Particulate organic carbon POC

The introduction of wet combustion methods for dissolved organic carbon (Parsons and Strickland,. 1959 Duursma, 1961) allowed a precise but 

Attempts to evaluate the organic matter content by microscopic observation seem to give results which are non-reproducible and quite different from the chemical analyses (Mel nikov, 1976 Pustel nikov, 1976). 

There have been many studies of the distribution of POC in the oceans (Dalpoint and Newell, 1963 Bogdanov, 1965 Holm-Hansen et al., 1966 Hobson, 1967 Menzel, 1967 Riley, 1970 Loder, 1971 Wangersky, 1976 and many others), but many of these works were carried out by investigators using different sampling techniques and analysis methods. It is therefore difficult to compare the results. Nevertheless, it can be observed that there is a trend to find much smaller quantities of POC with the improvement of techniques. 

The frequency distribution of POC with depth as reported by this author is of some interest (Fig. 3) and demonstrates a close agreement between the POC distribution in the Atlantic and Pacific Oceans, with the exception of surface vedues which are higher in South Atlantic waters. These differences in surface waters are however not significant because of the heterogeneity of the samples containing both living matter and detritus. The effects of seasonal or local hydrographic conditions are limited mainly to surface waters, which as a consequence show differences in productivity. 

The slow decrease of the values with depth is more interesting, since it supports the idea that organic matter is utilized by organisms at any depth. Differences between old deep waters and deep layers of young cold waters, richer in organic carbon, seem to confirm this hypothesis. 

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The quantity of primary production that is exported from the upper ocean is said to be equivalent to new production (18, 19) New primary production is that associated with allocthonous nutrients (i.e., those upwelled or mixed into the euphotic zone or input via rivers and rain). In order for steady state to be maintained, an equivalent flux out of the euphotic zone is required. Earlier studies (19) suggested that sediment-trap measurements of particulate organic carbon (POC) flux were equivalent to new primary production however, recently it has become clear that these measurements probably represent only a... 

Finally, the balance equation for the SMSL looks like Eq. 23-30, except for the reaction term which is not necessarily linear now. Note that Cssc depends also on z (the depth in the lake, not the depth in the sediment column). Every depth zone has its own SMSL, but it is assumed that these layers do not interact with each other. In fact, the distance between them is much too large for lateral molecular diffusion in the sediments to play any role. There is no equation for the particles in the SMSL. Their balance is indirectly included in the preservation factor (3(z). Remember that if total solids are used to describe the solid phase, (3 is about 1, whereas if particulate organic carbon (POC) is used, (3 is smaller than one because part of the POC is degraded in the SMSL. Finally, we get ... 

Bloesch, J., and M. Sturm, Settling flux and sinking velocities of particulate phosphorus (PP) and particulate organic carbon (POC) in Lake Zug, Switzerland . In Sediments and Water Interactions, P. G. Sly, Ed., Springer, New York, 1986, pp. 481-490. 

Particulate organic carbon POC DOC = VOC + NPDOC Suspended particles, moieties that are kept back by a 0.2-10 pm... 

Figure 13.10 Percentage particulate organic carbon (POC) and total suspended particulates (TSP) in the water column from three regions of the Sabine-Neches estuary, sampled from March 1992 to October 1993. (Modified from Bianchi et al., 1997a.)... 

Figure 13.11 Seasonal distribution of (a) total suspended particulates (TSP) and (b) particulate organic carbon (POC) along a salinity gradient and distance from the mouth of the Delaware Bay estuary. (Modified from Harvey and Mannino, 2001.)...

Figure 13.12 Seasonal range of particulate organic carbon (POC) in different regions of San Francisco Bay (1992-1993) and Chesapeake Bay (1995-1996) estuaries. Error bars represent standard deviations for mean concentrations when three sites were measured. (Modified from Canuel, 2001.)...

DOM is composed of small molecules that can be obtained by filtration. Quantification of organic matter in aquatic environment is performed by measuring the concentrations expressed in organic carbon. One measures total organic carbon (TOC) obtained from raw liquid sample, particulate organic carbon (POC) by analyzing the filter, and the dissolved organic carbon (DOC) characterized from the sample after filtration. 

For phytoplankton particulate organic carbon (POC) and particulate nitrogen (PON) determination, some suspended matter was collected on precombusted (450°C) Whatman GF/F filters, dried at 60°C and stored in polystyrene Petri dishes until analysis. POC and PON were analyzed with a Carlo Erba NA 2000 elemental analyzer. The analytical error of the... 

Table 1 Fe concentrations, Chi a per cell, P. antarctica cell abundance, particulate organic carbon (POC), particulate organic nitrogen (PON) and dissolved organic carbon (DOC) in the P. antarctica cultures under low Fe (<1 nM Fe, LFe) and Fe amended (FIFe) conditions used for bacterial regrowth experiments...

Vertical flux of particulate organic carbon (POC) and phytoplankton was measured with two parallel cylindrical sediment traps (aspect ratio 6.25), mounted in a gimballed frame equipped with a vane (KC maskiner og labora-... 

Fig. 6 Episodic vertical flux events of total particulate material (TPM) and particulate organic carbon (POC) at 100 m depth induced by P. pouchetii-deiived material quantified as transparent polymer particles (TEP, in terms of gum xanthan equivalents) in Balsfjord, northern Norway, from March to October, 1996. Vertical flux is given as mg nT2 d 1.

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