Effectiveness and toxicity of an oil dispersant in large outdoor salt water tanks

Use of the dispersant, Oilsperse 43, increased the dispersion of Venezuelan Guanipa crude oil. The resulting mixture was more homogeneous and the oil slick less viscous than in the oil tank. The dispersant appeared to retard formation of the familiar “crust” on the surface. A weathered crude oil plus dispersant mixture with an oil concentration of 250 μg/l was lethal to over 50% of the test organisms, green sea urchins, within 4 days. No mortalities occurred among urchins exposed to the crude oil treatment.