查看文章

We developed a microsensor for the amperometric detection of dissolved hydrogen sulfide, H 2 S, in sediments and biofilms. The microsensor exhibits a fast (t 90< 0.2 to 0.5 s) and linear response to H 2 S over a concentration range of 1 to> 1000 μmol H 2 S l-1, and has a low stirring dependency of the microsensor signal (< 1 to 2%). We used the new microsensor to obtain the first microprofiles of H 2 S in an acidic lake sediment with a several cm thick flocculant surface layer. Despite the low pH of 4.6, a relative low SO 4 2-level in the lake water, and a broad O 2 respiration zone of ca 6 mm, we were able to measure H 2 S depth profiles in the sediment at a good resolution, that allowed for calculation of specific sulfate reduction and H 2 S oxidation activities. Such calculations showed highest sulfate reduction activity in the anoxic sediment down to ca 20 mm depth. A comparison of calculated areal rates of O 2 …