Aquatic toxicity and environmental impact of leachate discharges from a municipal landfill

The final leachate from a municipal landfill, using a wetland tertiary trea tment system, and water in the receiving environment were chemically charac terized and evaluated for acute and sublethal aquatic toxicity In addition, the effects of leachate discharges on the benthic macroinvertebrate commun ity were determined. Samples were not acutely toxic to rainbow trout (Oncor hynchus mykiss), Daphnia magna and Vibrio fischeri. There was no detrimenta l effect on the survival and reproduction of Ceriodaphnia dubia, although a slight effect on reproduction was detected in river water at the control s tation (700 m upstream). Moderate toxicity to Selenastrum capricornutum was detected at the control and at station #2 (40 m from the outfall). Ames te sts revealed no mutagenic or cytotoxic effects in the final leachate or in river water downstream. Benthic macroinvertebrate sampling revealed that th e leachate discharge had a localized impact on community structure near the outfall, but by 50 m downstream the conditions were approaching those upst ream of the discharge point.