Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:20:p2
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 20 (pt 2/3)
Character Range: 1759337–1761831

 an alkaline clay soil (clay content 20%) with 10% iron content.
The resulting ACL(EC50), ABC and SQG(EC50) values are:
ACL(EC50):    470 mg/kg
ABC:    100 mg/kg
SQG(EC50):    570 mg/kg

10.7          Calculation of soil quality guidelines for aged trivalent chromium contamination

10.7.1     Calculation of an ageing and leaching factor for trivalent chromium
There are no ALFs available for Cr (III) nor data available to derive ALFs. Therefore, as an interim measure, the mean of the ALF values available for other cations (that is, Cd, Cu, Co, Ni, Pb and Zn) from Smolders et al. (2009) was determined. This resulted in a value of 2.35[4], which was rounded off to 2.5.

10.7.2     Calculation of added contaminant limits for aged trivalent chromium contamination
All the Cr (III) toxicity data was multiplied by the ALF of 2.5. Therefore, the aged SQG(NOEC & EC10), SQG(LOEC & EC30) and SQG(EC50) values are exactly 2.5 times the corresponding fresh SQGs for Cr (III). The resulting aged SQG(NOEC & EC10), SQG(LOEC & EC30) and SQG(EC50) values are presented in Table 87.

10.7.3     Calculation of ambient background concentration values
For aged contaminated sites (that is, the contamination has been in place for at least 2 years, Schedule B5b) the methodology recommends using the 25th percentiles of the ABC data for the 'old suburbs' of Olszowy et al. (1995) (see Table 88). Chromium concentrations in old suburbs are higher than those for new suburbs (Olszowy et al. 1995); therefore, it is appropriate to use the ABC values for aged suburbs. The Cr concentrations reported by Olszowy et al (1995) are for total Cr; however, as was the case with the Hamon et al. (2004) method, the majority of the Cr measured will be Cr (III) and thus the data can be used to estimate ABC values for Cr (III). The Olszowy et al. (1995) data was derived from soils low in geogenic Cr and, by using low ABCs, could create low SQGs in some areas with naturally high background Cr concentrations. This problem could be overcome in areas of high natural Cr (III) by using measured ABC values or using the Hamon et al. (2004) method.
Table 87. The ACLs based on NOEC and 10% effect concentration (EC10) data, LOEC and 30% effect concentration (EC30), and 50% effect concentration (EC50) toxicity data for trivalent chromium (Cr (III)) for various land uses. These are based on all the Cr (III) toxicity data, except the catalase and nitrogenase enzyme activity data.
Data type  Land use  Clay content