Using stable hydrogen and oxygen isotopes to study water movement in soil-plant-atmosphere continuum at Poyang Lake wetland, China
Water movement in the soil-plant-atmosphere continuum (SPAC) has a significant effect on the biogeochemical process in wetlands. This study investigated the water movement in the SPAC in Poyang Lake wetland, which is a protected area with an important ecological function within the Yangtze River basin, under different water-level conditions by analyzing the responses of river, groundwater, soil and plants to precipitation using stable hydrogen and oxygen isotopes. The results show that the stable hydrogen and oxygen isotopic compositions (δ18O and δD) of soil water decrease with increasing depth due to the near surface evaporation. During the dry season the water-level in Poyang Lake is low, when it rains the influencing depth of precipitation and evaporation on soil water isotopic signatures was 20 cm below the ground surface. The rain water infiltrates into the soil, recharges groundwater and flows to the river. When the water-level in Poyang Lake is low, the Xiu River is recharged by the groundwater, which recharges the soil water by capillary rise. During the flood season, the water-level is high and the water in Poyang Lake reaches or covers the meadows, recharges the groundwater and soil water. In the meantime, the water in Poyang Lake can be recharged by rain water when it rains. During the dry season when it doesn’t rain, plants mainly use groundwater, but soil water is preferred and plants don’t use rainwater directly when it rains. When the lake water-level is extremely low, the plants in Poyang Lake wetland may suffer from water stress, which is harmful for plant growth.
KeywordsWater movement SPAC Water-level Poyang Lake wetland
The authors would like to thank the National Natural Science Foundation of China.
This study was supported by the National Natural Science Foundation of China (Nos. 51279143, 51409191) and the Collaborative Innovation Center for Major Ecological Security Issues of Jiangxi Province and Monitoring Implementation (No.JXS-EW-00).
Compliance with ethical standards
Conflict of Interest
The authors declare that they have no conflict of interest.
This study does not involve human participants and animals.
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