Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:4:p3
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 4 (pt 3/5)
Character Range: 1582624–1585570

and is the geometric mean of the NOEC and LOEC.

4.4              Normalisation relationships
It is well known that soil physicochemical properties affect the toxicity and bioavailabiity of As. However, this knowledge is qualitative. For example, Sheppard (1992) reviewed the existing literature and concluded that the toxicity of As was five times more toxic in sands and loams than in clay soils. There is only one set of published normalisation relationships for As toxicity (Song et al. 2006). This relates the toxicity of As (i.e. barley root elongation) expressed in terms of total added As, ammonium sulphate [(NH4)2SO4]-extractable As or ammonium phosphate (NH4H2PO4)-extractable As to soil properties such as oxalate-extractable Mn and oxalate-extractable Fe concentrations. The normalisation relationships for EC10 and EC50 toxicity data expressed in terms of total added As (from Song et al. 2006) are:
EC10 = 0.1 (oxalate-extractable Mn) + 1.03 (% clay) – 9.25   (equation 3)
(r2 adj = 0.89, p = <0.001, n = 16)

EC50 = 0.21 (oxalate-extractable Mn) + 0.016 (oxalate-extractable Fe)
       + 4.29 (% clay) – 48.2      (equation 4)
(r2 adj = 0.91, p = <0.001, n = 16)

However, with the exception of the Song et al. (2006) data, none of the available As toxicity studies had expressed the toxicity in the units of the normalisation relationships nor had the studies measured the soil properties used in the normalisation relationships. Therefore, the normalisation relationships could not be used.

4.5              Sensitivity of organisms to arsenic
Figure 4 shows the SSD (that is, the cumulative distribution of the geometric means of species sensitivities to As) for all species for which As toxicity data was available. The distribution of the major groups of organisms along the SSD is uniform—thus all of the organism groups have a smilar sensitivity to As.

Figure 4. The species sensitivity distribution (plotted as a cumulative frequency against total arsenic (As) concentration) of As for soil invertebrate species, terrestrial vertebrate species and plant species.

4.6              Calculation of soil quality guidelines for fresh arsenic contamination
The As toxicity data could not be normalised to the Australian reference soil because none of the publications had reported the properties required by the one normalisation relationship available for As. Thus, soil-specific ACLs could not be derived. Rather, a single generic ACL for each land use was derived. These generic ACLs would apply to all Australian soils of the appropriate land use. For example, the single ACL for urban residential /public open space land use would apply to all Australian urban residential/public open space soils.

4.6.1         Calculation of soil quality guidelines for fresh arsenic contamination based on no observed effect concentration and 10% effect concentration toxicity data
All the available As toxicity data (apart from that