Problems and Control of
Unnatural Fertilization
of Lake Waters
John H. Neil, Biologist
Ontario Water Resources Commission
Toronto, Ontario
The Industrial Waste Conference has in the past been host to a
number of biologists who have given papers on a variety of subjects
relating to the effects of industrial pollution to the biology of water.
Such subjects as the toxicity of trade wastes to fish, the use of the
bio-assay technique and the value of biological indices in assessing
pollution have been ably covered. The effect of effluents containing
plant nutrients on a receiving body of water is another aspect of
biology in the study of pollution and is the subject of this paper.
The effect which nutrients have on a lake is dependent on the
nature and size of the receiving water. Some of these basic characteristics predetermine the effect which an effluent will produce, and
for this reason some fundamentals will be outlined to enable a better
understanding of the subject.
The branch of science studying fresh water is called Limnology.
Welsh1 defines Limnology as "that branch of science which deals
with biological productivity of inland waters and with all the casual
influences which determine it." A body of water is a medium in
which the total physical and chemical conditions form an environment which, because of its particular characteristics, determines the
types and numbers of a multitude of interdependent and interrelated organisms. For this reason, Limnology must enter other fields
of science such as physics for an understanding of water movement,
temperature and light relations, chemistry in order to relate the
organic to the inorganic, and geography and geology to understand
the natural conditions and changes within the environment.
In Welsh's definition of Limnology, the phrase biological productivity is included. This is a concept which is not often considered
by people other than aquatic biologists, but which is a common conception in agriculture. For instance, how much hay is produced on
100 acres or, perhaps, how many pounds of beef are produced per
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