scholarly journals The carbon dioxide system on the Mississippi River-dominated continental shelf in the northern Gulf of Mexico: 1. Distribution and air-sea CO2flux

2015 ◽  
Vol 120 (3) ◽  
pp. 1429-1445 ◽  
Author(s):  
Wei-Jen Huang ◽  
Wei-Jun Cai ◽  
Yongchen Wang ◽  
Steven E. Lohrenz ◽  
Michael C. Murrell
Keyword(s):  
Carbon Dioxide ◽  
Gulf Of Mexico ◽  
Continental Shelf ◽  
Mississippi River ◽  
Northern Gulf Of Mexico

scholarly journals Early Diagenesis in the Hypoxic and Acidified Zone of the Northern Gulf of Mexico: Is Organic Matter Recycling in Sediments Disconnected From the Water Column?

2021 ◽  
Vol 8 ◽  
Author(s):  
Christophe Rabouille ◽  
Bruno Lansard ◽  
Shannon M. Owings ◽  
Nancy N. Rabalais ◽  
Bruno Bombled ◽  
...  
Keyword(s):  
Organic Matter ◽  
Gulf Of Mexico ◽  
Continental Shelf ◽  
Mississippi River ◽  
Dissolved Inorganic Carbon ◽  
Low Oxygen ◽  
Northern Gulf Of Mexico ◽  
Bottom Waters ◽  
Seasonal Hypoxia ◽  
Organic Matter Recycling

Hypoxia and associated acidification are growing concerns for ecosystems and biogeochemical cycles in the coastal zone. The northern Gulf of Mexico (nGoM) has experienced large seasonal hypoxia for decades linked to the eutrophication of the continental shelf fueled by the Mississippi River nutrient discharge. Sediments play a key role in maintaining hypoxic and acidified bottom waters, but this role is still not completely understood. In the summer 2017, when the surface area of the hypoxic zone in the nGoM was the largest ever recorded, we investigated four stations on the continental shelf differentially influenced by river inputs of the Mississippi-Atchafalaya River System and seasonal hypoxia. We investigated diagenetic processes under normoxic, hypoxic, and nearly anoxic bottom waters by coupling amperometric, potentiometric, and voltammetric microprofiling with high-resolution diffusive equilibrium in thin-films (DET) profiles and porewater analyses. In addition, we used a time-series of bottom-water dissolved oxygen from May to November 2017, which indicated intense O2 consumption in bottom waters related to organic carbon recycling. At the sediment-water interface (SWI), we found that oxygen consumption linked to organic matter recycling was large with diffusive oxygen uptake (DOU) of 8 and 14 mmol m–2 d–1, except when the oxygen concentration was near anoxia (5 mmol m–2 d–1). Except at the station located near the Mississippi river outlet, the downcore pore water sulfate concentration decrease was limited, with little increase in alkalinity, dissolved inorganic carbon (DIC), ammonium, and phosphate suggesting that low oxygen conditions did not promote anoxic diagenesis as anticipated. We attributed the low anoxic diagenesis intensity to a limitation in organic substrate supply, possibly linked to the reduction of bioturbation during the hypoxic spring and summer.

scholarly journals Sediment Chemistry and Meiofauna from the Northern Gulf of Mexico Continental Shelf

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Ceil C. Martinec ◽  
Jonathan M. Miller ◽  
Nathan K. Barron ◽  
Rui Tao ◽  
Kewei Yu ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Gulf Of Mexico ◽  
Continental Shelf ◽  
Mississippi River ◽  
Coarse Sand ◽  
Sediment Chemistry ◽  
Mississippi River Delta ◽  
Northern Gulf Of Mexico ◽  
Total Pahs ◽  
Carbon Concentrations

This study examined sediment chemistry, granulometry, and meiofauna on the northern Gulf of Mexico continental shelf from central Louisiana to Apalachicola, Florida. Sediment samples were collected in October/November 2012 with a Shipek grab sampler from 26 locations (extending from 28°18′46.079′′N, 91°10′44.471′′W to 29°3′48.383′′N, 85°28′25.679′′W) at depths ranging from 49 to 361 m. Sediment analysis revealed two distinct profiles to the east and west of the Mississippi River Delta at approximately 88°30′W. The concentrations of silt + clay, organic carbon, Ba, Cr, Cu, Fe, Ni, Pb, V, and Zn were higher in western sites and positively correlated with Al concentrations. Eastern sites contained sandier sediments with lower organic carbon concentrations and higher Sr and Ca concentrations. Nematode densities were higher at western sites and positively correlated with Al, Cr, Cu, Fe, Ni, Pb, Zn, silt + clay, and organic carbon concentrations. Copepod densities correlated with very coarse + coarse sand, exhibiting higher densities at eastern sites. PAH concentrations were relatively low, with all sites having <1700 µg/kg total PAHs. This study has revealed two distinct sediment profiles in the eastern and western zones of the study, which appear to influence the nematode and copepod densities.

Chemical variations in sedimentary facies of an inner continental shelf environment, Northern Gulf of Mexico

1973 ◽  
Vol 9 (2) ◽  
pp. 101-115 ◽  
Author(s):  
Thomas T. Tieh ◽  
Thomas E. Pyle ◽  
David H. Eggler ◽  
Ronald A. Nelson
Keyword(s):  
Gulf Of Mexico ◽  
Continental Shelf ◽  
Sedimentary Facies ◽  
Northern Gulf Of Mexico ◽  
Inner Continental Shelf

Validating the occurrence of Caribbean reef sharks, Carcharhinus perezi (Poey), (Chondrichthyes: Carcharhiniformes) in the northern Gulf of Mexico, with a key for sharks of the family Carcharhinidae inhabiting the region

Zootaxa ◽  
2011 ◽  
Vol 2933 (1) ◽  
pp. 65 ◽  
Author(s):  
WILLIAM B. DRIGGERS III ◽  
ERIC R. HOFFMAYER ◽  
EMMA L. HICKERSON ◽  
TIMOTHY L. MARTIN ◽  
CHRISTOPHER T. GLEDHILL
Keyword(s):  
Gulf Of Mexico ◽  
North Atlantic ◽  
Mississippi River ◽  
North Atlantic Ocean ◽  
Shark Species ◽  
Mississippi River Delta ◽  
The Bahamas ◽  
Northern Gulf Of Mexico ◽  
The Family ◽  
Reef Sharks

Among the sharks inhabiting the continental shelf waters of the western North Atlantic Ocean, those within the genus Carcharhinus are the most speciose (Castro 2011). Authoritative sources agree on the presence of twelve species of carcharhinids in the northern Gulf of Mexico; however, they disagree on the presence of a thirteenth species, C. perezi (Poey), in the region (Compagno 1984, Compagno 2002, McEachran & Fechhelm 1998, Castro 2011). While the range of C. perezi is well-documented to extend from the southeastern coast of Florida and the Bahamas to Brazil (Castro 2011), published records of C. perezi occurring in the northern Gulf of Mexico are limited to two sources. In their description of Eulamia springeri, a junior synonym of C. perezi, Bigelow & Schroeder (1944) place the species in the northern Gulf of Mexico based on “a somewhat shrivelled skin with head” from a specimen collected off the west coast of Florida that was reported by the authors to be “probably of this species.” Later, Springer (1960) reported the capture of a single specimen off the Mississippi River Delta in 1947; however, no detail of the capture was provided other than it being listed within a table summarizing shark species collected during exploratory fishing operations.

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