Dissolved oxygen suppresses

Oxidation of As(in) to As(V) by lake sediments has been attributed to the presence of Mn oxides (Oscarson et al., 1980). In these experiments, elimination of dissolved oxygen and suppression of microbial activity had no effect on the rate of oxidation. However, treating the sediments with hydroxylamine hydrochloride or sodium acetate to remove Mn oxides significantly decreased oxidation of As(III) (Oscarson et al., 1981b). 

Zinc may also be used to prevent crevice corrosion of other materials. Work by Ito et al. (1989) shows that crevice corrosion resistance of zinc-plated stainless steels is superior to that of unplated in an NaCl solution. Good general corrosion resistance was also obtained. It seems that these beneficial results are due not only to sacrificial dissolution of zinc, but also to suppression of the cathodic reaction of dissolved oxygen by the corrosion products. A buffer action by the corrosion product also seems to play an important part in the prevention of corrosion. 

With an increasing concentration of ATP the oxidation of glucose by GOD is suppressed and the oxygen consumption is lower. Thus the increases level of dissolved oxygen compared to the reaction in the absence of ATP is related to the concentration of ATP. 

In a similar manner carbon steel is sensitive to pH. In the pH 4.5-9 range the corrosion rate is governed by dissolved oxygen. (See the following discussion on velocity effects.) Below pH 4.5 the corrosion rate is controlled by hydrogen evolution and above about pH 9, the rate is suppressed by an insoluble film of ferric hydroxide (Fig. 5) [IS]. At very high pH levels, especially at elevated temperatures, steel is susceptible to stress corrosion cracking [2i]. 

Released electrons are usually consumed in the reduction of dissolved oxygen. The rate of such a conjugated process depends on different factors, such as the oxygen concentration, the acidity of the medium, the copper surface state, and so on. Corrosion intensity can be also suppressed by inhibitors. 

Yegneswaran et al. (1991) used a Monte Carlo method and CTD similar to those of Namdev et al. (1991) to investigate the effects of dissolved oxygen on a culture of antibiotic producing Streptomyces clavuligerus. They found that the yield of cephamycin C was suppressed by almost 44% due to the Monte Carlo simulation as compared to constant period cycling. One limitation in the... 

Surfactants are commonly added to polarographic cells to suppress the overpotential associated with dissolved oxygen or other species. This phenomenon is periodically proposed as a general quantitative method for determination of surfactants in environmental samples (2-4). The approach is not useful for determining which surfactant is present. In natural waters, naturally occurring materials like humic acids are the predominant surface active materials detected by polarographic methods (5). 

---