Minerals control

It is likely that the minerals controlling /CO2 of hydrothermal solution at back-arc basins are dolomite, siderite, calcite, hematite, magnetite, graphite, K-mica and kaolinite. Most of these minerals are not found in altered ridge basalt. 

Surface-catalyzed degradation of pesticides has been examined in the context of research on contaminant-clay interactions. Such interactions were observed initially when clay minerals were used as carriers and diluents in the crop protection industry (Fowker et al. 1960). Later specific studies on the persistence of potential organic contaminants in the subsurface defined the mechanism of clay-induced transformation of organophosphate insecticides (Saltzman et al. 1974 Mingelgrin and Saltzman 1977) and s-triazine herbicides (Brown and White 1969). In both cases, contaminant degradation was attributed to the surface acidity of clay minerals, controlled by the hydration status of the system. 

Payne, T. E Lumpkin, G. R. Waite, T. D. 1998. Uranium(VI) adsorption on model minerals controlling factors and surface complexation modeling. In Jenne, E. (ed) Adsorption of Metals by Geomedia. Academic Press, San Diego, 75-97. 

Aiuppa, A., Avino, R., Brusca, L. et al. (2006) Mineral control of arsenic content in thermal waters from volcano-hosted hydrothermal systems Insights from island of Ischia and Phlegrean fields (Campanian volcanic province, Italy). Chemical Geology, 229(4), 313-30. 

Figure 2.4. Soil inventory carbon in soil organic matter (SOM) (a), A14C of SOM (b), noncrystalline minerals (c), and crystalline minerals (d) versus age of soil substrate. Filled circles, total profile filled triangles, surface (O and A) horizons. Reprinted from Torn, M. S.,Trumbore, S. E., Chadwick, O. A., et al. (1997). Mineral control of soil organic carbon storage and turnover. Nature 289,170-173, with permission from Macmillan.

Figure 7.38. A schematic representation illustrating the differences between diagenetic processes affecting a carbonate composed of calcite and one composed of a metastable polymineralic assemblage of magnesian calcite, aragonite and calcite. Water-controlled alteration (WCA) processes are driven principally by invasion and evasion of CO2, whereas mineral-controlled alteration (MCA) is mainly governed by the differences in the chemical reactivity of the carbonate minerals. (After James and Choquette, 1984.)...

The major mineral groups commonly found in soil include (1) aluminosilicates, (2) oxides, and (3) organic matter. Through their surface electrochemical properties, these soil minerals control adsorption, transformation, and release behavior of chemical constituents (e.g., nutrients and contaminants) to water or soil solution. Soil-surface electrochemical properties vary between soil types and depend on factors such as parent material, climate, and vegetation (Table 3.1). Generally, the overall makeup of soil is (Fig. 3.1)... 

Tom, M.S. et al., Mineral control of soil organic carbon storage and turnover, Nature, 389, 170, 1997. 

Mineral Control Mineral Autoclave Mineral Microwave... 

At intermediate depths (down to 500 m) groundwaters rapidly increase in concentration primarily by the addition of SO4 and Cl. The concentration of bicarbonate ions decreases because of the precipitation of mineral phases such as calcite. Local variations in chemistry and anions may be due to a variety of rock-water interactions or local processes that result in Na-SO4, Na-HC03, and Mg-S04 type waters. The pH begins to rise in this zone and oxygenconsuming reactions and redox mineral controls tend to lower the Eh. The brackish and saline waters found at these intermediate depths have longer residence times. Deep saline waters and brines occur in most locations below depths of 500 m. These fluids are Ca-Na-Cl or Na-Ca-Cl in composition and can have total dissolved loads up to 350 g L. Minor elements such as bromide and strontium can here be thousands of milligrams per liter. 

Pearson F. J., Jr. (1987) Models of mineral controls on the composition of saline groundwaters of the Canadian, shield. In Saline Water and Gases in Crystalline Rocks, Special Paper 33 (eds. P. Fritz and S. K. Frape). Geological Association of Canada, Memorial University, Newfoundland, pp. 39—51. 

Torn M. S., Trumbore S. E., Chadwick O. A., Vitousek P. M., and Hendricks D. M. (1997) Mineral control of soil organic carbon storage and turnover. Nature (London) 389(6647), 170-173. 

As a second example of mineral-controlled buffer capacity, consider the reaction in pure water between the clays kaolinite and illite (here assumed the same as muscovite), which may be written... 

Figure 4 also shows the removal of Mn " " from pore waters below the zone where it is added by reductive dissolution of Mn oxides. Equilibrium calculations have been used to infer that the mineral controlling Mn solubility in coastal and estuarine sediments is most likely to be a mixed Mn, Ca carbonate,... 

Interpreting Cullers (1988) showed that the silt fraction of a sediment most closely reflects the multi-element provenance of the sediment. The feldspars and sphene control concentrations of Ba, diagrams for Na, Rb and Cs ferromagnesian minerals control die concentradons of Ta Fe, Co, sediments Sc and Cr Hf is controlled by zircon and the REE and Th are controlled by sphene. The rados La/Sc, Th/Sc, La/Co, Th/Co, Eu/Sm and La/Lu are also good indicators of provenance. 

Goodfield and Saihan (1988) found a 44% prevalence of sensitivity to one or more fragrances in 35 coal miners, compared with 22% in male and 17% in female non-miner controls. The high frequency was attributed to the use of a highly perfumed body lotion provided at the pit-head bath, and to the facilitation of contact sensitisation due to the frequent occurrence of irritant dermatitis from working in the coal-mines (Goodfield and Saihan 1988). 

The concentration and/or activity of dissolved Fe(III) is thus controlled by different mineral phases depending on the pH. This is illustrated in Fig. 3, which plots the pH-dependent variation in the concentration and speciation of dissolved iron in different mine pit lakes of the IPB. Among the 15 pit lakes studied, jarosite was only observed to precipitate in Corta Atalaya, so that this mineral controls the apparent equilibrium which seems to exist between dissolved and particulate Fe(ni) in this lake. Conversely, ferrihydrite is the mineral form under which Fe(III) precipitates in Los Frailes pit lake. Most lakes, however, seem to be at or near equilibrium with respect to schwertmannite, which not only controls the solubility of Fe(III), but also buffers the systems at pH 2.5-3.5 (through reaction (5)), and sorbs toxic trace elements like As [5-14, 24—28]. 

Fluorite has not been identified by miner-alogical analysis, but it is frequently quoted as the mineral controlling the fluorine content in other marl or shale formations (Baeyens Bradbury 1994 Pearson Scholtis 1995). 

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