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(16-06) Phytoremediation of weathered hydrocarbon contaminated soil, bioavailability and toxicity of contaminants. Palmroth, Marja*,1, Vaajasaari, Kati2, Pichtel, John3, Joutti, Anneli4, Tuhkanen, Tuula1, 1 Tampere University of Technology, Tampere, Finland2 Pirkanmaa Regional Environment Centre, Tampere, Finland3 Ball State University, Muncie, USA4 Finnish Environment Institute, Helsinki, Finland ABSTRACT- Phytoremediation is an innovative technology, which uses green plants to remove, contain or render harmless environmental contaminants. Field scale phytoremediation of lead and weathered hydrocarbon contaminated soil from a bus depot was conducted. About one third of the lead was considered plant available. Hydrocarbons found in soil consisted of used lubricating oils and diesel fuel. Total petroleum hydrocarbon concentrations were about 10000 mg/kg and consisted of unresolved complex mixture (UCM). Lead concentration in the soil was in the range of 300 to 3000 mg/kg. High variation was found in contaminant concentrations, reflecting heterogeneity of the soil. Site was vegetated with pine, poplar, grass mixture and clover. Soil amendments tested included NPK-fertiliser and biosoil (composted sieved biowaste) as well as unfertilised control. Soil microbial activity was assessed using Biolog EcoTM plates and microbial extracellular enzymatic activity as parameters. pH of collected leachates was near neutral, but metal concentrations exceeded drinking water standards. However, leachate was not toxic to Vibrio fischeri BioToxTM, Finland). Metals did not accumulate into plant tissue considerably. Plants grew better at biosoil amended plots and exhibited less phytotoxicity symptoms. Toxicity was determined directly from the soil samples with Enchytraeus albidus survival tests and with an improved Vibrio fischeri test BioToxTM Flash test designed for sediment or solid samples. Soil toxicity to Vibrio fischeri decreased a bit during one year, but soil was not very toxic in the beginning either. Soil samples were nontoxic in E. albidus survival tests. Key words: Phytoremediation, Hydrocarbons, Ecotoxicity, Soil animals |
