Original paper

Quality of detritus impacts on spatial variation of methane emissions from littoral sediment of a boreal lake

Kankaala, Paula Käki; Ojala, Anne

Abstract

Spatial variation in CH4 emissions in relation to net primary production (NPP) of vegetation was studied in a reed (Phragmites australis)-dominated littoral zone of a boreal meso-eutrophic lake during three growing seasons. In a healthy reed stand close to the shoreline, the proportion of CH4 released to the atmosphere varied between 4% and 5% of NPP of P. australis. In a continuously flooded sparse reed stand in the middle infralittoral zone, this proportion was higher; plant-mediated emission was 18-24% of the NPP by P. australis, and the proportion of total emission (including ebullition) related to the NPP of all vegetation (including algae and Lemna trisulca) was 15-20%. In a batch experiment in the laboratory, detritus from L. trisulca and littoral algae maintained significantly higher CH4 production than detritus from P. australis. The results support the hypothesis that the high spatial and temporal variability in CH4 emissions in the littoral zone of the study lake was influenced by the quality and distribution of detritus in the anaerobic sediment.

Keywords

phragmitesplant-mediated emissiongreenhouse gasesmethanogens