Leaf Wax Hydrogen Isotopes as a Hydroclimate Proxy in the Tropical Pacific
| Autor: | Ashley E. Maloney, David Sear, Julian P. Sachs, Sarah Nemiah Ladd, Giorgia Camperio, Matthew Prebble, J. D. Hassall, Daniel B. Nelson, Nathalie Dubois, Peter G. Langdon |
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| Přispěvatelé: | Maloney, A. E., 4 School of Oceanography University of Washington Seattle WA USA, Nelson, D. B., 6 Department of Environmental Sciences‐Botany University of Basel Basel Switzerland, Prebble, M., 7 School of Earth and Environment University of Canterbury Christchurch New Zealand, Camperio, G., 1 Swiss Federal Institute of Aquatic Science and Technology (EAWAG) Dept. of Surface Waters—Research and Management Dübendorf Switzerland, Sear, D. A., 9 School of Geography and Environmental Science University of Southampton Southampton UK, Hassall, J. D., Langdon, P. G., Sachs, J. P., Dubois, N. |
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Atmospheric Science
010504 meteorology & atmospheric sciences Hydrogen Soil Science chemistry.chemical_element Aquatic Science 01 natural sciences Proxy (climate) 0105 earth and related environmental sciences Water Science and Technology Tropical pacific Wax Ecology Isotope Hydrogen isotope ddc:551 Paleontology Forestry 15. Life on land 16. Peace & justice chemistry 13. Climate action Environmental chemistry visual_art ddc:577.7 visual_art.visual_art_medium Environmental science Mangrove |
| Zdroj: | Journal of Geophysical Research: Biogeosciences, 126 (3) |
| Popis: | Hydrogen isotope ratios of sedimentary leaf waxes (δ2HWax values) are increasingly used to reconstruct past hydroclimate. Here, we add δ2HWax values from 19 lakes and four swamps on 15 tropical Pacific islands to an updated global compilation of published data from surface sediments and soils. Globally, there is a strong positive linear correlation between δ2H values of mean annual precipitation (δ2HP values) and the leaf waxes n‐C29‐alkane (R2 = 0.74, n = 665) and n‐C28‐acid (R2 = 0.74, n = 242). Tropical Pacific δ2HWax values fall within the predicted range of values based on the global calibration, and the largest residuals from the global regression line are no greater than those observed elsewhere, despite large uncertainties in δ2HP values at some Pacific sites. However, tropical Pacific δ2HWax values in isolation are not correlated with estimated δ2HP values from isoscapes or from isotope‐enabled general circulation models. Palynological analyses from these same Pacific sediment samples suggest no systematic relationship between any particular type of pollen distribution and deviations from the global calibration line. Rather, the poor correlations observed in the tropical Pacific are likely a function of the small range of δ2HP values relative to the typical residuals around the global calibration line. Our results suggest that δ2HWax values are currently most suitable for use in detecting large changes in precipitation in the tropical Pacific and elsewhere, but that ample room for improving this threshold exits in both improved understanding of δ2H variability in plants, as well as in precipitation. Plain Language Summary: Past precipitation patterns are difficult to reconstruct, limiting our ability to understand Earth’s climate system. Geochemists reconstruct past precipitation by measuring the amount of heavy hydrogen naturally incorporated into the waxy coating of leaves, which is preserved in mud that accumulates in lakes, soils, and oceans. Heavy hydrogen in leaf waxes is strongly correlated with local precipitation, allowing us to learn about rainfall intensity, temperature, and cloud movement. However, no existing calibration studies include sites from the tropical Pacific, home to the most intense rainfall on the planet and populations that rely on rain for drinking water and farming. We measured heavy hydrogen in leaf waxes from tropical Pacific islands and show that although values are within the global calibration error, no precipitation relationship exists within the region. Plant type distributions do not explain the lack of correlation, which is best attributed to poorly constrained estimates of heavy hydrogen in local rain and the relatively small range of variability within the region. At present, heavy hydrogen from ancient leaf waxes can show large changes in past precipitation, but improved process‐level understanding is needed to use this tool to understand smaller changes in the tropical Pacific and elsewhere. Key Points: Leaf wax 2H/1H ratios are correlated with mean annual precipitation 2H/1H ratios globally, but not in the tropical Pacific. Deviations from the global relationship between precipitation leaf wax 2H/1H ratios cannot be predicted from palynological assemblages. Small range and large uncertainties in estimates of tropical Pacific precipitation 2H/1H ratios likely account for poor correlations. Swiss National Science Foundation National Science Foundation (NSF) http://dx.doi.org/10.13039/100000001 Natural Environment Research Council (NERC) http://dx.doi.org/10.13039/501100000270 Department of Education and Training, Australian Research Council (ARC) http://dx.doi.org/10.13039/501100000923 http://10.0.15.89/ethz-b-000412154 |
| Databáze: | OpenAIRE |
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