The Use of Acute and Chronic Bioassays to Determine the Ecological Risk and Bioremediation Efficiency of Oil-Polluted Soils

Abstract

To compare the effectiveness of acute and chronic bioassays for the ecological risk assessment of polluted soils, soil samples from a site with an historical mineral oil contamination (< 50-3,300 mg oil/kg dry soil) at the Petroleum Harbour in Amsterdam, The Netherlands, were screened for ecological effects using acute and chronic bioassays. A two-step 0.001 M Ca(NO3)2 extraction at a final solution-to-soil ratio of 1:1 was used to prepare extracts for the acute bioassays. Acute bioassays (< or = 5 d) applied to the 0.001 M Ca(NO3)2 extracts from the polluted and reference soils included growth tests with bacteria (Bacillus sp.), algae (Raphidocelis subcapitata), and plants (Lactuca sativa), immobility tests with nematodes (Plectus acuminatus), springtails (Folsomia candida), and cladocerans (Daphnia magna), and the Microtox test (Vibrio fischeri). Chronic bioassays (four weeks) performed on the same soil samples included tests with L. sativa, F. candida, and earthworms (Eisenia fetida) and the bait-lamina test (substrate consumption). The acute bioassays on Microtox showed a response that corresponded with the level of oil pollution. All other acute bioassays did not show such a consistent response, probably because pollutant levels were too low to cause acute effects. All chronic bioassays showed sublethal responses according to the contaminant levels (oil and in some soils also metals). This shows that chronic bioassays on soil samples are more sensitive in assessing the toxicity of mineral oil contamination in soil than acute bioassays on soil extracts. A pilot scale bioremediation study on soils taken from the two most polluted sites and a control site showed a rapid decline of oil concentrations to reach a stable level within eight weeks. Acute bioassays applied to the soils, using Microtox, algae, and D. magna, and chronic bioassays, using plants, Collembola, earthworms, and bait-lamina consumption, in all cases showed a rapid reduction of toxicity, which could be attributed to the degradation of light oil fractions.

Environmental risk assessment of a metal-contaminated area in the Tropics. Tier I: screening phase

“…Such bioassays integrate the combined effect of mixtures and that of contaminants not analyzed or for which soil quality levels do not exist (Weeks et al 2004a;Fernandez et al 2005;Spurgeon et al 2005;Jensen and Mesman 2006). Whereas soil extracts (e.g., eluates) are used to perform widely established tests with cladocerans, microalgae, and the luminescent bacteria Vibrio fischeri (van Gestel et al 2001;Achazi 2002;Loureiro et al 2005a), soil samples are being increasingly evaluated through avoidance tests with earthworms (Hund-Rinke et al 2003;Antunes et al 2008) and collembolans (Natal-daLuz et al 2004). Earthworm avoidance tests have been shown to be a useful tool in the screening phase of risk assessment of contaminated soils , providing rapid information for future decisions (Schaefer 2003;Loureiro et al 2005b), while being ecological relevant and of low cost (Yeardley et al 1996).…”

Ecotoxicity assessment of aged petroleum sludge using a suite of effects-based end points in earthworm Eisenia fetida

“…Biological indicators have become increasingly important in hazard assessment and remediation of hydrocarbon-impacted soils for determining cleanup end points (Dorn and Salanitro 2000;Phillips et al 2000;Van Gestel et al 2001;MolinaBarahona et al 2005;Plaza et al 2005;Dawson et al 2007). A wide range of species from different trophic levels and a number of bioassay end points were applied (Dorn et al 1998;Saterbak et al 1999;Huang et al 2004;Booth et al 2005).…”

Evaluation of tests to assess the quality of mine-contaminated soils

“…For these reasons, chemical analyses are seldom suited for the evaluation of potential ecological risks, since they do not take into account the possible combined eVects of diVerent contaminants, as well as their bioavailability. Bioassays, which can overcome these constraints, are therefore recommended for the assessment of ecological risks in soils (van Gestel et al 2001).…”