Use of White Lupin Plant for Phytostabilization of Cd and As Polluted Acid Soil

Cadmium and arsenic are two of the most important and toxic pollutants ubiquitous in the environment. The occurrence of numerous polluted areas as the affected by the accident of Aznalcóllar pyrite mine has promoted the employment of the phytoremediation as a feasible technology able to control and reduce the risk of this contamination at low cost. White lupin plant is proposed as a candidate for phytoremediation. This work aims to study if it is possible to use white lupin in phytoremediation of soils affected by acid pyrite sludge, with simultaneous As and Cd pollution. Pot and field experiments with sludge-affected soil were carried out. The pot trial showed that the NTA treatment increased Cd and As concentrations in lixiviates, exceeding the maximum permissible levels, so that its use in field experiments was avoided. In the field experiment, phytoextraction of Cd and As by lupin plants was very low, suggesting that it was not recommended for phytoextraction. However, lupin culture in the field produced several benefits as: increase of acid soil pH probably by citrate excretion, decrease in soluble As and Cd fractions in soil, high concentration of As and Cd in roots with accumulation of heavy metals in root nodules. All these results support the use of Lupinus albus for phytostabilization and revegetation of the spill polluted soils.