THE EFFECT OF ORGANIC MATTER FROM BROWN COAL ON BIOAVAILABILITY OF HEAVY METALS IN CONTAMINATED SOILS

摘要

Organic matter is able to bind heavy metals. Enrichment of soil with organic matter could reduce the content of bioavailable metal species as a result of complexation of free ions of heavy metals. This process could be used for remediation to protect plants against metal pollution. The experiments were carried out on Haplic Luvisols in field pots sunk into the ground. A brown coal preparation (the "Rekulter") was used as an amendment of soils artificially contaminated with Cd, Pb and Zn. A winter rye was used as the test plant. The total content of heavy metals and concentration of their bioavailable species in the soil were determined using 2M HNO_3 and EDTA extraction, respectively. The content of bioavailable (soluble in EDTA) zinc, lead, cadmium in soil depended on the application rate of the "Rekulter" and decreased along with an increase in the amendment dosage. The highest efficiency of the "Rekulter" in preventing uptake of zinc, lead and cadmium by plants was observed for the largest dosage of this preparation. The bioaccumulation (BI) indexes of Cd, Pb, Zn indicate availability of Cd, Pb and Zn to plants. The BI decreased along with an increase in the brown coal amendment dosage.