Pumping iron

More than a fifth of the world's oceans have plenty of nutrients but only tiny amounts of iron. This lack of iron has long been suspected as one of the main limiting factors in phytoplankton production in some open ocean areas. Joint British-US experiments have now shown that this is indeed the case. Areas of the Pacific Ocean several kilometres across were 'fertilized' with iron sulphate. This resulted in a stupendous growth of marine algae (Van Scoy and Coale, 1994; Pearce, 1995). As the algae grew they used up large quantities of carbon dioxide from the ocean and the experiments were partly designed to see if this would result in a reduction in atmospheric carbon dioxide. Some success seems to have been achieved in this direction with obvious implications in the control of global warming (see Section 10.2.1). Whether the increased plankton production can be used directly or indirectly as a food source is another challenge (see Section 9.6.5).

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