Manuscript_NH_revised_final_OG.pdf (1.68 MB)
Download file

Hydrogen isotope fractionation of leaf wax n-alkanes in southern African soils

Download (1.68 MB)
journal contribution
posted on 21.04.2017, 10:42 by Nicole Herrmann, Arnoud Boom, Andrew S. Carr, Brian M. Chase, Adam G. West, Matthias Zabel, Enno Schefuss
The hydrogen isotope composition of plant leaf wax (δDwax) has been found to record the isotope composition of precipitation (δDp). Hence, δDwax is increasingly used for palaeohydrological reconstruction. δDwax is, however, also affected by secondary factors, such as vegetation type, evapotranspiration and environmental conditions, complicating its direct application as a quantitative palaeohydrological proxy. Here, we present δDwax data from soils along vegetation gradients and climatic transects in southern Africa to investigate the impact of different environmental factors on δDwax. We found that δDwax correlated significantly with annual δDp (obtained from the interpolated Online Isotopes in Precipitation Calculator data set) throughout the eastern and central South Africa, where the majority of the mean annual precipitation falls during the summer. We found evidence for the effect of evapotranspiration on δDwax, while vegetation change was of minor importance. In contrast, we found that δDwax did not correlate with annual δDp in western and southwestern South Africa, where most of the annual precipitation falls during winter. Wide microclimatic variability in this topographical variable region, including distinct vegetation communities and high vegetation diversity between biomes as well as a potential influence of summer rain in some locals, likely compromised identification of a clear relationship between δDwax and δDp in this region. Our findings have implications for palaeoenvironmental investigations using δDwax in southern Africa. In the summer rain dominated eastern and central region, δDwax should serve well as a qualitative palaeohydrological recorder. In contrast, the processes influencing δDwax in the winter rain dominated western and southwestern South Africa remain unclear and pending further analyses potentially constrain its use as palaeohydrological proxy in this region.

History

Citation

Organic Geochemistry, 2017, doi: http://doi.org/10.1016/j.orggeochem.2017.03.008

Author affiliation

/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Geography/Physical Geography

Version

AM (Accepted Manuscript)

Published in

Organic Geochemistry

Publisher

Elsevier for European Association of Organic Geochemists

issn

0146-6380

Acceptance date

22/03/2017

Copyright date

2017

Available date

30/09/2018

Publisher version

http://www.sciencedirect.com/science/article/pii/S0146638016302273

Notes

The file associated with this record is embargoed until 18 months after the date of publication. The final published version may be available through the links above. Following the embargo period the above license applies.

Language

en