Sediment nitrogen between

The simulation model depicts the flows of nitrogen between the compartments, and in particular is used to investigate the effect of sedimentation of phytoplankton and zooplankton faeces out of the euphotic zone which is assumed to be 60 m deep however the depth does not affect the conclusions drawn from the results. 

Henriksen, K., Hansen, J.I., and Blackburn, T.H. (1980) The influence of benthic infauna on exchange rates of inorganic nitrogen between sediment and water. Opheha 1, 249-256. 

Numerous biotic factors influence N processing within sediments, including the composition of the microbial, macrofaunal, and macrophyte communities, behaviors of the various infaunal communities, and trophic transfer of carbon and nitrogen between communities. Interactions between benthic communities may be physical, chemical, or biological in nature and, in turn, are influenced by the physical nature of the environment, sediment composition, and autotrophic dominance (Fig. 19.3). 

Fig. 6. Electron microscopy of Ca -ATPase crystals in thin sections. Sarcoplasmic reticulum (2mg of protein/ml) was solubilized in the standard crystallization medium with C12E8 (2mg/mg protein) and incubated under nitrogen at 2°C for 15 days. The crystalline sediment was embedded in Epon-Araldite mixture and processed for electron microscopy. Depending on conditions during fixation, embedding, sectioning and viewing, the observed periodicities in different specimens varied between 103 and 147 A. Magnification, x 207000. From Taylor et al. [156].

The nitrogen flows between the land, sea, atmosphere, and sediments are illustrated in Figure 24.2. Three estimates are provided for different time intervals (circa I860, early 1990s, and a projection for 2050) because human activities have significantly altered the rates of some of the critical transport pathways. The sizes of the major reservoirs are given in Table 24.2. 

The fact that the average ratio of Miner. C/Miner. N (2.83) is considerably smaller than the ratio of Org. C/Org. N of plankton (5.7) indicates clearly that the organic nitrogen in plankton is more easily mineralized than the organic carbon by microbiological activities and also that the mineralization processes are active in the lake water. This fact may account for the relationship between the ratios of Org. C/Org. N of plankton, of detritus and of surface bottom sediments, which has been shown previously. 

Solid state —> colloidal state — soluble or gaseous state In order that the relationship between the microbiological decomposition rates of organic carbon and nitrogen in the bottom sediments be known more fully, the following components were measured ... 

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