Detritus sinking

The object of the present study was to measure the ratios of organic carbon, nitrogen, and hydrogen in the detritus sinking in lake water and in the sediments and to discuss the decomposition processes of these components in order to gain basic knowledge concerning the mechanism of coal formation. 

The HNTC areas were enigmatic until the discovery of the role of iron in phytoplankton production. In the three main HNTC areas—the equatorial Pacific, subarctic Pacific and Southern Ocean—the phytoplanktonic communities are generally dominated by picoplankton. There are also periodic diatom blooms, from which a large proportion of the detritus sinks out of the euphotic zone, so silicate levels are also often low (Dugdale et al. 1995). Iron concentrations are very low, which in the subarctic Pacific and Southern Ocean may be due to the low aeolian contribution in the form of continental dust (Martin et al. 1991). 

The N-cycle model included an explicit representation of detritus-N production, transport, sinking and remineralization. Moreover, this model carried both NH4 and NO3 with a representation of NH4 inhibition of NO3 uptake by phytoplankton. Although the inhibition approach is now generally considered to lack a convincing mechanistic basis (see Section 3.2), both the N-cycle model and the achievement of coupling it to a dynamic circulation model represent significant advances in ocean N-cycle modeling. 

Other N-cycle models simulate detritus N formation, sinking and reminerahzation explicitly (e.g.. Hood et al, 2001 McCreary et al, 1996 Sarmiento et al, 1993). In its simplest form this involves specification of a detritus (D) pool that sinks with a constant sinking rate and remineralization rate e. If detritus is not produced or consumed by any other processes, then the detritus equation has the form... 

Particle aggregation effects can also be parameterized in explicit formulations by making the sinking rate of the detritus a function of detritus concentration. For example. Hood et al. (2003) applied this kind of simple parameterization in an NPZD model to account for aggregation that can occur in diatom blooms. In their model phytoplankton sink at the rate... 

In aquatic systems stratification of the water column has significant effects on nutrient availability and the timing of bursts of primary productivity. It is convenient to consider these effects in the oceans in terms of the latitudinal variations in stratification. Overall, due to the sinking of detritus out of the euphotic zone and the... 

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