Tracing of water movement in the unsaturated zone using stable isotopes of hydrogen and oxygen

Barnes, C. J.; Allison, G.B.

doi:10.1016/0022-1694(88)90184-9

Cited by 382 publications

(276 citation statements)

References 42 publications

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“…The fractionation signal was shown to be more pronounced for evaporation losses from drier soils compared to wetter soils Barnes and Allison, 1988).…”

Section: Vegetation Affects Critical Zone Evaporation Lossesmentioning

confidence: 94%

Soil water stable isotopes reveal evaporation dynamics at the soil–plant–atmosphere interface of the critical zone

Sprenger

Tetzlaff

Soulsby

2017

Hydrol. Earth Syst. Sci.

172

165

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Abstract. Understanding the influence of vegetation on water storage and flux in the upper soil is crucial in assessing the consequences of climate and land use change. We sampled the upper 20 cm of podzolic soils at 5 cm intervals in four sites differing in their vegetation (Scots Pine (Pinus sylvestris) and heather (Calluna sp. and Erica Sp)) and aspect. The sites were located within the Bruntland Burn longterm experimental catchment in the Scottish Highlands, a low energy, wet environment. Sampling took place on 11 occasions between September 2015 and September 2016 to capture seasonal variability in isotope dynamics. The pore waters of soil samples were analyzed for their isotopic composition (δ 2 H and δ 18 O) with the direct-equilibration method. Our results show that the soil waters in the top soil are, despite the low potential evaporation rates in such northern latitudes, kinetically fractionated compared to the precipitation input throughout the year. This fractionation signal decreases within the upper 15 cm resulting in the top 5 cm being isotopically differentiated to the soil at 15-20 cm soil depth. There are significant differences in the fractionation signal between soils beneath heather and soils beneath Scots pine, with the latter being more pronounced. But again, this difference diminishes within the upper 15 cm of soil. The enrichment in heavy isotopes in the topsoil follows a seasonal hysteresis pattern, indicating a lag time between the fractionation signal in the soil and the increase/decrease of soil evaporation in spring/autumn. Based on the kinetic enrichment of the soil water isotopes, we estimated the soil evaporation losses to be about 5 and 10 % of the infiltrating water for soils beneath heather and Scots pine, respectively. The high sampling frequency in time (monthly) and depth (5 cm intervals) revealed high temporal and spatial variability of the isotopic composition of soil waters, which can be critical, when using stable isotopes as tracers to assess plant water uptake patterns within the critical zone or applying them to calibrate traceraided hydrological models either at the plot to the catchment scale.

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“…The fractionation signal was shown to be more pronounced for evaporation losses from drier soils compared to wetter soils Barnes and Allison, 1988).…”

Section: Vegetation Affects Critical Zone Evaporation Lossesmentioning

confidence: 94%

Soil water stable isotopes reveal evaporation dynamics at the soil–plant–atmosphere interface of the critical zone

Sprenger

Tetzlaff

Soulsby

2017

Hydrol. Earth Syst. Sci.

172

165

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“…This is sometimes termed the equilibrium evaporation slope, which applies to evaporation of local precipitation [see Gat and Bowser, 1991], but is distinguished from nonequilibrium evaporation slopes, which describe evaporation of allochthonous water sources, i.e., waters introduced by long-distance river transport, regional groundwater flow, or artificial diversions. Local evaporation lines (LELs) have been widely reported from field studies of water bodies [e.g., Dinçer, 1968;Zuber, 1983;Gibson, 2002;Gibson et al, 1993Gibson et al, , 2005 and soil water [e.g., Barnes and Allison, 1988;. In general, soil water LELs have been reported as having lower slopes than open water LELs, attributed to vapor transport through the stagnant, diffusiondominated soil matrix.…”

Section: Theorymentioning

confidence: 99%

Global prediction of δ_A and δ²H‐δ¹⁸O evaporation slopes for lakes and soil water accounting for seasonality

Gibson¹,

Birks²,

Edwards

2008

Global Biogeochemical Cycles

220

152

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[1] Global trends in the d 2 H-d 18O enrichment slope of continental lakes and shallow soil water undergoing natural evaporation are predicted on the basis of a steady state isotope balance model using basic monthly climate data (i.e., temperature and humidity), isotopes in precipitation data, and a simple equilibrium liquid-vapor model to estimate isotopes in atmospheric moisture. The approach, which demonstrates the extension of well-known conceptual models in stable isotope hydrology to the global scale, is intended to serve as a baseline reference for evaluating field-based isotope measurements of vapor, surface water, and soil water and as a diagnostic tool for more complex ecosystem models, including isotope-equipped climate models. Our simulations reproduce the observed local evaporation line slopes (4-5 range for lakes and 2-3 range for soil water) for South America, Africa, Australia, and Europe. A systematic increase in slopes (5-8 range for lakes) toward the high latitudes is also predicted for lakes and soil water in northern North America, Asia, and Antarctica illustrating a latitudinal (mainly seasonality-related) control on the evaporation signals that has not been widely reported. The over-riding control on the poleward steepening of the local evaporation lines is found to be the isotopic separation between evaporation-flux-weighted atmospheric moisture and annual precipitation, and to lesser extents temperature and humidity, all of which are influenced by enhanced seasonality in cold regions.

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“…In the soil, specific isotopic profiles develop, characterized by an evaporative layer near the surface. The isotopic enrichment decreases exponentially with depth, representing a balance between the upward convective flux and the downward diffusion of the evaporative signature (Barnes and Allison, 1988). In humid and semihumid areas, this exponential decrease is generally interrupted by the precipitation isotopic signal.…”

Section: Introductionmentioning

confidence: 99%

Exploring water cycle dynamics by sampling multiple stable water isotope pools in a developed landscape in Germany

Orlowski

Kraft

Pferdmenges

2016

Hydrol. Earth Syst. Sci.

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Abstract. A dual stable water isotope (δ 2 H and δ 18 O) study was conducted in the developed (managed) landscape of the Schwingbach catchment (Germany). The 2-year weekly to biweekly measurements of precipitation, stream, and groundwater isotopes revealed that surface and groundwater are isotopically disconnected from the annual precipitation cycle but showed bidirectional interactions between each other. Apparently, snowmelt played a fundamental role for groundwater recharge explaining the observed differences to precipitation δ values.A spatially distributed snapshot sampling of soil water isotopes at two soil depths at 52 sampling points across different land uses (arable land, forest, and grassland) revealed that topsoil isotopic signatures were similar to the precipitation input signal. Preferential water flow paths occurred under forested soils, explaining the isotopic similarities between top-and subsoil isotopic signatures. Due to human-impacted agricultural land use (tilling and compression) of arable and grassland soils, water delivery to the deeper soil layers was reduced, resulting in significant different isotopic signatures. However, the land use influence became less pronounced with depth and soil water approached groundwater δ values. Seasonally tracing stable water isotopes through soil profiles showed that the influence of new percolating soil water decreased with depth as no remarkable seasonality in soil isotopic signatures was obvious at depths > 0.9 m and constant values were observed through space and time. Since classic isotope evaluation methods such as transfer-function-based mean transit time calculations did not provide a good fit between the observed and calculated data, we established a hydrological model to estimate spatially distributed groundwater ages and flow directions within the Vollnkirchener Bach subcatchment. Our model revealed that complex age dynamics exist within the subcatchment and that much of the runoff must has been stored for much longer than event water (average water age is 16 years). Tracing stable water isotopes through the water cycle in combination with our hydrological model was valuable for determining interactions between different water cycle components and unravelling age dynamics within the study area. This knowledge can further improve catchment-specific process understanding of developed, human-impacted landscapes.

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Tracing of water movement in the unsaturated zone using stable isotopes of hydrogen and oxygen

Cited by 382 publications

References 42 publications

Soil water stable isotopes reveal evaporation dynamics at the soil–plant–atmosphere interface of the critical zone

Soil water stable isotopes reveal evaporation dynamics at the soil–plant–atmosphere interface of the critical zone

Global prediction of δ_A and δ²H‐δ¹⁸O evaporation slopes for lakes and soil water accounting for seasonality

Exploring water cycle dynamics by sampling multiple stable water isotope pools in a developed landscape in Germany

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Tracing of water movement in the unsaturated zone using stable isotopes of hydrogen and oxygen

Cited by 382 publications

References 42 publications

Soil water stable isotopes reveal evaporation dynamics at the soil–plant–atmosphere interface of the critical zone

Soil water stable isotopes reveal evaporation dynamics at the soil–plant–atmosphere interface of the critical zone

Global prediction of δA and δ2H‐δ18O evaporation slopes for lakes and soil water accounting for seasonality

Exploring water cycle dynamics by sampling multiple stable water isotope pools in a developed landscape in Germany

Contact Info

Product

Resources

About

Global prediction of δ_A and δ²H‐δ¹⁸O evaporation slopes for lakes and soil water accounting for seasonality