Stable and Radiocarbon Isotopic Composition of Dissolved Organic Matter in the Gulf of Mexico

B. D. Walker; E. R. M. Druffel; J. Kolasinski; B. J. Roberts; X. Xu; B. E. Rosenheim

doi:10.1002/2017GL074155

Stable and Radiocarbon Isotopic Composition of Dissolved Organic Matter in the Gulf of Mexico

B. D. Walker, E. R. M. Druffel, J. Kolasinski, B. J. Roberts, X. Xu, B. E. Rosenheim

College of Marine Science

Research output: Contribution to journal › Article › peer-review

Abstract

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.

Original language	American English
Journal	Geophysical Research Letters
Volume	44
DOIs	https://doi.org/10.1002/2017GL074155
State	Published - Jan 1 2017

Keywords

dissolved organic matter
Gulf of Mexico
radiocarbon
dissolved organic carbon
13C
oil spill

Disciplines

Life Sciences

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title = "Stable and Radiocarbon Isotopic Composition of Dissolved Organic Matter in the Gulf of Mexico",

abstract = " 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.",

keywords = "dissolved organic matter, Gulf of Mexico, radiocarbon, dissolved organic carbon, 13C, oil spill",

author = "Walker, {B. D.} and Druffel, {E. R. M.} and J. Kolasinski and Roberts, {B. J.} and X. Xu and Rosenheim, {B. E.}",

year = "2017",

month = jan,

day = "1",

doi = "10.1002/2017GL074155",

language = "American English",

volume = "44",

journal = "Geophysical Research Letters",

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TY - JOUR

T1 - Stable and Radiocarbon Isotopic Composition of Dissolved Organic Matter in the Gulf of Mexico

AU - Walker, B. D.

AU - Druffel, E. R. M.

AU - Kolasinski, J.

AU - Roberts, B. J.

AU - Xu, X.

AU - Rosenheim, B. E.

PY - 2017/1/1

Y1 - 2017/1/1

N2 - 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.

AB - 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.

KW - dissolved organic matter

KW - Gulf of Mexico

KW - radiocarbon

KW - dissolved organic carbon

KW - 13C

KW - oil spill

UR - https://digitalcommons.usf.edu/msc_facpub/2429

U2 - 10.1002/2017GL074155

DO - 10.1002/2017GL074155

M3 - Article

VL - 44

JO - Geophysical Research Letters

JF - Geophysical Research Letters

ER -

Stable and Radiocarbon Isotopic Composition of Dissolved Organic Matter in the Gulf of Mexico

Abstract

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