Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:6
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 6
Character Range: 1719564–1722265

6        Respiration                          2.37 x – 0.36 (r2 = 0.92)

a = all CEC measurements were made using the silver thiourea method (Chhabra et al. 1975).

9.5              Sensitivity of organisms to nickel
Figure 9 shows the SSD (that is, the cumulative distribution of the geometric means of normalised NOEC and EC10 toxicity values) for the species used to derive the Ni SQGs. While there is an abundance of terrestrial toxicity data for Ni, the majority of data is for microbial processes and microbial enzymes, with only small amounts of data for plants and invertebrates. There does not appear to be any difference in the sensitivity of microbial processes and both plants and invertebrates. However, the distributions of the sensitivities of the plants and invertebrates only just overlap. Nonetheless, there are no marked differences in the sensitivity of the three groups of organisms and therefore all the available toxicity data was used to derive the Ni SQGs.

Figure 9. The SSD of normalised NOEC and 10% effect concentration (EC10) toxicity data for fresh nickel (Ni) contamination against soil Ni concentration for soil invertebrates, plants and microbial processes.

9.6              Calculation of soil quality guidelines for fresh nickel contamination
Soil quality guidelines were derived using three different sets of toxicity data (that is, NOEC and EC10, LOEC and EC30, and EC50 data) as part of this study.

9.6.1         Calculation of soil quality guidelines for fresh nickel contamination based on no observed effect concentration and 10% effect concentration toxicity data

9.6.1.1         Calculation of soil-specific added contaminant limits
All the toxicity data was normalised as set out earlier. The generic ACL(NOEC & EC10) values generated for fresh Ni contamination for the three land uses are presented in Table 74.
Table 74. Generic ACLS for fresh nickel (Ni) contamination based on NOEC and 10% effect concentration (EC10) toxicity data for various land uses.
Land use                             Generic added contaminant limit
                                     (mg added/kg)
Areas of ecological significance     6
Residential urban/public open space  50
Commercial/industrial                95

The normalisation equations were then used to calculate soil-specific ACL values at a range of CEC values. Then the lowest ACL at each CEC value was adopted as the soil-specific ACL (Table 75).
Table 75. The soil-specific ACLs (mg/kg) at a range of cation exchange capacities for fresh nickel (Ni) contamination based on NOEC and 10% effect concentration (EC10) toxicity data.
Land use                             Cation exchange capacities (cmolc/kg)a