Iron-rich rock helps oceans sink atmospheric carbon

First published in Chemistry World, 05.04.18

Adding crushed rocks containing magnesium and iron minerals to seawater allows it to sequester more carbon from the atmosphere, geoscientists have shown.

Oceans are the world’s most efficient carbon store. Around a quarter of all anthropogenic carbon dioxide emissions are sequestered into the sea, and oceans could take in up to 80% of manmade carbon if the process, which usually takes centuries, could be sped up.

A team led by Eric Oelkers from University College London, UK, spread finely milled peridotite – an ultramafic rock that is rich in iron – in tanks of seawater with simulated wave activity. As the powdered rock dissolved it raised the pH of the water, enabling it to react with more atmospheric CO2. The sequestered carbon mineralised into aragonite, a form of calcium carbonate, which sank to the bottom of the tanks.

If powdered peridotite was added to actual oceans, the researchers say, the aragonite would sink to the ocean floor and become sediment, storing carbon permanently. And in nature, aragonite is important for the calcification of corals, so it may even have the added bonus of supporting coral growth.

So far, the approach has only been tried in laboratory simulations. Oelkers says the method needs further scrutiny before it could be seen as a viable way to reduce atmospheric CO2.

‘With upscaling, there are many, many things to consider, some of them unexpected,’ he tells Chemistry World. For example, the extra iron in peridotite rocks could cause plankton blooms. The rocks also contain materials that are harmful to marine life, such as nickel, and it is not clear what impacts these would have on a large scale.

The energy and money required to mine and mill the peridotite also needs to be considered. The researchers propose that the method should be limited to coastal areas where peridotite is common, in order to limit carbon emissions from transport.

Juerg Matter, a geoengineer at the University of Southampton who was not involved in the research, says further refinement of the method could help lower the energy costs of peridotite powder production and save on emissions.

‘The question is really what the acceptable grain size could be,’ he says. ‘Is it really necessary to produce ultrafine particles, or could we tune the process [so] less milling time is required?’

Trump’s budget jettisons ‘irreplaceable’ marine mammals agency

This article first appeared in New Scientist on 25 May, 2017

The US Marine Mammal Commission, an organisation charged with restoring mammal populations in the world’s oceans, is set for the chop in president Donald Trump’s latest budget proposal.

The budget, released on 23 May, includes a 16 per cent cut to the National Oceanic and Atmospheric Administration’s bodies and agencies. This would close down the MMC, an independent federal agency, which costs around US$3.41 million a year, or around one penny per American.

The Maryland-based commission sees itself as a “one-stop shop” for marine mammal science and policies, says its chairman Daryl Boness. The commission reviews human activities in the ocean -including shipping, military drills and fossil fuel extraction – and uses the latest science to ascertain the impact of such activities on marine mammals.

“The commission’s role as an oversight agency on all issues related to marine mammals is unique; no one else in the world meets this mandate,” Boness told the New Scientist. “This service to the public, marine mammals and their ecosystem would end.”

The MMC was established in 1972. Its own small-scale science projects cover topics such developing fishing nets that catch fewer mammals, and Whale Alert app to help sailors avoid whales and to alert authorities to injured or distressed whales.

The commission looks after the stocks of many threatened American sea mammals, including such iconic species as the Hawaiian monk seal, Florida manatees, beluga whales, orcas and polar bears. For example, in April it hosted a summit with researchers, industry representatives and politicians to reduce the entanglement of North Atlantic right whales in fishing gear.

Uproar over irreplaceable agency

News of the commission’s possible demise has caused uproar among conservationists around the world. Ingrid Biedron, a marine scientist at international ocean protection group Oceana, says no other organisation can fill the MMC’s footsteps.

“By law, the commission has access to all federal studies and data related to marine mammals, and by law, other federal agencies are required to consider and respond to the commission’s recommendations,” Biedron explains. “This is not the case for academic experts on marine mammals.”

Other marine agencies are also at risk under the 2018 budget proposal. The National Marine Fisheries Service would lose $22m off its Fisheries Research and Management Program, while its protected species programme would lose $7m and, according to Oceana, become effectively unable to carry out its responsibilities.

Boness says the cuts are a blow to America’s “strong environmental ethic”. He worries that, without the MMC, marine exploitation will continue “without the necessary checks and balances that help to ensure that those activities are done in the most environmentally conscientious way possible”.