PARENT SESSION

1B+C Abiotic Transformations + Biodegradation
Poster Hall
8:30 AM - Monday, 28 April 2003
Chair: Peijnenburg, W.¹, ¹
Co-chair: Jafvert, C.T.², Gombar, V.K.³, ^{2 3}

(MOP/36) Earthworms and additives in oil contaminated soil: competitors or co-workers in biodegradation?

Schaefer, Maike¹, Filser, Juliane¹, ¹ Centre for Environmental Research and Environmental Technology (UFT), University of Bremen, Bremen, Bremen, Germany

ABSTRACT- The recent oil pollution at the Spanish coast after the average of an oil-tanker exemplifies the seriousness of oil pollution as a world-wide prevalent threat to the environment. The remediation of oil contaminated soils, sediments and water has become a major branch in environmental research. Bioremediation is a useful method in soil remediation, if pollutant concentrations are moderate and non-biological techniques are not economical. Ubiquitous micro-organisms, which are known to degrade alkanes in various steps into carboxylic acids, enhance the oil degradation in soil. Results of a preliminary test had shown that earthworms also stimulate the degradation of petroleum hydrocarbons in soil by enhancing the microbial activity. Aim of this study was to investigate the influence of additives and/or earthworms (Lumbricus terrestris) in a crude oil polluted soil (5000 mg/kg TPH). Criteria for the choice of the additives were cost effectiveness and short transport distances. Industrial waste products were therefore chosen: (i) coffee grounds, (ii) lopping and (iii) draff. Additives were either mixed into the soil or dispersed on soil surface in mass concentrations 1:10. 10 adult worms were applied to half of the test containers. Controls without additives served as references. After 28d a significant oil degradation (30-35%) was only observed in variants with (N-rich) draff (mixed) and with earthworms without additives, although soil respiration measurements showed clear enhanced microbial activity in all treatments. We hypothesise that micro-organisms prefer the more easy available additives as nutrient sources over the less easily degradable, nitrogen deficient long-chain crude oil. Thus, the application of additives does not necessarily enhance bioremediation. Despite high mortality, earthworms may trigger the degradation process.

Key words: Oil contaminated soil, Bioremediation, Earthworms, Additives