scholarly journals The Soil Water Evaporation Process from Mountains Based on the Stable Isotope Composition in a Headwater Basin and Northwest China

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2711 ◽  
Author(s):  
Leilei Yong ◽  
Guofeng Zhu ◽  
Qiaozhuo Wan ◽  
Yuanxiao Xu ◽  
Zhuanxia Zhang ◽  
...  
Keyword(s):  
Soil Water ◽  
Environmental Remediation ◽  
Isotope Composition ◽  
Salt Content ◽  
Water Isotopes ◽  
Water Evaporation ◽  
Hydrological Process ◽  
Arid Areas ◽  
Time Dynamics ◽  
Evaporation Loss

Soil water is a link between different water bodies. The study of soil water evaporation is of great significance to understand the regional hydrological process, promote environmental remediation in arid areas, and rationalize ecological water use. On the basis of soil water δ2H and δ18O data from April to October 2017 in the Xiying River basin in the upper reaches of the Qilian mountains, the lc-excess and Craig-Gordon model were applied to reflect the evaporating fractionation of soil water. The results show that the change in evaporation loss drives the enrichment of soil water isotopes. The signal of evaporative fractionation of soil water isotopes at different elevations has spatiotemporal heterogeneity. From the perspective of time dynamics, the evaporation loss of the whole region during the observation period was affected by temperature before July, while after July, it was controlled jointly by temperature and humidity, evaporation was weakened. Soil salt content and vegetation played an important role in evaporation loss. In terms of spatial dynamics, the soil moisture evaporation at the Xiying (2097 m) and Huajian (2390 m) stations in the foothills area is larger than that at the Nichan station (2721 m) on the hillside and Lenglong station (3637 m) on the mountain top. The surface soil water evaporation is strong, and the evaporation becomes weak with the increase of depth. The research has guiding significance for the restoration and protection of vegetation in arid areas and the formulation of reasonable animal husbandry policies.

scholarly journals The triple oxygen isotope composition of phytoliths as a proxy of continental atmospheric humidity: insights from climate chamber and climate transect calibrations

2017 ◽  
Author(s):  
Anne Alexandre ◽  
Amarelle Landais ◽  
Christine Vallet-Coulomb ◽  
Clément Piel ◽  
Sébastien Devidal ◽  
...  
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
Oxygen Isotope ◽  
Soil Water ◽  
Isotope Composition ◽  
Leaf Water ◽  
Growth Chamber ◽  
Water Evaporation ◽  
Atmospheric Humidity ◽  
Oxygen Isotope Fractionation

Abstract. Continental atmospheric relative humidity (RH) is a key climate-parameter. Combined with atmospheric temperature, it allows us to estimate the concentration of atmospheric water vapor which is one of the main components of the global water cycle and the most important gas contributing to the natural greenhouse effect. However, there is a lack of proxies suitable for reconstructing, in a quantitative way, past changes of continental atmospheric humidity. This reduces the possibility to make model-data comparisons necessary for the implementation of climate models. Over the past 10 years, analytical developments have enabled a few laboratories to reach sufficient precision for measuring the triple oxygen isotopes, expressed by the 17O-excess (17O-excess = ln (δ17O + 1) − 0.528 × ln (δ18O + 1)), in water, water vapor and minerals. The 17O-excess represents an alternative to deuterium-excess for investigating relative humidity conditions that prevail during water evaporation. Phytoliths are micrometric amorphous silica particles that form continuously in living plants. Phytolith morphological assemblages from soils and sediments are commonly used as past vegetation and hydrous stress indicators. In the present study, we examine whether changes in atmospheric RH imprint the 17O-excess of phytoliths in a measurable way and whether this imprint offers a potential for reconstructing past RH. For that purpose, we first monitored the 17O-excess evolution of soil water, grass leaf water and grass phytoliths in response to changes in RH (from 40 to 100 %) in a growth chamber experiment where transpiration reached a steady state. Decreasing RH decreases the 17O-excess of phytoliths by 4.1 per meg / % as a result of kinetic fractionation of the leaf water subject to evaporation. In order to model with accuracy the triple oxygen isotope fractionation in play in plant water and in phytoliths we recommend direct and continuous measurements of the triple isotope composition of water vapor. Then, we measured the 17O-excess of 57 phytolith assemblages collected from top soils along a RH and vegetation transect in inter-tropical West and Central Africa. Although scattered, the 17O-excess of phytoliths decreases with RH by 3.4 per meg / %. The similarity of the trends observed in the growth chamber and nature supports that RH is an important control of 17O-excess of phytoliths in the natural environment. However, other parameters such as changes in the triple isotope composition of the soil water or phytolith origin in the leaf tissue may come into play. Assessment of these parameters through additional growth chambers experiments and field campaigns will bring us closer to an accurate proxy of changes in relative humidity.

scholarly journals Simulation of Soil Water Evaporation during Freeze–Thaw Periods under Different Straw Mulch Thickness Conditions

Water ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 2003
Author(s):  
Junfeng Chen ◽  
Yizhao Wei ◽  
Xiping Zhao ◽  
Jing Xue ◽  
Shuyuan Xu ◽  
...  
Keyword(s):  
Soil Water ◽  
Field Experiments ◽  
Water Model ◽  
Water Evaporation ◽  
Arid Areas ◽  
Freeze Thaw ◽  
Straw Mulching ◽  
Straw Mulch ◽  
Thaw Period ◽  
Semi Arid

Straw mulching is an effective agricultural technology to reduce soil water loss in arid and semi-arid areas. Herein, the soil temperature and soil water content of bare land (LD) and 5 cm (JG5), 10 cm (JG10), 15 cm (JG15), 20 cm (JG20) and 30 cm (JG30) straw mulch thicknesses were measured through field experiments performed to assess the soil water evaporation using the simultaneous heat and water model during a freeze–thaw period. The results showed that the inhibiting effect of straw mulching on soil water evaporation during the freeze-thaw period reached 24–56.7%, and straw mulch reduced the range of daily soil water evaporation by 2.02–2.48 mm, the effects of random factors on the daily soil water evaporation were significantly decreased. The highest soil water evaporation rate occurs during the unstable freezing stage, and the lowest occurs during the stable freezing stage. When the straw mulch thickness exceeded 10 cm, the effect of increasing straw mulch thickness on daily soil water evaporation was reduced. The straw mulch layer could not completely inhibit the effect of the external environment on soil water evaporation even when the straw mulch thickness was increased to 30 cm. This research results can provide a basis for the scientific evaluation and prevention of soil water evaporation in arid and semi-arid areas.

scholarly journals The triple oxygen isotope composition of phytoliths as a proxy of continental atmospheric humidity: insights from climate chamber and climate transect calibrations

2018 ◽  
Vol 15 (10) ◽  
pp. 3223-3241 ◽  
Author(s):  
Anne Alexandre ◽  
Amarelle Landais ◽  
Christine Vallet-Coulomb ◽  
Clément Piel ◽  
Sébastien Devidal ◽  
...  
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
Oxygen Isotope ◽  
Soil Water ◽  
Isotope Composition ◽  
Leaf Water ◽  
Growth Chamber ◽  
Water Evaporation ◽  
Atmospheric Humidity ◽  
Oxygen Isotope Fractionation

Abstract. Continental atmospheric relative humidity (RH) is a key climate parameter. Combined with atmospheric temperature, it allows us to estimate the concentration of atmospheric water vapor, which is one of the main components of the global water cycle and the most important gas contributing to the natural greenhouse effect. However, there is a lack of proxies suitable for reconstructing, in a quantitative way, past changes of continental atmospheric humidity. This reduces the possibility of making model–data comparisons necessary for the implementation of climate models. Over the past 10 years, analytical developments have enabled a few laboratories to reach sufficient precision for measuring the triple oxygen isotopes, expressed by the 17O-excess (17O-excess = ln (δ17O + 1) – 0.528 × ln (δ18O + 1)), in water, water vapor and minerals. The 17O-excess represents an alternative to deuterium-excess for investigating relative humidity conditions that prevail during water evaporation. Phytoliths are micrometric amorphous silica particles that form continuously in living plants. Phytolith morphological assemblages from soils and sediments are commonly used as past vegetation and hydrous stress indicators. In the present study, we examine whether changes in atmospheric RH imprint the 17O-excess of phytoliths in a measurable way and whether this imprint offers a potential for reconstructing past RH. For that purpose, we first monitored the 17O-excess evolution of soil water, grass leaf water and grass phytoliths in response to changes in RH (from 40 to 100 %) in a growth chamber experiment where transpiration reached a steady state. Decreasing RH from 80 to 40 % decreases the 17O-excess of phytoliths by 4.1 per meg/% as a result of kinetic fractionation of the leaf water subject to evaporation. In order to model with accuracy the triple oxygen isotope fractionation in play in plant water and in phytoliths we recommend direct and continuous measurements of the triple isotope composition of water vapor. Then, we measured the 17O-excess of 57 phytolith assemblages collected from top soils along a RH and vegetation transect in inter-tropical West and Central Africa. Although scattered, the 17O-excess of phytoliths decreases with RH by 3.4 per meg/%. The similarity of the trends observed in the growth chamber and nature supports that RH is an important control of 17O-excess of phytoliths in the natural environment. However, other parameters such as changes in the triple isotope composition of the soil water or phytolith origin in the plant may come into play. Assessment of these parameters through additional growth chambers experiments and field campaigns will bring us closer to an accurate proxy of changes in relative humidity.

Using Triple Oxygen Isotopes of Pedogenic Carbonate to Identify Ancient Evaporation: First Steps from Modern Soils

2021 ◽  
Author(s):  
Julia Kelson ◽  
Tyler Huth ◽  
Benjamin Passey ◽  
Naomi Levin
Keyword(s):  
Soil Water ◽  
Oxygen Isotopes ◽  
Meteoric Water ◽  
Isotope Composition ◽  
Aridity Index ◽  
Water Evaporation ◽  
Mean Annual Precipitation ◽  
Carbonate Formation ◽  
Soil Carbonate ◽  
Soil Carbonates

<p>The stable isotope composition of soil carbonates is commonly used to reconstruct continental paleoclimates, but its utility is limited by an incomplete understanding of how soil carbonates form. In particular, it is often unclear if the parent soil water has been enriched in <sup>18</sup>O due to evaporation, muddying our ability to infer meteoric water δ<sup>18</sup>O from paleosol carbonates. Here we demonstrate the potential use of triple oxygen isotopes (termed ∆’<sup>17</sup>O) to account for evaporation and identify formation process through a study of modern soil carbonate isotope values.  Evaporation results in a decreased slope in the relationship between δ<sup>17</sup>O and δ<sup>18</sup>O and deviations from the global meteoric water line, such that ∆<sup>’17</sup>O values in soil water and resulting carbonate decrease with increased evaporation. We report ∆<sup>’17</sup>O values of CO<sub>2</sub> derived from soil carbonates and measured as O<sub>2</sub> on a mass spectrometer, with 1-4 replicates per soil carbonate. We find a step-like relationship between ∆’<sup>17</sup>O in globally distributed Holocene soil carbonate samples and aridity, where aridity is defined using the aridity index (AI, mean annual precipitation/potential evapotranspiration). Low ∆<sup>’17</sup>O values occur in hyper-arid climates (AI < 0.05), with mean ∆<sup>’17</sup>O = -0.164 ‰, SD = 0.004 ‰. A transition, or step, occurs in arid climates (AI from 0.05 to 0.2), with ∆<sup>’17</sup>O values that range from -0.129 ‰ to -0.165 ‰, and mean ∆<sup>’17</sup>O of -0.148 ‰, SD = 0.010‰. High ∆<sup>’17</sup>O values occur in semi-arid through humid climates (AI >0.5) with mean ∆<sup>’17</sup>O of -0.135 ‰, SD = 0.008 ‰.  The lowest observed ∆<sup>’17</sup>O values are consistent with extensive evaporation – for context, the ∆<sup>’17</sup>O values are similar to those measured in lacustrine carbonates from closed lake basins. The highest ∆<sup>’17</sup>O values are consistent with little soil water evaporation. We interpret the step-like pattern in ∆’<sup>17</sup>O values as an indication of the threshold in the importance of evaporation vs. transpiration in soil dewatering. This data highlights the potential to use ∆<sup>’17</sup>O to identify the extent of evaporation in paleosol carbonates. Eventually, we hope that this novel technique will lead to quantitative accounting of evaporation in soil water and improved reconstructions of meteoric water δ<sup>18</sup>O from soil carbonates. The ability to constrain the evaporative conditions of soil carbonate formation will also aid interpretations of δ<sup>13</sup>C (including pCO<sub>2</sub> reconstructions) and clumped isotope-based temperatures. These efforts will ultimately aid in our ability to integrate paleoclimate data from soil carbonates with data from other terrestrial records.  </p>

scholarly journals Identifying surface water evaporation loss of inland river basin based on evaporation enrichment model

2021 ◽  
Vol 35 (3) ◽  
Author(s):  
Zhigang Sun ◽  
Guofeng Zhu ◽  
Zhuanxia Zhang ◽  
Yuanxiao Xu ◽  
Leilei Yong ◽  
...  
Keyword(s):  
Surface Water ◽  
River Basin ◽  
Water Evaporation ◽  
Evaporation Loss ◽  
Inland River ◽  
Inland River Basin

Advances in Heat-Pulse Methods: Measuring Soil Water Evaporation with Sensible Heat Balance

2017 ◽  
Vol 2 (1) ◽  
pp. 0 ◽  
Author(s):  
J.L. Heitman ◽  
X. Zhang ◽  
X. Xiao ◽  
T. Ren ◽  
R. Horton
Keyword(s):  
Soil Water ◽  
Heat Balance ◽  
Heat Pulse ◽  
Water Evaporation ◽  
Sensible Heat

Analytical solution for soil water redistribution during evaporation process

2013 ◽  
Vol 68 (12) ◽  
pp. 2545-2551 ◽  
Author(s):  
Jidong Teng ◽  
Noriyuki Yasufuku ◽  
Qiang Liu ◽  
Shiyu Liu
Keyword(s):  
Analytical Solution ◽  
Water Content ◽  
Soil Water ◽  
Exponential Function ◽  
Experimental Result ◽  
Water Evaporation ◽  
Evaporation Process ◽  
Climate Control ◽  
Water Redistribution ◽  
Control Apparatus

Simulating the dynamics of soil water content and modeling soil water evaporation are critical for many environmental and agricultural strategies. The present study aims to develop an analytical solution to simulate soil water redistribution during the evaporation process. This analytical solution was derived utilizing an exponential function to describe the relation of hydraulic conductivity and water content on pressure head. The solution was obtained based on the initial condition of saturation and an exponential function to model the change of surface water content. Also, the evaporation experiments were conducted under a climate control apparatus to validate the theoretical development. Comparisons between the proposed analytical solution and experimental result are presented from the aspects of soil water redistribution, evaporative rate and cumulative evaporation. Their good agreement indicates that this analytical solution provides a reliable way to investigate the interaction of evaporation and soil water profile.

A global meta-analysis reveals a significant offset in δ2H between plant water and its sources

2021 ◽  
Author(s):  
Javier de la Casa ◽  
Adrià Barbeta ◽  
Asun Rodriguez-Uña ◽  
Lisa Wingate ◽  
Jérôme Ogeé ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Soil Water ◽  
Meta Analysis ◽  
Water Evaporation ◽  
Source Water ◽  
Plant Water ◽  
Water Line ◽  
Plant Source ◽  
Sampling Campaign ◽  
The Mean

<p> </p><p>Long-standing ecological theory establishes that the isotopic composition of the plant water reflects that of the root-accessed sources, at least in non-saline or non-xeric environments. However, a growing number of studies challenge this assumption by reporting plant-source offsets in water isotopic composition, for a wide range of ecosystems. We conducted a global meta-analysis to systematically quantify the magnitude of this plant-source offset in water isotopic composition and its potential explanatory factors. We compiled 108 studies reporting dual water isotopic composition (δ<sup>2</sup>H and δ<sup>18</sup>O) of plant and source water. From these studies, we extracted the δ<sup>2</sup>H and δ<sup>18</sup>O of both plant and source waters for 223 plant species from artic to tropical biomes. For each species and sampling campaign, within each study, we calculated the mean line conditioned excess (LC-excess), with the slope and intercept of the local meteoric water line, and the mean soil water line conditioned excess (SWL-excess), from the slope and intercept of the soil water evaporation line. For each study site and sampling campaign, we obtained land surface temperature and volumetric soil water from the ERA5 database. For each study species, we recorded the functional type, leaf habit and for those available wood density. We found, on average, a significantly negative SWL-excess: plant water was systematically more depleted in δ<sup>2</sup>H than soil water. In > 90% of the cases with significantly negative SWL-excess, we also found negative LC-excess values, meaning that access to sources alternative to soil water was unlikely to explain negative SWL-excess values. </p><p>Calculated SWL-excess was affected by temperature and humidity: there were larger mismatches between plant and source water in isotopic composition in colder and wetter sites. Angiosperms, broadleaved and deciduous species exhibited more negative SWL-excess values than gymnosperms, narrow-leaved and evergreen species. Our results suggest that when using the dual isotopic approach, potential biases in the adscription of plant water sources are more likely in broadleaved forests in humid, and cold regions. Potential underlying mechanism for these isotopic mismatches will be discussed.</p><p> </p>

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