Organic compounds in soils 27
1-Chlorohexane
1,1,1-Trichloroethane
2-Chloroethyl vinyl ether
1,1,2-Trichloroethane
Chloromethane
Trichloroethylene
Chloromethyl methyl ether
Trichlorofluoromethane
Dibromochloromethane
Trichloropropane
Dibromomethane
Vinyl chloride
Dichlorodifluoromethane
1,1-Dichloroethane
1,2-Dichloropropane
1,2-Dichloroethane
(trans)-1,2-Dichloropropylene
1,1-Dichloroethylene (Vinylidene chloride)
1,1,2,2-Tetrachloroethane
trans-1,2-Dichloroethylene
1,1,1,2-Tetrachloroethane
Dichloromethane
Tetrachloroethylene
Miscellaneous
Kerfoot et al [126] examined the performance of a grab sampling technique for soilgas measurement analysis at a site with ground water known to be contaminated with
chloroform. The study assessed the correlation between soil-gas and ground water
analysis with chloroform as a model volatile organic compound. Chloroform concentration in soil gas increased linearly with depth in the unsaturated zone.
A study of the vertical profile of chlorinated solvents in the soil, enables the
source of contamination to be distinguished; for atmospheric inputs a peak occurred a
short distance below ground, whereas for inputs from groundwater the concentration
increased progressively as the water table was approached.
Mehran et al [127] determined the distribution coefficient of trichloroethylene
in soil water systems. The distribution coefficient of trichloroethylene could be used
to define the retardation factor, which expressed the velocity of trichloroethylene
migration relative to an advancing water front. The two method used to obtain the
distribution coefficient were field measurements based on trichloroethylene concentrations in soil at various depths, and theoretical methods based on total organic carbon
content of the soil and octanol-water partition coefficient for trichloroethylene. The
average distribution coefficient was 0.18 mL per g and the average retardation factor
was 2.48 (19 field samples). Theoretical methods were valid for soils with greater than
1% organic carbon. Reasonable estimates for actual migration rates could be provided for soils low in organic carbon. Field methods were still preferred as the effect
of various factors on partitioning of trichloroethylene were integrated.
2.3.2 Chloroaromatic hydrocarbons
Chlorinated aromatic compounds are commonly found as contaminants in environmental soil samples. For example, chlorobenzenes have been listed as priority
pollutants and can be found in various matrixes such as water, soils, sediments and
sewage sludges. Polychlorinated biphenyls are probable human carcinogens but have
been applied in large doses in various industrial products.
Wenrrich et al [128] optimised important accelerated solvent extraction parameters, such as extraction temperature and time, using a spiked wetland soil. The
effect of small amounts of organic modifiers on the extraction yields was studied.
1-Chlorohexane
1,1,1-Trichloroethane
2-Chloroethyl vinyl ether
1,1,2-Trichloroethane
Chloromethane
Trichloroethylene
Chloromethyl methyl ether
Trichlorofluoromethane
Dibromochloromethane
Trichloropropane
Dibromomethane
Vinyl chloride
Dichlorodifluoromethane
1,1-Dichloroethane
1,2-Dichloropropane
1,2-Dichloroethane
(trans)-1,2-Dichloropropylene
1,1-Dichloroethylene (Vinylidene chloride)
1,1,2,2-Tetrachloroethane
trans-1,2-Dichloroethylene
1,1,1,2-Tetrachloroethane
Dichloromethane
Tetrachloroethylene
Miscellaneous
Kerfoot et al [126] examined the performance of a grab sampling technique for soilgas measurement analysis at a site with ground water known to be contaminated with
chloroform. The study assessed the correlation between soil-gas and ground water
analysis with chloroform as a model volatile organic compound. Chloroform concentration in soil gas increased linearly with depth in the unsaturated zone.
A study of the vertical profile of chlorinated solvents in the soil, enables the
source of contamination to be distinguished; for atmospheric inputs a peak occurred a
short distance below ground, whereas for inputs from groundwater the concentration
increased progressively as the water table was approached.
Mehran et al [127] determined the distribution coefficient of trichloroethylene
in soil water systems. The distribution coefficient of trichloroethylene could be used
to define the retardation factor, which expressed the velocity of trichloroethylene
migration relative to an advancing water front. The two method used to obtain the
distribution coefficient were field measurements based on trichloroethylene concentrations in soil at various depths, and theoretical methods based on total organic carbon
content of the soil and octanol-water partition coefficient for trichloroethylene. The
average distribution coefficient was 0.18 mL per g and the average retardation factor
was 2.48 (19 field samples). Theoretical methods were valid for soils with greater than
1% organic carbon. Reasonable estimates for actual migration rates could be provided for soils low in organic carbon. Field methods were still preferred as the effect
of various factors on partitioning of trichloroethylene were integrated.
2.3.2 Chloroaromatic hydrocarbons
Chlorinated aromatic compounds are commonly found as contaminants in environmental soil samples. For example, chlorobenzenes have been listed as priority
pollutants and can be found in various matrixes such as water, soils, sediments and
sewage sludges. Polychlorinated biphenyls are probable human carcinogens but have
been applied in large doses in various industrial products.
Wenrrich et al [128] optimised important accelerated solvent extraction parameters, such as extraction temperature and time, using a spiked wetland soil. The
effect of small amounts of organic modifiers on the extraction yields was studied.