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PHOTOINDUCED TOXICITY OF POLYCYCLIC AROMATIC HYDROCARBONS TO AQUATIC ORGANISMS

1987; Elsevier BV; Linguagem: Inglês

10.1016/b978-0-08-031862-2.50026-5

Peter F. Landrum, John P. Giesy, James T. Oris, Phillip M. Allred,

Aquatic Ecosystems and Phytoplankton Dynamics

Polycyclic aromatic hydrocarbons (PAH) such as anthracene are ubiquitous pollutants that are normally not considered acutely toxic to aquatic organisms because they are only sparingly soluble in water. Thus, bioassays conducted under the usual laboratory conditions have resulted in estimates of acute toxicity that exceed the aqueous solubilities of PAH. However, these studies are usually conducted under conditions that minimize photodegradation, and therefore the potential to observe ecologically relevant photoinduced toxicity is eliminated. Studies under more ecologically relevant conditions in an illuminated artificial stream microcosm have demonstrated that anthracene is acutely toxic (100% mortality) to juvenile bluegill sunfish at 12 μg-l−1 in less than 9 h. This toxicity is more than 400 times greater than previously reported no-effect concentrations. Daphnia pulex are even more sensitive (LT50, time to 50% immobilization - 13 min at 1.2 pgl−1). These dramatic effects occur as a result of the interaction of bioaccumulated parent PAH and light, not the action of externally formed photodegradation products. Preliminary screening has indicated that benzo (a) pyrene is even more toxic than anthracene. We predict that 50% of the aquatic organisms in a lake will be immobilized at a depth of 7.25 m with a 1.2 μgl−1 anthracene concentration based on the use of the Bunsen-Roscoe Law of Reciprocity, the measured extinction coefficient for UVB in Lake Michigan (0.575 m−1), an average summer day length of 14 h, and the LT50 for Daphnia pulex. These effects, the depths at which they may be occurring, and the concentrations of PAH in the Great Lakes indicate that acute effects could be occurring at present in the Lakes. With expected increases in PAH load due to increased coal usage and increased ambient levels of solar UV due to depletion of the ozone layer, the potential exists for large effects in the Great Lakes and other aquatic systems.