Subscribe free to our newsletters via your
. Earth Science News .




WATER WORLD
Intensity of desert storms may affect ocean phytoplankton
by Staff Writers
Boston MA (SPX) Sep 01, 2015


File image.

Each spring, powerful dust storms in the deserts of Mongolia and northern China send thick clouds of particles into the atmosphere. Eastward winds sweep these particles as far as the Pacific, where dust ultimately settles in the open ocean. This desert dust contains, among other minerals, iron -- an essential nutrient for hundreds of species of phytoplankton that make up the ocean's food base.

Now scientists at MIT, Columbia University, and Florida State University have determined that once iron is deposited in the ocean, it has a very short residence time, spending only six months in surface waters before sinking into the deep ocean. This high turnover of iron signals that large seasonal changes in desert dust may have dramatic effects on surface phytoplankton that depend on iron.

"If there are changes to the sizes of deserts in Asia, or changes in the way people are using land, there could be a larger source of dust to the ocean," says Chris Hayes, a postdoc in MIT's Department of Earth, Atmospheric, and Planetary Sciences (EAPS). "It's difficult to predict how the whole ecosystem will change, but because the residence time [of iron] is very short, year-to-year changes in dust will definitely have an impact on phytoplankton."

The team's results are published in the journal Geochemica et Cosmochimica Acta. Co-authors include Ed Boyle, a professor of ocean geochemistry at MIT; David McGee, the Kerr-McGee Career Development Assistant Professor in EAPS; and former postdoc Jessica Fitzsimmons.

Dust to dust
Certain species of phytoplankton, such as cyanobacteria, require iron as a main nutrient to fuel nitrogen fixation and other growth-related processes. Hayes estimates that up to 40 percent of the ocean contains phytoplankton species whose growth is limited by the amount of iron available.

As desert dust is one of the only sources of oceanic iron, Hayes wanted to see to what extent changing levels of dust would have an effect on iron concentrations in seawater: Does iron stick around in surface waters for long periods, thereby making phytoplankton less sensitive to changes in incoming dust? Or does the mineral make a short appearance before sinking to inaccessible depths, making phytoplankton depend much more on seasonal dust?

To get answers, Hayes and his colleagues traveled to Hawaii to collect ocean samples at a station called ALOHA, the site of a long-term oceanography program conducted by the University of Hawaii. In September 2013, the team took a half-day cruise into open ocean, and then spent two weeks collecting samples of ocean water at varying depths.

The researchers acidified the samples and transported them back to the lab at MIT, where they analyzed the water for both iron and thorium -- a chemical element that is found in dust alongside iron. As it's difficult to determine the rate at which iron sinks from the ocean's surface to deep waters, Hayes reasoned that thorium might be a reasonable proxy.

Thorium has a number of isotopes: Thorium-232 is typically found in dust, and thorium-230 is produced from the decay of uranium, which decays to thorium at the same rate throughout the ocean. By comparing the amount of thorium-230 detected in ocean samples to the amount produced by uranium decay, Hayes was able to calculate thorium's removal rate, or the time it takes for the chemical to sink after settling on the ocean's surface.

This removal rate, he reasoned, is equivalent to the input rate of dust, or the rate at which dust is supplied to an ocean region. As the composition of an average desert dust particle is known, Hayes then extrapolated the input rate to estimate iron's residence time in surface waters.

A small piece of a big question
The team found that on average, iron tends to stay within 150 meters of the ocean's surface -- the layer in which phytoplankton resides -- for about six months before accumulating on larger particles and sinking to the deep ocean. This residence time leaves a relatively short period for phytoplankton to absorb iron, making the organisms rather sensitive to any changes in incoming desert dust.

"Dust can change a lot from season to season -- by an order of magnitude," Hayes says. "From satellite images, you can see big pulses of dust coming from these deserts. That could change with climate change, and different precipitation patterns. So we're trying to keep track: If it does change, will it have an impact?"

As phytoplankton play a natural role in removing carbon dioxide from the atmosphere, better estimates of iron residence times, and desert dust inputs to the ocean, may help scientists gauge phytoplankton's role in combating climate change.

"It's a very small part that we're getting more quantitative about," Hayes says. "It's one piece that adds to trying to make the prediction: If there's more dust, will the ocean take up more carbon? That's a big-picture question that we can't totally answer with this, but we have one piece on the way to answering that."


Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only


.


Related Links
Massachusetts Institute of Technology
Water News - Science, Technology and Politics






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle








WATER WORLD
Nearly all seabirds will have ingested plastic by 2050
Miami (AFP) Aug 31, 2015
Most seabirds have already eaten plastic in the oceans, and scientists projected Monday that 99 percent will have done so by 2050. Plastics are pervasive in the world's waters due to pollution, and birds - including albatrosses, penguins and gulls - can mistake brightly colored bottle tops or other fragments for food. Birds can become sick and die if they ingest too much plastic. ... read more


WATER WORLD
Will talk of the 'Big One' shake the US into quake prep?

Japan holds annual disaster response drill

China chemical plant explosion kills five

EU to step up action against Mediterranean people smugglers

WATER WORLD
Using ultrathin sheets to discover new class of wrapped shapes

Smallest 3-D Camera Offers Brain Surgery Innovation

Scientists from NTU Singapore find electrifying solution to sticky problem

Combined disciplines, computational programs determine atomic structure

WATER WORLD
Intensity of desert storms may affect ocean phytoplankton

Nearly all seabirds will have ingested plastic by 2050

Understanding the deep sea is key to a sustainable blue economy

Climate change will irreversibly force key ocean bacteria into overdrive

WATER WORLD
Hot summer fuels dangerous glacier melting in Central Asia

Adapt or die: Arctic animals cope with climate change

Tallest mountain in North America renamed: White House

Greenland Campaign Takes Flight to Measure Ice Sheet

WATER WORLD
New peer-reviewed study rewrites genetic history of sheep

New fungi behind emerging wheat disease

Repurposing would-be wasted food to feed the hungry and create jobs

Humus depletion induced by climate change

WATER WORLD
What would a tsunami in the Mediterranean look like

Dominica pleads for help as storm death toll tops 30

West African archipelago hit in rare hurricane strike

Tropical storm kills at least 12 in 'badly beaten' Dominica

WATER WORLD
China's Xi calls indicted Sudanese leader Bashir 'old friend'

Africa uneasy as China turmoil threatens investment boom

S.Sudan rebels accuse government of breaking ceasefire

South Sudan rebel chief orders ceasefire: spokesman

WATER WORLD
Philistines introduced sycamore, cumin and opium poppy into Israel

Hypoallergenic parks: Coming soon?

US Catholics mostly accepting of non-traditional families

Testosterone therapy reveals differences between male, female brains




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.