Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:7:p1
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 7 (pt 1/2)
Character Range: 1523548–1526432

7        log EC50                  0.12 * pH +0.89 * log CEC + 1.1  Smolders et al. 2003

CEC = cation exchange capacity (cmolc/kg); OC = organic carbon content (%); PNR = potential nitrification rate; SIN = substrate induced respiration.

Table 6. Values of soil characteristics for the recommended Australian reference soil to be used to normalise toxicity data
Soil property   Value
pH              6
Clay (%)        10
CEC (cmolc/kg)  10
OC (%)          1

3.5              Sensitivity of organisms to zinc
The toxicity data (geometric means) used by the SSD method to calculate the ACL is shown in Table 2 for soil processes, Table 3 for soil invertebrates and Table 4 for plants. Figure 3 shows the SSD (that is, a cumulative distribution of the geometric means of the species) for all species for which there was Zn toxicity data. Toxicity data for plants, soil processes and soil invertebrates was evenly spread in the SSD, which indicates that these groups of organisms all have a similar sensitivity to Zn. Therefore, all the toxicity data was used to derive the ACLs, thus increasing the quantity of data used in the SSD method and increasing the reliability of the ACL values.
Figure 3. The species sensitivity distribution (plotted as a cumulative frequency against added zinc (Zn) concentration) for soil processes, soil invertebrates and plant species to Zn.

3.6              Calculation of soil quality guidelines for fresh zinc contamination
Soil quality guidelines were derived for fresh zinc contamination using three different sets of toxicity data: NOEC and EC10; LOEC and EC30; and EC50. The methods by which they were calculated and the resulting ACL and SQG values are presented in the following sections.

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

3.6.1.1         Calculation of soil-specific added contaminant limits
The NOEC and EC10 toxicity data were normalised using the equations presented in Table 5 to the Australian reference soil (Table 6) and then the lowest geometric mean for each species/soil microbial process was entered into the BurrliOZ species sensitivity distribution (Campbell et al. 2000) method. The SSD generated a single numerical value (that is, the ACL(NOEC & EC10) for each desired level of protection. These ACL(NOEC & EC10) values only apply to the Australian reference soil.

The ACL(NOEC & EC10) value for the Australian reference soil with an urban residential land/public open space use was approximately 100 mg/kg. These ACL(NOEC & EC10) values for the reference soil were then used to calculate ACL(NOEC & EC10) values for a range of soils (that is, soil-specific ACL(NOEC & EC10)) for each group of organisms using the same normalisation relationships as before but in the reverse manner. The