Oxygen continued depth profile

Figure 11. Depth profiles of oxygen consumption. The profile defined by the solid circles (m) was calculated from ETS activity measurements (o) as reported previously (55). The profile defined by the open triangles (a) is based on bacteriological studies (84). The family of continuous profile lines between A and B was generated by Suess s (93) model of oxygen-consumption rates.

Fig. 15.20 Left Oxygen and nitrate profiles influenced by bioirrigation within the upper 10 cm as modeled with an Excel spreadsheet according to the Press F9 method . The simulation was performed on the basis of anticipating a partial coupling of pore water to the concentrations prevalent in bottom water in the upper 10 cm of the sediment. Right Here, a quantity of bottom water was continually added in a specific depth. The result is related to the measurement shown in Figure 3.24 after Glud et al. (1994).

Among the first instruments to measure almost continuously the three basic parameters in the water column (Hinkelmann, 1957 Brown, 1974), the one developed by Brown was termed Conductivity Temperature Depth profiler (CTD). This name now is in general use for such instruments. Additional sensors are often attached, e.g., sensors to measure dissolved oxygen and pH values (see Chapter 14), fluorescence, light attenuation, sound velocity and others. 

Oxygen profiles in the ocean do not continually decrease with depth (Fig. 1.4). A typical dissolved O2 profile exhibits a minimum that is positioned above 1000 m. The main processes that contribute to this profile are the rapid and efficient respiration of settling organic matter (with more than half being degraded between 100 and... 

Results of experiments performed with oxidized PP doped with secondary HAS Tinuvin 770 show high concentration of nitroxides in the vicinity of both surfaces due to the DLO. This was observed after continuous exposure to radiation in the Weather-Ometer on the irradiated (front) and non-irradiated (back) surfaces as well as on the both surfaces of the samples e qjosed thermally in hot air oven. Very low concentration of nitroxides was present inside of the samples. The concentration profiles are of characteristic U-shape and indicate preferential surface oxidation of PP, with a specific response to thermal and photochemical stress (Fig. 2). The assumed complex HAS mechanism is thus more explicitly confirmed in thick samples than by monitoring nitroxide concentration in PP films. It is consistent with surface consumption of oxygen in thick plaques and lower availability of oxygenated products in the depth of the PP matrix necessary for a direct development of nitroxides from HAS as well as for nitroxide regeneration from O-alkylhydroxylamine >NOP within the regenerative cycle (7). 

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