Integrated hydrocarbon exposure concentrations for toxicity tests 2010_11

Experiments were done to quantify the Total Hydrocarbon Content (THC) in water accommodated fractions (WAF) of three fuels; Special Antarctic Blend diesel (SAB), Marine Gas Oil diesel (MGO) and an intermediate grade of marine bunker Fuel Oil (IFO 180).These tests measured the hydrocarbon content in freshly decanted WAFs and the resulting loss of hydrocarbons over time when WAFs were exposed in temperature controlled cabinets at 0°C. These tests are detailed in Dataset AAS_3054_THC_WAF.

The results of hydrocarbon WAF tests were used to calculate integrated concentration from measured hydrocarbon concentrations weighted to time to be used as the exposure concentrations for toxicity tests with Antarctic invertebrates. Exposure concentrations used to model sensitivity estimates were derived by calculating the time weighted mean THC between pairs of successive measurements in the 100% WAFs and dilutions to give overall exposure concentrations for each time point.These modelled concentrations integrated the loss of hydrocarbons over time, and renewal of test solutions at 4 d intervals Exposure concentrations of THC in µg/L are shown for endpoints from 24 h to 21 d