Oil in Water
Potential contributors to oil pollution are effects of oily substances on domestic water supplies may be grouped into the following categories:
(1) hazardous to health of consumers and aquatic communities,
(2) the production of tastes and odors,
(3) the presence of turbidity, films or iridescence, and
(4) the increased difficulty of water treatment.
The taste and odor factor will control the threshold or limiting concentration of oily material acceptable in a domestic water supply.
Many oily substances are harmful to fresh water aquatic life in the following manners:
Free oil and emulsions may act on the epithelial surfaces of fish. In other words, they adhere to the gills and interfere with respiration.
Free oil and emulsions may coat and destroy algae and other plankton thereby removing a source of fish food. The coated organisms may agglomerate with suspended solids and settle to the bottom of the stream.
Settleable oily substances may coat the bottom of the stream and destroy benthic organisms and interfere with spawning areas.
Soluble and emulsified material ingested by fish taint the flavor of the flesh.
Organic materials may deoxygenate the water sufficiently to kill the fish.
Heavy coatings of free oil on the surface may interfere with the natural processes of re-aeration and photosynthesis.
Water soluble principles may exert a direct toxic action on fish or fish food organisms. Such toxicity may be acute or chronic.
Oils are also used as solvents for pesticides. While the oil may not in itself be toxic, it frequently increases the toxicity of the pesticide.