Rotting oil and gas pipelines collapsing in the North Sea can release large volumes of toxins such as mercury, radioactive lead and polonium-210, which is notorious for its role in the poisoning of the Russian defector Alexander Litvinenkowarn scientists.
Mercury, an extremely toxic element, occurs naturally in oil and gas. It sticks to the inside of pipelines and builds up over time and is released into the ocean when the pipeline corrodes.
Some methylmercury, the most toxic form of the metal, is released through the pipelines, although other forms can be converted into it. The international Minamata Convention on mercury states that high levels in dolphins, whales and seals can lead to “reproductive failure, behavioral changes and even death”. Seabirds and large predatory fish such as tuna and swordfish are also particularly vulnerable.
Lhiam Paton, a researcher at the Institute of Analytical Chemistry at the University of Graz who raised the alarm about the mercury pollution, told the Guardian and Watershed Investigations that “even a small increase in mercury levels in the ocean will have a dramatic impact have on the animals at the top of the food web”.
There are approximately 27,000 km (16,800 miles) of gas pipelines in the North Sea, and scientists predict that the amount of metal in the ocean could increase anywhere from 3% to 160% from existing levels. In some countries, such as Australia, companies are required to remove them when the oil well stops working. But in the North Sea, companies are allowed to let them rot.
Paton, whose work is published in the Journal of Hazardous Materials, said: “Pipelines left on the seabed can trap significant amounts of mercury waiting to be released into the local marine environment if the pipelines are left to drain away. rust while they are after decommissioning. There is no way to predict the impact of this at the moment, but we do know that the bioaccumulation of mercury within the marine food web is already dramatic and an increase in oceanic mercury concentrations will only bring disadvantages.”
Effects on wildlife and food chains will depend on the form of mercury released from the decaying pipelines, with some forms much less likely to be taken up by marine life than others. According to Dr Darren Koppel, a research scientist from the Australian Institute of Marine Science, it is unlikely that all the mercury released from a corroded pipeline will end up in seawater. The “mercury is more likely to partition between the sediments, water, biota and atmosphere, contributing to the global mercury cycle”.
“We have yet to understand how clean pipelines must be of mercury to ensure that there will be no long-term impact on the marine environment. This requires research that examines the long-term fate of mercury if it is left in contaminated pipelines and the conditions that will lead to mercury ending up in food webs,” said Koppel.
Mercury is not the only substance that worries scientists. Dr Tom Cresswell of Australia’s Nuclear Science and Technology Organization is also investigating the impact of naturally occurring radioactive materials found in some subsea oil and gas reservoirs. Natural radionuclides such as dissolved radium can be extracted with oil and gas fluids, potentially building up as scales in undersea pipelines.
“Radium will physically decay into radioactive lead (210Pb) and polonium (210Po), which can be taken up by marine organisms and represent a radiological risk to these organisms,” said Cresswell, who called for more research.
Hugo Tagholm, executive director of Oceana UK, described the issue as “another example of the extreme damage that oil and gas developments are doing to marine wildlife. Mercury is a harmful toxin that accumulates in animals’ brains – leading to damage throughout the nervous system – and can be fatal”.
In January, the North Sea Transitional Authority announced that 24 new oil and gas licenses had been offered to companies such as Shell, Equinor, BP, Total and Neo in the latest licensing round.
The UK is a signatory to the Minamata Convention, an agreement aimed at tackling mercury pollution, named after the Japanese city of Minamata, which experienced mercury poisoning from industrial waste water. It infected fish and shellfish in the bay, killing many people who ate local seafood and severely disabling others.
Monika Stankiewicz of the Minamata Convention Secretariat, said: “It is difficult to predict what will happen, especially in the long term, if large amounts of mercury released into the environment in the pipelines that have been put into service. The rich biodiversity of the North Sea, and the millions of people who depend on it, will be at greater risk.”
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Ricky Thomson, Offshore Energies UK decommissioning manager, said the industry has taken full responsibility for meeting its obligations under national and international regulations and that all decommissioning programs consider the environmental impact before operations take place.
“Throughout the decommissioning programme, operators will apply for a series of permits and consents from the foreign environmental regulator Opred for which the operator must consider any potential risk to the environment and appropriate mitigation measures.
“Under current regulations, and where infrastructure may not be fully removed, the final approach to decommissioning involves a comparative assessment process that considers environmental, social, safety, technical and economic factors to ensure that the decision balance all these aspects.”
Opred is a part of the Department for Energy Security and Net Zero (DESNZ). A spokesman for the department said: “We do not accept the conclusions drawn from this report which ignore the routine maintenance carried out on all oil and gas pipelines. Mercury and other harmful substances are minimized throughout the lifetime of oil and gas pipelines, with corrosion levels regularly monitored by operators.”
“Before decommissioning oil and gas fields, the contents of a pipeline are also flushed and filled with seawater to minimize contaminants.”
In response to DESNZ’s statement, Paton said it was “not reasonable to assume that flushing with seawater will solve any problems. Dumping the water back into the sea is likely to only increase the risk of pollution. If all this water used to flush miles of pipeline is somehow treated to remove mercury, then it must be proven that all the mercury has been removed from the pipeline walls. The need for transparency, collaboration and further research is clear.”
Around 1.3 million km of oil and gas pipelines are currently being installed worldwide.
