Abstract
Ecotoxicity of landfill leachaetes were investigated using a battery of bioassay with freshwater and marine organisms. Raw and treated leachates from one waste treatment facility were collected at eleven sites in Japan from October 2001 to June 2003. Asfreshwater species, microalga, crustacea, duckweed, and lettuce seed were selected. Marine microalga and marine crustacea were used as salt tolerant species against the leachates showing high electric conductivity. Toxicity of the leachate sample was expressed in toxic unit (TU), which is the inverse of EC50 or LC50 value obtained from each toxicity test. The TUs of treated leachates were generally lower than those of raw samples except for six cases toward plant species. This means efficient treatment was performed in most facilities. Seven raw leachates showed high toxicity (TU>10) to freshwater zooplankton, but low toxicity to marine species. It was speculated that salts in the samples were causative toxic components to freshwater zooplankton. For phytoplankton, eight raw leachates indicated high toxicity (TU>10) to freshwater species, but six out of the eight also showed high toxicity to marine species. This suggests unknown compounds except for salts in those samples are probably toxic to phytoplankton.
