Dew water isotopic ratios and their relationships to ecosystem water pools and fluxes in a cropland and a grassland in China

Abstract

Dew formation has the potential to modulate the spatial and temporal variations of isotopic contents of atmospheric water vapor, oxygen and carbon dioxide. The goal of this paper is to improve our understanding of the isotopic interactions between dew water and ecosystem water pools and fluxes through two field experiments in a wheat/maize cropland and in a short steppe grassland in China. Measurements were made during 94 dew events of the D and (18)O compositions of dew, atmospheric vapor, leaf, xylem and soil water, and the whole ecosystem water flux. Our results demonstrate that the equilibrium fractionation played a dominant role over the kinetic fractionation in controlling the dew water isotopic compositions. A significant correlation between the isotopic compositions of leaf water and dew water suggests a large role of top-down exchange with atmospheric vapor controlling the leaf water turnover at night. According to the isotopic labeling, dew water consisted of a downward flux of water vapor from above the canopy (98%) and upward fluxes originated from soil evaporation and transpiration of the leaves in the lower canopy (2%).

Deuterium excess in the atmospheric water vapour of a Mediterranean coastal wetland: regional vs. local signatures

“…Whereas cryogenic trapping provides grab samples generally averaging a couple of hours, laser spectrometry performs continuous high frequency (up to ∼ 1 Hz) measurements of δ v (Kerstel and Gianfrani, 2008). This technology offers new insights into processes that affect the isotopic composition of atmospheric water vapour and the number of studies based on continuous ground level isotope measurements over multiweek periods is continuously increasing, either using a tunable diode laser (TDL) (Lee et al, 2006;Wen et al, 2010Wen et al, , 2012Griffis et al, 2011;Welp et al, 2012), off-axis integrated cavity output spectroscopy (OA-ICOS) (Sturm and Knohl, 2010;Sunmonu et al, 2012;Farlin et al, 2013;SteenLarsen et al, 2013) or wavelength-scanned cavity ring-down spectroscopy (WS-CRDS) Tremoy et al, 2012;Steen-Larsen et al, 2013. Among these experiments are some low latitude studies which have focused on the tracing of tropical or subtropical convective activity in West Africa (Tremoy et al, 2012) or in South America .…”

Wettability, Polarity, and Water Absorption of Holm Oak Leaves: Effect of Leaf Side and Age

“…Such surface features together with their chemical composition (Khayet and Fernández, 2012) may lead to a high degree of roughness and hydrophobicity (Koch and Barthlott, 2009;Konrad et al, 2012). The interactions of plant surfaces with water have been addressed in some investigations (Brewer et al, 1991;Brewer and Smith, 1997;Pandey and Nagar, 2003;Hanba et al, 2004;Dietz et al, 2007;Holder, 2007aHolder, , 2007bFernández et al, 2011Fernández et al, , 2014Roth-Nebelsick et al, 2012;Wen et al, 2012;Urrego-Pereira et al, 2013) and are a topic of growing interest for plant ecophysiology (Helliker and Griffiths, 2007;Aryal and Neuner, 2010;Limm and Dawson, 2010;Kim and Lee, 2011;Berry and Smith, 2012;Berry et al, 2013;Rosado and Holder, 2013;Helliker, 2014). On the other hand, the mechanisms of foliar uptake of water and solutes by plant surfaces are still not fully understood (Fernández and Eichert, 2009;Burkhardt and Hunsche, 2013), but they may play an important ecophysiological role (Limm et al, 2009;Johnstone and Dawson, 2010;Adamec, 2013;Berry et al, 2014).…”

Construction and progress of Chinese terrestrial ecosystem carbon, nitrogen and water fluxes coordinated observation

“…The development of in situ ecosystem carbon and water stable isotope fluxes measurement technique overcame the problem of nonlinear response of instruments (Wen et al, 2008(Wen et al, , 2012. It allowed in situ and continuous measurement of δ 18 O and δD of atmospheric water vapor , and isotopic ratio and flux ratio of atmospheric CO 2 δ 13 C (Pang et al, 2016).…”

“…This technology broke through the bottleneck of coordinated observation of eddy covariance and stable isotopes. It achieves the coordinated observation of ecosystem carbon and water vapor flux and δ 18 O, δD and δ 13 C fluxes (Wen et al, 2012(Wen et al, , 2015.…”