Spatial Heterogeneity of Methane Ebullition in a Large Tropical Reservoir

Tropical reservoirs have been identified as important methane (CH4) sources to the atmosphere, primarily through turbine and downstream degassing. However, the importance of ebullition (gas bubbling) remains unclear. We hypothesized that ebullition is a disproportionately large CH4 source from reser...

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Veröffentlicht in:Environmental science & technology 2011-12, Vol.45 (23), p.9866-9873
Hauptverfasser: DelSontro, Tonya, Kunz, Manuel J, Kempter, Tim, Wüest, Alfred, Wehrli, Bernhard, Senn, David B
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Sprache:eng
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Zusammenfassung:Tropical reservoirs have been identified as important methane (CH4) sources to the atmosphere, primarily through turbine and downstream degassing. However, the importance of ebullition (gas bubbling) remains unclear. We hypothesized that ebullition is a disproportionately large CH4 source from reservoirs with dendritic littoral zones because of ebullition hot spots occurring where rivers supply allochthonous organic material. We explored this hypothesis in Lake Kariba (Zambia/Zimbabwe; surface area >5000 km2) by surveying ebullition in bays with and without river inputs using an echosounder and traditional surface chambers. The two techniques yielded similar results, and revealed substantially higher fluxes in river deltas (∼103 mg CH4 m–2 d–1) compared to nonriver bays (
ISSN:0013-936X
1520-5851
DOI:10.1021/es2005545