Gas seepage in the Dnepr paleo-delta area (NW-Black Sea) and its regional impact on the water column methane cycle

作者：Schmale O^*; Beaubien S E; Rehder G; Greinert J; Lombardi S

来源：Journal of Marine Systems, 2010, 80(1-2): 90-100.

DOI：10.1016/j.jmarsys.2009.10.003

• Methane
• Gas seepages
• Marginal seas
• Anoxic basins
• Carbon isotope ratio
• Oxygen depletion

Methane concentrations and carbon stable isotopic ratios (delta C-13(CH4)), oxygen concentrations and hydrographic parameters (CTD) were investigated in the water column of the north-western Black Sea during the summers of 2003 and 2004. Water samples were collected along a transect which crosses three methane seep areas in 90,220, and 600 m water depth. These active seeps strongly influence methane distribution in the overlying anoxic and oxic water column. Methane concentration and stable isotope (delta C-13(CH4)) patterns indicate that water column stratification and microbial methane oxidation efficiently hamper the transfer of methane to the sea surface. Only the shelf seep site in 90 m water depth acts as a direct source of atmospheric methane. Microbial methane oxidation and/or gas stripping seem to cause oxygen depletion above the two shallower seep areas. The methane flux from the 90 m site into the water column is estimated to have been 0.599 x 10(6) mol yr(-1) (9.6 t yr(-1)) in 2003 and 0347 x 10(6) mol yr(-1) (5.6 t yr(-1)) in 2004. Comparison of results from the two years shows different water column methane inventories in the deep part of the transect, implying a variable methane source strength at the 600 m deep site. The flux from this area is estimated to have been 11.35 x 10(6) mol yr(-1) in 2003.

• 出版日期2010-2-20