![Sample our Physical Sciences journals, sign in here to start your FREE access for 14 days]({"type":"image" , "src" : "/sda/110819/TOC-Subject-Sample-2021-Physical-Sciences.jpg"})
Abstract
Based on the monthly δ18O value measured over a hydrology period in precipitation, runoff of five tributaries and the main lake of the Poyang Lake Basin, combined with hydrological and meteorological data, the characteristics of δ18O in precipitation (δ18OPPT) and runoff (δ18OSUR) are discussed. The δ18OPPT and δ18OSUR values range from−2.75 to−14.12 ‰ (annual mean value=−7.13 ‰ ) and from−2.30 to−8.56 ‰, respectively. The seasonal variation of δ18OPPT is controlled by the air mass circulation in this region, which is dominated by the Asian summer monsoon and the Siberian High during winter. The correlation between the wet seasonal averages of δ18OSUR in runoff of the rivers and δ18OPPT of precipitation at the corresponding stations shows that in the Poyang Lake catchment area the river water consists of 23% direct runoff (precipitation) and 77% base flow (shallow groundwater). This high proportion of groundwater in the river runoff points to the prevalence of wetland conditions in the Poyang Lake catchment during rainy season. Considering the oxygen isotopic composition of the main body of Poyang Lake, no isotopic enrichment relative to river inflow was found during the rainy season with maximum expansion of the lake. Thus, evaporation causing isotopic enrichment is a minor component of the lake water balance in the rainy period. During dry season, a slight isotopic enrichment has been observed, which suggests a certain evaporative loss of lake water in that period.
Acknowledgements
The authors would like to thank financial supports of Major Science and Technology Program for Water Pollution Control and Treatment (2008zx07526-008-03); the International Science and Technological Cooperation Projects of China (2006DFB91920); the National 11th Five-Year Technology Based Plan Top of China (2007BAB23CO2); National Natural Science Foundation of China (40672159; 41040032). Thanks are also addressed to the two anonymous reviewers whose comments helped to improve the manuscript.