It's Bottoms Up for Iron at Sea's Surface. (Science News of the Week)

By Perkins S. | Science News, January 5, 2002 | Go to article overview

It's Bottoms Up for Iron at Sea's Surface. (Science News of the Week)


Perkins S., Science News


Biological activity at the base of the food chain in many regions of the ocean is limited by the availability of dissolved iron. The algae that convert sunlight into food in the sea's top 100 meters or so can't fully use the other nutrients present because there isn't enough iron. Just where the crucial metal comes from is often not known.

An analysis of seafloor sediments obtained off Antarctica suggests that the dissolved iron in surface waters that fuels much of the region's biological productivity comes from deeper waters via upwelling currents.

Many scientists have thought that much of the ocean's dissolved iron comes from dust blowing off the continents, notes Gabriel M. Filippelli, a bio-geochemist at Indiana University-Purdue University in Indianapolis. However, his analysis of the seafloor sediments suggests that only 2 percent of the iron in the southern oceans comes from airborne dust. The rest is supplied by deep currents that hug the ocean bottom for hundreds of years before rising to the surface around Antarctica.

Filippelli and Jennifer C. Latimer, a geologist at Indiana University in Bloomington, analyzed sediments taken from two locations in the South Atlantic Ocean and one from the southern Indian Ocean. Evidence from these ancient muds, some up to 270,000 years old, show that 10 times as much iron had settled into the region's ocean-floor ooze during recent ice ages than is being deposited there now. The researchers presented their findings at the American Geophysical Union meeting in San Francisco last month, and their analysis also appeared in the December 2001 PALEOCEANOGRPHY.

By comparing the changing concentration of life-derived phosphorous in the mud with the relatively stable concentration of titanium--a metallic element that erodes from rock as iron does but that organisms don't typically use--Filippelli and Latimer could estimate variations in biological productivity in the southern oceans. …

The rest of this article is only available to active members of Questia

Already a member? Log in now.

Notes for this article

Add a new note
If you are trying to select text to create highlights or citations, remember that you must now click or tap on the first word, and then click or tap on the last word.
One moment ...
Default project is now your active project.
Project items

Items saved from this article

This article has been saved
Highlights (0)
Some of your highlights are legacy items.

Highlights saved before July 30, 2012 will not be displayed on their respective source pages.

You can easily re-create the highlights by opening the book page or article, selecting the text, and clicking “Highlight.”

Citations (0)
Some of your citations are legacy items.

Any citation created before July 30, 2012 will labeled as a “Cited page.” New citations will be saved as cited passages, pages or articles.

We also added the ability to view new citations from your projects or the book or article where you created them.

Notes (0)
Bookmarks (0)

You have no saved items from this article

Project items include:
  • Saved book/article
  • Highlights
  • Quotes/citations
  • Notes
  • Bookmarks
Notes
Cite this article

Cited article

Style
Citations are available only to our active members.
Buy instant access to cite pages or passages in MLA, APA and Chicago citation styles.

(Einhorn, 1992, p. 25)

(Einhorn 25)

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Cited article

It's Bottoms Up for Iron at Sea's Surface. (Science News of the Week)
Settings

Settings

Typeface
Text size Smaller Larger Reset View mode
Search within

Search within this article

Look up

Look up a word

  • Dictionary
  • Thesaurus
Please submit a word or phrase above.
Print this page

Print this page

Why can't I print more than one page at a time?

Help
Full screen

matching results for page

    Questia reader help

    How to highlight and cite specific passages

    1. Click or tap the first word you want to select.
    2. Click or tap the last word you want to select, and you’ll see everything in between get selected.
    3. You’ll then get a menu of options like creating a highlight or a citation from that passage of text.

    OK, got it!

    Cited passage

    Style
    Citations are available only to our active members.
    Buy instant access to cite pages or passages in MLA, APA and Chicago citation styles.

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn, 1992, p. 25).

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn 25)

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences."1

    1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

    Cited passage

    Thanks for trying Questia!

    Please continue trying out our research tools, but please note, full functionality is available only to our active members.

    Your work will be lost once you leave this Web page.

    Buy instant access to save your work.

    Already a member? Log in now.

    Author Advanced search

    Oops!

    An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.