Factors Affecting Concentration and Chemical Composition of Petroleum Hydrocarbons in Water Accommodated Fractions (WAF) of Iranian Heavy Crude Oil

Abstract

After the Hebei Spirit Oil Spill (HSOS) incident in December 2007, Korea, a number of bioassays with water accommodated fraction (WAF) of the spilled crude oil have been conducted in many laboratories. However, much of these data were not comparable because of differing WAF preparation methods used, as well as lack of analytical verification of exposure. There is a growing need to indentify factors affecting WAF preparation with Iranian Heavy Crude Oil (IHCO), a major spilled crude oil in HSOS. Factors affecting concentration of total petroleum hydrocarbons (TPH) and polycyclic aromatic hydrocarbons (PAHs) and their chemical composition in WAF of IHCO in seawater were studied. Mixing speeds (110 and 200 rpm) do not significantly (p > 0.05) affect TPH level of WAF. The functional saturation of TPH concentrations were attained within 24 h from 6 h to 48 h mixing duration. The TPH levels after filtration of WAF decreased by about 10 %, which implies 10% of TPH level in the WAF was contributed by oil droplet. TPH concentration of WAF stored in refrigerator demonstrated slight reduction for the first 12 h and remained comparable for 8 d. Parent and alkylated PAHs concentrations were not significantly changed for 8 d.