title: Assessment of toxicity hazards of dredged lake sediment contaminated by creosote.
abstract: In order to predict the potential toxicity hazards of sediment remediation by dredging, an experimental laboratory simulation was made by investigating seven ratios of creosote-contaminated sediment (Lake Jämsänvesi, central Finland) and artificial lake water mixtures. Sediment was suspended in water at the ratios of 1:1, 1:2, 1:4, 1:8, 1:16, 1:32, 1:64, 1:128 v/v. The elutriates were analysed for the acute toxicity by photoluminescence bacterial and waterflea (Daphnia magna Straus) tests. The concentrations of polycyclic aromatic hydrocarbons (PAHs) are determined by gas chromatography (GC/FID). The elutriate of ratio 1:2 was most toxic to bacteria (EC50 = 4.5%), whereas the ratio 1:4 was most toxic to waterfleas (EC50 = 21%). The elutriate of 1:1 contained the highest total PAH-concentration (1.67 mg/l) and total organic carbon (TOC) content (39.4 mg/l). When compared to the 1:1 ratio, taken as unity, the relative toxic emission yield (RTE) for bacteria was 307 for the ratio 1:128, so the high mixing ratio may cause a considerable ecotoxicological hazard. The highest amounts of PAHs were desorbed from sediment to water layer when the sediment was mixed with water at the ratios 1:1, 1:2 and 1:4 (v/v). It is assumed that dredging of creosote-contaminated sediment can potentially cause an ecotoxicological risk for a lake system at wide range of suspension ratios. We recommended that basic knowledge for these risks can be produced by simple laboratory simulation.
authors.affiliation: Department of Biological and Environmental Sciences, University of Jyväskylä, Finland.
authors.forename: T
authors.initials: T
authors.lastname: Hyötyläinen
authors.forename: A
authors.initials: A
authors.lastname: Oikari
mesh_terms: D000818:Animals; D002849:Chromatography, Gas; D003407:Creosote / Q000032:analysis* / Q000633:toxicity; D003621:Daphnia; D004784:Environmental Monitoring / Q000379:methods; D005387:Finland; D005618:Fresh Water; D019015:Geologic Sediments; D008163:Luminescent Measurements; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis; D014733:Vibrio / Q000187:drug effects; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000633:toxicity
chemical_list: D011084:Polycyclic Aromatic Hydrocarbons; D014874:Water Pollutants, Chemical; D003407:Creosote