Citation:
Bowers W.H.,Mercer J.J.,Pleasants M.S.,et al. A combination of soil water extraction methods quantifies the isotopic mixing of waters held at separate tensions in soil[J]. Hydrology and Earth System Sciences,2020-01-01,24(8)