Carbon isotopic evidence for microbial control of carbon supply to Orca Basin at the seawater–brine interface
Shah, Sunita R.
Joye, Samantha B.
Brandes, Jay A.
McNichol, Ann P.
MetadataShow full item record
Orca Basin, an intraslope basin on the Texas-Louisiana continental slope, hosts a hypersaline, anoxic brine in its lowermost 200 m in which limited microbial activity has been reported. This brine contains a large reservoir of reduced and aged carbon, and appears to be stable at decadal time scales: concentrations and isotopic composition of dissolved inorganic (DIC) and organic carbon (DOC) are similar to measurements made in the 1970s. Both DIC and DOC are more "aged" within the brine pool than in overlying water, and the isotopic contrast between brine carbon and seawater carbon is much greater for DIC than DOC. While the stable carbon isotopic composition of brine DIC points towards a combination of methane and organic carbon remineralization as its source, radiocarbon and box model results point to the brine interface as the major source region for DIC, allowing for only limited oxidation of methane diffusing upwards from sediments. This conclusion is consistent with previous studies that identify the seawater–brine interface as the focus of microbial activity associated with Orca Basin brine. Isotopic similarities between DIC and DOC suggest a different relationship between these two carbon reservoirs than is typically observed in deep ocean basins. Radiocarbon values implicate the seawater–brine interface region as the likely source region for DOC to the brine as well as DIC.
© The Author(s), 2013. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Biogeosciences 10 (2013): 3175-3183, doi:10.5194/bg-10-3175-2013.
The following license files are associated with this item:
Showing items related by title, author, creator and subject.
Combined carbonate carbon isotopic and cellular ultrastructural studies of individual benthic foraminifera : method description Martin, Jonathan B.; Bernhard, Joan M.; Curtis, Jason H.; Rathburn, Anthony E. (American Geophysical Union, 2010-06-11)Carbon isotopes of foraminiferal tests provide a widely used proxy for past oceanographic environmental conditions. This proxy can be calibrated using live specimens, which are reliably identified with observations of cell ...
Carbon-nitrogen interactions regulate climate-carbon cycle feedbacks : results from an atmosphere-ocean general circulation model Thornton, Peter E.; Doney, Scott C.; Lindsay, Keith; Moore, J. Keith; Mahowald, Natalie M.; Randerson, James T.; Fung, Inez Y.; Lamarque, J.-F.; Feddema, J. J.; Lee, Y.-H. (Copernicus Publications on behalf of the European Geosciences Union, 2009-10-08)Inclusion of fundamental ecological interactions between carbon and nitrogen cycles in the land component of an atmosphere-ocean general circulation model (AOGCM) leads to decreased carbon uptake associated with CO2 ...
Sources and accumulation of organic carbon in the Pearl River Estuary surface sediment as indicated by elemental, stable carbon isotopic, and carbohydrate compositions He, B.; Dai, Minhan; Huang, W.; Liu, Q.; Chen, H.; Xu, Li (Copernicus Publications on behalf of the European Geosciences Union, 2010-10-28)Organic matter in surface sediments from the upper reach of the Pearl River Estuary and Lingdingyang Bay, as well as the adjacent northern South China Sea shelf was characterized using a variety of techniques, including ...