Effect of weir impoundments on methane dynamics in a river.
We measured CH4concentration, CH4oxidation in the water column and total CH4emissions to the atmosphere (diffusion and ebullition) in three weir impoundments and river reaches between them, in order to understand their role in river methane (CH4) dynamics. Sediment samples were also collected to determine CH4consumption and production potentials together with the contribution of individual methanogenic pathways. The CH4surface water concentration increased 7.5 times in the 16km long river stretch. Microbial CH4oxidation in the water column reached values ranging from 51 to 403nmoll-1d-1and substantially contributed to the CH4removal from surface water, together with CH4emissions. The total CH4emissions to the atmosphere varied between 0.8 and 207.1mmolCH4m-2d-1with the highest values observed upstream of the weirs (mean 68.5±29.9mmolCH4m-2d-1). Most of the CH4was transported through the air-water interface by ebullition upstream of the weirs, while the ebullition accounted for 95.8±2.0% of the total CH4emissions. Both CH4production and oxidation potential of sediments were higher upstream of the weirs compared to downstream of the weirs. The contribution of hydrogenotrophic methanogenesis to total CH4sediment production was 36.7-89.4% and prevailed upstream of the weirs. Our findings indicate that weirs might influence river CH4dynamics, especially by increased CH4production and consumption by sediments, followed by increasing CH4emissions to the atmosphere.
Department of Ecology and Environmental Sciences, Laboratory of Aquatic Microbial Ecology, Faculty of Science, Palacky University in Olomouc, Olomouc, Czech Republic. Electronic address: adambednarik01@gmail.com.
Adam
A
Bednařík
Department of Biogeochemistry, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany.
Martin
M
Blaser
Faculty of Sciences, University of South Bohemia, České Budějovice, Czech Republic; Biology Centre of the Academy of Sciences of the Czech Republic, Institute of Hydrobiology, České Budějovice, Czech Republic.
Anna
A
Matoušů
Department of Ecology and Environmental Sciences, Laboratory of Aquatic Microbial Ecology, Faculty of Science, Palacky University in Olomouc, Olomouc, Czech Republic.
Petr
P
Hekera
Department of Ecology and Environmental Sciences, Laboratory of Aquatic Microbial Ecology, Faculty of Science, Palacky University in Olomouc, Olomouc, Czech Republic.
Martin
M
Rulík
Methane ebullition; Methane emission; Methane production; Methanogenic pathways; River impoundment; River sediment