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The hydrogen isotopic composition of plant wax (delta D-wax) inherits the isotopic values of the source water and isotopic fractionation that take place in lipid biosynthesis. The delta D-wax values of n-alkanes or n-acids in sediment records are considered to be effective paleo-delta D for precipitation proxies for different timescales. However, the vegetation effect also contributes substantially to the apparent fractionation values (epsilon(w-p)) between the precipitation and plant. Therefore, a method for evaluating the dominant plant source in the sediment records is key for reconstructing a reliable paleo-delta D-p record. In this study, based on field data from the extremely arid Qaidam Basin and the semi-arid central Chinese Loess Plateau (CLP), a plant type index (Pta), based on the traditional P-aq and n-alkane C-31/C-29 index, was used to evaluate the dominant plant type that contributed to the sediments. In the arid and semi-arid region, the Pta values of the aquatic plants were <90, while the shrub Pta ranged from 90 to 180 and the grass Pta was >180. A test on contemporary soils and surface lake sediments also showed that the Pta index could estimate the regional vegetation distribution in modern environments. We also evaluated the dominant n-alkane source for four sediment records in China during the last millennium and reconstructed a regional paleo-delta D-p by choosing a different epsilon(w-p). The estimated paleo-delta D-p values showed a good correlation with the modern regional summer delta D-p. We suggest that a large number of field studies are needed to improve the Pta index for quantitatively calculating the precise ratios for various plant sources. Such data would play a key role in improving hydrogen isotopic hydroclimatic research. (C) 2018 Elsevier Ltd. All rights reserved.