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Stable and radiocarbon isotopic composition of dissolved organic matter in the Gulf of Mexico
Author(s) -
Walker B. D.,
Druffel E. R. M.,
Kolasinski J.,
Roberts B. J.,
Xu X.,
Rosenheim B. E.
Publication year - 2017
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2017gl074155
Subject(s) - dissolved organic carbon , radiocarbon dating , oceanography , isotopic signature , environmental science , carbon cycle , population , submarine pipeline , geology , carbonate , organic matter , drainage basin , δ13c , hydrology (agriculture) , ecosystem , environmental chemistry , stable isotope ratio , ecology , geography , chemistry , demography , organic chemistry , geotechnical engineering , quantum mechanics , sociology , biology , cartography , paleontology , physics
Dissolved organic carbon (DOC) is of primary importance to marine ecosystems and the global carbon cycle. Stable carbon (δ 13 C) and radiocarbon (Δ 14 C) isotopic measurements are powerful tools for evaluating DOC sources and cycling. However, the isotopic signature of DOC in the Gulf of Mexico (GOM) remains almost completely unknown. Here we present the first DOC Δ 14 C and δ 13 C depth profiles from the GOM. Our results suggest the Mississippi River exports large amounts of DOC with an anthropogenic “bomb” Δ 14 C signature. Riverine DOC is removed and recycled offshore, and some marine production of DOC is observed in the river plume. Offshore profiles show that DOC has higher Δ 14 C than its Caribbean feed waters, indicative of a modern deep DOC source in the GOM basin. Finally, high DOC with negative δ 13 C and Δ 14 C values were observed near the Macondo Wellhead, suggesting a transformation of Deepwater Horizon hydrocarbons into a persistent population of DOC.