36 research outputs found
Pendant trois milliards d'années les micro-organismes sont les seuls habitants de la terre
National audienc
Immobilization of cadmium and zinc in soil by Al-montmorillonite and gravel sludge
We investigated the potential of montmorillonite, Alâmontmorillonite and gravel sludge to immobilize polluting heavy metals in agricultural soil. Batch experiments showed that both Alâmontmorillonite and montmorillonite immobilized zinc and cadmium. Zinc was bound specifically on Alâmontmorillonite and became increasingly incorporated into the interlayer hydroxyâAl polymer, whereas there was no specific sorption on montmorillonite. Cadmium was bound on montmorillonite and Alâmontmorillonite unspecifically by cation exchange, but there was no incorporation into the lattice.
In pot experiments montmorillonite, Alâmontmorillonite, or gravel sludge were added to a soil contaminated with zinc and cadmium. Increasing doses of these agents decreased the concentrations of NaNO3âextractable zinc and cadmium. Aluminiumâmontmorillonite and gravel sludge were more efficient than montmorillonite in immobilizing both zinc and cadmium. Remobilization tests at pH between 4 and 5.5 showed that cadmium and zinc desorbed more easily from montmorillonite than from Alâmontmorillonite. Gravel sludge application increased the buffer capacity of the contaminated soil substantially. The binding agents decreased zinc concentrations in red clover (Trifolium pratense), and gravel sludge also reduced the cadmium concentrations