Temperature, groundwaters

Temperature is a factor that often limits bioremediation. The first cold-temperature groundwater bioremediations are in progress. In soil treatment, heat generation during composting may overcome the temperature limitations. Bioavailability is another factor controlling bioremediation and strongly affects the residual concentrations achieved. 

Pesticides vary widely in their chemical and physical characteristics and it is their solubility, mobility and rate of degradation which govern their potential to contaminate Controlled Waters. This, however, is not easy to predict under differing environmental conditions. Many modern pesticides are known to break down quickly in sunlight or in soil, but are more likely to persist if they reach groundwater because of reduced microbial activity, absence of light, and lower temperatures in the sub-surface zone. 

Sorption of plutonium (l.fixlO-11 M) and americium (2xl0-9 M) in artificial groundwater (salt concentration 300 mg/liter total carbonate 120 mg/liter Ref. 59) on some geologic minerals, quartz, biotite, o apatite, o attapulgite, montmorillonite. Dashed lines indicate the range for major minerals in igneous rocks. Experimental conditions room temperature, particle size 0.04-0.06 mm, solid/liquid ratio 6-10 g/1, aerated system, contact time 6 days. 

A new class of solvents called ionic liquids has been developed to meet this need. A typical ionic liquid has a relatively small anion, such as BF4, and a relatively large, organic cation, such as l-butyl-3-methylimidazolium (16). Because the cation has a large nonpolar region and is often asymmetrical, the compound does not crystallize easily and so is liquid at room temperature. However, the attractions between the ions reduces the vapor pressure to about the same as that of an ionic solid, thereby reducing air pollution. Because different cations and anions can be used, solvents can be designed for specific uses. For example, one formulation can dissolve the rubber in old tires so that it can be recycled. Other solvents can be used to extract radioactive waste from groundwater. 

When temperatures of volcanic gases containing SO2 decrease, the reaction (1-35) proceeds to the right hand side. This reaction causes a considerable decrease in pH due to the formation of sulfuric acid. Advanced argillic alteration is formed by the interaction of volcanic gas with groundwater. 

They calculated the change in 8 0 values of hydrothermally altered volcanic rocks as a function of water to rock ratio by weight and temperature, assuming that oxygen isotopic equilibrium is attained in a closed system, and demonstrated that the increase in 8 0 values of altered andesitic rocks from the veins towards peripheral zones can be interpreted as a decrease in temperature from the vein system (Fig. 1.135). In their calculations, the effect of mixing of hydrothermal solution with groundwater was not considered. 

Oxygen isotopic fractionation factors used for the calculation were taken from Taylor (1997). Initial 8 0 value of hydrothermal solution (0%o) was estimated from 8 0 values of K-feldspar and quartz in the veins and homogenization temperatures (Shikazono and Nagayama, 1993), and that of groundwater (—7%c) was estimated from meteoric water value of the south Kyushu district (—7%c) (Matsubaya et al., 1975). 

Figure 1.141. Temperature-aK+/°H+ activity) trend due to the mixing of hydrothermal solution and groundwater accompanied by hydrothermal alteration (Hemley and Jones, 1964). HS hydrothermal solution, GW groundwater, A hydrothermal solution-groundwater mixing line, B hydrothermal solution-acidic groundwater mixing line (Shikazono et al., 2002).

Volume flow rates of incoming hydrothermal solution and groundwater to each reservoir were estimated from the temperature of reservoirs and initial hydrothermal solution (250°C) and groundwater (25°C)... 

Fig. 2.17. 8D and S 0 of Osorezan hot springs (Aoki, 1992b). P deep hotwater, HTVG high temperature volcanic gas, solid circle groundwater, the other symbols hot springs in this area. 

Cold groundwaters descend to the permeable zones. Mixing of the deep fluids with the cold waters brings about a rapid decrease in temperature and there by results in the precipitation of Fe-rich chlorite of about 0.5 of Fe/Fe - - Mg ratio. 

From Chapter 8 onwards, the focus of the volume shifts to lower temperature geochemistry, starting with a chapter on the behavior of the U-series nuclides in groundwaters. This subject merited a chapter on its own in the Ivanovich and Harmon (1992) volume and its continued interest has led to significant advances in understanding... 

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