Silica pump model

A box model fiar the marine silica cycle is presented in Figure 6.11 with respect to the processes that control DSi and BSi. An oceanic budget is provided in Table 16.3 in which site-specific contributions to oceanic outputs are given. This table illustrates that considerable uncertainty still exists in estimating the burial rate of BSi. Regardless, burial of BSi is responsible for most of the removal of the oceanic inputs of DSi, with the latter being predominantly delivered via river runoff. This demonstrates the importance of the biological silica pump in the crustal-ocean-atmosphere factory. 

Pondaven, P., Fravalo, C., Ruiz-Pino, D., Treguer, P., Queguiner, B., and Jeandel, C. (1998). Modelling the silica pump in the permanendy open ocean zone in the Southern Ocean. J. Mar. Syst. 17, 587-619. 

One of the earliest models is illustrated in Figure 13.3, which clearly shows the principles used in later improvements. The LC effluent was pumped along a length of silica capillary tubing inside... 

Hadj-Mahammed et al. analyzed a mixture of flavone, 5-methoxyflavone, and tangeretin by supercritical CO2 SFC on capillary columns with two types of detectors flame ionization (FID) and FT-IR. Peafe identification was achieved with the help of the FT-IR fingerprint of each compound. However, the separation was satisfactory only by the use of supercritical C02g density programs, without the use of a phase modifier. The separations were accomplished using a Carlo Erbaa SFC system equipped with a Model SFC 300 pump and Model SFC 3000 oven. The fused silica capillary column were BPl (12 mxO.l mm I.D. 0.1-pm film of di- methylpolysiloxane) and DB5 (15 mxO.l mm TD. 0.4-pm film of 94% dimethyl-, 5% diphenyl-, and 1% vinylpolysiloxane). The two supercritical CO2 density programs used in this work were PI [from 0.127 g/mIi->... 

Figure 8.4 Origin of the electro-osmotic flow in a capillary filled with an electrolyte. Model of the double layer. If the inner wall has not been treated (polyanionic layer of a silica or glass capillary) then a pumping effect arises from the anodic to the cathodic compartment this is the electro-osmotic flow which is reliant upon the potential which exists on the inner surface of the wall. If the wall is coated with a non polar film (e.g. octadecyl) then this flow no longer exists. The electro-osmotic flow is proportional to the thickness of the double cationic layer attached to the wall. It is reduced if the concentration of the buffer electrolyte increases. Ugos pH dependant between pH 7 and 8 can increase by as much as 35 per cent.

Conventional ancillary equipment was used with these sedimentation FFF systems. Sed I, for example, utilized a model 410 high-performance liquid chromatography (HPLC) pump from Kontron Electrolab (London) and a UV Spectroflow Monitor SF770 from Kratos Analytical Instruments (Westwood, NJ). Fractions of eluted silica were collected by means of a model FC-80K Microfractionator from Gilson Medical Electronics (Middleton, WI). 

---