Temperature as a significant determining factor of petroleum hydrocarbon toxicity in marine spills

The relationship between temperature and petroleum hydrocarbon toxicity to marine invertebrate is not well documented in the current literature. A complex relationship exists wherein higher temperatures can both increase... [ view full abstract ]

The relationship between temperature and petroleum hydrocarbon toxicity to marine invertebrate is not well documented in the current literature. A complex relationship exists wherein higher temperatures can both increase bioavailability to a marine organism yet at the same time increase hydrocarbon volatilisation and degradation thus reducing the aqueous concentration. Five petroleum hydrocarbons commonly found in light crude oil and refined petroleum were analysed for toxicity at two different temperatures using the amphipod Allorchestes compressa. The concentration that killed 50 percent of the A.compressa test population (LC50) was determined (USEPA, 2010) for each of the hydrocarbons at 16°C and 22°C for exposures of up to 96 h. Results showed that the low molecular weight, highly volatile hydrocarbons were more toxic at 16°C whereas the higher molecular weight, poorly soluble hydrocarbons were significantly more toxic at 22°C. Chemical analysis was performed to determine the exact concentration pre and post testing for each experiment. The results illustrate the importance of taking temperature into account when performing an environmental risk analysis.