Origin and behaviour of heavy metals in agricultural Calcaric Fluvisols in semiarid conditions

A 6-year study of the behaviour of heavy metals in Calcaric Fluvisols dedicated to agricultural use was made. The total metal content and the fractions extractable in bicarbonate, nitric acid, DTPA and citrate-dithionite solutions were determined and the mineralogical fractions to which the metals were bound were examined. When the factors that, according to the bibliography, most influence heavy metal behaviour in soils, such as pH, OM content, calcium carbonate content, EC, SAR, clay, chlorides, sulphates, available phosphorus and nitrates, were studied, it was found that they had in practice little effect in the soils in question. On the contrary, heavy metal mobility was more likely to be influenced by the mineral fraction to which they were bound.