Oil-mineral fine interactions and toxicity studies

The interaction of oiled sediments and minerals was studied as part of the Svalbard study, including an evaluation of the possible transport of oil from treated plots into adjacent water and sub-tidal sediments. Results showed a significant increase in oil-mineral aggregate numbers on the first tide following sediment relocation. This natural process was most active at Site One where the wave energy regime was lower. This in turn was correlated with a higher suspension of mineral fine density. Toxicity associated with oil transported offshore was also evaluated. No toxicity was detected by MicrotoxR analysis of water samples. Suspended sediment and near-shore bottom sediment samples had toxicity levels below the regulatory threshold value for ocean disposal of contaminated sediment. MicrotoxR analysis of extracts from semi-permeable membrane devices deployed in the water column at Sites No. One and Three showed toxicity levels lower than those measured at an 'unoiled control' beach site within the study region. The observed changes in toxicity are believed to be related to gravimetric data and not to the type of treatment used at the various sites