Y = 0.55 + 0.1614X
= 0.9411
where
Y represents the man-days per hectare and X is the dosage in grams
of aluminum per cubic meter.
Aluminum sulfate costs vary with the market and, in recent years, a ton
of liquid al- m has cost about
-u
to '0. Equipment costs also will vary
with the size of the application. Dominie's (1980) technique of using a barge
big enough to load tank truck trailers on it represents a way of reducing
costs, since lakeshore storage and delivery systems would not be needed.
Also, as suggested earlier, a large harvesting machine could be modified for
The cost of the equipment, as well as labor, may
use as an alum applicator.
Several treatments have been
also vary with the depth of application.
directed toward hypolimnetic sediments only, and a manifold or other injection
device was needed that could pump materials to the
A surface
Phosphorus inactivation
treatment could be accomplished with less equipment.
is a procedure that would benefit from new designs for application.
Limitations and Concerns
The potential for serious negative impacts from
or the toxic
effects of dissolved aluminum clearly exists with the addition of an aluminum
Aluminum sulfate, as described earlier, will produce a
salt to a reservoir.
5.5, dissolved aluminum Al
will begin to
shift toward a low
At
Toxic
appear, and its concentration will increase rapidly as
declines.
conditions could be reached.
Fish mortality has not occurred during alum applications (Funk et al.
There was little or no appearance or accumula-
1982, Lamb and Bailey 1983).
tion of aluminum in the tissues of rainbow trout
gairdneri), as
or in tissues of channel catfish
reported by Buergel and Soltero
punctatus), largemouth bass (Micropterus salmoides), and gizzard
as reported by Berg and Burns
in lakes
shad (Dorosoma
Biesinger and
treated with alum but maintained at a
of 7.0 or greater.
and Lamb and Bailey (1981,
Christensen
Peterson et al. (1973,
1983) have indicated that a dissolved aluminum concentration below
will not bring about harmful effects to
50
Al
56
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