**9. Current work**

#### **Applications of biomarkers in oil spill source identification**

Although oil is the dominant energy source, oil spill occurs worldwide causing a severe global environmental problems (Abostate et al., 2011). Egypt is suffering from oil pollution owing to the increasing petroleum activities in the last decades. Environmental protection is currently an important subject of increasing public and research concern and as a result, special efforts have already been done so as to develop oil spill detection and fingerprinting. Therefore, to unambiguously characterize, identify, categorize, and quantify all sources of hydrocarbons entering the environment is very important for environmental damage assessment, evaluation of the relative risks to the ecosystem posed by each spill and selecting appropriate spill response and taking effective cleanup measures. Biomarkers are the most important hydrocarbon groups for chemical fingerprinting which play a very important role in source identification in environmental forensic investigations of oil spills. It was a useful analogy to explain this type of forensic analyses for spilled oil. However, it was recognized then, and remains true today, that the analyses of spilled oils do not have the statistical discriminating power of the human fingerprint in the sense that each human has an individual fingerprint. Analyses of spilled oils and potential sources are usually undertaken by increasingly sophisticated chemical analyses until either all but one potential source oil remains that cannot be distinguished from the spilled oil, or all potential sources have been eliminated and the spill is then a "mystery". The presumption for success using fingerprinting is that a complete collection of possible sources has been secured for the matching analyses. The term "passive tagging" has been used in place of fingerprinting in the past to describe the chemical analyses of oils. The term derives from the process of using the chemicals naturally present in the oil as "tags". The "passive" part of the term was used because there were proposals and some experiments conducted in the late 1960s and early 1970s to introduce "active tags" into various oil cargos to allow for identifying the oils if they were spilled (Adlard, 1972). Various chemicals were proposed as active tags, but the obvious international administrative and logistical effort needed to keep track of such "active tags" prevented operational use of active tagging systems.

Nothing sparks concerns about contaminates in the environment quite like a petroleum release. Unfortunately, the events of 2010 served to heighten the awareness and need to

Biomarkers 183

evaluation than the mere visual comparison of the chromatograms. In addition, these parameters may also be used for finding oils in the database, which are similar to the spill sample. The system is fast and greatly saves laboratory resources and reliable and

Biomarkers are naturally occurring, ubiquitous and stable complexes that are objectively measured and evaluated as an indicator of a certain state. It is used in many scientific fields;

Due to the variety of geological conditions and ages under which oil was formed, every crude oil exhibits a unique biomarker fingerprint. From the identification point of view, biomarkers are the most important hydrocarbon groups in petroleum because they can be used for chemical fingerprinting which provides unique clues to the identity of source rocks from which petroleum samples are derived and the biological source organisms which generated the organic matter, the environmental conditions that prevailed in the water column and sediment at the time, the thermal history (maturity) of both the rock and the oil,

GC-MS is considered the most widely used method for biomarkers detection and identification which is a true combination of its separate parts (gas chromatography, GC and mass spectrometry, MS). The mass spectrometer has long been recognized as the most powerful detector for gas chromatography due to its high sensitivity, specificity and capability to elucidate compound structure. Mass fragmentography provides a satisfactory tool for obtaining specific fingerprints for classes and homologous series of compounds resolved by gas chromatography. The development of more sensitive and selective identification tool for biomarker analysis purpose especially for crude oils containing low concentration biomarkers as weathered and light oils can be considered as one of the most important research points in this field. After separation and identification of biomarkers, principal component analysis PCA, a mathematical procedure, can be used for analyses of chromatograms using a fast and objective procedure with more comprehensive data usage compared to other fingerprinting methods. The discriminative power of PCA was enhanced by deselecting the most uncertain variables or scaling them according to their uncertainty. Chemical analysis of biomarkers generates information of great importance to environmental forensic investigations in terms of determining the source of spilled oil. The patterns of the biomarkers and a set of parameters were used to construct an Egyptian computerized oil spill identification database. This can greatly increase the possibilities for finding the sources of oil pollution by comparing an unknown pollutant sample with any similar oil sample stored in the database. A much stronger connection between a distinct oil

Abostate, M.A.; Moustafa, Y.M. & Mohamed, N. H. (2011). Biodegradation of slop wax

Adlard, E. (1972). Review of Methods for Identification of Persistent Hydrocarbon Pollutants on Seas and Beache, *Journal of Institute petroleum*, Vol. 58 (560) 63-74.

byBacillusspecies isolated from chronic crude oil contaminated soils, *Fuel Processing* 

medicine, cell biology, exposure assessment, geology and astrobiology.

and the degree of microbial biodegradation.

spill and its actual source may be established than before.

*Technology,* Vol. 92, 2348-2352.

comfortable.

**10. Conclusion** 

**11. References** 

have the capability to monitor and characterize the extent and breadth of the impact of these events. Using petroleum biomarker analysis make it possible to accurately identify the source of contaminates back to the specific origin as well as determining the absolute concentrations of priority pollutant PAHs.

Generally, gas chromatograms of two oil samples are compared by comparing the envelop shapes of the n-alkanes, the unresolved backgrounds and individual peak intensities. By means of GC/MS, a big number of compound classes of oils may be separately detected and compared. Computerized oil spill identification (COSI) may highly support analysts in GC and GC/MS results evaluation and adds a new dimension to forensic oil spill identification. It is greatly increases the possibilities for finding the sources of oil pollution. The patterns of the biomarkers and a set of parameters based on the literature findings was chosen to be investigated for most Egyptian crude oil and stored in the database in order to construct an Egyptian computerized oil spill identification database of local crude oils. Gas-chromatograms and mass-fragmentograms are rapidly produced from raw GC- and GC/MS-data for comparing an unknown pollutant sample with any oil sample stored in the database then simultaneously a much stronger connection between a distinct oil spill and its actual source accurately established than before, as shown clearly in Figure 8. These parameters allow a more objective, provable and defensible result

Fig. 8. Representative model of computerized oil spill identification matching.

have the capability to monitor and characterize the extent and breadth of the impact of these events. Using petroleum biomarker analysis make it possible to accurately identify the source of contaminates back to the specific origin as well as determining the absolute

Generally, gas chromatograms of two oil samples are compared by comparing the envelop shapes of the n-alkanes, the unresolved backgrounds and individual peak intensities. By means of GC/MS, a big number of compound classes of oils may be separately detected and compared. Computerized oil spill identification (COSI) may highly support analysts in GC and GC/MS results evaluation and adds a new dimension to forensic oil spill identification. It is greatly increases the possibilities for finding the sources of oil pollution. The patterns of the biomarkers and a set of parameters based on the literature findings was chosen to be investigated for most Egyptian crude oil and stored in the database in order to construct an Egyptian computerized oil spill identification database of local crude oils. Gas-chromatograms and mass-fragmentograms are rapidly produced from raw GC- and GC/MS-data for comparing an unknown pollutant sample with any oil sample stored in the database then simultaneously a much stronger connection between a distinct oil spill and its actual source accurately established than before, as shown clearly in Figure 8. These parameters allow a more objective, provable and defensible result

Fig. 8. Representative model of computerized oil spill identification matching.

concentrations of priority pollutant PAHs.

evaluation than the mere visual comparison of the chromatograms. In addition, these parameters may also be used for finding oils in the database, which are similar to the spill sample. The system is fast and greatly saves laboratory resources and reliable and comfortable.
