Extreme triple oxygen isotope fractionation in Equisetum

• 成果类型: Article
• 署名作者: Sharp, Zachary; Wostbrock, Jordan; Gargano, Anthony; Hare, Vincent; Johnson, Jessica; Cerling, Thure; Banerjee, Payal; Peshek, Catherine; Knutson, Cloe; Hartzell, Lauren; Cano, Erick; Stiles, Elena; Bassett, Kelley R.; Holland, Kira; Dowd, Michael H.; Sae-Lim, Jarunetr (nadia); Dominguez, Teresa; Bryant, Dalton; Di Marcantonio, Eduardo; Wainwright, Jensen; Horsford, Maxwell; Botte, Paul; Gagnon, Catherine; Rudall, Paula J.; Ehleringer, James
• 署名单位: University of New Mexico; Yale University; University of Cape Town; Utah System of Higher Education; University of Utah; Utah System of Higher Education; University of Utah; University of California System; University of California Santa Cruz; University of Washington; University of Washington Seattle; Swedish University of Agricultural Sciences; University of Alberta; University of Hawaii System; University of Hawaii Manoa; University of California System; University of California Irvine; University of Alabama System; University of Alabama Tuscaloosa; Sapienza University Rome; University of Oregon; State University of New York (SUNY) System; University at Albany, SUNY; State University of New York (SUNY) College of Environmental Science & Forestry; Brown University; Royal Botanic Gardens, Kew
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.2507455122
• 发表日期: 2025-11-04
• 页码: e2507455122
• 关键词: triple oxygen isotopes; extreme isotope fractionation; plant physiology; phytolith isotope chemistry; paleoclimatology; LEAF WATER; SILICA BODIES; PHYTOLITHS; hydrogen; MODEL; proxy; cellulose; humidity; patterns; insights

摘要

Triple oxygen isotope values of xylem water were measured along the length of smooth horsetail stems (Equisetum laevigatum). Extreme isotope enrichment is observed moving from base to stem tip. delta 18O values range from-8.3%o at the base to 82.6%o at the tip. Delta ' 17O values range from 0 to-1,797 per meg. The delta 18O and Delta ' 17O values are the most extreme measured for any terrestrial material and expand the known range of Delta ' 17O values by fivefold for mass-dependent fractionation on Earth. The extreme isotope enrichments are explained using a hybrid evaporation/chain-of-lakes model, allowing us to refine the leaf respiration coefficient to theta k = 0.511 +/- 0.001. This new value is required to explain the low Delta ' 17O values previously measured in desert plants and animals and is critical when using fossil samples for paleoclimate reconstruction. Coexisting phytoliths and stem water were also measured. The 1000ln18 alpha silica-water value at the plant base (35.89%o) appears to be in isotopic equilibrium, with far smaller fractionations of 10.3%o near the tip. The smaller fractionations at higher levels are explained by continual silica deposition as the plant elongates and the delta 18O values of each segment become higher. The overall integrated phytolith value is a combination of early and late silica growth. The Delta ' 17Osilica-Delta ' 17Owater values are not in equilibrium, explained by a kinetic isotope effect, with a lambda value of 0.5205 vs. 0.5244 for equilibrium. Phytolith isotope values may lead to erroneous interpretations for paleoclimate reconstruction.