Temporal variations of atmospheric water vapor δD and δ18O above an arid artificial oasis cropland in the Heihe River Basin

The high temporal resolution measurements of δD, δ18O, and deuterium excess (d) of atmospheric water vapor provide an improved understanding of atmospheric and ecohydrological processes at ecosystem to global scales. In this study, δD, δ18O, and d of water vapor and their flux ratios were continuously measured from May to September 2012 using an in situ technique above an arid artificial oasis in the Heihe River Basin, which has a typical continental arid climate. The monthly δD and δ18O increased slowly and then decreased, whereas the monthly d showed a steady decrease. δD, δ18O, and d exhibited a marked diurnal cycle, indicating the influence of the entrainment, local evapotranspiration (ET), and dewfall. The departures of δD, δ18O, and d from equilibrium prediction were significantly correlated with rain amount, relative humidity (RH), and air temperature (T). The “amount effect” was observed during one precipitation event. δD and δ18O were log linear dependent on water vapor mixing ratio with respective R2 of 17% and 14%, whereas d was significantly correlated with local RH and T, suggesting the less influence of air mass advection and more important contribution of the local source of moisture to atmospheric water vapor. Throughout the experiment, the local ET acted to increase δD and δ18O, with isofluxes of 102.5 and 23.50 mmol m−2 s−1‰, respectively. However, the dominated effect of entrainment still decreased δD and δ18O by 10.1 and 2.24‰, respectively. Both of the local ET and entrainment exerted a positive forcing on the diurnal variability in d.

[1]  X. Lee,et al.  Transition of stable isotope ratios of leaf water under simulated dew formation. , 2011, Plant, cell & environment.

[2]  G. Hsiao,et al.  The nocturnal water cycle in an open‐canopy forest , 2013 .

[3]  Kenneth P. Bowman,et al.  Stable isotopic composition of water vapor in the tropics , 2004 .

[4]  Xuhui Lee,et al.  Dew water isotopic ratios and their relationships to ecosystem water pools and fluxes in a cropland and a grassland in China , 2011, Oecologia.

[5]  Hans-Christian Steen-Larsen,et al.  Continuous measurements of atmospheric water vapour isotopes in western Siberia (Kourovka) , 2014 .

[6]  E. K. Webb,et al.  Correction of flux measurements for density effects due to heat and water vapour transfer , 1980 .

[7]  Kelly K. Caylor,et al.  On the calibration of continuous, high-precision delta18O and delta2H measurements using an off-axis integrated cavity output spectrometer. , 2009, Rapid communications in mass spectrometry : RCM.

[8]  Yohei Matsui,et al.  Evidence of deuterium excess in water vapor as an indicator of ocean surface conditions , 2008 .

[9]  D. Benson,et al.  Particle tracking and the diffusion‐reaction equation , 2013 .

[10]  R. Koster,et al.  Water isotopes in precipitation:. data/model comparison for present-day and past climates , 2000 .

[11]  I. Fung,et al.  “Amount effect” of water isotopes and quantitative analysis of post‐condensation processes , 2008 .

[12]  D. Yakir,et al.  Seasonal variations in the isotopic composition of near-surface water vapour in the eastern Mediterranean , 2008 .

[13]  L. Araguás‐Araguás,et al.  Deuterium and oxygen‐18 isotope composition of precipitation and atmospheric moisture , 2000 .

[14]  X. Lee,et al.  Modeling biophysical controls on canopy foliage water 18O enrichment in wheat and corn , 2012 .

[15]  X. Lee,et al.  Partitioning of evapotranspiration through oxygen isotopic measurements of water pools and fluxes in a temperate grassland , 2014 .

[16]  Ronald B. Smith,et al.  Stable isotope composition of water vapor in the atmospheric boundary layer above the forests of New England , 1999 .

[17]  X. Lee,et al.  deltaO of water vapour, evapotranspiration and the sites of leaf water evaporation in a soybean canopy. , 2008, Plant, cell & environment.

[18]  H. Scheifinger,et al.  Deuterium excess in precipitation of Alpine regions – moisture recycling , 2008, Isotopes in environmental and health studies.

[19]  Scot M. Miller,et al.  Vegetation induced changes in the stable isotope composition of near surface humidity , 2014 .

[20]  J. Richards,et al.  Nighttime Stomatal Conductance and Transpiration in C3 and C4 Plants1[W] , 2006, Plant Physiology.

[21]  X. Lee,et al.  Determining the Oxygen Isotope Composition of Evapotranspiration Using Eddy Covariance , 2010 .

[22]  J. Gat.  OXYGEN AND HYDROGEN ISOTOPES IN THE HYDROLOGIC CYCLE , 1996 .

[23]  R. W. Vachon,et al.  Stable isotopic variations in west China: A consideration of moisture sources , 2007 .

[24]  R. Bradley,et al.  Stable isotopes in precipitation in the Asian monsoon region , 2005 .

[25]  Timothy J. Griffis,et al.  Tracing the flow of carbon dioxide and water vapor between the biosphere and atmosphere: A review of optical isotope techniques and their application , 2013 .

[26]  Z. Sharp,et al.  Surface measurements of upper tropospheric water vapor isotopic composition on the Chajnantor Plateau, Chile , 2011 .

[27]  W. Liu,et al.  An overview of precipitation isotopes over the Extensive Hexi Region in NW China , 2015, Arabian Journal of Geosciences.

[28]  D. Yakir,et al.  Fluxes of CO2 and water between terrestrial vegetation and the atmosphere estimated from isotope measurements , 1996, Nature.

[29]  Zhian Sun,et al.  Deuterium excess variations of rainfall events in a coastal area of South Australia and its relationship with synoptic weather systems and atmospheric moisture sources , 2013 .

[30]  J. Ehleringer,et al.  Contributions of evaporation, isotopic non-steady state transpiration and atmospheric mixing on the delta18O of water vapour in Pacific Northwest coniferous forests. , 2006, Plant, cell & environment.

[31]  M. Majoube.  Fractionnement en oxygène 18 et en deutérium entre l’eau et sa vapeur , 1971 .

[32]  X. Lee,et al.  Water vapour 18O/16O isotope ratio in surface air in New England, USA , 2006 .

[33]  Harald Sodemann,et al.  Continuous monitoring of summer surface water vapor isotopic composition above the Greenland Ice Sheet , 2013 .

[34]  M. Tsujimura,et al.  Isotopic variation of precipitation over eastern Mongolia and its implication for the atmospheric water cycle , 2007 .

[35]  K. Yoshimura,et al.  Characteristics of Seasonal Variation of Near-Surface Water Vapor D/H Isotope Ratio Revealed by Continuous in situ Measurement in Sapporo, Japan , 2012 .

[36]  W. Dansgaard.  The Abundance of O18 in Atmospheric Water and Water Vapour , 1953 .

[37]  T. Yao,et al.  Relationships between δ18O in summer precipitation and temperature and moisture trajectories at Muztagata, western China , 2006 .

[38]  M. Heimann,et al.  Water isotope modeling in the Asian monsoon region , 1997 .

[39]  Ke Wang,et al.  Atmospheric water vapor transport from westerly and monsoon over the Northwest China , 2005 .

[40]  Jonathon S. Wright,et al.  Properties of air mass mixing and humidity in the subtropics from measurements of the D/H isotope ratio of water vapor at the Mauna Loa Observatory , 2011 .

[41]  Salah Er-Raki,et al.  Evapotranspiration components determined by stable isotope, sap flow and eddy covariance techniques , 2004 .

[42]  C. Sonntag,et al.  An 8‐year record of the seasonal variation of 2H and 18O in atmospheric water vapour and precipitation at Heidelberg, Germany , 1991 .

[43]  J. Worden,et al.  A test of the advection‐condensation model for subtropical water vapor using stable isotopologue observations from Mauna Loa Observatory, Hawaii , 2012 .

[44]  X. Lee,et al.  Oxygen isotope composition of evapotranspiration and its relation to C4 photosynthetic discrimination , 2009 .

[45]  X. Lee,et al.  Intercomparison of four commercial analyzers for water vapor isotope measurement , 2012 .

[46]  J. Jouzel,et al.  Global Climatic Interpretation of the Deuterium-Oxygen 18 Relationship , 1979 .

[47]  X. Lee,et al.  Water vapor and precipitation isotope ratios in Beijing, China , 2010 .

[48]  Kelly K. Caylor,et al.  Uncertainties in the assessment of the isotopic composition of surface fluxes: A direct comparison of techniques using laser-based water vapor isotope analyzers , 2012 .

[49]  Qing Xiao,et al.  Heihe Watershed Allied Telemetry Experimental Research (HiWATER): Scientific Objectives and Experimental Design , 2013 .

[50]  Sun Xiaomin,et al.  Short-term variations of vapor isotope ratios reveal the influence of atmospheric processes , 2011 .

[51]  A. Bass,et al.  Extreme short‐term stable isotope variability revealed by continuous rainwater analysis , 2012 .

[52]  J. Ehleringer,et al.  Deuterium excess reveals diurnal sources of water vapor in forest air , 2010, Oecologia.

[53]  L. Sternberg,et al.  The use of stable isotopes to study ecosystem gas exchange , 2000, Oecologia.

[54]  X. Lee,et al.  Continuous measurement of water vapor D/H and 18 O/ 16 O isotope ratios in the atmosphere , 2008 .

[55]  D. Noone.  Pairing Measurements of the Water Vapor Isotope Ratio with Humidity to Deduce Atmospheric Moistening and Dehydration in the Tropical Midtroposphere , 2012 .

[56]  Jiemin Wang,et al.  Intercomparison of surface energy flux measurement systems used during the HiWATER‐MUSOEXE , 2013 .

[57]  Livio Gianfrani,et al.  Advances in laser-based isotope ratio measurements: selected applications , 2008 .

[58]  F. Gasse,et al.  Seasonal evolution of the isotopic composition of atmospheric water vapour above a tropical lake: Deuterium excess and implication for water recycling , 2008 .

[59]  K. Yoshimura,et al.  Influence of synoptic weather events on the isotopic composition of atmospheric moisture in a coastal city of the western United States , 2013 .

[60]  A. Knohl,et al.  Water vapor δ 2 H and δ 18 O measurements using off-axis integrated cavity output spectroscopy , 2009 .

[61]  B. Helliker,et al.  Novel Approaches for Monitoring of Water Vapor Isotope Ratios: Plants, Lasers and Satellites , 2010 .

[62]  J. Rambo.  Investigating forest-atmosphere water exchange with high frequency spectroscopy isotope observations , 2013 .

[63]  Jianping Huang,et al.  A meta‐analysis of water vapor deuterium‐excess in the midlatitude atmospheric surface layer , 2012 .

[64]  S. Bony,et al.  Evolution of the stable water isotopic composition of the rain sampled along Sahelian squall lines , 2010 .

[65]  X. Lee,et al.  In Situ Measurement of the Water Vapor 18O/16O Isotope Ratio for Atmospheric and Ecological Applications , 2005 .

[66]  M. Stewart.  Stable isotope fractionation due to evaporation and isotopic exchange of falling waterdrops: Applications to atmospheric processes and evaporation of lakes , 1975 .

[67]  Heini Wernli,et al.  Air parcel trajectory analysis of stable isotopes in water vapor in the eastern Mediterranean , 2008 .

[68]  X. Lee,et al.  A modeling investigation of canopy-air oxygen isotopic exchange of water vapor and carbon dioxide in a soybean field , 2010 .

[69]  Harald Sodemann,et al.  Deuterium excess as a proxy for continental moisture recycling and plant transpiration , 2013 .

[70]  K. Bowman,et al.  Estimate of bias in Aura TES HDO/H 2 O profiles from comparison of TES and in situ HDO/H 2 O measurements at the Mauna Loa observatory , 2010 .

[71]  H. Celle-Jeanton,et al.  Oxygen-18 variations of rainwater during precipitation: application of the Rayleigh model to selected rainfalls in Southern France , 2004 .

[72]  X. Lee,et al.  Temporal variations of the 18O/16O signal of the whole‐canopy transpiration in a temperate forest , 2007 .

[73]  Dan Yakir,et al.  Using stable isotopes of water in evapotranspiration studies , 2000 .