Sedimentation, bioturbation, and Hg uptake in the sediments of the estuary and Gulf of St. Lawrence

Smith, J. N.; Schafer, Charles T.

doi:10.4319/lo.1999.44.1.0207

Cited by 59 publications

(46 citation statements)

References 44 publications

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“…Data from Silverberg et al (1987) except for the depth and bottom water oxygen concentration (Gilbert et al, 2005), mass accumulation rate (Smith and Schafer, 1999) and the U accumulation rate (Sundby et al, 2004). Note that the sum of the organic carbon oxidation and burial rates results in the calculated organic carbon rain rate for station 1 from the Laurentian Trough (12-22 mmol/m 2 /d) that is consistent with the mean organic carbon flux measured from 32 sediment traps (16 mmol/m 2 /d; Silverberg et al, 1987).…”

Section: Oc426supporting

confidence: 67%

“…Data from Silverberg et al (2000) except for depth and bottom water oxygen (Gilbert et al, 2005) and the U accumulation rate (Sundby et al, 2004). The mass accumulation rate at station 4 is consistent between Smith and Schafer (1999) and Silverberg et al (2000), but variable at station 2 where Silverberg et al (2000) suggests a lower value relative to Smith and Schafer (1999). k. The mass accumulation rate is from Alperin et al (2002) and Thomas et al (2002).…”

Section: Oc426mentioning

confidence: 93%

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Uranium diagenesis in sediments underlying bottom waters with high oxygen content

Morford

Martin

Carney

2009

Geochimica et Cosmochimica Acta

104

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We measured U in sediments (both pore waters and solid phase) from three locations on the middle Atlantic Bight (MAB) from the eastern margin of the United States: a northern location on the continental shelf off Massachusetts (OC426, 75 m water depth), and two southern locations off North Carolina (EN433-1, 647 m water depth and EN433-2, 2648 m water depth). These sediments underlie high oxygen bottom waters (250-270 M), but become reducing below the sediment-water interface due to the relatively high organic carbon oxidation rates in sediments (EN433-1: 212 mol C/cm 2 /y; OC426: 12010 mol C/cm 2 /y; EN433-2: 33mol C/cm 2 /y). Pore water oxygen goes to zero by 1.4-1.5 cm at EN433-1 and OC426 and slightly deeper oxygen penetration depths were measured at EN433-2 (~4 cm).All of the pore water profiles show removal of U from pore waters. Calculated pore water fluxes are greatest at EN433-1 (0.660.08 nmol/cm 2 /y) and less at EN433-2 and OC426 (0.240.05 and 0.130.05 nmol/cm 2 /y, respectively). Solid phase profiles show authigenic U enrichment in sediments from all three locations. The average authigenic U concentrations are greater at EN433-1 and OC426 (5.80.7 nmol/g and 5.40.2 nmol/g, respectively) relative to EN433-2 (4.10.8 nmol/g). This progression is consistent with their relative ordering of 'reduction intensity', with greatest reducing conditions in sediments from EN433-1, less at OC426 and least at EN433-2. The authigenic U accumulation rate is largest at EN433-1 (0.470.05 nmol/cm 2 /y), but the average among the three sites on the MAB is ~0.2 nmol/cm 2 /y. Pore water profiles suggest diffusive fluxes across the sediment-water interface that are 1.4-1.7 times greater than authigenic accumulation rates at EN433-1 and EN433-2. These differences are consistent with oxidation and loss of U from the solid phase via irrigation and/or bioturbation, which may compromise the sequestration of U in continental margin sediments that underlie bottom waters with high oxygen concentrations.

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Section: Oc426supporting

confidence: 67%

Section: Oc426mentioning

confidence: 93%

Uranium diagenesis in sediments underlying bottom waters with high oxygen content

Morford

Martin

Carney

2009

Geochimica et Cosmochimica Acta

104

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“…Nevertheless, solubility calculations indicated that precipitation of CdS may occur in suboxic sediments in the presence of trace levels of sulfide that are below routine detection limits (Rosenthal et al 1995b). Higher Cd concentrations in cores from the Gulf agreed with previous observations (Gendron et al 1986, Gobeil et al 1987, 1997a and were due to lower sedimentation rates in the Gulf (<1 mm yr -1 compared to 3 to 7 mm yr -1 in the Estuary; Smith & Schafer 1999), which resulted in a less important dilution of authigenic Cd by Cd-poor terrigenous particles (Gendron et al 1986). The fact that sedimentary Cd concentrations and hepatic Cd burden of fish were both higher in the Gulf than in the Estuary indicated that early diagenetic processes affect the bioaccumulation of Cd, if sedimentary Cd is similarly bioavailable in the Gulf and the Estuary.…”

Section: Cadmium Pathways At the Sediment-water Interfacesupporting

confidence: 89%

Cadmium accumulation in coastal demersal fish

Rouleau¹,

Gobeil²,

Tjälve³

2006

Mar. Ecol. Prog. Ser.

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The hepatic Cd burden, measured on 291 individuals of 4 species of demersal fish (Gadus morhua, Reinhardtius hippoglossoides, Hippoglossoides platessoides, and Raja radiata), is 2 to 5 times higher in fish from the open Gulf of St. Lawrence than in fish from the St. Lawrence Estuary, 600 km landward. The higher Cd burden in the open Gulf is not related to the input of anthropogenic Cd, nor can it be attributed to differences in size, sex, sampling season, or state of health. Rather, the Cd burden in demersal fish may be related to sediment diagenesis, since the concentration of authigenic Cd (i.e. Cd minerals formed in the sediments) is higher in the Gulf than in the Estuary, which may lead in turn to Cd-enrichment in sediment-dwelling organisms. Measured Cd burdens in the liver agree with predictions made with a simple biokinetic model that uses realistic estimates of the Cd content of benthic invertebrates in combination with kinetic parameters determined in H. platessoides with in vivo gamma counting. These results strongly suggest that the Cd content of the diet, rather than of the water phase, determines the hepatic Cd burden in these demersal fish species.

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“…The sediment accumulation rate, which decreases seaward by one order of magnitude, is the principal variable along the axis of the channel (Smith and Schafer, 1999). Previous studies have shown that the lower sediment accumulation rates in the seaward portion of the Laurentian Trough favor higher concentrations of cadmium, pyrite, and arsenic (Gobeil et al, 1987;Belzile, 1988;Gagnon et al, 1995).…”

Section: Introductionmentioning

confidence: 98%

Comparative geochemistry of cadmium, rhenium, uranium, and molybdenum in continental margin sediments

Sundby

Martinez

Gobeil

2004

Geochimica et Cosmochimica Acta

145

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Sedimentation, bioturbation, and Hg uptake in the sediments of the estuary and Gulf of St. Lawrence

Cited by 59 publications

References 44 publications

Uranium diagenesis in sediments underlying bottom waters with high oxygen content

Uranium diagenesis in sediments underlying bottom waters with high oxygen content

Cadmium accumulation in coastal demersal fish

Comparative geochemistry of cadmium, rhenium, uranium, and molybdenum in continental margin sediments

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