water stable isotope
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2021 ◽  
pp. 1-10
Author(s):  
Alexey A. Ekaykin ◽  
Alexey V. Bolshunov ◽  
Vladimir Ya. Lipenkov ◽  
Mirko Scheinert ◽  
Lutz Eberlein ◽  
...  

Abstract The region of Ridge B in central East Antarctica is one of the last unexplored parts of the continent and, at the same time, ranks among the most promising places to search for Earth's oldest ice. In January 2020, we carried out the first scientific traverse from Russia's Vostok Station to the topographical dome of Ridge B (Dome B, 3807 m above sea level, 79.02°S, 93.69°E). The glaciological programme included continuous snow-radar profiling and geodetic positioning along the traverse's route, installation of snow stakes, measurements of snow density, collection of samples for stable water isotope and chemical analyses and drilling of a 20 m firn core. The first results of the traverse show that the surface mass balance at Dome B (2.28 g cm−2 year−1) is among the lowest in Antarctica. The firn temperature below the layer of annual variations is −58.1 ± 0.2°C. A very low value of heavy water stable isotope content (-58.2‰ for oxygen-18) was discovered at a distance of 170 km from Vostok Station. This work is the first step towards a comprehensive reconnaissance study of the Ridge B area aimed at locating the best site for future deep drilling for the oldest Antarctic ice.


2021 ◽  
Author(s):  
Paula Martín Gómez ◽  
Jérôme Ogée ◽  
Régis Burlett ◽  
Adrià Barbeta ◽  
Nicolas Devert ◽  
...  

<p>During winter dormancy in deciduous species, water stops flowing in the xylem and buds become isolated from the stem xylem conduits by a physical barrier made of callose deposits. During bud break, the plant builds new vascular connections between the growing buds and the xylem to support sap flow and transpiration in the developing leaves. However, little is known about the exact timing when these new vascular connections are made, or about the origin of the water supporting bud swelling prior to bud break. This information is particularly limited in forest tree species. We aimed to clarify the origin of the water entering the buds at different developmental stages in temperate forest tree species using water stable isotope tracing techniques to track water movement between soil, stem and buds. More specifically, we developed a method to collect sap water separately from water in other stem tissues (Barbeta et al. 2020). At different leaf phenological stages during the 2018 growing season, we collected soil, stem, bud and leaf samples from 5 adult trees and 3 species (<em>Fagus sylvatica</em>, <em>Quercus robur</em>, <em>Pinus pinaster</em>) growing in a riparian forest in Southwest France. We estimated the relative water content in each sample by extracting bulk water by cryogenic vacuum distillation, and also extracted sap water from stem samples using our new method. All water samples were then analysed for their stable isotope composition (δ<sup>18</sup>O, δ<sup>2</sup>H). These results, complemented by some additional labelling experiments, provide key information about the timing of hydraulic reconnection between the buds and the xylem and about the source of water supporting bud swelling and bud break, demonstrating the usefulness of water stable isotope measurements to understand water transport pathways during bud development and canopy leaf out.</p><p> </p><p>Reference:</p><p>Barbeta, A., Burlett, R., Martín-Gómez, P., Fréjaville, B., Devert, N., Wingate, L., Domec, J.-C., et al. (2020). Evidence for distinct isotopic composition of sap and tissue water in tree stems: Consequences for plant water source identification. <em>BioRxiv</em>, 2020.06.18.160002.</p>


Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2487
Author(s):  
Dragana Dogančić ◽  
Ardalan Afrasiabian ◽  
Nikola Kranjčić ◽  
Bojan Đurin

Unpredictable climate changes are affecting water resources, especially in karst arid and semiarid areas. In such locations, the need for additional sources of water always arises. The paper gives insight into hydrogeological characteristics of Kazeroo County and resolves some unknowns around the catchment area of the springs important for water supply of the wider urban area of the city of Kazeroon, Iran, by using stable isotope analysis (δD and δ18O) and tracer test. Multiple tracer test and stable isotope analysis were conducted for research purposes. The uranine injected at Tale Milek 1 borehole was detected in the Chenar Shahijan spring in less than 2 and in the Seyed Hossein spring after 6 days. Small amounts of uranine were detected in the Sasan and Pirsabz springs. Based on the high apparent flow velocity (approximately 1750–2000 m/day), the underground system has a quick response to the precipitation during dry seasons. The assumed hydraulic connection between Shahneshin North (Asmari) and Dashtak Northzones has been confirmed by tracer test since the dye injected in Northern Asmari Shahneshin anticline appeared in the springs in Dashtak North zone. The results of water stable isotope measurements show that the catchment area of karst springs in the vicinity of Kazeroo is probably over 2000 m at the area of Shahneshin anticline and is positioned lower than the catchment area of Arjan spring.


2020 ◽  
Vol 125 (17) ◽  
Author(s):  
Aymeric P. M. Servettaz ◽  
Anais J. Orsi ◽  
Mark A. J. Curran ◽  
Andrew D. Moy ◽  
Amaelle Landais ◽  
...  

2020 ◽  
Vol 56 (5-6) ◽  
pp. 465-479 ◽  
Author(s):  
Orlando Mauricio Quiroz Londoño ◽  
Asunción Romanelli ◽  
Daniel Emilio Martínez ◽  
Héctor Enrique Massone

Data in Brief ◽  
2020 ◽  
Vol 30 ◽  
pp. 105607
Author(s):  
Andis Kalvāns ◽  
Alise Babre ◽  
Aija Dēliņa ◽  
Konrāds Popovs

2020 ◽  
Author(s):  
Songyi Kim ◽  
Yeongcheol Han ◽  
Soon Do Hur ◽  
HeeJin Hwang ◽  
Changhee Han ◽  
...  

<p>A snow pit samples contain information of atmospheric composition and weather condition for recent years. In this study, water isotope ratio and concentrations of major ions and rare earth elements (REE) were determined from a 2 m snow pit sampled at 5 cm intervals at Hercules Neve in northern Victoria Land, Antarctica (73° 03'S, 165° 25'E, 2900m). The water stable isotope ratios range from -45.10 to -29.51 ‰ for δ18O and from 355.8 to -229.2 ‰ for δD. From their clear seasonality, the snow pit is expected to cover the period of 2012–2015. The REE patterns reveal that there exist at least two distinct sources of terrestrial aerosols; One that makes superior contribution when sea salt input is high is likely located closer than another. </p>


2020 ◽  
Author(s):  
Matthias Cuntz ◽  
Lucas A Cernusak ◽  

<p>Several important isotopic biomarkers derive at least part of their signal from the stable isotope composition of leaf water (e.g., leaf wax δ<sup>2</sup>H, cellulose δ<sup>2</sup>H and δ<sup>18</sup>O, lignin δ<sup>18</sup>O). In order to interpret these isotopic proxies, it is therefore helpful to know which environmental variable most strongly controls a given leaf water stable isotope signal. We collated observations of the stable isotope compositions of leaf water, xylem water, and atmospheric vapour, along with air temperature and relative humidity, to test whether the dominant driver of leaf water <sup>2</sup>H concentration could differ from that of <sup>18</sup>O concentration. Our dataset comprises 690 observations from 35 sites with broad geographical coverage. We limited our analysis to daytime observations, when the photosynthetic processes that incorporate the leaf water isotopic signal primarily take place. The Craig-Gordon equation was generally a good predictor for daytime bulk leaf water stable isotope composition for both δ<sup>2</sup>H (R<sup>2</sup>=0.86, p<0.001) and δ<sup>18</sup>O (R<sup>2</sup>=0.63, p<0.001). It showed about 10% admixture of source water was caused by unenriched water pools such as leaf veins or the Péclet effect. Solving the Craig-Gordon equation requires knowledge of relative humidity, air temperature, and the stable isotope compositions of source water and atmospheric vapour. However, it is not possible to invert the Craig-Gordon equation to solve for one of these parameters unless the others are known. Here we show that the two isotopic signals of δ<sup>2</sup>H and δ<sup>18</sup>O are predominantly driven by different environmental variables: leaf water δ<sup>2</sup>H correlated most strongly with the δ<sup>2</sup>H of source water (R<sup>2</sup>=0.68, p<0.001) and atmospheric vapour (R<sup>2</sup>=0.63, p<0.001), whereas leaf water δ<sup>18</sup>O correlated most strongly with air relative humidity (R<sup>2</sup>=0.46, p<0.001). We conclude that these two isotopic signals of leaf water are not simply mirror images of the same environmental information, but carry distinct signals of different climate factors, with crucial implications for the interpretation of downstream isotopic biomarkers.</p>


2020 ◽  
Author(s):  
Yongyong Zhang ◽  
Wenzhi Zhao ◽  
Chun Zhao

<p>Soil water and groundwater convert frequently under cropland in a desert-oasis transition area, Northwest China. Crops variedly utilize soil water and groundwater during different growth periods under the cropland with shallow groundwater. The study of water exchange process under irrigated cropland has important significance for regulating the contradiction between water saving and groundwater recharge in the desert-oasis transition area. Soil moisture and soil matric potential at depths ranging from 0 to 70 cm were measured using HydraProbe II and TEROS-21 soil sensors in maize (Zea mays L.) fields in 2019. Stable isotope (δ<sup>2</sup>H、δ<sup>18</sup>O) in different water sources (precipitation, irrigation water, soil water, crop stem, and groundwater) was also measured. The results showed that the groundwater depth varied between 0.57-1.07 m during the maize growth periods. The groundwater depth increased in summer due to the influence of pumped well, while the depth decreased in autumn resulting from the irrigation return water. In the maize growing season, soil moisture and water potential at depths from 10 cm to 30 cm responded to three irrigation times, while soil moisture and water potential below the depth of 50 cm were greater and kept a steady state, which were affected by upward capillary rise of groundwater. The relationship of soil water stable isotope values ​​was δ<sup>2</sup>H=2.45δ<sup>18</sup>O-31.41, which was lower than the slope of the local atmospheric precipitation line due to the evaporation effect. The soil water stable isotope values at depth of 10 cm varied, while the variation of soil water stable isotope values decreased with the increase of soil depth. The soil water stable isotope values at the depths from 70 to 90cm were close to the groundwater isotope values, which were affected by the groundwater. The stable isotope values in crop stem water were relatively scattered, indicating that the maize used multiple water sources and the water use strategy changed during the growth periods.</p>


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