Ama. Mazen et Omo. Elmaghraby, ACCUMULATION OF CADMIUM, LEAD AND STRONTIUM, AND A ROLE OF CALCIUM-OXALATE IN WATER HYACINTH TOLERANCE, Biologia plantarum, 40(3), 1998, pp. 411-417
Eichhornia crassipes plants brought from the River Nile were cultured
in jars containing river water supplemented with various concentration
s of Cd, Pb, and Sr (0 to 100 mu g cm(-3)), added simultaneously. Trea
tment continued for 20 d during which each cultivation solution was be
ing replaced with fresh one every 3 d. The growth of Eichhornia was dr
astically retarded at heavy metal concentrations higher than 15 mu g c
m(-3). At concentrations 15 or 25 mu g cm(-3), the accumulation of Cd
and Pb to levels several times higher than those in control plants was
found. More than 50 % of the uptaken metals were retained by roots al
one. Leaves and leaf petiols received around 30 and 20 % of the accumu
lated metals, respectively. X-ray microanalysis indicated the presence
of the three heavy metals in Ca oxalate crystals. Content of metals i
n the crystals increased progressively over time of exposure in a way
similar to those in whole plant tissues. These results suggest a possi
ble role for Ca oxalate crystalization in toxic heavy metal deposition
and thus tolerance by Eichhornia.