HR: 0800h
AN: B41C-06    [Abstracts]
TI: Methane and Nitrous Oxide in the Central and Eastern Black Sea
AU: * Diem, T
EM: torsten.diem@eawag.ch
AF: EAWAG, Seestrasse 79, Kastanienbaum, 6047, Switzerland
AU: Wehrli, B
EM: bernhard.wehrli@eawag.ch
AF: EAWAG, Seestrasse 79, Kastanienbaum, 6047, Switzerland
AU: Schubert, C J
EM: carsten.schubert@eawag.ch
AF: EAWAG, Seestrasse 79, Kastanienbaum, 6047, Switzerland
AB: Methane (CH4) and nitrous oxide (N2O) are two major greenhouse gases whose concentrations have risen significantly since 1750. The Black Sea has been identified as a source for both of these greenhouse gases. The methane emitted is thought to origin from the anoxic deep waters or from bubble transport bypassing the oxic/anoxic boundary, while the nitrous oxide stems from nitrification and denitrification in low oxygen and suboxic zones. Data availability for both gases is best for the Western and North-Western area of the basin, and scarce for the Eastern part. In this study we wanted to enlarge the data base by collecting samples from the Central and Eastern Black Sea. We measured concentration and isotopic composition of CH4 and N2O every five meters across the oxic/anoxic boundary, as well as about every twenty meters in the surface water. This way we tried to distinguish between methane from the anoxic deep waters and methane produced in the surface waters, as well as to determine the amount of methane oxidized aerobically compared to anaerobically. For N2O we could distinguish zones of production and consumption, as well as surface water concentrations not influenced by the nutrient inputs of the Danube or other major rivers.
DE: 0454 Isotopic composition and chemistry (1041, 4870)
DE: 0471 Oxidation/reduction reactions (4851)
DE: 0490 Trace gases
SC: Biogeosciences [B]
MN: 2007 Joint Assembly