The Marine Inorganic Carbon System along the Gulf of Mexico and Atlantic Coast of the United States: Shelf-ocean exchange and Ocean Acidification Status
Abstract
The inorganic carbon system of the Gulf of Mexico (GOM) and the Atlantic Coast of the United States (U.S.) was comprehensively surveyed in the summer of 2007 to obtain synoptic baseline conditions, carbon fluxes, and biogeochemistry. Most surveyed areas released CO2 to the atmosphere. The mean CO2 flux of surveyed waters was 1.6 mmol m^-2 d^-1. In contrast, the Mississippi River plume in the GOM and the Merrimack River plume in the Gulf of Maine (GoME) were strong biologically-driven CO2 sinks. The mean aragonite saturation state (ΩA) decreased latitudinally more than two fold (4.1 to 1.8) from northern GOM shelf waters to waters in the GoME. This change was accompanied by a 0.4-unit decrease in mean shelf-water pH (at 25 °C). The influence of biologically mediated processes on dissolved inorganic carbon (DIC), nutrients, and O2 in Gulf Stream Water (GSW) varied substantially with location. In the GOM, the GSW receives approximately 1.4 - 1.6 × 10^11 gC d^-1 of DIC exported from the shelf. Biologically induced chemical changes in GSW along the southeastern U.S. coast were dominated by physical mixing from North Atlantic sub-tropical recirculation. Southward, along-shore transport of the Labrador Coastal Current in the Mid-Atlantic Bight creates a mid-salinity end-member on the shelf. Mixing of the slope and shelf waters with this coastal current accounts for 47% of the total north-south gradient in the mean salinity-normalized DIC, while biological processes account for about 14%. Northeastern U.S. coastal water is vulnerable to ocean acidification due to its low ΩA and low buffer capacity.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFMOS42B..03W
- Keywords:
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- 0428 BIOGEOSCIENCES / Carbon cycling;
- 1635 GLOBAL CHANGE / Oceans;
- 4217 OCEANOGRAPHY: GENERAL / Coastal processes;
- 4806 OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL / Carbon cycling