Environment indicators

If uranium is internally cycled in coastal environments or if the riverine delivery of U shows some variability, residence time estimates (regardless of their precision) cannot be sensitive indicators of oceanic uranium reactivity. Based on very precise measurements of dissolved uranium in the open ocean, Chen et alJ concluded that uranium may be somewhat more reactive in marine environments than previously inferred. Furthermore, recent studies in high-energy coastal environments " indicate that uranium may be actively cycled and repartitioned (non-conservative) from one phase to the next. 

Experience with uncoated IN-738 blades in this very hostile environment indicates about 25,000 hours blade life can be attained. The coated blade life, based on this interim evaluation, should add an additional 20,000 hours of life. 

Most waste treatment systems operate in the mesophilic region. The expense of altering the temperature of wastes encountered in abnormally cold or warm environments indicates the desirability of developing organisms which are suited to extremes of ambient waste temperatures. 

The ever-increasing problems occurring in our man-made environment indicate the complete inability on the part of both designers and others to realize the significance of other... 

The 1994 estimates on the degree of TCDD contamination in the environment indicated that approximately 500,000 tons of soil and sediment in the United States were contaminated with... 

An example under consideration could be hydrogen FC systems with three options including natural gas turbine, PV and wind energy systems representing different RES power plant option. These options are evaluated with the multicriteria method comprising the following indicators performance indicator, market indicator, environment indicator and social indicator. The indicators are composed... 

The fin shown has a base maintained at 300°C and is exposed to the convection environment indicated. Calculate the steady-state temperatures of the nodes shown and the heat loss if k - 1.0 W/m °C. 

The weak retention by the sand of As(III), particularly in the oxidizing environment, indicates that the interaction between As(III) and Fe(III), the hydrated ferric oxide, is much weaker than that between As(V) and Fe(III). On the basis of other studies (10,11,12) increased adsorption of As (III) would be expected as the pH of the eluting water is increased (as more reducing ground waters are used). However, decreased adsorption of As(III) is observed, and this is attributed to the reduction of Fe(III) to Fe(II) on the column. 

Properties of PCDEs, including physicochemical ones, are not well known as the literature reviews of PCDEs have shown [4, 11,40,46]. PCDEs resemble PCBs structurally and in their chemical and physical properties, which, like PCDDs, PCDFs, and related compounds, are known to be stable and resistant to breakdown by heat, hydrolysis, bases, and acids. PCBs are also quite stable to oxidation under moderate conditions [3], but there is not much data about PCDEs concerning their stability. There is some evidence that PCDEs are resistant to bases and acids and the occurrence of PCDEs in the environment indicates that PCDEs are persistent and bioaccumulating compounds. The study of Firestone et al. [37] already showed that PCDEs are quite stable, since PCDEs could be measured in chlorophenol extracts after sulfuric acid treatment. Tetra- and octachlorinated PCDE congeners were later proven resistant in treatment with... 

Observations of these reactions in the natural environment indicate that they take place on the order of years per chlorine removed for aryl halides in sediments (Brown et al., 1987 Adriaens et al., 1999 Fu et al., 2001 Gaus et al., 2002), and months to years for alkyl halides or pesticides in groundwater (Potter and Carpenter, 1995 Wiedemeier et al., 1999 Skubal et al., 2001). Accurate calculations account for the metabolic rates measured in sediments or soils (Henrichs and Reeburgh, 1987 Schlesinger, 1991 Murphy and Schramke, 1998). For example, Fu et al. (2001) estimated the rate of cometabolic dioxin dechlorination in estuarine Passaic River sediments at 3-8 pg of diCDD per gram sediment per year, based on sediment respiration rates, and the ratios of dioxin dechlorination as compared to methane production, which represented the dominant TEAP under which these reactions occurred. 

Foams are ubiquitous in the environment, commonly seen as discolored patches on streams, rivers, lakes, and sea water. They often are assumed to be anthropogenic in origin as they are aesthetically unpleasant, yet they frequently appear in pristine environments indicating a natural origin. The chemical nature of foam, however, is ill defined, and geomorphological and geochemical constraints on natural jfoam formation are not well characterized. 

A qualitative difference in essential oil composition between two or more phenotypes, which are raised in the same environment, indicates that one or more factors in one of the original specific environments was either above or below the influence threshold for the production of a specific essential oil (4). 

The USEPA standards for 24-h PM, and PM2.5 concentrations in ambient environments are 150 and 65 pg/m , respectively. Indeed in some settings the levels exceed what is considered acceptable for even occupational exposures. The threshold limit value adopted by the American Conference of Governmental Industrial Hygienists for respirable dusts is 5,000 pg/m and for carbon monoxide is 29 mg/m The comparison with these health-based standards (although currently available for settings other than indoor household environments) indicates the potential for significant health risks. 

MAS spectra (14.1 T) of recombinant Cur. inaequalis VClPO (bottom trace, with the best model for the vanadium environment indicated). For comparison, the solid-state NMR spectra of a model compound (centre), sodinm orthovanadate (top) and hovine serum alhumin [BSA, trace (h)] are also shown. An asterisk indicates the isotropic peak. Reproduced from N. Pooransingh-Margohs et at, J. Am. Chem. Soc. 128, 5190-5208. Copyright (2006), with permission from the American Chemical Society. 

But studies of the kinetics of polymerization of different monomers, under different conditions and chemical environments, indicate that ideal behavior is probably more an exception than the rule. Most practical free-radical polymerizations will deviate to a greater or lesser extent from the standard conditions outlined in the reaction scheme (6.3) to (6.10) either because the actual reaction conditions are not entirely as postulated in the ideal kinetic scheme or because some of the assumptions that underlie the ideal scheme are not valid. 

The simulation correctly reproduces the closeness of the gas phase and protein absorption A. Geometry optimizations in the different environments indicate that the protein, gas phase and solution spectral features are related to the nature of the chromophore structure. Notice that, remarkably, as shown in Fig. 12.7, the equilibrium structures in the protein (Fig. 12.7a) and in the gas phase (Fig. 12.7c) display close absorption maxima in spite of the different geometrical structures. In contrast, the solution equilibrium structure (Fig. 12.7b) differs dramatically. Thus, even the geometrical analysis is consistent with the spectroscopy. 

A variety of physiological groups of bacteria are of importance for water quaUty. They participate in various natural processes in water. In addition, other bacteria are introduced from the environment, indicating general and faecal pollution. They include conditionally pathogenic and pathogenic bacteria. 

No specific studies appear to have been carried out on the influence of O2 and CO2 on soft rot. The observations of soft rot in waterlogged wood suggest that the responsible fungi are able to attack wood at levels of oxygen that are too low for wood-degrading basidiomycetes. The absence of soft rot and presence of bacterial attack in samples from certain aquatic environments indicate that bacteria are even more tolerant of low oxygen concentrations. 

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