The Question of Iron

Filed Under (cruise blog) by Ting on 17-08-2009 and tagged


When you think of iron, do you think of the iron that great grandma used to iron the wrinkles out of clothes, or the iron rails of an ornate fence? In a science class you may have used a magnet to remove iron filings from sand. There are many things made of iron, including the Research Vessel Wecoma.

IMG_0056.smaller(2)Research Assistant, Chris Holm, is looking for iron so small that it can only be seen with specialized instruments. Just like using a microscope to see the cells that make up your body, he uses an instrument to detect or ‘see’ iron in water, except this instrument uses a chemical reaction that creates color in the presence of iron.

Chris says, “It is by measuring how much light passes through this colored solution that we can measure these low concentrations in seawater.  The concentration of iron that is routinely measured in seawater is roughly equivalent to dissolving a paper clip in 50 Olympic swimming pools.”


The entire structure of the boat is made of iron. So, when you collect a sample of water on an iron boat, chances are, it will include some iron. Since Chris is looking for iron in seawater, his challenge has been to collect seawater that isn’t contaminated with added iron from the boat or from human hands. Special gloves are worn when working with water samples being collected for iron detection.

The environment of Oregon’s continental shelf, where the water samples are collected, is unique. It is 150 meters deep (about 450 feet), and it’s dark. The question is, are growing organisms, such as bacteria on the ocean floor or plankton near the ocean’s surface, using iron and if so, how much iron? In other words, what’s the daily requirement of iron needed to support life in the ocean?

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