Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Sediment greenhouse gases (methane and carbon dioxide) in the Lobo‐Broa Reservoir, São Paulo State, Brazil: Concentrations and diffuse emission fluxes for carbon budget considerations
Carbon gases (methane, CH4, and carbon dioxide, CO2) were measured for the first time in sediments of the Lobo‐Broa Reservoir, near São Carlos in São Paulo State, Brazil. It is believed these are the first measurements of this kind in any of the many reservoirs located in Brazil. Even though the Lobo‐Broa Reservoir is classified as oligotrophic, the sediment gas concentrations were exceedingly high, ranging from 0.4–3 mmol L−1 for CH4 and 1–9 mmol L−1 for CO2. Both gases exceeded their in situ gas saturation values at these shallow water depths (7 m in central basin; 11 m at dam), resulting in numerous sediment bubbles. Organic matter was highly concentrated in the reservoir sediments, averaging 25.5% loss on ignition (LOI) (dam) to 26.9% LOI (central basin) for the 0–12 cm depth interval, with values as high as 29–30% LOI (12% organic carbon) in the surface 0–5 mm layer. The theoretical flux of dissolved pore water carbon gases to the sediment–water interface (SWI) averaged 3.4 mmol L−1 m−2 day−1 CH4 and 7.3 mmol L−1 m−2 day−1 CO2 for the surface 0–10 mm. From gas emission measurements at the water surface, it was calculated that 90% of CH4 is consumed either at the SWI or in the water column, resulting in a loss of 0.31 mmol L−1 m−2 day−1 of CH4 to the atmosphere. However, only 20% of the total CO2 gas transported across the water–atmosphere interface (36.3 mmol L−1 m−2 day−1, or 1600 mg CO2 m−2 day−1) was produced in the sediments. The remaining 80% of CO2 probably comes from other carbon sources. With CH4 oxidation in the aerobic water column, close to 30% of the carbon gas flux to the atmosphere could be accounted for by gas production of CO2 and CH4 in the sediments and their diffuse transport to the water column.
Sediment greenhouse gases (methane and carbon dioxide) in the Lobo‐Broa Reservoir, São Paulo State, Brazil: Concentrations and diffuse emission fluxes for carbon budget considerations
Carbon gases (methane, CH4, and carbon dioxide, CO2) were measured for the first time in sediments of the Lobo‐Broa Reservoir, near São Carlos in São Paulo State, Brazil. It is believed these are the first measurements of this kind in any of the many reservoirs located in Brazil. Even though the Lobo‐Broa Reservoir is classified as oligotrophic, the sediment gas concentrations were exceedingly high, ranging from 0.4–3 mmol L−1 for CH4 and 1–9 mmol L−1 for CO2. Both gases exceeded their in situ gas saturation values at these shallow water depths (7 m in central basin; 11 m at dam), resulting in numerous sediment bubbles. Organic matter was highly concentrated in the reservoir sediments, averaging 25.5% loss on ignition (LOI) (dam) to 26.9% LOI (central basin) for the 0–12 cm depth interval, with values as high as 29–30% LOI (12% organic carbon) in the surface 0–5 mm layer. The theoretical flux of dissolved pore water carbon gases to the sediment–water interface (SWI) averaged 3.4 mmol L−1 m−2 day−1 CH4 and 7.3 mmol L−1 m−2 day−1 CO2 for the surface 0–10 mm. From gas emission measurements at the water surface, it was calculated that 90% of CH4 is consumed either at the SWI or in the water column, resulting in a loss of 0.31 mmol L−1 m−2 day−1 of CH4 to the atmosphere. However, only 20% of the total CO2 gas transported across the water–atmosphere interface (36.3 mmol L−1 m−2 day−1, or 1600 mg CO2 m−2 day−1) was produced in the sediments. The remaining 80% of CO2 probably comes from other carbon sources. With CH4 oxidation in the aerobic water column, close to 30% of the carbon gas flux to the atmosphere could be accounted for by gas production of CO2 and CH4 in the sediments and their diffuse transport to the water column.
Sediment greenhouse gases (methane and carbon dioxide) in the Lobo‐Broa Reservoir, São Paulo State, Brazil: Concentrations and diffuse emission fluxes for carbon budget considerations
Abe, Donato S. (Autor:in) / Adams, Donald D. (Autor:in) / Galli, Corina V. Sidagis (Autor:in) / Sikar, Elizabeth (Autor:in) / Tundisi, José G. (Autor:in)
Lakes & Reservoirs: Research & Management ; 10 ; 201-209
01.12.2005
9 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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