Soil partition coefficient

In its simplest form a partitioning model evaluates the distribution of a chemical between environmental compartments based on the thermodynamics of the system. The chemical will interact with its environment and tend to reach an equilibrium state among compartments. Hamaker(l) first used such an approach in attempting to calculate the percent of a chemical in the soil air in an air, water, solids soil system. The relationships between compartments were chemical equilibrium constants between the water and soil (soil partition coefficient) and between the water and air (Henry s Law constant). This model, as is true with all models of this type, assumes that all compartments are well mixed, at equilibrium, and are homogeneous. At this level the rates of movement between compartments and degradation rates within compartments are not considered. 

Lohninger, H. (1994) Estimation of soil partition coefficients of pesticides from their chemical structure. Chemosphere 29,1611-1626. 

Physical and Chemical Properties. As reported in Section 3.2, the relevant physical and chemical properties of cyanide compounds are known. Certain physical parameters such as octanol/water partition coefficient and soil partition coefficient that are used generally for covalently bound organic compounds to predict environmental fate and transport are neither available nor useful for most of the ionic cyanide compounds. 

The bulk air-soil partition coefficient, Kiasoii, encompasses absorption into soil or-... 

Lohninger, H., Estimation of Soil Partition Coefficients of Pesticides from Their Chemical Structure. Chemosphere, 1994 29, 1611-1626. 

Lide, D.R., Editor (2003) Handbook of Chemistry and Physics. 84th Edition, CRC Press, LLC. Boca Raton, Florida Lohninger, H. (1994) Estimation of soil partition coefficients of pesticides from their chemical structure. Chemosphere 29(8), 1611-1626. Lord, K.A., Briggs, G.C., Nearle, M.C., Manlove, R. (1980) Uptake of pesticides from water and soil by earthworms. Pest. Sci. 11, 401 108. 

The volatility potential (slope of the vapor pressme vs. concentration in soil organics) of GA is 2.4 x 10" mm Hg/mg/kg and its air-soil partition coefficient (for a soil density of 1.4 g/cm ) of 1 x 10 mg/m (MacNaughton and Brewer, 1994), indicate that GA will evaporate from soil into the air. Results of a field trial with GA showed 10% evaporation in 0.27 horns and 90% evaporation in 4.66 hours (Morrill et al., 1985). 

The measurement of water solubility, water-octanol and water-soil partition coefficients presented several unique challenges. Novel experimental methods and data are reported for these physical constants. In some cases, experimental data is at odds with earlier published values. Comprehensive comparison of all available estimated, calculated, and experimental data are presented. The new values impact the calculation of the mobility of dioxin in soil, as well as other distribution properties. 

Jackson, et al.(6), examined the leaching potential of TCDD-contaminated soils Fom various sites. Soil partition coefficients were large (the mean log for two samples was 5.9 and 6.02), indicating that TCDD is only very slightly soluble and that only very small amounts of TCDD will be released into water. The authors concluded that the rates of TCDD movement in soils are so slow that other transport mechanisms such as wind and water erosion are likely to be more significant. 

Kow octanol/water partition coefficient, K c soil partition coefficient. 

Trichloroethane will enter the atmosphere from its use in the manufacture of vinylidene chloride and its use as a solvent. Once in the atmosphere, 1,1,2-trichloroethane will photodegrade slowly by reaction with hydroxyl radicals (half-life 24 to 50 days in unpolluted atmospheres and within a few days in polluted atmospheres). The soil partition coefficient of 1,2-trichloroethane is low and it will readily leach in the case of eventual, very slow biodegradation. Bioconcentration is not a significant process. It will also be discharged in wastewater associated with these uses and in... 

PCDDs exhibit widely varying water solubilities, octanol/water partitioning coefficients, and soil partition coefficients (Table 10.6). The variation could be as much as 1 X 10. Thus, when a mixture of PCDD is... 

A correlation between root/soil partition coefficients with log Koc was also obtained and it was reported that in long-term studies, a constant RCF was approached only after 100 days or more, presumably reflecting the slow transport of sparingly soluble more hydrophobic substances. 

---