Low organic carbon content

The vacuum extraction method has been effectively applied to removing VOCs with low organic carbon content from well-drained soil, although it may also be effective for finer and wetter soils, but with comparatively slower removal rates. There are generally significant differences in the air permeability of various strata, which can influence process performance. Contaminants with low vapor pressure or high water solubilities are difficult to remove. 

In soil, alachlor is photolytically unstable. After an 8-h exposure to sunlight, degradation yields in a sandy loam, loam, silt loam, and clay were 22, 27, 36, and 39%, respectively. Degradation appeared to be enhanced in soils having low organic carbon content and low pH (Fang et al., 1979). 

Larsen. T.. Kjeldsen, P.. and Christensen. T.H. Correlation of benzene, 1,1,1-trichloroethane, and naphthalene distribution coefficients to the characteristics of aquifer materials with low organic carbon content, Chemosphere, 24 (8) 979-991.1992. 

Sorption. In aquifers characterized by low organic carbon content, most of the XOCs found in leachate plumes are only weakly attenuated by sorption. This applies to the aromatic hydrocarbons, chlorinated hydrocarbons, and the polar compounds. Very few detailed sorption studies involving landfill leachate have been reported (Kjeldsen et al., 1990 Larsen et al., 1992). Preliminary evidence suggests that the presence of leachate, in particular in terms of dissolved organic carbon, does not affect the sorption of XOCs significantly and as such the traditional methods for estimating retardation in aquifers are valid. 

Solvent Extraction of Simazine firem Soil. Soil samples of 10 grams (sandy loam with low organic carbon content) were dried at 80 °C, suspended in 10 ml of ethyl acetate, and shaken or sonicated at low power for 30 min. Solids were allowed to settle, and the extract was decanted. The soil was resuspended in 10 ml of ethyl acetate, and this second extract was added to the first one, and filtered through Na2S04. These extracts were used directly for gas chromatography. For EIA, the ethyl acetate was evaporated to diyness, the eluate was reconstituted in 1 ml PBS-Tween, and aliquots were taken directly into the EIA. 

Low organic carbon content water can be readily prepared by bulk UV irradiation of distilled water using an irradiator similar in design to Fig. 16-3, but with the coil replaced by 200 mL capacity (35 mm diameter, main body 255 mm long) silica tubes positioned around the lamp. Free radical formation is aided by the addition of ca. 0.25 mL of 30 % (w/v) hydro-... 

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