Pollution factors affecting potential

An evaluation of the factors affecting the reliability of the ammonium pyrrolidinecarbodithioate-methyl isobutyl ketone (APCD-MIBK) extraction system for Cd, Cu, Ni, Pb, and Zn in seawater established that pH control of the aqueous phase is important. The pH range 2.1 to 2.3 was the best for extracting these metals. In addition, the amount of APCD added was important both because of potential corn-petition reactions and because of metal contamination in the APCD reagent. The overall precision of the technique and the precision of the atomic absorption measurements were calculated. This technique can be used effectively in both clean coastal waters and more polluted harbor waters. 

As long as landfill continues as an accepted form of waste disposal, there will always be potential for related pollution events, and an understanding of the factors affecting such pollution is important. 

The interfacial microenvironment around a microbial community, that is the sum of the physical, chemical, and biological parameters which affect a microorganism, determines whether a particular microorganism will survive and/or metabolize. The occurrence and abundance of microorganisms in an environment are determined by nutrient availability, and various physicochemical factors such as pH, redox potential, temperature, and solid phase texture and moisture. Because a limitation imposed by any one of these factors can inhibit biodegradation, the cause of the persistence of a pollutant is sometimes difficult to pinpoint. The summary follows [39,92,94,97,109,110,172,173,176,189,190, 195,248-252,256-300]. 

Contaminants may reach the subsurface in a gaseous phase, dissolved in water, as an immiscible hquid, or as suspended particles. Contaminant partitioning in the subsurface is controlled by the physicochemical properties and the porosity of the earth materials, the composition of the subsurface water, as well as the properties of the contaminants themselves. While the physicochemical and mineralogical characteristics of the subsurface sohd phase define the retention capacity of contaminants, the porosity and aggregation stams determine the potential volume of liquid and air that are accessible for contaminant redistribution among the subsurface phases. Enviromnental factors, such as temperature and water content in the subsurface prior to contamination, also affect the pollution pattern. 

Contaminant volatilization from subsurface solid and aqueous phases may lead, on the one hand, to pollution of the atmosphere and, on the other hand, to contamination (by vapor transport) of the vadose zone and groundwater. Potential volatihty of a contaminant is related to its inherent vapor pressure, but actual vaporization rates depend on the environmental conditions and other factors that control behavior of chemicals at the solid-gas-water interface. For surface deposits, the actual rate of loss, or the pro-portionahty constant relating vapor pressure to volatilization rates, depends on external conditions (such as turbulence, surface roughness, and wind speed) that affect movement away from the evaporating surface. Close to the evaporating surface, there is relatively little movement of air and the vaporized substance is transported from the surface through the stagnant air layer only by molecular diffusion. The rate of contaminant volatilization from the subsurface is a function of the equilibrium distribution between the gas, water, and solid phases, as related to vapor pressure solubility and adsorption, as well as of the rate of contaminant movement to the soil surface. 

Such a transformation process will affect its mobility and increase its toxicity. This we can see in the corresponding data, reported in Table 1.2 [i.e., the carcinogenic potential or slope factor, the reference dose for oral and inhaled intake (RfD), its solubility, and its vapor pressure]. If these pollutants reach a certain exposure level for a community who breathes contaminated air or consumes polluted water, its members will be at risk. 

The major emphasis of this discussion centered on the importance of surface and subsurface soil characteristics in influencing deep pesticide leaching. Some factors, such as the depth to groundwater and the amount of incipient rainfall or irrigation, are clearly important factors that do affect the probability of pesticide residues reaching groundwater. Similarly, properties of the pesticide itself (especially its inherent mobility and chemical/biological stability) correlate closely with pollution potential, but their evaluation is outside the scope of this review. 

Because pollution potential cannot be determined on a regional scale, smaller "hydrogeologic settings" were developed within each of the regions described by Heath (5). These hydrogeologic settings create units which are mappable and, at the same time, permit further delineation of the factors which affect pollution potential. 

Inherent in each hydrogeologic setting are the physical characteristics which affect the ground-water pollution potential. Many different biological, physical and chemical mechanisms may actively affect the attenuation of a contaminant and, thus, the pollution potential of that system. Because it is neither practical nor feasible to obtain quantitative evaluations of intrinsic mechanisms from a regional perspective, it is necessary to look at the broader parameters which incorporate the many processes. After a complete evaluation of many characteristics and the mappability of the data, the most important mappable factors that control the ground-water pollution potential were determined to be ... 

Because of the heterogeneous nature of landfill, the bacterial population and therefore gas ratios, gas production rates and leachate composition can diange from one region to the next, and can affect the landfill pollution potential. Other factors of major significance include moisture content, pH and temperature. The available surface area and the nature of the surface of refuse particles will also be important determinands of microbial activity, and will thus affect the nature of the hazard posed by landfill gas and leachate. 

As has been shown, the energy content of various fuels may vary quite considerably. Factors other than the actual energy content of the fuel play a big role in determining which of these fuels we use. Availability, ease of transport and storage, pollution-producing potential, cost, and even perceived danger may affect our perception and use of the fuels. Let s look at where some of the petroleum-based fuels come from before addressing the question of which is the best fuel ... 

In Fig. 1, we present a diagram of om understanding of the human exposure pathways and potential factors that affect human asthma susceptibility between mban and rmal areas. In this model, different environmental mban-based exposures (e.g., particulate or gaseous air pollutants from vehicular traffic, and indusfiy), and similar ones in rmal areas (e.g., indoor pollution from biomass fuel combustion, and keeping or herding animals) are known to potentially affect susceptible adult hosts. Such exposmes may produce airway inflammation and obstruction. However, there... 

A potential role of various seasonal and meteorological factors in the etiology of asthma and asthma-related symptoms has long been suspected. There is evidence that climate may affect asthma symptom prevalence and frequency, either directly (e.g., via an effect of air temperature on airway responsiveness) or indirectly (e.g., via altered exposure to infections, aeroallergens, or air pollutants) (Metintas and Kurt 2010 Franco et al. 2009 Hales et al. 1998 Verlato et al. 2002 Chen et al. 2006). 

Several important soil biological, chemical, and physical processes have major effects on the environment and are important for understanding the basis for several important environmental issues including air, soil, and water pollution, climate change, and the fate of pollutants and other materials added to soil. The magnitude and rate of many of these processes are affected by abiotic factors, such as temperature, aeration, soil water content, and soil moisture potential. 

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