Effect of chemical forms of lead and cadmium in polluted soils on their uptake by radish plants.

Abstract

Soils which had been polluted with heavy metals from Non-Ferrous-MetalWorks near Plovdiv, Bulgaria were sequentially extd. so that Pb andCd could be partitioned into five operationally defined chem. fractions:exchangeable, bound to carbonate, bound to Fe-Mn oxides, bound toorg. matter and residual. Radishes were planted in the soils to examinethe effects of concn. and different chem. forms of the elements inthe soil on their uptake. The results of this expt. confirmed thatthe potential bioavailability of heavy metals is strongly controlledby their chem. forms related to soly. Exchangeable and carbonateforms are the most important forms of heavy metals taken up by theplants. The highest amt. of Pb was bound with forms hardly availablefor plants - Fe-Mn oxides and residual fraction. In terms of Cd,in contrast to the lead, a significant part of it is found in availableforms, which make it potentially dangerous and call for a precisecontrol on the crops grown in the studied region. The main part ofPb and Cd were accumulated in the underground parts, mainly in theroots and edible parts of radish. Pb in the leaves of radishes wasconsiderably lower compared to the radish roots, good evidence forrestricted mobility of Pb, while the opposite was true for Cd. Thedata obtained by regression anal. shows that a significant correlationexists between total quantity of Pb and Cd in soil and that in radishes.The results obtained on the effects of chem. forms revealed thatexchangeable and carbonate forms exhibited stronger influence onuptake than the total concn. in soil. It can be concluded that theradish may be used as a bioindicator of Cd or Pb contamination. [onSciFinder(R)]