Methane fluxes from the littoral zone of hypereutrophic Taihu Lake, China

Abstract

Methane (CH 4) fluxes were measured in hypereutrophic Meiliang Bay of Taihu Lake wit static chambers for 1 year. The results showed that the macrophyte-covered infralittoral zones were the "hotspots" of CH 4 emission in water systems. There were large temporal variations for CH 4 fluxes, ranging from - 1.7 to 131 mg CH 4 m -2 h -1, in the macrophyte-covered littoral zone. The highest CH 4 emissions occurred during the period of the summer algal bloom. The amount of CH 4 flux from June to September accounted for about 50-90% of the annual fluxes. CH 4 fluxes from the bare infralittoral zone (-0.2∼4.2 mg CH 4 m -2 h -1) were low and close to those in the pelagic zone. The difference in CH 4 fluxes between macrophyte-covered and bare infralittoral zones indicated that vegetation in the inundated area played an essential role in CH 4 production. In the infralittoral zone, the redox condition (DO, Eh), temperature, and primary production controlled CH 4 fluxes; these variables explained 47% of flux variation, whereas such influences were not detected in the pelagic zone. Copyright 2006 by the American Geophysical Union.