Some properties of methane oxidation in a thermally stratified lake

This is the authors' abstract. We don't add key points for this paper.

Profiles of 14 CH 4 and 14 CO oxidation and concentrations of CH 4 , NH 4 + , and nitrogen oxides (N 2 O, NH 2 - , NH 3 - ) were studied in Lake St. George, Ontario, during late summer stratification. Metalimnetic maxima of the nitrogen oxides occurred and high rates of oxidation of CH 4 and CO were limited to a narrow band (<1 m) below the nitrogen oxide peaks at the oxic-anoxic interface. Oxidation of CH 4 and CO was strongly inhibited by the nitrification inhibitor allylthiourea. The affinity of the oxidizers for CH 4 (approximate K m = 4.6 µM), their sensitivity to picolinic acid, and the ratio of CH 4 oxidation to allylthiourea-sensitive CO oxidation together suggest that methanotrophs were responsible for the observed CH 4 oxidation. Pure cultures of Nitrosomonas europaea, although less sensitive to picolinic acid than the CH 4 oxidizers of Lake St. George, were affected by the inhibitor (approximate K i for inhibition of NH 4 + oxidation = 51 µM).