Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:1:p7
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 1 (pt 7/9)
Character Range: 2860588–2863392

0.9 for HIL B and 0.8 for HIL D)
         Um  = mean annual wind speed at a height of 10m (m/s), assumed to be 8.75 km/hr (or 2.4 m/s) based on the average 9 am and 3 pm winds from Canberra
         Ut  = threshold value of wind speed at a height of 10m (m/s), which is how much wind is required to generate dust at a given site from an erodible surface. A default value of 7.2 m/s has been used in the derivation of HILs (EA 2009)
         Fx  = empirical function calculated based on the ratio of mean and threshold wind speeds as noted by EA (2009). For the derivation of HILs the following was used:
,   where        Equation 20

The PEF calculated for indoor air (and outdoors for HIL C) is based on a dust loading factor. The PEF is calculated as follows:
         Equation 21
where:
    DL = dust loading factor (mg dust/m3 air)
    10-6 = conversion factor for mg to kg

1.5         Calculation of plant concentration factors
The concentration of contaminants in edible portions of fruit and vegetables is estimated from the relationship between soil and plant and described using a soil-to-plant concentration factor (CFx).
For inorganic contaminants, the CFx values are derived from available literature (relevant to below- or above-ground crops).
For organic contaminants, there is a range of equations available that is based on experimental data. Where relevant, plant uptake of organic compounds has been estimated in the derivation of HILs using the equations presented by EA (2009), which are detailed as follows (refer to EA (2009) for further explanation of the basis for these equations):

Root Crops
      Equation 22
where:
    Q  = transpiration stream flow rate, (cm3/day) (assumed equal to the default of 1000)
    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)
    W  = root water content, (g/g) (assumed equal to the default of 0.89)
    L  = root lipid content on a mass basis, (g/g) (assumed equal to the default of 0.025)
    ρp  = plant root density, (g/cm3) (assumed equal to the default of 1)
    kg  = first order growth rate constant, per day (assumed equal to the default of 0.1)
    Km  = first order metabolism rate constant, (per day) (assumed equal to the default of 0)
    RV  = root volume, (cm3) (assumed equal to the default of 1000)

Tuber Crops
Calculations presented for tuber 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