Indicator of Bioavailability of Heavy Metals in Phyto-Stabilized Processes of Fly Ash Deposits

The study refers to the assessment of the effectiveness of treatments of topsoil of fly ash from a fresh deposit. Bioavailability reduction of metals: chromium, copper and lead from soil to the plant tissue, for a healthy vegetation cover of a leguminous plant species is aimed. The modification of metal mobility in the top layer of fly ash through the use of biosolids (municipal sludge) as organic fertilizers alone or mixed with pillared indigenous tuff is indicated by a bioavailability index of metal accumulation in plant tissue. This indicator of bioavailability of heavy metals is called transfer factor (TF) and is the ratio of metal content in plant tissue QP mg/kg DM of total metal content in fly ash treated or untreated site QS mg/kg DM TF = QP/QS. Transfer factor from soil to plant tissue for chromium and copper decreases from 0.11 – 0.18 to 0.06 – 0.08 and from 0.28 to 0.03 for lead when treating the top layer of fly ash with biosolids mixed with pillared indigenous tuff