Ascending and descending fluxes of lipid compounds in North Atlantic and North Pacific abyssal waters

Grimalt, Joan O.; Simoneit, Bernd R.T.; Gomez-Belinchon, Josep I.; Fischer, Kathleen M.; Dymond, Jack

doi:10.1038/345147a0

Cited by 27 publications

(12 citation statements)

References 26 publications

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“…There are several areas of model-data disagreement that can not readily be resolved without postulating additional sources of P, such as low export (Table 4), and high surface DIC in summer, assuming that biological export is an important factor in removing this ''excess'' DIC (Quay and Stutsman 2003). There are several possible P sources or transport mechanisms that are unresolved by the model: Vertical migration of buoyancy-regulating cyanobacteria (Karl et al 1992;Villareal and Carpenter 2003), upward fluxes of positively buoyant particulate P (Grimalt et al 1990), mesoscale upwelling (Letelier et al 2000), or largescale convergence in the lateral advection of DOP (Abell et al 2000). An additional possible ''source'' is that upper limits to C : P and N : P ratios, and therefore growth and export at very low concentrations of P, are larger than considered here.…”

Section: Discussionmentioning

confidence: 99%

Biogeochemical cycling in the oligotrophic ocean: Redfield and non-Redfield models

Christian

2005

Limnol. Oceanogr.

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The assumption of fixed elemental ratios in ocean biogeochemical models was tested using the Hawaii Ocean Time-Series data set from the subtropical North Pacific Ocean, where nutrient-starvation is a permanent condition for near-surface phytoplankton populations. Two three-element (C, N, P) ecosystem models were coupled to a mixed-layer model, an inorganic carbon chemistry model, and dynamic pools of dissolved organic C, N, and P. One model has fixed Redfield ratios for phytoplankton (constant ratio model, CRM), whereas the other has varying ratios (variable ratio model, VRM). The results suggest that the ecosystem is strongly phosphorus limited, but would be nitrogen limited in the absence of dinitrogen fixation (DNF), and may be nitrogen limited in the lower part of the euphotic zone. Known sources of phosphorus appear to be close to those required to sustain observed levels of export, given plasticity of elemental ratios. The vertical profile and seasonal time course of primary production of organic carbon are simulated well by the VRM but poorly by the CRM, as are surface concentrations of dissolved organic carbon. The seasonal cycles of air-sea CO 2 flux and export of organic carbon by sedimentation are similar in the two models, but there is a slight but persistent bias toward greater downward fluxes in the VRM. The ability of oceanic phytoplankton to adapt to P stress by reducing cellular requirements can therefore potentially enhance the oceanic sink for atmospheric carbon over vast areas of low-latitude ocean, but there is potential for saturation of this enhancement if DNF increases.

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Section: Discussionmentioning

confidence: 99%

Biogeochemical cycling in the oligotrophic ocean: Redfield and non-Redfield models

Christian

2005

Limnol. Oceanogr.

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“…In a similar way to terrestrial organisms and vascular plants, carbohydrates are common structural (chitin, mureine, and chondroitin;Brock et al 1994;Benner and Kaiser 2003) and storage (glucans; Painter 1983) compounds in marine planktonic organisms, including bacteria. In contrast to some classes of lipids, the ubiquitous character of carbohydrates does not allow a distinction between potential marine sources such as phytoplankton, zooplankton, and bacteria, which contribute to sinking (>10 µm), suspended (0.7-10 µm), or dissolved (<0.7 µm) organic material (Cowie andHedges 1984a, 1984b;Saliot et al 1982;Wakeham et al 1983;Grimalt et al 1990). Therefore, very limited information on the source of organic matter can be derived from carbohydrate analysis.…”

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confidence: 99%

Analytical methods for the determination of sugars in marine samples: A historical perspective and future directions

Panagiotopoulos

Sempéré

2005

Limnology & Ocean Methods

122

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Analytical techniques employed over the past three decades for sugar determination in marine samples are reviewed. This review first summarizes the different hydrolysis protocols used by marine biogeochemists to extract sugars from various marine matrices including sinking particulate organic matter (POM), dissolved organic matter (DOM), ultrafiltrated dissolved organic matter (UDOM), and sediments. The most commonly used methods for total sugar estimation are phenol sulfuric acid (PSA), 3‐methyl‐2‐benzo thiazoline hydrazone hydrochloride (MBTH), and 2,4,6‐tripyridyl‐s‐triazine (TPTZ). For individual sugars, gas chromatographyflame ionization detection (GC‐FID), liquid chromatography‐borate complexes (LC), high performance liquid chromatography‐ethylenediamine derivatives (HPLC‐EDA), high performance liquid chromatography‐p‐aminobenzoic acid derivatives (HPLC‐p‐AMBA), and high performance anion exchange chromatography‐pulsed amperometric detection (HPAEC‐PAD) have been employed, the last method being the most widely used. This study demonstrated that mild and strong hydrolysis give comparable results for open ocean samples, including POM, DOM, and UDOM (except for sediments) using chromatographic or colorimetric techniques. A survey of 130 sugar data sets revealed that more than half of the sugar‐C escapes analysis using chromatographic or colorimetric techniques compared to 1H and 13C NMR techniques. The reconciliation of the NMR and colorimetric or chromatographic measurements is likely to be the key to the understanding of the composition of DOM. This study also demonstrated that most of the published sugar data obtained by chromatographic techniques are related to suspended or sinking POM and sediments, and that there is a need for data on sugar composition in DOM and UDOM, which involve further analytical difficulties for chromatographic analysis.

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“…A variety of other factors may influence the accuracy of sediment trap collections. Buoyant particles may cause an upward particulate flux that has been previously ignored and that for short periods of time may be an important material transport Grimalt et al, 1990]. Thus accurate measurements of downward particle flux may not provide a quantitative estimate of material transport at a particular depth horizon.…”

Section: Sediment Trapsmentioning

confidence: 99%

Ocean flux studies: A status report

Jahnke¹

1990

Reviews of Geophysics

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Marine biogenic cycles play a key role in controlling atmospheric CO 2 concentrations. To predict future atmospheric CO2 levels and to interpret past changes that may have been associated with global climatic events, it is necessary to determine on a global scale the rates at which carbon is cycled through the ocean and the factors that may alter the rates of transfer. Because of uncertainties and limitations in existing measurement techniques and the extreme spatial and temporal variability of ocean properties and processes, studies have not yet produced an accurate, comprehensive description of the marine carbon cycle. While some advances in the measurement of specific components of the carbon cycle have been made, the fundamental problem of undersampling an extremely heterogeneous ocean has remained. Recently, satellitedeployed sensors have provided large-scale, nearly synoptic images of ocean surface water properties, such as temperature and color, which have revealed mesoscale features not observed previously. In addition, moored and free-drifting observation systems are being developed to determine directly the temporal variability of surface and subsurface water characteristics. With these remotely sensed properties to provide the space and time framework by which individual measurements of ocean processes and material fluxes can be extrapolated throughout ocean basins and over decadal time scales, we are poised to make a fundamental improvement in our understanding of ocean elemental cycles. fraction of the biogenic material sinks or is actively transported out of the surface waters into deeper water masses where it is decomposed and oxidized back to CO•. This combination of processes, referred to as the "biological pump" [Longhurst and Harrison, 1989], tends to continually strip CO• from the surface ocean that is in contact with the atmosphere and sequester it in the deeper water masses where it cannot directly exchange with the atmosphere. Except for short-term perturbations such as that caused by anthropogenic CO2 release, gas exchange with the surface ocean controls atmospheric levels of CO•. Thus the biological pump maintains atmospheric CO• at a lower level than if the ocean were abiotic. Changes in the biological pump have been suggested as the cause of the increase in atmospheric CO• at the end of the last glacial period [Broecker, 1982; McElroy, 1983; Martin and Gordon, 1988]. The biological pump may also influence how the ocean responds to and takes up anthropogenic CO• released to the atmosphere. However, it is important to recognize that ocean productivity is limited by a variety of factors such as the availability of nutrients and/or light and not by the availability of CO2. Thus increased atmospheric levels of CO• may have little effect on ocean productivity. Under steady state conditions the biological pump may have a negligible influence on the ocean's response to anthropogenic CO• [Peng and Broecker, 1984; Wagener and Rebello, 1987]. However, rapid changes in the biological pump could hav...

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Ascending and descending fluxes of lipid compounds in North Atlantic and North Pacific abyssal waters

Cited by 27 publications

References 26 publications

Biogeochemical cycling in the oligotrophic ocean: Redfield and non-Redfield models

Biogeochemical cycling in the oligotrophic ocean: Redfield and non-Redfield models

Analytical methods for the determination of sugars in marine samples: A historical perspective and future directions

Ocean flux studies: A status report

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