Mineralization soil chlorine

Organic contaminants such as petroleum hydrocarbons or chlorinated solvents can be directly metabolized by proteins and enzymes, leading to the degradation, metabolism, or mineralization of the contaminants. Furthermore, many of these contaminants can be broken down into harmless products or converted into a source of food and energy for the plants or soil organisms.50... 

Chemicals degraded by WRF include pesticides such as organochlorines DDT and its very toxic metabolite DDE [8, 9] and organophosphate pesticides such as chlorpyrifos, fonofos and terbufos [10] polychlorinated biphenyls (PCBs) of different degrees of chlorine substitution [11-13], some even to mineralization [14, 15] diverse polycyclic aromatic hydrocarbons (PAHs) in liquid media and from contaminated soils or in complex mixtures such as creosote [16-18] components of munition wastes including TNT and its metabolites DNT [19-23], nitroglycerin [24] and RDX [25]. 

Their mobility may be increased by the simultaneous presence of organic solvents such as mineral oil. The half-life of TCDD in soil has been reported as 10-12 years, whereas photochemical degradation seems to be considerably faster but with a large variation that might be explained by experimental differences (solvents used, etc.). Highly chlorinated PCDD/PCDFs seem to be more resistant to degradation than those with just a few chlorine atoms. 

HCZyme has been demonstrated in bench-scale tests and at field remediations to be effective on benzene, toluene, ethylene, and xylene (BTEX), Polycyclic aromatic hydrocarbons (PAHs), trichloroethylene (TCE), dichloroethylene (DCE), mineral spirits, fuel oils, motor oils, and hydraulic fluids. The vendor claims that HCZyme has been tested and used on over 2 million tons of petroleum-contaminated soils and is effective in breaking down petroleum hydrocarbons, polychlorinated biphenyls (PCBs), creosote, sludges, waste oils, free product, tank bottoms, and other chlorinated compounds (D18208L, p. 15). 

The Vaportech technology has been used in the past to treat soils contaminated with chlorinated solvents such as perchloroethylene (PERC) and trichloroethylene (TCE) benzene, toluene, ethylbenzene, xylenes (BTEX) aromatics, ketones, gasoline-range and diesel-range organics, phenols, and other cyclic and noncyclic carbon compounds including ketones, naphtha, mineral spirits, and lacquer diluter. 

The 4-ft unit is primarily used to treat soils contaminated with gasoline, diesel, jet fuel, oil, mineral oil, and kerosene. The 5-ft and 6-ft parallel flow LTTD units are designed to treat Bunker C oil, crude oil, and creosote soil contaminants. These plants can also treat soils contaminated with chlorinated hydrocarbons, pesticides, and solvents. 

Trans Coastal Marine Services (formerly Envirosystems, Inc.) and Louisiana State University (LSU) have developed several bioreactor systems to facihtate petroleum hydrocarbon mineralization and the bioremediation of organic wood preservatives utilizing an immobilized microbe bioreactor (IMBR) technology. These technologies can treat petroleum hydrocarbons, chlorinated solvents, pesticide-contaminated soils, and contaminated groundwater. 

The U.S. Department of Energy s Office of Technology Development has sponsored full-scale environmental restoration technology demonstrations since 1990. The Savannah River Site Integrated Demonstration focuses on the bioremediation of groundwater contaminated by chlorinated solvents. Several laboratories, including the Savannah River site, have demonstrated the ability of methanotrophic bacteria (i.e., those that oxidize methane) found in soil, sediment, and aqueous material, to completely degrade or mineralize chlorinated solvents. 

Zeddel, A., Majcherczyk, A. Huttermann, A. (1994). Degradation and mineralization of polychlorinated biphenyls by white-rot fungi in solid-phase and soil incubation experiments. In Bioremed tation of Chlorinated and Polycyclic Aromatic Hydrocarbon Compounds, ed. R. E. Hinchee, A. Leeson, L. Semprini S. K. Ong, pp. 436-40. New York Lewis Publishers. 

Table 6.4 shows first-order rate coefficients and tx/2 values for degradation of a number of pesticides in soils (Rao and Davidson, 1982). The k and t1/2 values calculated from field data are based on the disappearance of the parent compound (solvent extractable). Table 6.4 also includes k and t1/2 values calculated on mineralization (14C02 evolution) and parent-compound disappearance from laboratory studies. The t1/2 values were smaller for field than for laboratory studies. Rao and Davidson (1980) attribute this to the multitude of factors that can affect pesticide disappearance in the field while only one factor is studied in the laboratory. Rao and Davidson (1982) suggested that pesticides be classified into three groups based on values (Table 6.5) nonpersistent (t1/2 < 20 days), moderately persistent (20 < t1/2 < 100 days), and persistent (/1/2 > 100 days). Most chlorinated hydrocarbons are grouped as persistent, while carboxyl-kanoic acid herbicides are nonpersistent. The s-triazines, substituted ureas, and carbamate pesticides are moderately persistent. 

In some sorption cases 1/n equals 1. When this condition is met, a plot of -SC versus C will produce a straight line with KD as slope (C-type isotherm Fig. 4.16). This type of isotherm best describes soil sorption of hydrophobic organics (e.g., chlorinated hydrocarbons) (Fig. 4.17). The linearity of such data can be explained by the schematic model in Figure 4.18. In this model, (linear partition model), the hydrophobic organic contaminant distributes itself linearly between hydrophobic organic matter adsorbed on an inorganic mineral particle and solution. Linearity... 

The impact of the various substances listed above may result in low-quality water with bad taste, odor, and turbidity or toxicity from the high concentration of heavy metals, chlorinated hydrocarbons, and/or pathogenic bacteria and viruses. Water purity, however, is not a prerequisite to good water quality with respect to human consumption or agricultural and industrial uses. When water contacts soil, the latter contributes dissolved minerals (e.g., Ca, Mg, K) which may increase the potential water quality for biological uses because these minerals serve as nutrients. 

Although TES and THEMIS are sensitive to carbonates and sulfates, these minerals have not yet been detected unambiguously from orbit (Bandfield, 2002). The low carbon abundance in APXS-analyzed soils rules out much carbonate, although appreciable sulfur and chlorine are present in all soils. Thermodynamic stability considerations suggest that sulfates and iron carbonates should be present under martian conditions (Clark and Van Hart, 1981 Catling, 1999). It is unclear whether sulfate formed by reactions with acidic vapor from volcanic exhalations (Banin et al., 1997) or evaporation of surface brines (Warren, 1998 McSween and Harvey, 1998). 

The Hydrophobic Effect Hydrophobic Sorption Hydrophobic ( water-hating ) compounds, for example, hydrocarbons and chlorinated hydrocarbons such as the polychlorinated biphenyls are soluble in many nonpolar solvents but not readily soluble in water. Because of the incompatibility of the hydro-phobic substance with water, these substances have a tendency to avoid contact with water and seek to associate with nonpolar environments such as the surface of a mineral or an organic particle (Tanford, 1980). The sorption of hydro-phobic substances to solid materials (particles, soils, sediments) that contain organic carbon may be compared with the partitioning of a solute between two solvents—water and the organic phase. 

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