Flare pit hydrocarbon toxicity: Implications for soil assessment and remediation.

摘要

The toxicity of flare pit hydrocarbons was evaluated by two methods. First, the leachability and toxicity of water-soluble contamination from hydrocarbon contaminated flare pit soil was evaluated using a column leaching technique. Although soluble salts and metals in the flare pit soil were found to demonstrate some toxicity, the hydrocarbons within the flare pit soil were not toxic to bioassay organisms, nor were they leachable from the soil. Consequentially, the hydrocarbon contamination at the flare pit does not appear to be a serious ecotoxicological risk, on or off-site.; Secondly, the effective and intrinsic toxicity of extracted Hare pit hydrocarbons and crude oil hydrocarbons were evaluated. Several toxicity bioassays were used to evaluate the whole hydrocarbon mixtures, and saturate and aromatic fractions of the whole mixtures, in water and sod matrices. Gas chromatography determination of lethal body burdens in earthworm time was used to evaluate the intrinsic toxicity of the hydrocarbon mixtures. Both the flare and crude hydrocarbon mixtures were found to contain toxic hydrocarbon fractions; aromatic hydrocarbons were found to be more toxic than saturate hydrocarbons. The toxicity of the crude whole mixture was determined by the toxicity of the constituent saturate and aromatic fractions. However, the flare whole hydrocarbon mixture was much less bioavailable, and consequentially less toxic, than the crude whole mixture due the high concentration of aspaltene and polar compounds in the weathered flare pit hydrocarbon mixture. The difference in effective toxicity of the two whole mixtures has important implications for the use of chemically based soil guidelines for the assessment and remediation of hydrocarbon contaminated industrial sites. Some soil assessment and remediation guidelines currently in use are derived from tests of crude oil toxicity. The high toxicity of the crude hydrocarbon mixture may cause those guidelines to be very conservative when applied to weathered hydrocarbon contaminated sites high in asphaltene and polar compounds.