Heavy hydrocarbon fate and transport in the environment

Heavy hydrocarbons are a heterogeneous mixture of compounds consisting mainly of alkylated cyclics, resins and asphaltenes and, depending on the source, can form a significant proportion of crude oil. Their prevalence is expected to increase in the future as heavy oil reserves are increasingly exploited for growing worldwide energy demands. Despite their growing use, heavy hydrocarbons are generally overlooked when assessing the risk of hydrocarbons to human health, ecology and water reserves. Although their human and environmental health risks are considered low, heavy hydrocarbons are known to persist in the environment. This review considers the fate, transport and toxicity of heavy hydrocarbons. It provides a description of the possible mechanisms involved in heavy hydrocarbon attenuation and offers some interpretation of data that provides insight into their persistence in the environment.