ACCUMULATION AND TRANSLOCATION OF LEAD IN CUCUMBER PLANTS MONITORED BY GRAPHITE-FURNACE ATOMIC-ABSORPTION SPECTROMETRY

The lead concentration in different parts of cucumber plants, growing in ''lead-free'' and lead-contaminated nutrient solutions, was determi ned by the graphite furnace atomic absorption spectrometry technique a fter microwave-assisted acidic digestion of the dried plant parts. The lead accumulates first inion the roots, where its concentration can e xceed 10 mg/g. In the upper parts of the plant (stem and leaves) the l ead concentration is lower by about two orders of magnitude than it is iri the roots. The lead distribution within the plants shows a tenden cy to decrease with increasing leaf storage. An increment of the Pb(NO 3)(2) concentration in the nutrient solution from 10(-8) to 10(-4) mol /dm(3) results in about 500 times higher lead concentration in the lea ves. Nearly 20% of the deposited lead translocates from the contaminat ed lower stem part to the old leaves and to the new roots during the r erooting of a decapitated plant grown in lead-free nutrient solution. However, the new shoots which form during this period do not participa te in this redistribution process. (C) 1995 Academic Press, Inc.