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Arid Land Geography ›› 2022, Vol. 45 ›› Issue (3): 860-866.doi: 10.12118/j.issn.1000-6060.2021.318

• Biology and Pedology • Previous Articles     Next Articles

Continuous dynamic characteristics of wetland soil gas emission response to water level changes

LU Haibo1,2()   

  1. 1. College of Environmente and Life Sciences, Weinan Normal University, Weinan 714000, Shaanxi, China
    2. Key Laboratory of River Wetland Ecology and Environment in Shaanxi Province, Weinan 714000, Shaanxi, China
  • Received:2021-07-13 Revised:2021-12-15 Online:2022-05-25 Published:2022-05-31

Abstract:

Wetlands have an ecological purpose that is correlated with global climate change. On the background of climate change, the spatial and temporal variations of global precipitation amplify the effect on the water environment of river wetlands via catchment confluence, affecting the ecological function of wetlands significantly. To examine the relationship between wetland water level changes and soil gas emission, half water injection and full water injection treatments were considered in reed wetlands in the middle reaches of the Yellow River in China, and the differences in soil gas emission during the 7-day monitored were compared. Compared with natural sites, water injection created a significant difference in soil CO2 emission rate. Except for the H2O emission rate of full water injection, H2O, CO2, and H2S emission rates all considered upward trend with soil temperature rising. In the monitoring process, for the effect of half and full water injection, H2O emissions rate half and full water injection were basically the same, while the difference was higher in the later stage, the effect of did not disappear until 125.64 h, totally water injection resulted in an increase of 76.3% and 31.3% respectively; CO2 emissions rate appeared asynchronous-converging characteristics, the changes of environment in the initial stage resulted in the consistent reduction of CO2 emission, and considered a significant difference between 37.69 h and 68.66 h, although the water level recovered from 68.66 h to 125.64 h, the differences still existed, water injection resulted in a reduction of CO2 total emissions by 50.1% and 43.2% respectively. H2S emissions rate experienced changeless-asynchronous-changeless process, and totally, resulted in 42.3% and 32.3% increase. The study tracked the dynamic process of soil H2O, CO2, and H2S emission rates after water level rise and found that the effect of a rise of water level on the soil gas emission rate was asynchronous and persistent, demonstrating a long response cycle to CO2 emissions rate. The results consider high significance to the ecological function of river wetlands, the delayed response of wetland soil gas emission to water level change means that it has a significant effect on wetland ecological function, its fluctuation process needs a longer period of accurate study.

Key words: soil CO2 emission, changes of wetland water level, ecological function, the water injection test