Seawater biological organisms

Recent Hartree-Fock simulations [94] of serine-silicate complexes, identified as likely templating candidates [95] in SDVs, seem to suggest that five-coordinate complexes are not favored in the acidic environment of the SDV however, four coordinate serO-Si(OH)3 were lOkcalmoF more exothermic than serOH-Si(OH)4 interactions. At the basic pH values of seawater, sihcic acid was favored over Si-O-C bonds. In a recent Minireview, Perry and Keeling-Tucker [96] discuss research in the area of biosilicification and conclude that biological organisms exert controls not easily mimicked in vitro. 

Williams, P. J. LeB. (1975). Biological and chemical aspects of dissolved organic matter in seawater. In "Chemical Oceanography," Vol. 2 (J. P. Riley and G. Skirrow, eds). Academic Press, London. 

The biological cycle of arsenic in the surface ocean involves the uptake of arsenate by plankton, the conversion of arsenate to a number of as yet unidentified organic compounds, and the release of arsenite and methylated species into the seawater. Biological demethylation of the methyl-arsenicals and the oxidation of arsenite by as yet... 

Changes in the distribution of organic compounds in a seawater sample can be due to physical, chemical, or biological factors. As a physical factor, we might consider the absorption of surface-active materials on the walls of the sample container. While this effect cannot be eliminated it can be minimised by the use of the largest convenient sample bottle, and the avoidance of plastic (especially Teflon) containers. Another possible method of eliminating this source of error would be to draw the sample directly into the container in which the analytical reaction is to be run. 

Degradation rate of chlorpyrifos in abiotic substrates varies, ranging from about 1 week in seawater (50% degradation) to more than 24 weeks in soils under conditions of dryness, low temperatures, reduced microbial activity, and low organic content. Intermediate degradation rates reported have been 3.4 weeks for sediments and 7.6 weeks for distilled water. In biological samples, degradation time is comparatively short — usually less than 9 h in fishes and probably the same in birds and invertebrates. 

---