Fossil methane source dominates Cariaco Basin water column methane geochemistry

TitleFossil methane source dominates Cariaco Basin water column methane geochemistry
Publication TypeJournal Article
Year of Publication2005
AuthorsKessler, J. D., Reeburgh W. S., Southon J., & Varela R.
JournalGeophysical Research Letters
Date Published06/2005
ISBN Number0094-8276
Accession NumberWOS:000230169900002
Keywords1705; Keck / AMS Lab; Research

[ 1] Natural radiocarbon measurements on methane ((14)C-CH(4)) extracted from the Cariaco Basin water column show that 98% of the methane in Cariaco Basin waters is derived from fossil ( radiocarbon-free) sources. Previous work on Cariaco Basin methane ( CH(4)) considered only a diagenetic sediment source. Similar measurements of sediment (14)C-CH(4) indicate that sediment CH(4) is produced from modern particulate material; thus the sediment and water column CH(4) have distinct sources. Using time-dependent CH(4) geochemical box models which include a fossil seep CH(4) source term, we estimate 1) 0.024-0.028 Tg y(-1) of seep CH(4) are added to the Cariaco Basin water column, 2) the water column CH(4) will reach a steady-state concentration by the year 2065, and 3) the seep CH(4) inputs possibly began in 1967, following the July 30 Caracas earthquake. Oxidizing this CH(4) to dissolved inorganic carbon does not appear to affect Cariaco Basin (14)C chronologies.

ESS Associations
Research Area: 
Biogeochemical Cycles
Research Lab: 
Keck / AMS Lab