The relation between pore water chemistry and benthic fluxes of nutrients and manganese in Narragansett Bay, Rhode Island

McCaffrey, R. J.; Myers, Allen C.; Davey, Earl; Morrison, George; Bender, Michael L.; Luedtke, Nile A.; Cullen, Douglas; Froelich, Philip N.; Klinkhammer, Gary P.

doi:10.4319/lo.1980.25.1.0031

Cited by 190 publications

(64 citation statements)

References 7 publications

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“…m-2.d-1; fluxes were highest during the summer experiment. These values are comparable with those from other investigations in coastal regions (van Bennekom et al 1974;Vanderborght et al 1977;Balzer 1978;McCaffrey et al 1980;Aller and Benninger 198 1;Elderfield et al 198 1). Except in the winter experiment, the measured fluxes differ greatly from the much smaller fluxes calculated from the porewater gradients and the molecular diffusion coefficient (Table 1) Effective diffusion coefficients of the order of 1 Oe4 cm2.…”

Section: Discussionsupporting

confidence: 82%

The asphyxiation technique: An approach to distinguishing between molecular diffusion and biologically mediated transport at the sediment—water interface

Loeff

Anderson

Hall

et al. 1984

Limnology & Oceanography

134

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On the assumption that lack of oxygen will cause the activity of benthic infauna to cease and thereby limit solute transport to that accomplished by molecular diffusion, we have measured the flux of dissolved silicate across the sediment-water interface of sediments incubated in situ under parallel benthic flux chambers. In one chamber the oxygen concentration was allowed to go to zero, and in the other the oxygen and pH remained at ambient values.As long as oxygen was present in the chambers, the measured summer and fall fluxes were 2-10 times those calculated from porewater profiles assuming one-dimensional molecular diffusion. The differences in fluxes predicted from the densities of macrobenthos at two different sites agree well with the flux measurements. After oxygen depletion, the silicate fluxes decreased and approached the values calculated on the basis of molecular diffusion. In one experiment the ratio between the oxic and anoxic fluxes was nearly identical to the ratio between the effective diffusion coefficient, as measured under oxic conditions using 22Na as a tracer, and the whole-sediment molecular diffusion coefficient. In winter (-1'C) measured and calculated Fickian fluxes agreed closely, indicating a negligible effect of benthos on solute transport.The regeneration of biogenic silicate in the sediment and its subsequent transport to the water column represent a major contribution to silica budgets in estuarine and nearshore marine waters (van Bennekom et al. 1974;Rutgers van der Loeff 1980; Aller and Benninger 198 1). The flux of dissolved I Permanent address: Netherlands Inst. Sea Res.,

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Section: Discussionsupporting

confidence: 82%

The asphyxiation technique: An approach to distinguishing between molecular diffusion and biologically mediated transport at the sediment—water interface

Loeff

Anderson

Hall

et al. 1984

Limnology & Oceanography

134

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“…Smith 1978;Smith et al 1978Smith et al , 1979Hinga et al 1979) and indirectly with porewater profiles and Fick's law of diffusion (Murray and Grundmanis 1980;Goloway and Bender 1982;Jahnke et al 1982;Reimers et al 1984). Both techniques have been compared at a common location for determinations of the sediment-water exchange of methane, radon, ammonium, phosphate, C02, manganese, and silicate (McCaffrey et al 1980;Klump and Martens 198 1;Jahnke et al 1983;Andrews and Hargrave 1984), but not for the exchange of oxygen.…”

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confidence: 99%

Reconciling measured and predicted fluxes of oxygen across the deep sea sediment‐water interface1

Reimers

Smith

1986

Limnology & Oceanography

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Rates of sediment community oxygen consumption determined in situ are compared to fluxes predicted from oxygen microelectrode gradients measured in cores from -3,750-m water depth in the eastern North Pacific. Oxygen concentrations decrease exponentially over > 1.5 cm and suggest that organic matter in the sediments is degraded most rapidly immediately below the sediment-water interface.Molecular diffusion of oxygen across the interface is modeled as an "internal regime" and can account for nearly all the directly measured in situ flux, 0.2Ot-0.02 pmol cm-2 d-l. This differs from published accounts of nearshore marine environments, where activity of bottom-dwelling macrofauna or bubble ebullition enhances benthic fluxes of dissolved nutrients or gases 2-4 times. Millimeter depth-scale profiles of porosity, organic C, carbonate C, and bacterial abundance are reported to provide additional constraints on interface processes, including the relative effects of organic matter degradation and bioturbation. The highest organic C, bacterial, and porosity values are in the uppermost sediments (O-O.2 cm). Within the stratum O-l cm, porewater flux ratios of oxygen to nitrate support a model of exchange by diffusion leading to organic matter oxidation and nitrification according to Redfield stoichiometry. Below the oxygen reduction zone, changes in the porewater concentrations of N03-, Mn2+, Fe2+, NH4+, and alkalinity indicate that anaerobic respiration reactions using N03-, MnO,, Fe,O,, and S042-as electron acceptors complete the early oxidation of organic matter at this site.

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“…These calculations, however, neglect patchiness and produce very large volume fluxes (Smethie et al 1981). Several recent studies have taken advantage of the natural tracer ZZZRn (Hammond and Fuller 1979;Smethie et al 1981) or added 22Na (McCaffrey et al 1980) to obtain estimates of irrigation fluxes in marine sediments. The results of these studies, which represent lower limits, integrate the volume flux of water across the sedimentwater interface over several days and are summarized in Table 3.…”

Section: Discussionmentioning

confidence: 99%

Fluxes associated with brine motion in growing sea ice

Reeburgh

1984

Polar Biol

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Summary. Laboratory and field studies have demonstrated that fluid motion occurs at two locations in growing sea ice: in a network of brine channels and within the skeletal layer at the ice-water interface. Brine channel fluxes estimated using brine channel areal density from natural sea ice and channel velocities from laboratory studies are compared with recent measurements reported in the literature. Fluxes into the porous skeletal layer of sea ice may be estimated using rates of nutrient uptake by ice algae and adjacent seawater nutrient concentrations. Both approaches indicate fluxes of the order of 10 -6 cc cm -2 s -1 (1 m -2 h-l), which are about equal to fluxes reported in bioirrigated sediments. Fluxes of this magnitude indicate a very short residence time for the liquid phase in the skeletal layer, suggesting that this fluid motion may be important in maintaining the ice algae community.

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The relation between pore water chemistry and benthic fluxes of nutrients and manganese in Narragansett Bay, Rhode Island

Cited by 190 publications

References 7 publications

The asphyxiation technique: An approach to distinguishing between molecular diffusion and biologically mediated transport at the sediment—water interface

The asphyxiation technique: An approach to distinguishing between molecular diffusion and biologically mediated transport at the sediment—water interface

Reconciling measured and predicted fluxes of oxygen across the deep sea sediment‐water interface1

Fluxes associated with brine motion in growing sea ice

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