Column oxygen

A number of reactions in the production of pharmaceuticals or crop protection chemicals are conducted in bubble columns. Oxygen, chlorine, etc., may be the reactant gas. 

Reay, W. G., Gallagher, D. L., and Simmons, G. M., Jr. (1995). Sediment-water column oxygen and nutrient fluxes in nearshore environments of the lower Delmarva Peninsula, USA. Mar. Ecol. Prog. Ser. 118, 215-227. 

A) Water column oxygen consumption rate (from sediment trap and OUR determinations) and benthic flux (pmol O2 m y ) as a function of depth in the ocean. Redrawn from Jahnke and Jackson (1987). The benthic fluxes are normalized to the volume of water exposed per unit of sediment area and indicate that below 3000 m the respiration contribution from the sediments is greater than that in the water. The hypsometric curve in (B) indicates that the region between 3000 and 5000 m depth also has the greatest sea floor area to ocean volume ratio, which is indicated by the shaded region in (A). 

Aphotic zone oxygen consumption rates that, when vertically integrated, provide a net water column oxygen demand that can then be related stoichiometrically to a carbon export flux. 

Historic data on Secchi disk depth in the northern Adriatic Sea in 1911 through the present, with few interruptions of data collection, provide a measure of water transparency that could be interpreted to depict surface water productivity. These data coupled with surface and bottom water dissolved oxygen content determined by Winkler titrations and nutrient loads outline the sequence of eutrophication in the northern Adriatic Sea. Similar historical data from other coastal areas around the world demonstrate a decrease in water clarity due to phytoplankton production in response to increased nutrient loads that are paralleled by declines in water column oxygen levels. 

In aquatic systems such as lakes, water column oxygen can regulate the availability of copper (Balistrieri et al., 1992). During periods of the year when the water column was aerobic, copper was dominated by CuCOj and Cu species in the water column. When all the oxygen disappeared, the copper was dominated exclusively by a cuprous sulfide form. From this study it is clear that the change in oxygen status from aerobic to anaerobic has some marked effects on the copper chemistry. 

Just as in the pressure column, also in the low-pressure column oxygen is rectified downwards and nitrogen upwards. Argon accumulates both above and below the feeding of the evaporated crude oxygen (j) in the form of an argon concentration... 

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