Factors Influencing Dissolved Oxygen Concentration

DO levels are also affected by depth. Temperature differences at different 

Nutrient availability can impact on DO levels in several ways. Excess nutrients lead to an increase in ph3doplankton and other types of algae. When the algae die and decompose, they use up oxygen in the estuary, resulting in low DO conditions. In some cases, living phytoplankton or algae can also cause low DO conditions. 

Data obtained from station 13 show that DO variation with time can be mainly attributed to the influence of phj ical factors in the mixed water region (Table 4.17). The influence of salinity on DO variation with time was greater than that of temperature based on the correlation coefficients between them and DO. The significant positive correlation between DO and water temperature is inconsistent with thermodynamic knowledge, which suggests that the influence of other factors on DO variations with time is more significant than the thermodynamic factor. When only the data obtained at the water surface are considered, none of the five parameters, viz., salinity, water temperature, Chi a, NO3 and PO concentrations, has significant correlation with DO. 

Abril G, Borges AV (2005) Carbon dioxide and methane emissions from estuaries. In Tremblay A, Vaxfalvy L, Roehm C, Garneau M (eds.) Greenhouse Gas Emissions—Fluxes and Processes. Springer Berlin Heidelberg, Germany, pp. 187-207 

Abril G, Etcheber H, Borges AV, Prankignoulle M (2000) Excess atmospheric carbon dioxide transported by rivers into the Scheldt Estuary. Compt Rend Acad Sci Ser IIA-Earth Planet Sci 330(ll) 761-768 Abril G, Etcheber H, Delille B, Prankignoulle M, Borges AV (2003) Carbonate dissolution in the turbid and eutrophic Loire Estuary. Mar Ecol Prog Ser 259(Sept.) 129-138 

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Many factors influence acid corrosion. Metallurgy, temperature, water turbulence, surface geometry, dissolved oxygen concentration, metal-ion concentration, surface fouling, corrosion-product formation, chemical treatment, and, of course, the kind of acid (oxidizing or nonoxidizing, strong or weak) may markedly alter corrosion. 

Rapid and complete As(III) oxidation was obtained in our laboratory by Ti02-photocatalysis and further addition of Fe(III) salfs (Mafeu, 2007). The influence of photocatalyst mass, pH, and As(III) concentration were analyzed. It was found that dissolved oxygen concentration was one of the most important factors for the reproducibility of fhe experimenfs. Addition of H2O2 increased fhe rate, while addition of Fe(III) af fhe beginning of irradiation caused complete As(III) removal from the suspension. 

In the glucose oxidase system, dissolved oxygen concentration as well as glucose levels will influence dehvery response requiring close control of mass-transfer limitations. For both systems containing a protein component, stabihty factors may limit operational hfetime. This may be particularly severe in the case of glucose oxidase where the reaction product H2O2 will accelerate enzyme denaturation unless it is rapidly removed by diffusion or reaction with a second enzyme (peroxidase or catalase). 

The MW of natural chitin is normally higher than 1,000,000 Da and that of commercially available chitosan is around 100,000-1,200,000 Da (Li et al., 1992 Lower, 1984). Numerous forces during commercial production may influence the MW of chitosan. Factors such as high temperature (>280 °C thermal degradation of chitosan occurs and the polymer chains quickly break down), dissolved oxygen concentration, and shear stress may cause these changes to occur (Li et al., 1992 Muzzarelli, 1977). 

While seawater is a ubiquitous environment and quite similar in terms of chloride content and pH, the corrosivity is site-specific, and likely to be influenced by a myriad of other factors such as temperature, dissolved oxygen concentration, flow, degree of fouling, bacterial activity, and pollution. All of these factors often are interrelated. The test program followed the guidelines provided in ASTM G 52 (Standturd Practice for Conducting Surface Seawater Exposure Tests on Metals and Alloys). 

It is often difficult to conduct laboratory tests in which both the environmental and stressing conditions approximate to those encountered in service. This applies particularly to the corrosive conditions, since it is necessary to find a means of applying cyclic stresses that will also permit maintenance around the stressed areas of a corrosive environment in which the factors that influence the initiation and growth of corrosion fatigue cracks may be controlled. Among these factors are electrolyte species and concentration, temperature, pressure, pH, flow rate, dissolved oxygen content and potential (free corrosion potential or applied). 

There are several factors that have a large influence on metabolic pathways. Among the external factors, the most important are the dissolved oxygen and carbon dioxide concentration, the pH, and the temperature of the culture. These factors are discussed in Chapter 2, but here their effects on metabolic pathways are described. 

If there is a fundamental kinetic limitation at the standard process temperature, it may be possible to adopt more severe process conditions, bearing in mind that intensified equipment will entail much shorter residence times. Thus the balance between the desired and undesired reactions may be influenced favourably. Certain processes may spuriously appear to be kinetically limited, especially if the reaction involves intermediates which are only present in small concentrations, e.g. dissolved oxygen in fermentations or organic oxidations. The key factor is the half-life of the relevant reacting species. If this is short, compared with the mixing rate or circulation time in the reactor, then the system is limited by the prevailing fluid dynamics rather than the kinetics. Obviously, when the kinetics are not limiting, the fluid environment must be intensified to relax the other restrictions. 

Fig. 2-5 shows that, below the boiling point, as the temperature increases, the rate of corrosion at each acid concentration also increases. At each acid concentration two factors influence the rate of corrosion of B-3 alloy (Fig. 2-5), namely the dissolved oxygen content in the acidic solution and the temperature. The higher the dissolved oxygen content and the higher the temperature, the higher the rate of corrosion. It is known... 

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