Biodegradation, Bioaccumulation and Toxicity of Oil Spill Herding Agents in Arctic Waters As Part of an Ecotoxicological Screening

Oil spills from ship traffic or oil production represent a huge threat to the environment. A controlled and thick oil slick is crucial in relation to combatting oil spills, not least for Arctic waters, before introducing the oil spill response method in situ burning. Recently, herding agents have been introduced, with success, as a measure to contain and thicken oil spills, when sprayed to the perimeter of the slick. In this study, we evaluated potential environmental impacts of using herding agents. Toxicity, bioaccumulation and biodegradability of the two herders ThickSlick 6535 (TS6535) and Siltech OP‐40 (OP‐40) were studied in laboratory set-ups with Arctic water and the high Arctic copepod, Calanus hyperboreus. TS6535 was found to biodegrade rapidly within 7 days, and did not seem to bioaccumulate in the copepods or affect their grazing activity. Tests with OP-40 showed bioaccumulation in the copepods, sublethal effects (as reduced grazing activity) and limited biodegradation. The results thus indicate that OP-40 may possibly pose a risk to the Arctic marine environment. The data and knowledge from the tests poses valuable input to assess the potential environmental impacts from using herders in Arctic waters in connection with oil spill response. However, more knowledge is still needed to fully understand the fate and effect of herders in the environment; this also includes possible combined and/or cumulative effects from herders and oil.