Controls on leaf wax fractionation and δ2H values in tundra vascular plants from western Greenland

摘要: Abstract Hydrogen isotope ratios of leaf waxes are used to reconstruct past hydroclimate because they a reflection meteoric water, but the interpretation these signatures from ancient sedimentary archives relies on thorough understanding drivers modern variability and controls fractionation. These studies particularly valuable in high latitudes, regions especially vulnerable rapid climate change increasingly for plant-based proxy reconstructions hydroclimate, also where vegetation is understudied compared lower latitudes. Here we investigate δ2H values wax n-alkanes vascular tundra plants Kangerlussuaq area western Greenland. We collected variety common species study possible interspecies including dwarf shrubs (Betula nana, Empetrum hermaphroditum, Salix glauca), forbs graminoids (Vaccinium uliginosum, Rhododendron tomentosum, Calamagrostis lapponica), horsetail (Equisetum arvense), submerged aquatic macrophyte local lake (Stuckenia filiformis). Using previously measured stem waters help constrain potential n-alkane values, find that overall net fractionation (eapp) studied −75 ± 20‰. The eapp at consistent with other Arctic smaller than majority latitude sites. water xylem (elw/xw) precipitation (exw/p) both relatively constant, suggesting stable soil related fractionations across species. Estimates biosynthetic (ebio), as evidenced (ewax/lw), not constant sometimes assumed, small (average ebio −120 ± 27‰) many published estimates. This supports significant role shaping this setting, lipid biosynthesis may be driving differences values. finding suggests lipids rely use some proportion different hydrogen sources during synthesis, such stored NADPH. cumulative results survey water-wax suggest latitudes short summer growing season play an important governing low Better appropriate importance controlling plant necessary future using regions.