In situ methane production in a small, hypereutrophic, hard‐water lake: Loss of methane from sediments by vertical diffusion and ebullition 1

Abstract

The rate and quantity of methane produced by sediments of Wintergreen Lake were estimated by separately measuring methane lost by ebullition using bubble traps and by estimating methane lost to the water column by diffusion. The maximum rates of methane loss by ebullition occurred in late summer and were 35 mmol·m−2·d−1 in 1972 and 37 in 1973. The average dissolved methane flux for 1972 was estimated to be in the range of 10–46 mmol·m−2·d−1. The minimum value was estimated by summing dissolved methane concentrations in the water column for each sampling date. The maximum value was estimated using the eddy diffusion coefficient of 4.9 × 10−3 cm2·s−1, calculated from the temperature method of Hutchinson. This methane diffusion rate was about two times the average rate of methane lost by ebullition (21 mmol·m−2·d−1) over the same time period. Dissolved methane was detected only in anoxic waters during summer stratification and within a meter of both the sediment and ice during winter. Ebullition also occurred during winter.