Extreme Methane Bubbling Emissions from a Subtropical Shallow Eutrophic Pond

Abstract

For the first time we report on real time diel bubble and diffusion gas fluxes lasting for 48 hours of a subtropical shallow pond. The averaged diffusion fluxes of methane and carbon dioxide were 0.074 and 62.70 mg•m-2•h-1, and the averaged ebullition fluxes of methane and carbon dioxide were 24.726 and 1.92 mg•m-2•h-1 respectively. Bubble emissions of CH4 and CO2 accounted for 99.7% of the total CH4 emission and only 3.0% of the totalCO2 from the pond respectively. The CH4 flux across the water-air interface of the pond was 595.20 mg•m-2•h-1 and equaledCO2 flux of 14880.0 mg•m-2•d-1 by multiplying its global warming potential. Thus, the small pond added equivalent of 35.712 kg/dCO2 emission by transferring CO2 to CH4 in the summer, in which process CO2 was absorbed owing to alga propagation and CH4 emission was derived from the anaerobic degradation of dead alga buried on its bottom.