Bioassay-directed fractionation of marine sediment solvent extracts from the east coast of Ireland

Crude solvent extracts were prepared from three sediment sites in Ireland namely Bull Lagoon, Dunmore East and Dublin Port. These were assayed with Tisbe battagliai and the Microtox® system. The extracts were chemically characterised using a variety of analytical techniques for a suite of organic contaminants. Metals and organic contaminant concentration data are reported for the three sites. On the basis of determined toxicity and chemical analysis of these crude extracts, a further bioassay-directed fractionation (BDF) employing the Dunmore East crude organic extract was conducted in addition to chemical analysis. For the crude extracts, T. battagliai and Microtox® system demonstrated an order of decreasing toxicity for each of the three sites to be Dublin Port > Dunmore East > Bull Lagoon. Microtox® system EC10 values after 30 min exposure were 1.08%, 11.6% and 26.9% solvent extract for these sites, respectively. Fractionation of the Dunmore East extract revealed that fraction 1 was the most toxic fraction to both the T. battagliai and the Microtox® system demonstrating EC50’s after 48 h and 30 min of 44.7% and 16.8% solvent extract for the T. battagliai and Microtox® assays, respectively. T. battagliai however did show increased sensitivity to fraction 3 when comparing EC10 values and demonstrated an EC10 value of 17.8% solvent extract after 48 h. Fraction 1 was shown to contain the highest quantity of the butyltins, in particular TBT in relation to fractions 2 and 3. A useful BDF technique was developed and employed in this study.