The Phytotoxicity of Crude Oil Spills in Freshwater

Abstract

Abstract Field and laboratory experiments have been carried out to determine the toxicity to planktonic algae of crude oil, crude oil - water extracts and also selected oil components. Field experiments were performed in a half-acre pond. Localised spills of crude oil were confined within specially constructed floating cylinders with an attached collar. Three different effects of crude oil spills were noted - 1) certain species were inhibited in their growth 2) other species did not appear to be effected and 3) a number of species showed apparent stimulation following the spill. These results emphasize the great differences in response between species and suggest the actual planktonic composition of a water body of considerable importance in predicting the effects of an oil spill. In laboratory studies the toxicity of the water soluble components of crude oil only were tested. These extracts had a significant effect in increasing acidity of the water, which by itself, reduced algal growth. However, it was found that toxic factors were present, in addition to pH effects. There toxic factors or components appeared to be volatile. Tests with benzene, toluene and xylene - three water soluble crude oil components - showes them all to be toxic, with toxicity increasing in the order indicated.