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This study aimed to assess the toxicity of the water soluble fraction (WSF) and correlate the effects of three oils and their compositions, through the bioassay with the Mysidopsis juniae, the analysis of n-alkanes and specific gravity. The PET01 and PET02 oils were classified as light oils ºAPI 39.8 and 32.8 and paraphynics with more abundant n-alkane ranges from n-C10 to n-C16, and n-C9 to n-C32. The PET03 oil was classified as heavy (°API 19.7), with more abundant hydrocarbons in the range of n-C29 and n-C33. It was also possible to evaluate the concentrations of metals in petroleum, Ba (3.41-4.45 mg/kg), Fe (5.42-9.01 mg/kg), Zn (0.18-0.53 mg/kg) and Ni (1.77-3.55 mg/kg) were present in the composition and may have harmful effect even at low concentrations. The acute toxicity of WSF from the oils varied by oil type, with LC50 11.4-27.6 of % WSF. Spill simulations indicated that short-term exposures in areas spilled with these oils are less toxic, but with increasing oil and seawater contact time (>1 h), the toxicity and solubility of total BTEX increases. The toxicity of the samples was directly related to the composition of the oils and categorized by the ecotoxicological risk to the environment from PET01 > PET02 > PET03. These results provide reliable data for ecotoxicological risk assessments in cases of oil spillage in marine environments.

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The objective of this study was to evaluate and obtain mathematical models, using the experimental design methodology, capable of predicting the contamination of benzene, toluene, ethylbenzene and xylenes (BTEX) in cases of oil spillage at sea, and to evaluate the acute toxicity of the soluble petroleum fraction (FSA). The factorial experimental planning was developed to describe the concentration of each compound according to the variables: oil °API, contact time oil/seawater after spillage and ambient temperature. The models presented can be used to quantitatively predict BTEX contamination in seawater with accuracy greater than 99%, within the studied ranges. The contact time oil seawater was the most determining factor in the concentration/contamination of BTEX in the Petroleum FSA. According to CL50% the soluble fraction of oil of °API 39.8 showed higher toxicity, with a LC50% of 46.07 with 1 h, and 11.38 with 96 hours of contact time oil/seawater, while the oil °API 32.8 showed lower toxicity, however presented higher concentrations of BTEX in FSA, this is possibly due to the synergistic effect of other hydrocarbons that became bioavailable to Mysidopsis juniae during the tests. The samples demonstrated potential environmental risk in cases of oil spillage, and these results can help in the development of a risk assessment of oil spills and serve as a useful analytical tool for emergencies.