July 20, 2010

Scientists Studying Volcanic Ash Effect On North Atlantic

A team of scientists has returned to the North Atlantic to gather more data on the Icelandic volcanic eruption that took place earlier this year.

The researchers are studying whether iron within the vast volcanic ash cloud entered the ocean, causing an extended bloom of tiny organisms known as phytoplankton.

The scientists have recorded "enhanced levels" of iron in samples they have collected.

The most recent project follows an earlier cruise, which was carried out in the spring.

The international team of researchers hopes to find out if trace elements from the ash have had an impact on the region's phytoplankton blooms.

"A hundred million cubic meters of ash was produced by the volcano - that must have gone somewhere and a large part has fallen into the ocean - so that is a significant iron source," lead scientist Eric Achterberg, from the University of Southampton, National Oceanography Centre, UK, told BBC news.

Achterberg said the team had limited time to analyze data collected on their first cruise before they headed out to sea again.

"The guys only had six or seven weeks to pack and remobilize for the next cruise," he said.

However, he also told BBC that they did manage to glean some initial information: "For example, when they were right underneath the volcanic ash cloud in Iceland, they found that the iron levels were very high."

"But we have not got a really large-scale picture yet - there is so much data."

The area of the North Atlantic where researchers have been collecting samples normally has very low inputs of iron and other nutrients from the atmosphere; leading scientists to assume phytoplankton were growing in a sub-optimum manner.

"The original objective for this cruise was to go out... and look at the conditions in the ocean after the massive spring bloom," said Achterberg.

"The hypothesis was that the system would have run out of iron by this point."

However, he added, the eruption of Iceland's Eyjafjallajokul volcano could potentially change this.

"What we are doing is taking samples from the ocean, the atmosphere, and we are looking at biological growth in the ocean," he told BBC.

"We are seeing some enhanced levels (of dissolved iron) below the 'mixed layers' of 65-130 feet deep."

"It may be a result of the volcanic ash, but we really need to have a better look at this on a wider scale."

If ash from the volcano's eruption added a significant amount of iron to the ocean, the scientist hope to collect data in order to confirm that it triggered extended phytoplankton growth.

"It is something that we are hoping to see," said Achterberg.

"This would also mean that the phytoplankton would take up more atmospheric CO2 than what it usually does in a normal year."

The expedition is part of a climate change project that is looking at the efficiency of phytoplankton to absorb atmospheric CO2 and sequester it in the ocean.

Achterberg explained that the cruise, which was originally planned five years ago, provided a "totally unique opportunity."

"Never, at this scale, have people been able to do this."

"Firstly, we do not get that many volcanic eruptions on this scale, and secondly, it is only recently that we have been able to take the iron sampling and carry out analysis in the manner that we can do now."

"It has luckily come together in a very nice manner."

Achterberg told BBC that the researchers hope to make the results available "within months" of returning from the current cruise, which is scheduled to end in mid-August.

The research will take place aboard the RRS Discovery, a Natural Environment Research Council (Nerc) vessel.


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