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Modified: July 06, 2016
© S.M. Mandaville Post-Grad Dip., Professional Lake Manage. (limneschebucto.ns.ca)
The citation for this documentation is:
Mandaville, S.M. TP/Cha Predictive Models. Nova Scotia, Canada. Electronic media.
Predictive TP modelling was based primarily on the following: extensive decadal research spearheaded by several international peers in limnology under the chairmanship of Richard A. Vollenweider PhD, formerly of the Canada Centre for Inland Waters, Environment Canada, which culminated with the consensus OECD (1982)- Organisation for Economic Co-Operation and Development Report; on the Vollenweider(1976) TP Predictive Model; and the published research of Peter J. Dillon FRSC et al., formerly of the Dorset Research Centre, Ontario Ministry of the Environment.
In addition, Mandaville has been incorporating other regressions published in the latest international limnological journals as deemed necessary. This process will take several years for model revisions as well as calibrations.
The natural background (+ direct aerial deposition) concentrations were computed utilizing published export coefficients in generally undisturbed similar natural soils in Nova Scotia (cf., Hart et al, 1978; Mandaville, 2000; Scott et al, 2000; Scott et al, 2003); the post-development concentrations were obtained utilizing published export coefficients (end-of-pipe mean year averages) of typical residential and commercial/institutional developments (cf., Mandaville, 2000; Scott et al, 2003; Vokey, 1998; and typical pollutants in stormwater runoff).
As opportunity presents itself, we are continuing our intensive field sampling, generally at storm sewer outfalls (inclusive of open channels), in order to expand the data base for post-development scenarios and revise the predictive models, if needed.
to areas served by
systems, our revised models did not incorporate the same assumptions as
in Hart et al (1978)
and Scott et al (2003) where the authors assumed
50% septic-derived phosphorus retention within 300m
of lakes in the Halifax/Wolfville soils. In
the Scott et al (2003)
report where Mandaville was a co-author, there was an inadvertent
omission made by not noting this down (and Mandaville regrets that).
Our export coefficients in such areas include all potential sources of
phosphorus inputs incorporated into the 50% export assumption; it
actually varied from 50% in some watersheds based on local info.
as I upgrade the models as needed, I am applying a much higher soil
retention of phosphorus in areas served with contour beds in comparison
with areas served with area beds. This was as a result of intense
discussions over the years with the engineering developer of contour
beds, David Pask MEng PEng.
As a worst case scenario, 0% retention may be assumed for the long term as per the Province of Ontario's guidelines, "Protecting Water Quality in Inland Lakes on Ontario’s Precambrian Shield" (2010).
|General level of production ........||low||medium||high|
|Green and/or blue-green algae fractions||low||variable||high|
|Hypolimnetic oxygen content .....||high||variable||low|
|Impairment of multi-purpose use of lake||little||variable||great|
Background -plus- aerial deposition (B+A):The theoretical background loading -plus- direct aerial deposition have been noted as "Th B+A", and in clearwater lakes it is expected that these were the natural background values including direct aerial deposition.
The predictive modelling does not take into account potential large inputs of phosphorus directly from waterfowl, failing pumping stations, bypasses from treatment plants, cross-connections between sanitary and storm sewers, and other unforeseen sources. But if a value is known, it can easily be added in the `miscellaneous' column of the control spreadsheets. For contributions from waterfowl, peruse our submission to the Halifax Watershed Advisory Board in year-2000.
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