In freshwater aquatic environments, dissolution is the greatest physical weathering process after evaporation.Schmidt T, Kleinert P, Stengel C, Goss K, Haderlein S. Poler fuel constituents: compound identification and equilibrium partitioning between non aqueous phase liquids and water. Environmental Science and Technology 2002;36(19):4074-4080. Under the same conditions, the rate of dissolution is between 0.01% and 1% of the rate of evaporation for alkanes and aromatic compounds.Gill R, Robotham P. Input, behaviour and fates of petroleum hydrocarbons. In Trett M, Green J, editors. The fate and effects of oil in freshwater: Elsevier Applied Science, 1989;41-79. Once dissolved, these components are more available to organisms and therefore susceptible to biodegradation processes and experience increased rates of photochemical and chemical degradation.Brown M. Biodegradation of oil in freshwater. In Trett M, Green J, editors. The fate and effects of oil in freshwater: Elsevier Applied Science, 1989;197-213. These components represent some of the most toxic oil ingredients because of their increased bioavailability, with reduction in toxicity occurring on emulsification or absorption to colloids which restrict availability to organisms.Suthersan S, Natural and enhanced remediation systems. CRC, 2001.Lamont N. The screening of petroleum hydrocarbons based on the water associated fraction. Global Forensic Science today 2013.Gray G, Chappel K, Broscomb-Smith V. Solvent enhanced bioremediation of weathered oil contamination. In: Garcia-Martinez R, and Brebbia C, editors. Oil and hydrocarbon spills: Modelling, Analysis and Control. Wessex Institute of Technology Press, 1998;315-321.
