The tanker Prestige sank on November 19, 2002, off the Costa da Morte with 77,000 tons of fuel on board, causing the largest ecological disaster in Spain’s history. Now, as the oil slick has faded, coastal monitoring and cleanup programs are ending, and interest in continued ecological impact analysis is beginning to wane. A group of researchers led by Océano-ECIMAT investigator Ana Bernabeu has just published a study demonstrating that tar still continues to reach the beaches in the most affected areas, driven by wave action.
The study, published in the specialized journal Journal of Hazardous Materials, presents the results of annual monitoring campaigns conducted by these researchers from 2004 to 2011 on two of the beaches most affected by the spill: Nemiña in Muxía and O Rostro in Fisterra. “During all this time, we visited the beaches once or twice a year for periods of one to three days, and we always found tar patties in the intertidal zone of O Rostro beach and, in most campaigns, also at Nemiña beach, leaving no doubt that this is a persistent phenomenon,” emphasizes Ana Bernabeu. She explains that the published work involved researchers from the Marine and Environmental Geology group of the University of Vigo, the GLADYS group from the University of Montpellier, and the Environmental Chemistry group of the Spanish National Research Council (CSIC).
The monitoring and cleanup program could be “inexpensive.”
The multiple pieces of evidence showing that these are recurring events of low-concentration fuel, but persistent over time, make it, in the researchers’ view, necessary to design an action protocol. Considering the limited volume of fuel reaching the coast and its specific location, controlled by the waves, “it should not require a major effort, either in human or financial resources,” notes Bernabeu. She adds that the benefits achieved by such a monitoring and cleanup program could be significant by removing fuel from the marine environment.
Although there are currently no figures regarding the total volume of these events, nor is the final fate of these oil remnants fully known, and risk assessments of potential contamination have not yet been carried out, the researchers express concern that these spills—small in volume but recurring over the long term—could constitute a significant source of ocean pollution.
Waves are the main transporting agent
The study results leave no doubt that waves are the primary transport mechanism for the fuel. The researchers are firm in arguing that, with a thorough analysis of wave conditions along the coast using numerical models, it would be possible to identify the areas most likely to receive this contamination.
The annual monitoring conducted since 2004 allowed them to observe a greater and more direct impact of wave action on O Rostro beach, where fuel was always found. In contrast, at Nemiña, a more wave-sheltered site, tar only appeared when there had been a southwest storm in the preceding weeks, a direction to which the beach is highly exposed. “Furthermore, at Nemiña beach, wave action is concentrated mainly on the northern third of the beach, and that is where the fuel appears,” adds Bernabeu.
Numerous national and international collaborations
Since the monitoring campaigns began in 2004, many researchers and institutions have participated. Nationally, the Environmental Chemistry group of Professor Joan Albaigés (CSIC) and the Hydraulic Institute of Cantabria, led by Professor Raúl Medina, were involved. Internationally, the Marine and Environmental Geology group of the University of Vigo also coordinated a European project together with the University of Montpellier-2, led by Professor Frederic Bouchette, and the CIIMAR and ICBAS groups of the University of Porto, headed by researchers Marisa Almeida and Ana Paula Mucha.
Source: University of Vigo Newspaper (DUVI)
