Isotopic equilibrium between precipitation and water vapor in Northern Patagonia and its consequences on δ18Ocellulose estimate

2020 ◽  
Author(s):  
Tiphaine Penchenat ◽  
Françoise Vimeux ◽  
Valérie Daux ◽  
Olivier Cattani ◽  
Maximiliano Viale ◽  
...  
Keyword(s):  
Water Vapor ◽  
Isotopic Composition ◽  
Tree Ring ◽  
Late Summer ◽  
Oxygen Isotopic Composition ◽  
Source Water ◽  
Isotopic Equilibrium ◽  
Perfect Agreement ◽  
The Impact ◽  
Tree Ring Cellulose

<div> <div> <div> <p>Modelling of the oxygen isotopic composition (δ<sup>18</sup>O) of tree-ring cellulose rely on the isotopic equilibrium assumption between the atmospheric water vapor and the tree source water, which is frequently assimilated to integrated precipitation. We explore the veracity of this assumption based on observations collected (δ<sup>18</sup>O of rain, rivers, leaves, tree-rings) or monitored (δ<sup>18</sup>O of water vapor) during a field campaign in Río Negro province, Argentina, in late summer 2017 (February-March). We examine, firstly, how the δ<sup>18</sup>O of water vapor deviate from the equilibrium with precipitation and, secondly, what is the impact of the isotopic equilibrium assumption on the calculation of the isotopic composition of tree-ring cellulose.</p> <p>For oxygen, the isotopic disequilibrium between rain and vapor range between -2.0 and 4.1‰. Rain drops re-evaporation during their fall, evaporation of soil water and vegetation transpiration (resulting in transpired water accounting for 14 to 29% of ambient water vapor) could produce this disequilibrium. The small value of the disequilibrium at the study site is likely due to the high level of relative humidity (from 70 to 96%) favoring the isotopic diffusive exchanges between the two water phases and thus promoting the isotopic equilibrium.</p> <p>A perfect agreement between observed and calculated isotopic composition of cellulose is obtained if the source water is assumed to be in isotopic equilibrium with the measured water vapor. This hypothetical source water has a significantly higher δ<sup>18</sup>O than the expected averaged isotopic composition of precipitation over the growing period or than the groundwater (river value). The veracity of the hypothesis of the isotopic equilibrium between water vapor and source water in tree-ring paleoclimate studies is discussed in light of these results.</p> </div> </div> </div>

scholarly journals Climate Response of Oxygen Isotopic Compositions in Tree-Ring Cellulose in Java: Evaluation Using a Proxy System Model

Atmosphere ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 310
Author(s):  
Ryo Hisamochi ◽  
Yumiko Watanabe ◽  
Naoyuki Kurita ◽  
Takahiro Tagami
Keyword(s):  
Relative Humidity ◽  
Isotopic Composition ◽  
Tree Ring ◽  
Temporal Variations ◽  
Oxygen Isotopic Composition ◽  
System Model ◽  
Climate Response ◽  
Growing Period ◽  
Oxygen Isotopic ◽  
Tree Ring Cellulose

Tree-ring cellulose oxygen isotopic composition (δ18O) is controlled by several hydrological factors such as precipitation, relative humidity, and temperature. A proxy system model can reveal how these factors affect tree-ring cellulose δ18O. In this study, to identify a key control on tree-ring cellulose δ18O variations, we performed model calculation of year-to year variation of tree-ring cellulose δ18O of Javanese teak in Indonesia from 1960 to 1998. Our model results reasonably reproduce the observed δ18O values and their temporal variations (r = 0.6; p < 0.001). Moreover, the sensitivity test shows that the cellulose δ18O values are sensitive to the teak growing period. The simulation result with earlier or later shifts of the growing period captured the amplitude of observed δ18O variations over 39 years. These results indicate that the tree-ring cellulose δ18O of Javanese teak might be influenced by a subtle shift of the intra-annual growing period.

scholarly journals Using δ13C and δ18O to analyze loblolly pine (Pinus taeda L.) response to experimental drought and fertilization

2019 ◽  
Vol 39 (12) ◽  
pp. 1984-1994
Author(s):  
Wen Lin ◽  
Jean-Christophe Domec ◽  
Eric J Ward ◽  
John Marshall ◽  
John S King ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Isotopic Composition ◽  
Oxygen Isotope ◽  
Pinus Taeda ◽  
Tree Ring ◽  
Loblolly Pine ◽  
Leaf Temperature ◽  
Drought Treatment ◽  
Pinus Taeda L ◽  
Tree Ring Cellulose

Abstract Drought frequency and intensity are projected to increase throughout the southeastern USA, the natural range of loblolly pine (Pinus taeda L.), and are expected to have major ecological and economic implications. We analyzed the carbon and oxygen isotopic compositions in tree ring cellulose of loblolly pine in a factorial drought (~30% throughfall reduction) and fertilization experiment, supplemented with trunk sap flow, allometry and microclimate data. We then simulated leaf temperature and applied a multi-dimensional sensitivity analysis to interpret the changes in the oxygen isotope data. This analysis found that the observed changes in tree ring cellulose could only be accounted for by inferring a change in the isotopic composition of the source water, indicating that the drought treatment increased the uptake of stored moisture from earlier precipitation events. The drought treatment also increased intrinsic water-use efficiency, but had no effect on growth, indicating that photosynthesis remained relatively unaffected despite 19% decrease in canopy conductance. In contrast, fertilization increased growth, but had no effect on the isotopic composition of tree ring cellulose, indicating that the fertilizer gains in biomass were attributable to greater leaf area and not to changes in leaf-level gas exchange. The multi-dimensional sensitivity analysis explored model behavior under different scenarios, highlighting the importance of explicit consideration of leaf temperature in the oxygen isotope discrimination (Δ18Oc) simulation and is expected to expand the inference space of the Δ18Oc models for plant ecophysiological studies.

scholarly journals Borehole equilibration: testing a new method to monitor the isotopic composition of tree xylem water in situ

2020 ◽  
Author(s):  
John Marshall ◽  
Matthias Cuntz ◽  
Matthias Beyer ◽  
Maren Dubbert ◽  
Kathrin Kuehnhammer
Keyword(s):  
Water Vapor ◽  
Isotopic Composition ◽  
Theoretical Models ◽  
New Method ◽  
Data Sets ◽  
Source Water ◽  
Plant Water ◽  
Limited Time ◽  
Slow Moving

&lt;p&gt;Forest water use has been difficult to quantify. One promising approach is to measure the isotopic composition of plant water, e.g.&lt;br&gt;the transpired water vapor or xylem water, which often differs from that of other water vapor sources. Traditionally such&lt;br&gt;measurements have relied on the extraction of wood samples, which provide limited time resolution at great expense, and risk&lt;br&gt;possible artefacts. Utilizing a borehole drilled through a trees&amp;#8217; stem, we propose a new method based on the notion that water&lt;br&gt;vapor in a slow-moving airstream approaches equilibration with the much greater mass of liquid water in the xylem. We present&lt;br&gt;two empirical data sets showing that the method can work in practice. We then present theoretical models estimating the&lt;br&gt;equilibration times and exploring the limits at which the approach will fail. Given long enough boreholes and slow enough flows,&lt;br&gt;the method provides a simple, cheap, and accurate means of continuously estimating the isotopic composition of the source water&lt;br&gt;for transpiration.&lt;/p&gt;

Water vapor isotopic signature along the EAIIST traverse (East Antarctica Plateau)

2021 ◽  
Author(s):  
Mathieu Casado ◽  
Christophe Leroy-Dos Santos ◽  
Elise Fourré ◽  
Vincent Favier ◽  
Cécile Agosta ◽  
...  
Keyword(s):  
Water Vapor ◽  
Isotopic Composition ◽  
Ice Cores ◽  
East Antarctica ◽  
Polar Regions ◽  
Surface Mass ◽  
Antarctic Plateau ◽  
Starting Point ◽  
Weather Stations ◽  
The Impact

&lt;p&gt;Stable water isotopes are effective hydrological tracers due to fractionation processes throughout the water cycle, and thus, the stable isotopes from ice cores can serve as valuable proxies for past changes in the climate and local environment of polar regions. Proper interpretation of these isotopes requires to understand the influence of each potential fractionating process, such as initial evaporation over the ocean and precipitation events, but also the effects of post-depositional exchange between snow and moisture in the atmosphere. Thanks to new developments in infrared spectroscopy, it is now possible to continuously monitor the isotopic composition of atmospheric water vapor in coordination with discrete snow sampling. This allows us to readily document the isotopic and mass exchanges between snow and vapor as well as the stability of the atmospheric boundary layer, as has recently been shown on the East Antarctic Plateau at Kohnen (Ritter et al., TC, 2016) and Dome C (Casado et al., ACP, 2016) stations where substantial diurnal isotopic variations have been recorded.&lt;/p&gt;&lt;p&gt;In this study, we present the first vapor monitoring of an East Antarctic transect that covered more than 3600 km over a period of 3 months from November 2019 to February 2020 as part of the EAIIST mission. The isotopic record therefore describes the evolution from typical coastal values to highly depleted values deep inside the continent on the high-altitude plateau. In parallel, we also monitored the vapor isotopic composition at two stations: the coastal starting point of Dumont D&amp;#8217;Urville (DDU) and the plateau halfway point of Dome C. Two automatic weather stations (at Paleo and Megadunes sites) were also installed in a previously unexplored region of the East Antarctic plateau that was covered by this transect. This suite of cross-calibrated vapor isotope observations and weather stations, coupled with Modele Atmospherique R&amp;#233;gional (MAR) climate modeling, offers a unique opportunity to compare the spatial and temporal gradients of humidity, temperature, and water vapor isotopic composition in East Antarctica during the summer season, and to estimate how the water vapour isotope measurements at Dome C and DDU are representative of the conditions in East Antarctica. The quantitative agreement between the EAIIST record and those recorded at DDU and Dome C stations at the times the raid was nearby, gives confidence in the quality of the results acquired on this traverse. Although further comparisons with the surface snow isotopic composition are required to quantify the impact of the snow-atmosphere exchanges on the local surface mass balance, these initial results of vapor isotopic composition show the potential of using water stables isotopes to evaluate hydrological processes in East Antarctica and better reconstruct past climate changes through ice cores.&lt;/p&gt;

scholarly journals Cryogenic and non-cryogenic pool calcites indicating permafrost and non-permafrost periods: a case study from the Herbstlabyrinth-Advent Cave system (Germany)

2010 ◽  
Vol 4 (4) ◽  
pp. 501-509 ◽  
Author(s):  
D. K. Richter ◽  
P. Meissner ◽  
A. Immenhauser ◽  
U. Schulte ◽  
I. Dorsten
Keyword(s):  
Isotopic Composition ◽  
Isotope Geochemistry ◽  
Isotope Ratios ◽  
Oxygen Isotopic Composition ◽  
Isotopic Equilibrium ◽  
Climate History ◽  
Cave System ◽  
Air Ventilation ◽  
Oxygen Isotopic

Abstract. Weichselian cryogenic calcites collected in what is referred to as the Rätselhalle of the Herbstlabyrinth-Advent Cave system are structurally classified as rhombohedral crystals and spherulitic aggregates. The carbon and oxygen isotopic composition of these precipitates (δ13C = +0.6 to −7.3‰ δ18O = −6.9 to −18.0‰) corresponds to those of known slowly precipitated cryogenic cave calcites under conditions of isotopic equilibrium between water and ice of Central European caves. The carbon and oxygen isotopic composition varies between different caves which is attributed to the effects of cave air ventilation before the freezing started. By petrographic and geochemical comparisons of Weichselian cryogenic calcite with recent to sub-recent precipitates as well as Weichselian non-cryogenic calcites of the same locality, a model for the precipitation of these calcites is proposed. While the recent and sub-recent pool-calcites isotopically match the composition of interglacial speleothems (stalagmites, etc.), isotope ratios of Weichselian non-cryogenic pool-calcites reflect cooler conditions. Weichselian cryogenic calcites show a trend towards low δ18O values with higher carbon isotope ratios reflecting slow freezing of the precipitating solution. In essence, the isotope geochemistry of the Weichselian calcites reflects the climate history changing from overall initial permafrost conditions to permafrost-free and subsequently to renewed permafrost conditions. Judging from the data compiled here, the last permafrost stage in the Rätselhalle is followed by a warm period (interstadial and/or Holocene). During this warmer period, the cave ice melted and cryogenic and non-cryogenic Weichselian calcite precipitates were deposited on the cave ground or on fallen blocks, respectively.

scholarly journals Measured and modelled source water δ18O based on tree-ring cellulose of larch and pine trees from the permafrost zone

2020 ◽  
Vol 13 (1) ◽  
pp. 224-229
Author(s):  
OV Churakova-Sidorova ◽  
S Lienert ◽  
G Timofeeva ◽  
R Siegwolf ◽  
J Roden ◽  
...  
Keyword(s):  
Tree Ring ◽  
Permafrost Zone ◽  
Source Water ◽  
Pine Trees ◽  
Tree Ring Cellulose

scholarly journals Climate impacts on radial growth and vegetation activity of two co-existing Mediterranean pine species

2015 ◽  
Vol 45 (12) ◽  
pp. 1748-1756 ◽  
Author(s):  
Edmond Pasho ◽  
Arben Q. Alla
Keyword(s):  
Time Scales ◽  
Tree Ring ◽  
Radial Growth ◽  
Vegetation Index ◽  
Late Summer ◽  
Climate Impacts ◽  
Drought Indices ◽  
Vegetation Activity ◽  
Earlywood Width ◽  
The Impact

Improved knowledge of the time scales at which drought stress mostly influences tree growth is crucial for the early detection of forest dieback. This study aimed to evaluate the impact of climate (temperature and precipitation) on vegetation activity (normalized difference vegetation index (NDVI) and enhanced vegetation index (EVI)) of Pinus halepensis Mill. and Pinus pinea L. mixed forest located in western Albania and to assess the drought impact (standardized precipitation index (SPI) and standardized precipitation evapotranspiration index (SPEI)) calculated at different time scales (1–12 months) on radial growth (earlywood width, latewood width, and tree-ring width) and vegetation activity of these species. Both vegetation indices showed a negative response to August temperatures, and the EVI responded positively to September precipitation. NDVI and EVI were significantly affected by the SPI in spring and late summer. All tree-ring features in P. halepensis were positively related with EVI in August, whereas P. pinea latewood width showed a significant and positive relationship with NDVI in September. Radial growth of P. halepensis responded significantly to both drought indices in late summer and early autumn, particularly the latewood width. Contrastingly, in P. pinea, only earlywood width showed vulnerability, mostly to the summer SPEI drought indices. These results are relevant to understand the impacts of increased drought intensity and frequency on tree radial growth and vegetation activity in a region that is vulnerable to climate variability.

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