Learning Material

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Trace metals

Trace metals are present at vanishingly low concentrations in seawater, and yet have important biological functions. Like other nutrients, the supply of trace metals (such as iron, copper and zinc) is largely dependent on exchange between the deep and surface ocean. However, trace metals are also supplied from the atmosphere, the cryosphere, hydrothermally in the deep ocean, and possibly extraterrestrially.

The chemistry of many metals is highly sensitive to pH changes. Particular trace metals like iron (Fe), copper (Cu), zinc (Zn), act as vital micronutrients for phytoplankton growth and serve as a cofactor in a number of key enzymes, particularly for oxidation-reduction reactions. Usually these metals are found at very low concentrations in the seawater; however, at elevated levels these metals can be potentially toxic for both primary producers and consumers. There are also other trace metals like mercury (Hg) and lead (Pb) that do not have any biological function, but can have high toxicity levels, even at trace concentrations.

Physical and chemical interactions with other drivers: Trace metal concentrations in seawater are affected by carbonate chemistry, stratification, pollution, temperature and nutrient levels.


References and resources