JOURNAL OF NATURAL RESOURCES ›› 2015, Vol. 30 ›› Issue (9): 1594-1605.doi: 10.11849/zrzyxb.2015.09.015

• Comprehensive Discussion • Previous Articles     Next Articles

Advances in the Research on Methane Emissions of Coastal Saline Wetlands in China

XU Xin-wanghao1, ZHAO Yi-fei1, ZOU Xin-qing1, TANG De-hao1, LIU Da-wei2   

  1. 1. Key Laboratory of Coastal and Island Development of Ministry of Education, Nanjing University, Nanjing 210023, China;
    2. Yancheng National Nature Reserve for Wetland Rare Birds, Yancheng 224057, China
  • Received:2014-07-17 Revised:2015-02-26 Online:2015-09-15 Published:2015-09-15

Abstract:

Methane is mainly produced by methanogenesis under anaerobic conditions, oxidized by methanotrophic bacteria under aerobic environment, and transported to atmosphere by diffusion, ebullition and aerenchyma of plants. Coastal saline wetlands store large proportion of carbon compared to the other ecosystems, and become a significant source of atmosphere CH4 due to the anaerobic environment. Coastal wetlands are characterized by high temporal and spatial variations of methane emission due to topographic feature, vegetation cover and astronomic tidal fluctuation, resulting in the difficulty in the field sampling of greenhouse gas, especially methane flux which is sensitive to global climate change. Consequently, it’s urgent to comprehensively investigate and review the methane emission in the coastal wetlands in order to accurately evaluate the contribution of coastal wetlands to global warming. The mechanism, spatial-temporal variations and controlling environment factors of CH4 emissions were summarized in this paper. We may safely draw the conclusion that the mean CH4 emissions from Minjiang River estuary were higher than those from Yangtze River estuary and Jiangsu coastal saline wetland. The average CH4 fluxes in spring, summer, autumn and winter were -0.0109, -0.0174, -0.0141 and -0.0089 mg CH4?m-2?h-1, indicating that the coastal marsh in Yellow River estuary acted as CH4 sink. In addition, significant differences existed among different tidal flats in Mangrove in South China. The effect of tidal fluctuation on CH4 emission presented to be a trend of “M”. When the tide rises, the CH4 fluxes firstly increase, and then begin to decrease with the increasing of tidal water. Later when the tide ebbs, the CH4 emit to the atmosphere obviously increase due to high abundant of produced CH4 in the spring tide. When the tide falls below the surface soil, CH4 is easily oxidized and so its flux decreased. However, there existed some problems we need to solve: 1) lacking of the standard system of the research method; 2) lacking of the research on the effect of microorganism and microbial enzymes on the CH4 emission; 3) strengthening the studies of effects of flood and ebb on the CH4 emission. Finally, we proposed the principles and methods of sampling when chamber was used to collect the gas sampling, which uses different sampling frequency, and samples at different site layouts according to the research objects and the variations of vegetation, soil, and hydrology in the coastal wetlands.

CLC Number: 

  • X502