Soil organic carbon partition coefficient

Wet soil For wet soils Voutsas et al. proposed two models. The first, Eq. (13), requires the knowledge of the soil/organic carbon partition coefficient and the Henry s law constant and the second, Eq. (14), the vapour pressure of the chemical involved. 

This equation is widely used to describe adsorption in soil and near-surface aquatic environments. Another widely used linear coefficient is the organic-carbon partition coefficient Koc, which is equal to the distribution coefficient divided by the percentage of organic carbon present in the system as proposed by Flamaker and Thompson.131... 

Generally, it is clear how Kd can be predicted for organic hydrophobic pollutants which obey a linear isotherm relationship. First, the organic carbon partition coefficient (i. e.,K0C) is predicted based on either solubility or the octanol-water partition coefficient (K0Vf). Then based on an estimate of the organic carbon fraction in the fine and coarse sediments/soils, Kd can be estimated from Eqs. (a and b) (Table 1). 

Diazinon released to water from both point and nonpoint sources may be emitted to the atmosphere by volatilization, sorbed to soils and sediments, or accumulated in aquatic organisms. While evaporation may not be expected to be significant based upon the Henry s law constant (see Table 3-2), volatilization of diazinon can be an important transport process. Sanders and Seiber (1983) reported that 17% of the diazinon added to a model pond volatilized in 24 hours. Diazinon released to water also may be adsorbed moderately by soils and sediments based on its organic carbon partition coefficient (K00) values measured in soil (Sharom et al. 1980a). Because this pesticide is only moderately adsorbed by some soils, leaching into groundwater can occur. 

The chemical and physical properties of pesticides affect their behavior in the environment. Solubility in water, soil half-life, and organic carbon partition coefficient (Koc) play a major role in determining a chemical s runoff potential. Because families of pesticides have similar chemical structures and physical properties, similar frequencies of detections would be expected when... 

Soil-Water partition coefficient normalised for organic carbon content Soil-Organic matter partition coefficient Octanol-Water partition coefficient Apparent Octanol-Water partition coefficient... 

Soil organic carbon-water partitioning coefficient (K,c) 115-11500... 

Di-ft-octylphthalate also strongly adsorbs to soils and does not undergo leaching to groundwater, as indicated by its estimated soil organic carbon/water partition coefficient (Koc) of about 19,000. Volatilization from soils is not expected to be significant (HSDB 1994 Vista Chemical 1992). 

Soil organic carbon/water partition coefficient, log Koc ... 

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