LAUSR

Abstract The high concentrations of lipid biomarkers in peat and the close relation between peatland development and hydrological conditions merit further assessment of the paleohydrological proxy potential of the 2H/1H ratio of leaf wax n-alkanes (δ2Halk) in peat deposits. In the context of the dynamics of the East Asian summer monsoon, detailed investigation of modern processes is an important way to improve our understanding of the controls on δ2Halk records from Chinese peat deposits. This review first synthesizes the results of investigations of modern processes in the Dajiuhu peatland of central China, complemented by results from other peatlands and nearby non-peatland sites, to evaluate how the 2H/1H ratio changes from source water to leaf water and then to lipids in leaf waxes and ultimately to peat deposits. The results reveal that the precipitation δ2H values and the peatland plant types are the two major factors that control the δ2Halk signals preserved in peat at Dajiuhu. Comparison of results from Holocene δ2Halk sequences from other Chinese peat deposits illustrates how peat δ2Halk values respond to paleoclimate changes on centennial to millennial timescales throughout the East Asian summer monsoon region. Finally, proposed incubations of peat-forming plants in controlled chambers that could assess the response of plant δ2Halk values to environmental stresses are described. As an example, responses of the compound-specific biomarker δ2H and δ13C values of Sphagnum, the dominant plant in the Dajiuhu peatland, could provide important information on the symbiotic relation between Sphagnum and microbes. It is expected that experiments such as these that combine the carbon and hydrogen isotope compositions of multiple lipids will yield important new insights into the responses of peatland ecosystems to climate changes.