R.S. Khoiyangbam, Kangabam Kripaliya Devi, Nongthombam Suraj Singh, Naorem Twinkle Devi, Geetanjali Pukhrambam and Suraj S. Chingangbam
Abstract
The methane (CH4) flux from thick floating vegetative biomass (phumdi) in Loktak Lake was measured in situ under aerobic and anaerobic conditions. The CH4 emission under the anaerobic condition (274 ± 10.71 mg m-2 d-1) was consistently higher than measurements under the aerobic condition (171.24 ± 9.00 mg m-2 d-1). The difference between the anaerobic and aerobic CH4 flux was apparently due to CH4 oxidation. Approximately 37 % of the biogenically produced CH4 in the phumdi was oxidised before emission. Methane production in phumdi was stratified vertically, ranging between 24.52 ± 1.24 and 165.99 ± 19.5 ?mol L phumdi-1 d-1 in different depth zones. The highest rates of CH4 production occurred in the 10-20 cm core. A short spell draw down of water level below the lake sediment translocates the peak of methanogenic activity down the phumdi profile. CH4 oxidation was recorded highest in the surface phumdi (0-10 cm), consuming 59-61 % of the produced methane.