Protocol for the Derivation of Environmental and Human ... - CCME

Appendix A
4.1 Agricultural and Residential/Parkland Land Uses
4.1.1 Nitrification and Nitrogen-fixation Data
Using nitrification and N-fixation data, the weight of evidence, LOEC and median effects methods are
applied (see Part B, Sections 7.5.2.2 to 7.5.2.4) with the exception that quantity requirements for
invertebrate and plant studies are replaced by required balance between N-fixation and nitrification
studies. In addition, single dose studies (control plus one level of contaminant) are acceptable as a
source of "pseudo-LOEC" data if the effects dose does not exceed a 40% response for nitrogen
fixation and nitrification processes.
4.1.2 Decomposition, Respiration and Nitrogen Mineralization Data
If data are insufficient to generate a criterion check value on the basis of N-fixation and nitrification, C
cycling and N mineralization data can be used to supplement or, less desirably, replace these data in
modified LOEC or median effects methods.
In the modified LOEC method, a criterion is derived from the geometric mean of LOECs from a
minimum of 3 studies (as before) but with the following conditions. First, because C cycling and N
mineralization measurements are expected to be less sensitive than N-fixation and nitrification data (see
Section 2.0 in this appendix), unrestricted use of LOEC data is not recommended. In particular, LOEC
values for C cycling and N mineralization should not exceed a response. Second, "single dose" studies
(control plus one level of contaminant) are acceptable as a source of "pseudo-LOEC" data if the effects
dose does not exceed a 40% response for N-fixation and nitrification or a 25% response for C cycling
and N mineralization data. Although data of the latter type does not meet all formal requirements for
reporting a LOEC, it is nevertheless considered scientifically and technically defensible in consideration
of the restrictions imposed, peer-reviewed status, and importance of the biological processes involved.
If only the minimum number of LOEC studies are available, professional judgement should be used to
assess whether the resulting microbial value represents an accurate measure of potential process-level
effects, otherwise, this method may be discarded and the median effects method (using microbial EC 50
values, see Part B, Section 7.5.2.4) applied with an application factor of 5. The median effects method
is applied in the same way if the requirements for the modified LOEC method cannot be met. If data
are insufficient for any of the methods above, no energy and nutrient cycling value for comparison will be
generated. Data gaps and areas for further research will be noted.
4.2 Commercial and Industrial Land Use
4.2.1 Nitrification and Nitrogen-fixation Data
The weight of evidence method or LOEC method are applied (see Part B, Section 7.5.3) with the
exception that quantity requirements for invertebrate and plant studies, are replaced by a required
balance between nitrogen-fixation and nitrification studies. In addition, single dose studies (control plus
124