The application of biochar to soils have been proven to be effective in changing their physical and chemical characteristics (e.g. water holding capacity, nutrient retention, pH and EC). Moreover, its influence on the soil properties extends to the mobility of pollutants. For its intrinsically high resistance to degradation, long term effects are expected.
The application of biochar to industrial and mine wastes may be a solution to reduce environmental risks posed by the pollutants release because of leaching into the groundwater. Besides, the reduction in terms of bioavailability of toxic elements and other physical and nutritional modifications to the substrate may be of help to plant growth and therefore to establish a green cover on top of the wastes for a long term stabilization.
Wastes from the formerly Pertusola Sud zinc smelter (Crotone, Italy) and the Cave del Predil mining site (Udine, Italy) rich in As, Cd, Pb, Tl and Zn, were mixed with biochars from three different feedstocks at the dose of 3% (DW/DW). Column leach tests were set up to evaluate the effects of the biochars on the mobility of the toxic elements. Soil water was sampled at three depths with Rhyzon® and the leachate at the bottom was collected by gravity. The results on the mobility behavior of the toxic elements as consequence of the type of biochar will be presented. The use of biochar to improve plant growth and reduce metals leaching may be a viable technique.
