A mechanistic view of the particulate biodiffusion coefficient: Step lengths, rest periods and transport directions

Wheatcroft, Robert A.; Jumars, Peter A.; Smith, Craig R.; Nowell, Arthur R. M.

doi:10.1357/002224090784984560

Cited by 213 publications

(179 citation statements)

References 65 publications

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“…The positive relationship between L and POC flux is likely driven by the influence of food availability on both infaunal body sizes and feeding strategies. In the quiescent deep sea, POC flux appears to be positively correlated with body size of those animals thought to control mixing, i.e., the deposit feeders (e.g., Hessler 1974;Thiel 1979;Jumars and Gallagher 1982;Wheatcroft et al 1990;Smith 1992); larger body sizes in turn should increase the particle step lengths and mixing depths of biogenic reworking (Wheatcroft et al 1990;Smith 1992). Higher POC fluxes may also cause a shift in deposit-feeding strategies by enhancing the food availability, abundances, and feeding rates of subsurface deposit feeders at given depths within the sediment (Rice and Rhoads 1989).…”

Section: Discussionmentioning

confidence: 99%

“…In particular, we test the prediction that L will vary positively with annual POC flux (Smith 1992), falling to a minimum in oligotrophic regions and approaching an asymptotic value in relatively eutrophic settings. The sequence of reasoning behind this prediction is as follows: (1) based on dimensional analyses, the rates and depths of biogenic mixing in the deep sea appear to be controlled by the larger deposit-feeding benthos (i.e., the macrofauna and megafauna), with body size controlling the length scales of particle displacement (Wheatcroft et al 1990;Smith 1992); (2) in the food-poor deep sea, the abundance and mean body size of macrobenthos and megabenthos, including important sediment mixers, appear to be strongly correlated with annual POC flux to the seafloor (Thiel 1979;Smith 1992;Smith et al 1997); (3) above a certain POC-flux threshold, i.e., under relatively eutrophic conditions, infaunal body size is likely to be released from food limitation and become controlled by other factors, such as body-plan constraints or the costs of burrowing through compacted sediments (Jumars and Wheatcroft 1989), ultimately causing L to plateau in relation to POC flux.…”

Section: Acknowledgmentsmentioning

confidence: 99%

“…We make this prediction because the larger benthos apparently responsible for most biogenic mixing (Wheatcroft et al 1990) should be able to maintain contact with oxygenated bottom water, even if they live Ͼ10 cm deep in anoxic sediments. In addition, we use the newly compiled deep-sea data set to test the generality of the Boudreau (1998) model, which explicitly relates the magnitude of L to D b and the decay constant (k) for organic carbon.…”

Section: Acknowledgmentsmentioning

confidence: 99%

“…In particular, the recycling and burial of organic carbon, nutrients, and pollutants, as well as the resolution of the stratigraphic record, depend substantially on the rates and depths of biogenic sediment mixing (e.g., Aller 1982;Wheatcroft et al 1990;Smith et al 1993).…”

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What controls the mixed‐layer depth in deep‐sea sediments? The importance of POC flux

Smith

Rabouille

2002

Limnology & Oceanography

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The depth of biogenic particle mixing, i.e., the mixed-layer depth (L), is fundamental in models of organic-matter recycling and paleoreconstructions for deep-sea sediments. Factors postulated to control L in the oxygenated deep sea include particulate organic carbon (POC) flux, oxygen penetration into the sediment, and a balance between the downward mixing and decay of labile POC. We explore the dependence of L on biogeochemical characteristics by compiling, from 36 sites in three oceans, an internally consistent set of deep-sea estimates of L, POC flux, biogenic mixing intensity (D b ), and POC reactivity. We use excess 210 Pb as a tracer for L and D b to avoid the confounding effects of tracer-dependent mixing. We find that L, estimated from the penetration depth of excess 210 Pb, varies systematically with POC flux, with an asymptotic function explaining 88% of the variance in L. Stepwise multiple regression suggests that the penetration depth of excess 210 Pb (and estimated L) is much more likely to be controlled by POC flux than by (1) the sediment inventory of excess 210 Pb or (2) biogenic mixing intensity (D b ). In addition, L is negatively related to oxygen penetration into the sediment (r ϭ Ϫ0.629) and not significantly related to predictions of L from a recent mixing/POC-decay model. We conclude that in the food-poor deep sea, POC flux substantially controls the size and activities of the sediment-mixing benthos and, in turn, the thickness of the biogenic mixed layer. Thus, in contrast to previous suggestions, average mixed-layer depth is not environmentally invariant but rather responds predictably to ecologically important parameters such as POC flux.The mixing of sediment grains by animal activity (i.e., biogenic particle mixing) profoundly influences the structure and geochemistry of marine sediments. In particular, the recycling and burial of organic carbon, nutrients, and pollutants, as well as the resolution of the stratigraphic record, depend substantially on the rates and depths of biogenic sediment mixing (e.g., Aller 1982;Wheatcroft et al. 1990; Smith et al. 1993).In deep-sea regions characterized by low current velocities, low sedimentation rates, and well-oxygenated bottom water, biogenic mixing is thought to control the movement of particles in near-surface sediments. Under these conditions, biogenic mixing is usually parameterized as eddy diffusion, described by an intensity coefficient D b (units of length 2 time Ϫ1 ) that operates over a sediment depth interval, L, called the mixed-layer depth (e.g., Guinasso and Schink 1975;Boudreau 1998). Based on this formulation, at steady

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Section: Discussionmentioning

confidence: 99%

Section: Acknowledgmentsmentioning

confidence: 99%

Section: Acknowledgmentsmentioning

confidence: 99%

mentioning

confidence: 99%

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What controls the mixed‐layer depth in deep‐sea sediments? The importance of POC flux

Smith

Rabouille

2002

Limnology & Oceanography

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“…The infaunal redistribution of sediment particles and dissolved species has been represented as a vertical diffusive process using the biodiffusion coefficient [Wheatcroft et al, 1990]. One-dimensional irrigation coefficients have been widely used to represent the vertical redistribution of dissolved species due to infaunal ventilation of their burrow habitats [Emerson et al, 1984].…”

Section: Introductionmentioning

confidence: 99%

Biogeochemical consequences of infaunal activities

Furukawa¹

2005

Coastal and Estuarine Studies

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The public reporting burden for this collection of Information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, Activities of sedimentary infauna have significant consequences on overall sedimentary diagenesis. Infauna directly participate in sedimentary processes by organic matter metabolization coupled to aerobic respiration and metabolite excretion. In addition, they indirectly influence the diagenetic pathways by changing the transport regimes of dissolved and particulate species as well as by modifying microbial habitats. The couplings between infaunal activities and their biogeochemical consequences have been studied in recent years, but many of the results and conclusions remain site-and species-specific due to the diverse and highly interrelated ways in which sedimentary infauna interact with the transport. reaction, and microbial regimes. A generalized understanding of infauna-influenced sedimentary systems will require (It a systematic classification of the infauna-sediment interaction mechanisms Activities of sedimentary infauna have significant consequences on overall sedimentary diagenesis. Infauna directly participate in sedimentary processes by organic matter metabolization coupled to aerobic respiration and metabolite excretion. In addition, they indirectly influence the diagenetic pathways by changing the transport regimes of dissolved and particulate species as well as by modifying microbial habitats. The couplings between infaunal activities and their biogeochemical consequences have been studied in recent years, but many of the results and conclusions remain site-and species-specific due to the diverse and highly interrelated ways in which sedimentary infauna interact with the transport, reaction, and microbial regimes. A generalized understanding of infauna-influenced sedimentary systems will require (1) a systematic classification of the infauna-sediment interaction mechanisms and (2) a comprehensive model framework that incorporates all known effects of infauna-sediment interactions associated with transport, reaction, and microbial regimes.

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Magnetotaxis and acquisition of detrital remanent magnetization by magnetotactic bacteria in natural sediment: First experimental results and theory

Mao

Egli

Petersen

et al. 2014

Geochem Geophys Geosyst

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[1] The widespread occurrence of magnetotactic bacteria (MTB) in several types of marine and freshwater sediment, and the role of fossil magnetosomes (magnetofossils) as main remanent magnetization carriers therein, has important paleomagnetic and paleoenvironmental implications. Despite numerous studies on MTB biology and on magnetofossil preservation in geological records, no detailed information is yet available on how magnetotaxis (i.e., the ability to navigate along magnetic field lines) is performed in sedimentary environments, and on how magnetofossils possibly record the Earth magnetic field. We provide for the first time experimental evidence for these processes. MTB living in sediment are poorly aligned with the geomagnetic field, contrary to what is observed in water. This can explain the seemingly excessive magnetic moment of most MTB. The observed alignment is sufficient for supporting magnetotaxis across the typical thickness of chemical gradients. Experiments with magnetofossil-rich sediment suggest that a natural remanent magnetization (NRM) is acquired by magnetofossils in the so-called benthic mixed layer, where natural MTB populations usually occur. The acquired NRM is proportional to the applied field at least up to $160 mT, and its intensity is compatible with values observed in nature for same sediment types. Therefore, if fossil magnetosome chains are not subjected to further alteration by early diagenetic processes, they can provide useful relative paleointensities. We propose a preliminary model to explain early stages of magnetofossil NRM acquisition as the result of a dynamic equilibrium between magnetic torques and randomizing forces due to sediment mixing.

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A mechanistic view of the particulate biodiffusion coefficient: Step lengths, rest periods and transport directions

Cited by 213 publications

References 65 publications

What controls the mixed‐layer depth in deep‐sea sediments? The importance of POC flux

What controls the mixed‐layer depth in deep‐sea sediments? The importance of POC flux

Biogeochemical consequences of infaunal activities

Magnetotaxis and acquisition of detrital remanent magnetization by magnetotactic bacteria in natural sediment: First experimental results and theory

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