Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:9:p3
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 9 (pt 3/3)
Character Range: 1714821–1716830

relationships for Ni the CEC was the best parameter (Oorts et al. 2006b; Rooney et al. 2007; EC 2008b). Only six normalisation relationships could explain more than 50% of the variation in the toxicity data (i.e. r2 > 0.5) and these are presented in Table 73. The majority of the normalisation relationships had r2 values of <0.1.

Normalisation relationships are available for a variety of biological end points based on both NOEC and EC10 data and on EC50 data. The relationships used to normalise the data in the current study were relationships 1, 5 and 9 from Table 72 for glucose-induced respiration, nitrification and tomato, and relationships 2, 3, 5, 6 from Table 73 for barley, all invertebrates, maize residue mineralisation and respiration. The relationships with the lowest gradients for each species were selected. The exception to this was the relationship for invertebrates. This was selected as it was based on all invertebrate species and its gradient was only marginally higher than the invertebrate relationship with the lowest gradient. For the species that did not have normalisation relationships, the relationship for the most closely related species was used, or in the case where there were relationships for several related species, the relationship with the lowest gradient was used. Thus, all plant species (apart from tomato) were normalised with the EC10 relationship for barley and all the microbial processes without a relationship were normalised with the EC10 relationship for maize residue mineralisation.

Table 72. Normalisation relationships between soil CEC and the toxicity of nickel (Ni) to a variety of soil plant and invertebrate species and soil microbial processes for both fresh and aged contamination. The relationships used to normalise the toxicity data in this project are in bold.
Eqn no.                             Species/soil process          Y parameter                      X parameter(s)                   Reference
Northern hemisphere relationshipsa