Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:3:p2
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 3 (pt 2/4)
Character Range: 1515070–1519281

was expressed in terms of total contaminant concentration but the background concentration was not reported then the Dutch background correction equation (Lexmond et al. 1986) was used to estimate the background concentration.

background Zn = 1.5 * [2 * organic matter (%) + clay content (%)]  (equation 1)

The background concentration was then subtracted from the total concentration data to derive the added concentration toxicity value.

The toxicity database used to calculate the SQG(NOEC & EC10) values for Zn included EC10 and NOEC toxicity data for nine soil processes (Table 2), 14 invertebrate species and 1 invertebrate community measurement (Table 3) and 22 plant species (Table 4). The raw data used to generate Tables 2–4 is provided in Appendix A. There was sufficient data (that is, toxicity data) for at least five species or soil processes that belong to at least three taxonomic or nutrient groups (Schedule B5b) available to derive SQG(NOEC & EC10) values using a species sensitivity distribution (SSD) methodology. Given that Zn does not biomagnify, the level of protection recommended for non-biomagnifying contaminants was used to generate the SQG for each land use.

Table 2. The geometric mean values of the zinc toxicity data (expressed in terms of added Zn) for individual soil processes.
Soil process           Geometric means (mg/kg added Zn)
                       EC10 or NOEC                      EC30 or LOEC  EC50
Acetate decomposition  187                               280           560
Amidase                121                               182           364
Ammonification         98                                148           295
Arylsulphatase         289                               434           868
Glucose decomposition  274                               1169          2904
Nitrate reductase      56                                84            168
Nitrification          455                               706           930
Phosphatase            674                               1011          2022
Respiration            104                               157           313

Table 3. The geometric mean values of zinc (Zn) toxicity data (as added Zn) for soil invertebrate species and an invertebrate community.
Species/endpoint  Geometric means (mg/kg added Zn)
Common name       Scientific name                   EC10 or NOEC  EC30 or LOEC  EC50
Earthworm         Aporrectodea caliginosa           223           274           391
Earthworm         Aporrectodea rosea                390           407           436
Earthworm         Eisenia fetida                    201           296           575
Earthworm         Lumbriculus rubellus              220           285           443
Earthworm         Lumbriculus terrestris            1062          1257          1675
Nematode          Acrobeloides sp.                  221           332           663
Nematode          Caenorhabditis elegans            122           183           366
Nematode          C. elegans (dauer larvae)         689           1034          2068
Nematode          Community nematodes               306           459           919
Nematode          Eucephalobus sp.                  135           202           403
Nematode          Plectus sp.                       23            35            70
Nematode          Rhabditidae sp.                   199           299           597
Potworm           Enchytraeus albidus               121           181           363
Potworm           Enchytraeus crypticus             276           414           828
Springtail        Folsomia candida                  188           283           565

Table 4. The geometric mean values of the zinc (Zn) toxicity data (expressed in terms of added Zn) for individual plant species.
Plant species          Geometric means (mg/kg added Zn)
Common name            Scientific name                   EC10 or NOEC  EC30 or LOEC  EC50
Alfalfa                Medicago sativa                   198           297           595
Barley                 Hordeum vulgare                   83            233           495
Beet                   Beta vulgaris                     198           297           595
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