Thesis Title: Determination of hydrocarbon concentration entering the water column due to rain under in situ burning conditions

Thursday 11 July 2019, at: 13:00, Venue: Hall Κ2.A3

Examination Committee

• Professor Nicolas Kalogerakis (advisor)
• Professor Nikolaos Pasadakis
• Dr. Eleftheria Antoniou

Abstract

In spite of the efforts made to replace conventional renewable energy sources, oil is still one of the most important sources of energy for human industry. The risk of marine oil spills for the marine ecosystem due to human activity or accidents is one of the major problems of marine pollution, as evidenced by the reported accidents such as Exxon Valdez in Alaska and the most recent Deepwater Horizon in bay of Mexico. The effects of such marine accidents are extremely destructive to the ecosystem, lead to the mortality of a large number of marine organisms and lead to significant environmental degradation with long-term effects. Therefore, remediation and decontamination of marine ecosystems by oil spills is urgently needed.

Conventional oil spill clean-up methods, such as natural removal, rarely achieve complete oil spill purifying, while chemical dispersants can become toxic to the biodiversity of marine ecosystems. It is therefore imperative to use more efficient and cost-effective methods of dealing with oil spills.

In situ burning is a method which is difficult to apply due to environmental impacts on ecosystems, water or land, as well as the legislation that has been enacted, which prohibits its use in some countries. Nevertheless, in situ burning is a very promising method of dealing with large quantities of oil spill as it has the ability to remove up to 95% of oil and is an economical and not very complex response method, which has immediate effects on the treatment of the oil.

In this thesis we examined the waste gas generated during in situ burning of oil spill at sea and its impact on precipitation. The concentrations of hydrocarbons (saturates and aromatics) were determined before, during and after oil burning and a comparison of the results was made. Experimental firing was done using the mesocosmos at the Hellenic Center for Marine Research (HCMR) in Heraklion, Crete, under the code name "BurnImpact", and then the samples collected were processed by extraction. The detection and quantification of hydrocarbons was performed by gas chromatography and mass spectrometry (GC / MS) techniques.

The existing literature on the specific object, the flue gas and the soot of in-situ burning is extremely incomplete, as all the accidents are mainly concerned with residues resulting from combustion and not with the environmental impact of soot. Therefore, its analysis is of particular importance as some substances may be toxic and carcinogenic for organisms.

According to the results, increased concentrations of aromatic compounds are observed in the soot mesocosms immediately after the burning process as well as in the subsequent days of sampling, while low values for the concentrations of saturated compounds were observed compared to those of the control mesocosms. Although the concentrations recorded appear in ppt, soot is characterized as moderate toxic and affects the life of marine organisms.

Ultimately, tackling oil spills with in-situ burning deserves particular attention considering the environmental impact of accidents such as the Deepwater horizon in the Bay of Mexico, and it is necessary to continually control the releases released and further analyze their chemical composition as they may be toxic for the marine ecosystem.