Effects of biological sediment mixing on the210Pb chronology and trace metal distribution in a Long Island Sound sediment core

Benninger, Larry K.; Aller, Robert C.; Cochran, J. Kirk; Turekian, Karl K.

doi:10.1016/0012-821x(79)90208-5

Cited by 239 publications

(67 citation statements)

References 11 publications

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“…10b,c). Similar uniformity of Hg(II) or total Hg in the upper 10 cm of sediment has been observed in other coastal systems (Varekamp et al, 2000;Sunderland et al, 2004;Choe et al, 2004), and, in many cases, it can be attributed to the mixing and homogenization of sediment particles by the within-sediment migration of benthic infauna (Benninger et al, 1979). Profiles of Hg(II) in filtered pore water were less homogeneous, but measured concentrations and the K D of Hg(II) varied by only 2-fold or less with depth at each station (Fig.…”

Section: Stratigraphy Of Hg Speciessupporting

confidence: 78%

Methylmercury cycling in sediments on the continental shelf of southern New England

Hammerschmidt

Fitzgerald

2006

Geochimica et Cosmochimica Acta

169

127

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Exposure of humans to monomethylmercury (MMHg) occurs primarily through consumption of marine fish, yet there is limited understanding concerning the bioaccumulation and biogeochemistry of MMHg in the biologically productive coastal ocean. We examined the cycling of MMHg in sediments at three locations on the continental shelf of southern New Moreover, the efflux of dissolved MMHg to overlying water (i.e., net production at steady state) is correlated with the gross potential rate of MMHg production in surface sediments. These results suggest that the production and efflux of MMHg from coastal marine sediments is limited by Hg(II), loadings of which presumably are principally from atmospheric deposition to this region of the continental shelf. The estimated diffusive flux of MMHg from the shelf sediments averages 9 pmol m −2 d −1 . This flux is comparable to that required to sustain the current rate of MMHg accumulation by marine fish, and may be enhanced by the efflux of MMHg from nearshore deposits contaminated more substantially with anthropogenic Hg. Hence, production and subsequent mobilization of MMHg from sediments in the coastal zone may be a major source of MMHg to the ocean and marine biota, including fishes consumed by humans.

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Section: Stratigraphy Of Hg Speciessupporting

confidence: 78%

Methylmercury cycling in sediments on the continental shelf of southern New England

Hammerschmidt

Fitzgerald

2006

Geochimica et Cosmochimica Acta

169

127

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“…The most direct estimates of this depth within the siltklay sedments of the deeper regions of the Gulf of Maine comes from the combined results Anderson and Keafer (1985), Keafer et al (1992), and Hines (1991), which suggest dg -1 cm. Results in Massachusetts Bay and in Long Island sound are not grossly inconsistent with this estimate (Aller and Cochran, 1976, Benninger, et al, 1979, Krishnaswami, et al, 1980, Wheatcroft, et al, 1994, although the reporting mixing depth is slightly larger.…”

Section: Function Constructionmentioning

confidence: 58%

Blooms of the toxic dinoflagellate Alexandrium fundyense in the Gulf of Maine : investigations using physical-biological model

Stock¹

2005

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“…Fickian-type eddy diffusion, where the sediment mixing term in diagenetic equations can described by biodiffusion coefficients (Da) within the upper mixed layer of sediments (Goldberg and Koide, 1962;Guinasso and Schink, 1975;Benninger et al, 1979). This approach has had some success in modelling the sediment profiles of natural radioactive elements with appropriate half-lives, such as 21 oPb (t 1 , 2 = 22.3 yrs.)…”

Section: Sediment Mixing Processes Have Been Modelled As Being Analagmentioning

confidence: 99%

“…The distribution of 2 1 0 Pb has been modelled here in terms of a one-dimensional steady-state model following the example of Nozaki et al (1977) and Benninger et al (1979). The unsupported 2'oPb activity (A; A = 2 ' 0 Pb -226 Ra in dpm/g) can be given by: When all data are considered for 2 1 oPb and the effect of sedimentation is neglected, applying equation 4-20 yields a constant biodiffusion coefficient of 1.3 x 10 -7 cm 2 /sec.…”

Section: Sediment Mixing Processes Have Been Modelled As Being Analagmentioning

confidence: 99%

The role of colloidal organic matter in the marine geochemistry of PCBs

Brownawell¹

1986

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WITHDRAWN AD -sT~i~Bñ~c i~tZ4-2-ABSTRACT Polychlorinated biphenyls (PCBs) were used as model hydrophobic organic compounds (HOC) to study physical-chemical processes which affect the speciation and fate of HOC in coastal environments. The focus of this study is on the sorption of PCBs with colloidal organic matter in seawater, and the influence of this process on the distribution of PCBs in coastal sediments. Laboratory and field experiments were used to make quantitative estimates of PCB-organic matter sorption, and to test predictions of three-phase equilibrium models.A static headspace partitioning method was developed to measure the sorption of several individual chlorobiphenyls with colloidal organic matter enriched from coastal seawater by hollow fiber ultrafiltration. This technique directly measured the dissolved phase fugacity of PCBs in experimental bottles, and avoided uncertain separation techniques often used in isolating various chemical phases. Colloidal organic carbon normalized partition coefficients (Koc) were determined from linear sorption isotherms, and increased from 1.9 x 10' (L/Kg) for 2,4'-dichlorobiphenyl to 3.5 x 10 s for 2,2',3,4,5'-pentachlorobiphenyl. Sorption tended to increase with increasing octanol-water partition coefficients (Kow) of the sorbate, and values of Koc were within a range of those reported in other experimental sorption studies with sediments and dissolved humic substances. Experimental partitioning results support the hypothesis that HOC-organic colloid sorption is similar to HOC sorption by sediment organic matter.PCBs were measured in the interstitial waters and sediments of three box cores obtained from New Bedford Harbor and Buzzards Bay, Massachusetts. The three sites studied had a wide range of sediment PCB concentrations, and reducing conditions provided environments containing high concentrations of colloidal organic matter. Dissolved organic carbon (DOC) and total sediment organic carbon (TOC) were measured in two cores to test the role of organic matter on the observed partitioning of PCBs. PCB concentrations, particularly those of less soluble chlorobiphenyls, were highly elevated in interstitial waters compared to water column concentrations at all three sites. The measured apparent distribution coefficients (K'd) of individual chlorobiphenyls did not increase with hydrophobicity (Kow) and indicate that a large fraction of PCBs in interstitial waters must be sorbed to organic colloids. A three-phase equilibrium sorption model, in which dissolved PCBs are in a dynamic equilibrium with colloidal and sediment organic matter, accounts for many aspects of the field data. There is good agreement of observed partitioning at New Bedford Station 67 and Buzzards Bay Station M with model calculations based on predictions derived from laboratory experiments of HOC sorption with sediments and organic colloids, but model calculations underpredict K'd at Station 84 in New Bedford Harbor.-3-The sediment-interstitial water results were contrasted with a study of PCB pa...

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Effects of biological sediment mixing on the210Pb chronology and trace metal distribution in a Long Island Sound sediment core

Cited by 239 publications

References 11 publications

Methylmercury cycling in sediments on the continental shelf of southern New England

Methylmercury cycling in sediments on the continental shelf of southern New England

Blooms of the toxic dinoflagellate Alexandrium fundyense in the Gulf of Maine : investigations using physical-biological model

The role of colloidal organic matter in the marine geochemistry of PCBs

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