EFFECTS OF CHRONIC EXPOSURE TO COAL-DERIVED OIL ON FRESHWATER ECOSYSTEMS: I. MICROCOSMS

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Abstract
Sixteen 67 l freshwater microcosms were treated for 8 wk with an unrefined coal-oil at 0.03-7 ml/wk. Phenols made up 95% of the water-soluble compounds in this oil, and dissolved phenol concentrations averaged < 0.01 mg/l in the lowest dose and 10 mg/l in the highest. The microcosms were severely damaged at the highest treatment level; macrophytes, zooplankton and insects were eliminated, and the ecosystems became anaerobic. Microcosms did not recover to pretreatment conditions within 5 mo. At lower dosages there were temporary effect on ecosystem metabolism, water chemistry and community structure. The most sensitive indices, community respiration, production/respiration ratio, pH and cladoceran zooplankton numbers, were affected at phenol concentrations below the lowest observable effect concentration of a chronic Daphnia magna bioassay.