Study On The Oil Weathering And Indentification Of Spilled Oil On The Sea

With the development of oil exploitation and petroleum transportation, oil spill occurs often and make serious damage for halobios and natural resources. To unambiguously identify spilled oils and petroleum products and to link them to the knownsource are extremely importend in settling questions of environmental impact and legal liability.Oils from different product place or after different refine processes have different distinct character. This difference is"oil fingerprint"and the figerprint can be described by chemical instrument. When oil enters the ocean, the fate and behaviour of spilled oils in the environmental depends on a number of physicochemical and biological factors including evaporation, dissolution, photooxidation, microbial degradation and so on. These processes change the compositions of oil and some of them are the key to identify the spilled oil. So understanding the relationship between the weathering processes and compositions change is very important. Just depend on the weathering laws of oil collected at the scene after the oil spill accident is not enough. How to take the initiative and systematic methods to study the impact of weathering factors to the oil play a vital important role for accurate identification source of oil spill.In this paper, heavy fuel oil, light fuel oil, marine fuel oil were weathered in specially designed weathering simulator over the same period, then detected n-alkanes, PAHs, biomarkers by gas chromatography-mass spectrometry (GC-MS ) respectively and analyzed the spectrum and characteristics, researched oils'weathering laws. At the same time, oil spills and suspected oil and other oil-like were analysised and identified.The results are shown as the follows:(1) The diagnostic ratios of alkanes C17/Pr, C18/Ph, Pr / Ph, (C19+C20) / (C21+C22) difference between oils and can be used as indicators of unweathered oils. And in moderate weathered time (7 days), the ratio keep stable and can be used as indicators of oil spill identification.(2) The ratio of PAHs C2D/C2P, C3D/C3P,ΣP / (ΣD +ΣP) in the moderate weathered time (30 days), maintain stable, and can be used as indicators of oil spill identification. Isomers C1D (m/z=198), C1P (m/z=192) can be used as the identification of indicators of moderate weathered oils.(3) The biomarker ratios remain stable and can be used as indicators of moderate and serious weathered oil combined with other indicators .(4) In five PAHs series, naphthalenes weathered fastest, followed by fluorens; DBTs, phenanthrenes and chrysenes weathered slow on the other hand.(5) Because of the differences of the physical properties and chemical properties in three oils, the speed of weathering rate and the variations of the ratios presence some differences.(6) Through the use of n-alkanes characteristics of the ratio of the average absolute difference, as well as t test analysis of the ratios of biomarkers and PAHs, the identification was much more scientific and quantitative.