ZINC AND CADMIUM ACCUMULATION IN HYSSOPUS OFFICINALIS L. AND SATUREJA MONTANA L.

Accumulation of cadmium and zinc in two Mediterranean plants, Hyssopus officinalis L. and Satureja montana L., is described here. Two concentrations for each metal have been used in an artificially contaminated substrate: 200 and 1400 ppm zinc, and 21 and 108 ppm cadmium. Plant growth has been monitored for three months after metal addition. Total metal uptake has been determined by ICP-OES measurements on samples harvested at 30, 60 and 90 days from the beginning of the experiment. Hyssopus officinalis L. and Satureja montana L. seemed to be tolerant to both cadmium and zinc, as progressive metal accumulation vs. time has been observed with no toxicity symptoms. Zinc and cadmium concentrations have also been measured in the different plant organs: a significant metal translocation to the upper parts (stem and leaves) was detected. Specifically, Hyssopus seemed to be more efficient in translocating Zn than Cd; by contrast, Satureja accumulated higher quantities of cadmium in the aerial parts compared to Hyssopus. The addition of an organic chelator (citric acid) to substrate was also considered, as a means to improve metal bioavailability and explore the possible use of these two species for phytoremediation. Citric acid enhanced zinc and cadmium accumulation, mostly at root level.