Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:1:p8
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 1 (pt 8/9)
Character Range: 2863105–2866237

crops are based on potatoes as representative crops for this group.
         Equation 23
where:
         Equation 24

               Equation 25

                Equation 26

where:
    k1  = rate of chemical flux into the potato, (per hour) (Equation 24)
    k2  = rate of chemical flux out of the potato, (per hour) (Equation 26)
    kg  = exponential rate of growth of the potato, (per hour) (assumed equal to the default of 0.0014)
    Foc  = fraction of organic carbon in the soil, (unitless)
    Koc  =organic carbonwater partition coefficient for the contaminant, (cm3/g) (compound-specific)

    Dwater  = chemical diffusion coefficient in water, (m2/s) (compound-specific)
    ρp  = potato tissue density, (g/cm3) (assumed equal to the default of 1)
    R  = radius of the potato, (m) (assumed equal to the default of 0.04)
    W  = water content of potato, (g/g) (assumed equal to the default of 0.79)
    Kpw  = equilibrium partition coefficient between potato and water, (cm3/g) (Equation 25)
    fch  = fraction of carbohydrates in the potato, (unitless) (assumed equal to the default of 0.209)
    L  = lipid content of potato on a mass basis, (g/g) (assumed equal to the default of 0.001)
    Kow  = octanolwater partition coefficient, (unitless) (compound-specific)
         Kch  = carbohydratewater partition coefficient, (cm3/g) (calculated from chemical lipophilicity according to the following table)

Chemical log Kow  Chemical Kch (cm3/g)
<0                0.1
0 but <1         0.2
1 but <2         0.5
2 but <3         1
3 but <4         2
4                3

Green Vegetables

  (mg/kg fresh weight [fw] plant per mg/kg dry weight [dw] soil)                    Equation 27

where:
    Koc  =organic carbonwater partition coefficient for the contaminant, (cm3/g) (compound-specific)
    foc  = fraction of organic carbon in the soil, (unitless)
    Kow  = octanol-water partition coefficient, (unitless) (compound-specific)
    ρs  = dry soil bulk density, (g/cm3)
    θWS  = soil-water content by volume, (cm3/cm3)

Tree Fruit

        Equation 28
where:
      Equation 29

       Equation 30

where:
    Mf  = mass of fruit, (g fw) (assumed equal to the default of 1)
    Qfruit  = water flow rate per unit mass of fruit, (cm3/g fw) (assumed equal to the default of 20)
    DMfruit  = dry matter content of fruit, (g/g) (assumed equal to the default of 0.16)
    Cstem  = chemical concentration in the woody stem (mg/g) (Equation 29)
    Kwood  = woodwater partition coefficient, (mg/g dw wood per mg/cm3 water) (Equation 30)
    Csoil  = total chemical concentration in soil, (mg/kg dw) (assumed to be 1 for establishing ratio)
    Koc  = organic carbonwater partition coefficient for the contaminant, (cm3/g) (compound-specific)
    foc  = fraction of organic carbon in the soil, (unitless)
    Kow  = octanolwater partition coefficient, (unitless) (compound-specific)
    Q  = transpiration stream flow rate, (cm3/year) (assumed equal to the default of 25,000,000)
    M  = mass of the woody stem, (g dw) (assumed equal to the default of 50,000)
    ke  = rate of chemical metabolism, (per