RP9 Terrestrial Ecotoxicology
Thursday, 17 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(AAA-1117-468903) Ecotoxicitiy of main gasoline components to Asian earthworm Perionyx excavatus.

An, YJ¹, Jeong, S², ¹ Konkuk University, Seoul, South Korea² Kunsan National University, Department of Environmental Engineering

ABSTRACT- Soil pollution by gasoline has become a significant environmental problem due to its adverse eco-effects. Toluene and methyl tert-butyl ether (MTBE) are major volatile organic compounds (VOCs) of gasoline. Due to their high volume percentage in fuel as well as their physicochemical properties, they are commonly found in gasoline-contaminated soils. Toluene is known to be toxic to a range of biota. MTBE is classified as a potential human carcinogen by U. S. EPA. They are released into environment not as a single component, and often found as a mixture. It is important to know the influence of main gasoline components such toluene and MTBE to soil organisms, which can be initially exposed to those compounds as a result of the leakage of gasoline from underground storage tanks. There is little information available on the toxicity of toluene and MTBE to soil biota. In this study, the comparative and combined toxicities of toluene and MTBE to the Asian earthworm, Perionyx excavatus were evaluated. Earthworms have been widely used as bioindicators for soil ecotoxicity assessment, and Perionyx excavatus was reported to be a sensitive earthworm species. The median lethal concentration (LC50) was measured to determine the toxic levels of toluene and MTBE individually. The combined effect of toluene and MTBE was investigated using toxic unit model. It was found that toluene was more toxic than MTBE, and the combined toxicity was almost additive to P.excavatus. Treatment with toluene and MTBE also affected the behavior and morphology of P. excavatus. The morphological abnormalities included coiling, curing, mucous secretions, swelling, thinning and fragmentation. It appeared that the VOCs induced metabolic and functional damages in earthworms.

Key words: ecotoxicity, earthworm, toluene, methyl tert-butyl ether