Hydrogen isotope fractionation in modern plants along a boreal-tundra transect in Alaska

摘要: Abstract An increasing number of studies from high latitude settings use the stable hydrogen isotope ratio (δ2H) plant leaf waxes to quantify changes in past precipitation. Calibration modern vegetation and source water these landscapes is important more accurately reconstruct hydroclimate variability using sedimentary wax δ2H values. Here, we determine plant-water fractionations 12 sites along a south-north transect central Alaska, Fairbanks Deadhorse (64-70°N). We characterize values n-alkanes n-alkanoic acids plants their xylem values, as well surface soils, soil core, previously collected meteoric data region. find both transpiration (eLW/XW) biosynthetic (ewax/LW) fractionation are sensitive environmental controls with latitude, increased north, potentially due summer sunlight hours. Soil show near linear 2H enrichment toward associated evaporation, value ∼40 cm matching mean annual precipitation (MAP). Average net was calculated chain length weighted (ewax/XW) nearly same for n-alkanes, −112 ± 27‰, acids, −110 ± 23‰, common vascular plants. To provide range likely this transect, also calculate average MAP, finding less negative than waters (ewax/MAP, −89 ± 28‰ −86 ± 24‰ acids). compare across studies, determined ewax/MAP all available calibration found enriched (smaller fractionations) C27 (-87 ± 29‰), C29 (-87 ± 32‰), C31 (-91 ± 31‰) those global homolog averages. This new work Alaska contributes our growing understanding water-wax latitudes paleoprecipitation estimates.