A European-funded mesocosm experiment will try to answer
It was in the middle of a storm, on December 14th 1907, when the Thomas W. Lawson, a seven-masted steel-hulled schooner, was sank in the Isles of Scilly (UK), releasing 7,400 tonnes of paraffin oil in the sea; an event that is considered as the first large marine oil-spill in history. Since then, it is estimated that approximately 7 million tonnes have been released in the marine environment from more than 140 major spill events, while only a single event, the explosion of the Deepwater Horizon oil rig in 2010, resulted in the release of more than 700,000 tonnes of crude oil in the Gulf of Mexico. Today, it is well known that oil spills can be disastrous to any ecosystem and have extensive environmental and economic impact, as they cause mass mortalities of birds, mammals and fishes, reduce species diversity and sediment quality and affect aquaculture and fisheries.
In order to reduce the consequences of such catastrophic events, environmental and first-response state agencies from all-over the world apply three main mitigation strategies: (1) mechanical removal of oil, (2) use of chemical dispersants to break-down the oil and (3) in-situ oil burning. Mechanical recovery, which typically features the use of devises such as booms and skimmers to concentrate and collect the oil from the water surface, is the most common oil-spill response method. Although it is an efficient and well-established method, it has specific limitations (need for extensive equipment, wastes, low removal rate, etc) which enhance further on large scale oil-spill events. In such events, the chemical break down, using dispersants, and the in-situ burning of the oil seem ideal mitigation strategies. However, there is a big issue with them: their effects on the environment are still unknown and, as a consequence, their use is very limited or even they are banned by many countries. This lack of knowledge is something that has to change.
In order to answer whether in-situ oil burning is an acceptable mitigation option for marine oil-spills in terms of toxicity to the marine environment, a mesocosm experiment, funded by the European Union and codenamed as “BurnImpact”, will take place in Crete, Greece in May 2018. “Mesocosms is an ideal tool to study the potential effects of pollutants on the marine environment” says Dr Paraskevi Pitta, coordinator of the CretaCosmos/HCMR mesocosm facility, “because in mesocosms we can keep large volumes of marine water enclosed and isolated from the sea, we can perform experiments with contaminants in controlled and also in almost-natural conditions without the danger of contaminating the sea. In addition, due to their large volume, we can study their effects on the marine food web, from viruses to copepods”.
During the BurnImpact experiment, scientists from Italy (University of Bologna, UNIBO), Denmark (Denmark Technical University, DTU), Czech Republic (Biology Centre of the Czech Academy of Sciences, CAS) and Greece (Technical University of Crete, TUC and Hellenic Centre for Marine Research, HCMR) will collaborate to answer the question: Is the ISB of oil an alternative option to the mechanical oil recovery? To answer that, they will investigate the fate of the burned-oil residues and soot in the marine environment and their toxicity and effects on the marine organisms.
The first aim of the experiment is to investigate the generation and transformation of the in-situ oil-burning products in the sea. Professor Nikos Kalogerakis (TUC) pointed out that “ISB of oil as a mitigation measure has been used extensively in North America (e.g., more than 400 burns were carried out in the Deepwater Horizon incident in the Gulf of Mexico) whereas it is not allowed to be used in European waters. Nonetheless, the toxicity of the oil burning by-products is well established in terms of atmospheric pollution; however, limited research has been carried out for the adverse effects on the marine environment. This is what the BurnImpact experiment comes to answer”. The fate, degradation and weathering of oil-burning residues and soot in the marine water will be studied by scientists from TUC and CAS. On the other hand, marine bacteria, the smallest living organisms in the planet, play an important role in oil-spill events as they are capable of degrading oil very effectively. Therefore, UNIBO and HCMR scientists will investigate the abundance, activity, oil-related toxicity and diversity changes of the bacterial community and in collaboration with the TUC and CAS teams, they will try to answer whether, and how efficiently, marine microbes degrade the residues of in-situ oil burning as they are dispersed and dissolved in the water column.
The second aim is to assess the effects of in-situ oil burning on marine plankton organisms. Toxicity and bioaccumulation of hydrocarbons as well as the effects on community composition of burned-oil residues and soot on marine planktonic organisms will be assessed by DTU and HCMR by studying plankton abundance, grazing and diversity in the mesocosms and also in extra parallel microcosm experiments. The study of effects on plankton is vital as “most biological processes in the ocean are due to planktonic organisms, which are among the first marine organisms to interact with spilled crude oil. Therefore, assessing the impact of oil spills on marine ecosystems requires a clear understanding of the effects of oil pollution on planktonic communities” says Dr Rodrigo Almeda, postdoc researcher at DTU. Also, studying plankton organisms is particularly important as they serve as food for fishes and as a consequence, burnt residues and soot can end to the higher levels of the food web (via bioaccumulation) affecting fisheries industry and potentially become a public health danger. Finally, the toxicity of soot on mussels, which are important organisms in both financial and biomonitoring terms, will be investigated by UNIBO scientists.
The results of this experiment will provide valuable information not only to the scientific community but also to public environmental agencies about the potential usage of in-situ oil burning after a major spill event in European waters. Especially in an enclosed marine area, such as the Mediterranean Sea, in which tourism and fisheries are important financial industries and, on the same time, marine traffic (many of which are oil tankers) is increased and drills for hydrocarbons extraction are planned for the next decade, the development and testing of effective oil-spill mitigation strategies is a matter of high importance.
BurnImpact mesocosm experiment is funded by the AQUACOSM project (EU H2020 – INFRAIA 73106) in the frame of AQUACOSM Transnational Access (TA) scheme.
By Iordanis Magiopoulos,
Environmental Microbiologist and Materials Scientist
Hellenic Centre for Marine Research (HCMR)
The BurnImpact Team:
Giulio Zanaroli (Project coordinator)
Anette Maria Christensen
Paraskevi (Vivi) Pitta
Dark clouds of smoke and fire emerge as oil burns during a controlled fire in the Gulf of Mexico, May 6, 2010. This Image was released by the United States Navy with the ID 100506-N-6070S-346