Stem water cryogenic extraction biases estimation in deuterium isotope composition of plant source water
Yongle Chen, Brent R. Helliker, Xianhui Tang, Fang Li, Youping Zhou, Xin Song
Abstract
Significance Stem xylem uptake and transport of plant source water is widely considered a critical component of the global water cycle. The deuterium signature of cryogenically extracted plant stem water (δ 2 H stem_CVD ) provides a useful means for studying water fluxes, but recent studies have shown uncertainty as to whether δ 2 H stem_CVD is a faithful reflection of true source water isotopic signal (δ 2 H source ). Here we confirm the common presence of significant deviations in δ 2 H stem_CVD from δ 2 H source in various plant species and demonstrate that this phenomenon is not caused by deuterium fractionation during root water uptake as traditionally thought, but rather is rooted in a cryogenic extraction-associated methodological artifact. Our findings may have wide-ranging implications for isotope-based ecohydrological and climate change studies.