Effect of application of increasing concentrations of contaminated water on the different fractions of Cu and Co in sandy loam and clay loam soils

This study aimed to establish the fate of copper (Cu) and cobalt (Co) in sandy loam and clay loam soils that had been irrigated with increasing concentrations of contaminated water. A sequential extraction procedure was used to determine the fractions of Cu and Co in these soils. The concentration of bioavailable Cu and Co on clay loam was 1.7 times that of sandy loam soil. Cu on sandy loam soil was largely in the organic > residual > exchangeable > water-soluble > carbonate fractions, whereas on clay loam soil the element was largely in organic > exchangeable > residual > carbonate > water-soluble fractions. Co was largely observed in the exchangeable, water-soluble, and carbonate fractions, but with no particular trend observed in both soil types. When crops are grown on sandy soils that have a low capacity to hold heavy metals, the resulting effect would be high uptake of the heavy metals in crop plants. Because the predominant forms of Cu and Co vary in soils, it is expected that the metals will behave differently in the soils.