Acute toxicity of water soluble fractions derived from a coal liquid (SCR-II) to three aquatic organisms

Acute toxicity screening tests were conducted with water soluble fractions (WSFs) of a solvent refined coal (SRC-II) liquid from a pilot plant and three reference organisms: the cladoceran Daphnia magna , the fathead (FH) minnow Pimephales promelas , and larvae of the midge fly Chironomus tentans . Acute toxicity was also examined under other water quality conditions. The coal liquid was less toxic to daphnids at 10 degree C than at 20 or 25 degree C, but response of other orgamisms at different temperatures varied. The pH of the liquid had little effect on toxicity values. All organisms were less susceptible in hard water. Chemical compositions of stock WSFs were similar, suggesting that temperature, pH, and hardness had little effect on solubility of major synfuel components. Dilution indexes for stock WSFs were higher than for petroleum oils, and reflect the greater solubility of chemicals from the liquified coal in freshwater.