Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:20:p1
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 20 (pt 1/4)
Character Range: 1588885–1591905

20             18

4.6.2         Calculation of soil quality guidelines for fresh arsenic contamination based on protecting aquatic ecosystems from leaching
The log Kd value for As (Crommentuijn et al. 2000) was below 3 and therefore in accordance with the  SQG derivation methodology (Schedule B5b) SQG(NOEC & EC10) values were derived to protect aquatic ecosystems from the effects of leached As from freshly contaminated soils.

The As SQG(NOEC & EC10) values based on protecting groundwater ecosystems were calculated using the US EPA method (US EPA 1996). The generic SQG(NOEC & EC10) values were calculated using DAF values of one and 20 and these are presented in Table 33. There is a linear relationship between the DAF and the SQGs, thus the SQGs calculated using a DAF of 20 are 20 times larger than those calculated using a DAF of 1.
Table 33. Generic arsenic (As) soil quality guidelines (SQGs, mg total As/kg) based on no observed effect concentration and 10% effect concentration toxicity data to protect groundwater ecosystems from leaching.

Dilution factor  1    20
SQG (mg/kg)      4.6  91

4.6.3         Calculation of soil quality guidelines for fresh arsenic contamination based on lowest observed effect concentration and 30% effect concentration toxicity data, and based on 50% effect concentration toxicity data
The SQG(LOEC & EC30) and SQG(EC50) values were calculated using the same method as for the As SQG(NOEC & EC10) values ,except that different toxicity data was used. The data used is presented in Table 29. To maximise the data available to generate the SQG(LOEC & EC30) and SQG(EC50) values, the available toxicity data was converted to the appropriate measure of toxicity using the default conversion factors presented in Table 30.

As with the SQG(NOEC & EC10) values for As, soil-specific SQG(LOEC & EC30) and SQG(EC50) values could not be generated, but rather a single generic SQG(LOEC & EC30) and SQG(EC50) value was generated for each of the three land uses (Table 34). Also, all toxicity data was expressed as total As rather than added As. As these are generic SQG(LOEC & EC30) and SQG(EC50) values ,they should be applied to all Australian soils with a particular land use.

Table 34: Generic soil quality guidelines based on lowest observed effect concentration and 30% effect concentration toxicity data (SQG(LOEC & EC30)), and based on 50% effect concentration toxicity data (SQG(EC50)) for soil with different land uses.
Land use                             SQG(LOEC & EC30)  SQG(EC50)
                                     (mg/kg total As)  (mg/kg total As)
Areas of ecological significance     20                30
Urban residential/public open space  50                90
Commercial/industrial                80                140

4.7              Calculation of soil quality guidelines for aged arsenic contamination

4.7.1         Calculation of an ageing and leaching factor for arsenic
Song et al. (2006) conducted some experiments to determine the effect of