Biochar immobilizes cadmium and zinc and improves phytoextraction potential of willow plants on extremely contaminated soil

Abstract

The availability of risk elements in soil can be possibly reduced by various soil additives. Among them, the attention has been recently focused on the research of unconventional soil additive - biochar. The aim of this study was (i) to observe the effect of biochar application on risk elements transport through the soil profile and (ii) to assess the availability of risk elements in biochar amended soil to willow growth. The experiment was established at greenhouse conditions and extremely contaminated soil, reaching 43 mg/kg cadmium (Cd) and 4340 mg/kg zinc (Zn), was used. To observe risk element content in leachate, the lysimeter cylinders were tested. The rates of biochar were 0 (control); 5, 10, and 15% per mass of soil. The results showed that biochar significantly increased biomass production whereas the plant Cd and Zn contents remained unchanged in most cases. In leachate, Cd and Zn content decreased by 99% at all the biochar treatments. We can summarize that biochar appears to be a very effective regulator of availability of observed risk elements and improver agent for biomass production of plants and remediation efficiency.

Keywords

• heavy metals
• soil contamination
• salix × smithiana
• phytoremediation
• stabilization