Status: this discussion paper is a preprint. It has been under review for the journal Biogeosciences (BG). The manuscript was not accepted for further review after discussion.
Environmental controls on leaf wax δD ratios in surface peats across the monsoonal region of China
X. Huang,J. Xue,X. Wang,and P. A. Meyers
Abstract. Leaf wax molecular and isotopic ratios are generally considered robust isotopic paleohydrologic proxies. Here we evaluate the proxy value of the molecular distributions and hydrogen isotopic compositions of long chain n-alkanes (δDalk) in surface peats collected from peatlands across a range of annual air temperatures from 1 to 15 °C and a range of annual mean precipitation from 720 to 2070 mm in the monsoonal region of China. The alkane ratios (ACL and CPI) and δDalk values show relatively large variations in multiple samples from a single site, highlighting the complexity of these ratios at a small spatial scale. In the montane Zoigê peatland, the apparent fractionation between precipitation and δDalk is more positive than in the other six sites, which is possibly an effect of the higher conductivity of the water in this high elevation site (3500 m a.s.l.). At a larger spatial scale, the site-averaged CPI ratios and the δDalk values of n-C29 and n-C31 alkanes show significant correlation with the air temperature and precipitation. These results support the application of the CPI ratio and the δDalk ratios of n-C29 and n-C31 alkanes as sensitive paleohydrologic proxies on millennial and larger timescales.
Received: 09 Aug 2015 – Discussion started: 14 Sep 2015
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