Short-Term Study on Variations of Carbon Dioxide and Methane Emissions from Intertidal Zone of the Yellow River Estuary during Autumn and Winter

Abstract

To investigate the spatial and temporal variations of carbon dioxide (CO2) and methane (CH4) emissions and determine the key environmental factors influencing their fluxes across the coastal marsh dominated by Suaeda salsa in the Yellow River estuary (China), short-term measurements were conducted in intertidal zone in autumn and winter during 2011–2012. Results showed that mean CO2 and CH4 fluxes and their cumulative emissions indicated intertidal zone of the examined marshes as strong CO2 source and weak CH4 sink over all sampling seasons with values of 34.35 mgCO2·m−2·h−1 and -0.0084 mgCH4·m−2·h−1 and 804.21 gCO2·m−2 and -198.85 mgCH4·m−2, respectively. Temporal variations of CO2 emission were strongly correlated with air and sediment temperatures, while spatial variations were mainly affected by vegetation composition at spatial scale. The freeze/thaw cycles in sediments during early winter and midwinter were one of main factors influencing the temporal variations of CH4 emission, while the concentrations of sulfate might greatly influence the spatial variation of CH4 fluxes. Next step, to assess the CO2 and CH4 inventory precisely during autumn and winter, the potential effects of exogenous nutrient loading on their emissions from intertidal zone of the Yellow River estuary should be emphasized and the long-term studies should be conducted.