ABSTRACT
Rocks are generally hard and impermeable and do not support much chemical or biological activity. The availability of trace elements is influenced by many factors, of which the most obvious are soil acidity and drainage. The transformation of rocks into soil sometimes proceeds in a roundabout way. Artificial fertilisers, applied to increase the soil content of nitrogen, phosphorus or potassium, contain small amounts of several trace elements. In 1978 the village of Shipham in Somerset was invaded by geologists, chemists, doctors and journalists after cadmium, zinc and lead were found in unusually high concentrations in soil samples taken in locations where zinc had been mined during the 18th and 19th centuries. An unpleasant modification of the soil-plant-food relationship came to light unexpectedly after the nuclear accident at Chernobyl in 1986, which released large amounts of radioactive fall-out, including caesium-134 (half life 2.1 years) and caesium-137 (half life 30 years).
