Status of Methane Emission from Indian Wetlands (Saline vs. Freshwater): A Mini Review

Wetlands are amongst the most important natural ecosystems on earth. India is blessed to have several multifunctional wetland ecosystems. Apart from their functional significance, wetlands also act as sources or sinks for greenhouse gases (GHGs) depending on their intrinsic factors. Methane (CH4), one of the major GHGs, is emitted from wetlands. The present paper attempts to review the status of Indian wetlands in terms of CH4 emission. Selected studies have been taken into consideration in the present paper to have an idea about the range of fluxes observed in air–water and air–soil interface of Indian wetlands, with special emphasis on the differences between saline and freshwater wetlands. The present study also emphasises important controlling factors such as dissolved oxygen (DO), salinity, sulphate, soil temperature, pH and sediment water content that are responsible for seasonal variations in CH4 flux. Mean air–soil CH4 flux in Indian wetlands ranged between ~ 6 and ~ 526 mg m−2 h−1, whereas air–water methane CH4 fluxes ranged between ~ 3 and ~ 194 mg m−2 h−1.