Determination of particulate organic carbon

An alternative method for the determination of particulate organic carbon in marine sediments is based on oxidation with potassium persulfate followed by measurement of carbon dioxide by a Carlo Erba non-dispersive infrared analyser [152,153]. This procedure has been applied to estuarine and high-carbonate oceanic sediments, and results compared with those obtained by a high-temperature combustion method. 

Ehrhardt M (1976) Determination of particulate organic carbon and nitrogen. In Grasshoff K (ed) Methods of seawater analysis. Verlag Chemie, New York, pp 215-220... 

Infrared spectroscopy has been applied to the determination of particulate organic carbon in non-saline sediments, aliphatic hydrocarbons and total organic carbon in saline sediments and mixtures of organics in sludges. 

Dankers and Laane [43] compared two methods, based on wet oxidation with potassium peroxydisulphate and loss on ignition at 560°C, for the determination of particulate organic carbon in estuarine suspended matter. They found that in estuarine sediments with a high clay content, loss on... 

Raimbault, P., Diaz, F., Pouvesle, W., and BoudjeUal, B. (1999a). Simultaneous determination of particulate organic carbon, nitrogen, and phosphorus collected on filters, using a semi automatic wet-oxidation method. Mar. Ecol. Prog. Ser. 180, 289-295. 

Copin-Montegut, C. and Copin-Montegut, G., 1973. Comparison between two processes of determination of particulate organic carbon in sea water. Mar. Chem., 1 151—156. 

Salonen K. 1979. Comparison of different glass fibre and silver metal filters for the determination of particulate organic carbon. Hydrobiologia 67 29-32. 

Pike S.M. and Moran S.B. 1997. Use of Poretics (super R) 0.7 jun pore size glass fiber filters for determination of particulate organic carbon and nitrogen in seawater and freshwater. Mar. Chem. 57 355-360. 

Murray, J. W., Young, J., Newton, J. et al. (1996). Export flux of particulate organic carbon from the central equatorial Pacific determined using a combined drifting trap- Th approach. Deep-Sea Res. II 45,1095-1132. 

Measurements of radionuclides are also used to determine removal mechanisms and controls for carbon and metal cycling in the ocean. For example, the removal of Th from the euphotic zone is closely coupled to the vertical flux of particulate organic carbon. The deficiency of Th with respect to its parent—near-surface waters is used to estimate the export flux of particulate organic carbon (Buesseler, 1991). Measurements of Th and in the upper water column provided the primary data relahng to particulate carbon fluxes during JGOFS. 

Figure 14 Fluxes and composition of particulate organic carbon in the equatorial Pacific Ocean, (a) POC fluxes (mgm d ). (b) Corresponding fractions of amino acid, carbohydrate, lipid, and molecularly uncharacterized carbon (biochemical class-carbon as a percentage of total OC) in plankton, sediment traps (105 m, l,000m, >3,500 m) and surface sediment samples. The fraction of molecularly uncharacterized organic carbon (calculated as the difference between total OC and the sum of amino acid - - carbohydrate - - Upid) increases with more extensive degradation to become the major constituent in deeper POC samples (after Wakeham et al., 1997). (c) Calculated weight percentages of amino acid, carbohydrate, and lipid in plankton and in sinking (sediment trap) particles in the upper and lower water column as determined by solid-state C-NMR spectroscopy (source Hedges et al., 2001).

Despite these limitations, empirically determined transfer functions are freqnently applied, which predominately describe the relation between water depth and particle flnx (e.g. Suess 1980 Pace et al. 1987 Antia et al. 2001). Thns, the flnx of particulate organic carbon to ocean floor is applied as the rate limiting control parameter (Schliiter et al. 2000 Wenzhbfer and Glnd 2002). Although less precise the use of transfer functions is also very helpful for the use in coupled benthic-pelagic models (cf. Fig. 12.20). Some of these... 

This method was developed by Stefan Huber (Karlsruhe, Germany) and consists of three size exclusion chromatography columns which divide the organic carbon into several fractions as a function of size, but also hydrophobic and ionogenic characteristics. A sample of up to 3 mL is injected into the instrument and filtered in-line with a 0.45 )um filter. The deposit on the filter is backwashed after 5 minutes and directly analysed with the TOC analyser to determine the particulate organic carbon content (POC). 

Biogenic silicon (BSI) was determined, with minor modifications, by the method of DeMaster (17). As adapted, the technique involved time-course leaching of <20-mg samples of particulate matter in 30 mL of 1.0% Na2C03 in a water bath at 85 °C. Silica in leachates was quantified either colorimetrically (Technicon autoanalyzer procedure) or by nitrous oxide flame atomic absorption. A high-temperature catalytic-combustion technique (Perkin Elmer 240C) was used for particulate organic carbon determinations. Particulate inorganic (carbonate) carbon was measured on the same instrument by CO 2 evolution after treatment of the particles with phosphoric acid. 

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