Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:3:p21
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 3 (pt 21/21)
Character Range: 1400176–1401980

of EILs, the 50th percentile of the data (that is, the regression equation) should be used to estimate ABC values.

The relationships developed by Hamon et al. (2004) take the form
    ABC  = a* log Fe or Mn + b     (equation 17)

To calculate the ABC, measure the Fe and Mn concentration in the soil (expressed in %) using aqua regia digestion (Hamon et al. 2004), and substitute the appropriate metal concentration into the appropriate equation. It is, however, necessary to ascertain that the Fe and Mn content of the soil at the site in question is not elevated by contamination. These elements are normally determined in chemical analysis of soils to determine total metal concentrations and therefore minimal extra cost is involved.

3.3.3         Organics
Most organic contaminants of interest to contaminated sites are xenobiotics, hence they have no natural background concentration. Notable exceptions to this include lipids and fats, hormones (for example, oestrogen, testosterone), fatty acids, alcohols, hydrocarbons, polycyclic aromatic hydrocarbons and dioxins. Therefore, ABCs will have to be generated by direct measurement or a default ABC of zero (Crommentuijn et al. 2000b) could be assumed. There are no equivalent models to that of Hamon et al. (2004) available for organic contaminants.

For pyrogenic and naturally occurring organic contamination, a site-specific assessment should be conducted to determine if the measured concentrations are background concentrations for that region. If a site-specific assessment is conducted, then the upper 80th percentile of the ABCs should be used as the background as per the Australian and New Zealand WQGs (ANZECC & ARMCANZ 2000). However, even if they are considered ABCs, this does not imply that there is no risk to terrestrial biota.