Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Ocean Islands Fuel Productivity and Carbon Sequestration Through Natural Iron Fertilization

02.02.2009
An experiment to study the effects of naturally deposited iron in the Southern Ocean has filled in a key piece of the puzzle surrounding iron’s role in locking atmospheric carbon dioxide (CO2) in the ocean.

The research, conducted by an international team led by Raymond Pollard of the National Oceanography Centre, Southampton, and included Matthew Charette, a marine chemist at the Woods Hole Oceanographic Institution (WHOI), found that natural iron fertilization enhanced the export of carbon to the deep ocean. The research was published January 29, 2009, in the journal Nature.

Scientists have generally accepted the fact that biological productivity in large areas of the Southern Ocean is limited by the supply of iron, an important micronutrient for phytoplankton. However, downstream of ocean islands in this study area, massive phytoplankton blooms have been observed, leading to the idea that the islands themselves are somehow fertilizing the ocean with iron. The team showed that this natural iron fertilization enhanced phytoplankton growth and productivity and the amount of carbon exported from the surface layer (100 meters) by two to three times. Moreover, they found that the amount of carbon stored at 3,000 meters and in the sediment was similarly two to three times higher beneath the natural fertilized region than for the nearby iron-poor region.

“This work demonstrated for the first time that Southern Ocean phytoplankton blooms fueled by natural sources of iron have the potential to sequester carbon in the deep ocean,” said Charette.

The team conducted their experiment in 2004-2005 on the seas around the Crozet Islands and Plateau at the northern boundary of the Southern Ocean, about 1,400 miles (2,200 kilometers) southeast of South Africa. These seas provided a natural laboratory, because each spring the waters north of Crozet experience an enormous bloom containing billions of individual phytoplankton and covering 120,000 square kilometers (the size of Ireland). In contrast, the area south of Crozet experiences only a small, short bloom later in the season.

“Our first question was, ‘where does the iron come from?’” said Charette. “Airborne dust wasn’t the solution — there isn’t enough exposed soil on Crozet for winds to carry iron from the island to the deep water where the bloom occurs. While other studies concluded that upwelling from the deep ocean was the main source of the iron, we wanted to test the hypothesis that the iron was coming from the island itself and the iron-rich sediments in the shallow water and the plateau area around it.”

Since the currents move from south to north over Crozet, the researchers reasoned that iron could be entrained in the water column as it flows over the plateau. First, they needed a way to understand how long it would take iron to travel from the island’s shore to the bloom site and if the rate of supply was enough to kick-start and sustain the bloom for several months. Iron concentrations in the water wouldn’t tell them where it came from, so the team sampled waters around Crozet looking for naturally-occurring radium isotopes, which, like iron, originate in the sediments and can therefore be used to quantify the amount of iron that the islands and surrounding sediments can supply to the bloom area. The decaying isotopes provided a built-in clock for the investigators to determine how quickly the water moves over the plateau and into deeper water. The distribution of radium in the water column demonstrated that the source of the iron was the island and the sediments in the shallow water around it and the plateau.

A second question the team sought to answer was whether the differences in the blooms between the north and south sides of Crozet would result in greater amounts of carbon held in the deep ocean. Using sediment traps and sediment cores, the researchers uncovered the first evidence that carbon deposited at 3,000 meters and in the sediment was two to three times higher beneath the natural fertilized region than for the nearby iron-poor region. In addition, the sediment record shows that this has been so throughout the Holocene (about 10,000 years ago until present).

In recent years, schemes to fight global warming have included sequestering carbon in the deep ocean by fertilizing the ocean with iron to artificially induce plankton blooms. As public interest in these ideas has increased, the authors point out that the amount of carbon sequestered in the deep ocean for a given input of iron falls far short of previous geoengineering estimates, “with significant implications for proposals to mitigate the effects of climate change through purposeful addition of iron to the ocean,” wrote lead author Pollard.

Support for this project came from the Natural Environment Research Council and the National Science Foundation.

The Woods Hole Oceanographic Institution is a private, independent organization in Falmouth, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the oceans and their interaction with the Earth as a whole, and to communicate a basic understanding of the oceans’ role in the changing global environment.

Stephanie Murphy | EurekAlert!
Further information:
http://www.whoi.edu

More articles from Ecology, The Environment and Conservation:

nachricht Foxes in the city: citizen science helps researchers to study urban wildlife
14.12.2018 | Veterinärmedizinische Universität Wien

nachricht Machine learning helps predict worldwide plant-conservation priorities
04.12.2018 | Ohio State University

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Data use draining your battery? Tiny device to speed up memory while also saving power

The more objects we make "smart," from watches to entire buildings, the greater the need for these devices to store and retrieve massive amounts of data quickly without consuming too much power.

Millions of new memory cells could be part of a computer chip and provide that speed and energy savings, thanks to the discovery of a previously unobserved...

Im Focus: An energy-efficient way to stay warm: Sew high-tech heating patches to your clothes

Personal patches could reduce energy waste in buildings, Rutgers-led study says

What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...

Im Focus: Lethal combination: Drug cocktail turns off the juice to cancer cells

A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.

The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...

Im Focus: New Foldable Drone Flies through Narrow Holes in Rescue Missions

A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.

Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...

Im Focus: Topological material switched off and on for the first time

Key advance for future topological transistors

Over the last decade, there has been much excitement about the discovery, recognised by the Nobel Prize in Physics only two years ago, that there are two types...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

New Plastics Economy Investor Forum - Meeting Point for Innovations

10.12.2018 | Event News

EGU 2019 meeting: Media registration now open

06.12.2018 | Event News

 
Latest News

Data use draining your battery? Tiny device to speed up memory while also saving power

14.12.2018 | Power and Electrical Engineering

Tangled magnetic fields power cosmic particle accelerators

14.12.2018 | Physics and Astronomy

In search of missing worlds, Hubble finds a fast evaporating exoplanet

14.12.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>