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In nature, metals are only bio-available when they are in a form that can be directly absorbed by living creatures. In this case, they must be present as a chemically utilisable ion. However, the copper ion is not stable in the environment, in other words, copper is generally not bio-available.
Plants must isolate the essential trace element copper that they require from the soil. Part of the copper is dissolved through the reaction of rain with the soil, thus making it bio-available. Plant roots are also able to dissolve copper from the soil by releasing acid. Animals and humans cover most of their copper requirements by eating plants and meat. In this case, the copper is mainly present in a bio-available form.
If dissolved copper is released in the environment it quickly bonds with humic substances (organic compounds) and is converted into a non-bio-available form. Copper can be dissolved in the soil by acid rain, so that more bio-available copper is present. Plants and animals are capable of handling surplus copper. They have effective excretion mechanisms or storage systems (e.g. plants’ leaves). In waterways, copper is deposited in the sediment. As long as sufficient copper is present in natural waters, only the amount required by the water organisms is dissolved. A natural equilibrium then sets in.
Behaviour of copper ions in the soil and waterways.
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