|
|
 |
1. The importance of iron
In the unit on "Oceanic Nutrients" you found out that iron is essential for the life of many organisms.
Exercise: Gather information about the basic chemical properties of iron and its importance as nutrient from the internet or an encyclopaedia.
|
|
Iron is also an important nutrient for humans. We need between 10 and 15 milligrams of iron everyday. We normally get this small amount from our food.
|
Exercise: Which foods contain high amounts of iron?
The following link may help you: www.vegetarismus.ch/info/e17.htm
|
|
|
|
Iron is an essential part of the red blood pigment haemoglobin which transports oxygen around our bodies. Iron is also involved in the production of hormones, the detoxification of foreign substances in our liver, in the transfer of energy in our cells and plays a part in transmitting signals in our brain.
|
 |
|
|
2. Cartoon from Hemera.
Big Box of Art.
|
|
|
The consequences of lack of iron can be anaemia, pale skin, headaches, tiredness, vertigo, loss of hair and stomach upsets.
|
2. Transport of Iron
Iron containing dust is blown by the wind from the great deserts of the world into the sea. Once dissolved in the seawater iron can then be taken up by phytoplankton and used as a nutrient.
The following picture shows you the major dust transport routes. Click in the picture to enlarge it (151 kb).
|
 |
|
|
3. Advanced Very High Resolution Radiometer (AVHRR) images of particle transport in the atmosphere between June and August. These images show the major dust transport routes across the Atlantic and Indian Oceans. As they measure all particles in the air, they also show particles coming off southwest Africa from biomass burning and pollutants coming off the eastern coast of North America. Copyright American Geophysical Union. Click on the picture for a better view (151 kb).
|
|
The image above shows that iron containing dust is blown by the wind from the deserts to large areas of the world. The dust is deposited into the oceans and onto other continents. Under some weather conditions, Saharan dust can be seen as far north as Central Europe.
|
Calculation exercise:
How fast do dust particles move in the wind?
It takes about one week for dust particles to travel from the Sahara, across the Altantic Ocean to The United States of America. Calculate their average speed in km h-1, assuming that the distance from the Sahara to the American East coast is 7000 km!
|
|
 |
|
|
4. Picture from Hemera.
Big Box of Art.
|
|
Exercise
Have another look at the text, then answer the following questions:
Click the GREEN button, if you think that the answer is correct and the RED button, if you think that the statement is wrong.
|
a) Iron makes up 20% of the Earth's crust.
|
|
|
b) Iron is mainly transported by dust into the oceans.
|
|
|
c) Oceans containing small amounts of phytoplankton are close to the deserts.
|
|
|
d) The arid areas of the Northern Hemisphere are the main sources of the iron rich dust which enters the oceans.
|
|
|
e) Lowest concentrations of atmospheric dust are seen over the Southern Ocean near Antarctica.
|
|
|
f) Wind transports dust particles across the Atlantic Ocean at a height of 50 meters above the sea.
|
|
|
g) Dust particles either fall into the sea as dry particles into the sea or are incorporated into raindrops.
|
|
|
h) Iron is not very soluble in water and is usually found in iron-III-compounds.
|
|
|
i) Ocean areas with high concentrations of phytoplankton are called High Nitrate, Low Chlorophyll (HNLC) regions.
|
|
|
j) HNLC ocean regions are far away from the huge deserts of the world.
|
|
|
About this page:
author: Bernd Wohlhöfer - University of Nürnberg, Nürnberg, Germany
scientific reviewing: Dr. Lucinda Spokes - School of Environmental Sciences, University of East Anglia, Norwich, U.K.
educational reviewing: Prof. Dr. Helmut Schrettenbrunner, Dr. Yvonne Schleicher and Julia Heres - University of Nürnberg, Nürnberg, Germany
last update: 2004-11-18
|
|
|
|
