Accumulation of hg and cr by three aquatic species and subsequent changes in several physiological and biochemical plant parameters

Abstract

Accumulation of Hg and Cr and subsequent changes in the physiological and biochemical parameters were studied in species of the aquatic genera, Eichhornia crassipes (Mart.) Solms., Hydrilla verticillata (L.f.) Royle and Oedogonium areolatum Lagarh. Accumulation of Cr was highest in Eichhornia [10.21 μmol (g dry tissue wt)−1], followed by Hydrilla (9.0) and Oedogonium (6.02); that of Hg was maximum in Hydrilla (4.21), followed by Oedogonium (3.35) and Eichhornia (2.79). Accumulation of Cr and Hg in roots of Eichhornia was about twelve and two times higher, respectively, than that in shoots of the genus. Higher accumulation of Cr than that of Hg in the aquatics was observed. In general, Cr (19.23 × 10−6 M) and Hg (4.98 × 10−6 M) did not show significant changes over control data in these parameters, Hill activity, chlorophyll, protein, free amino acid, inorganic phosphorus, RNA, DNA, dry wt, permeability, the activities of protease, RNase, catalase and peroxidase, and acid: alkaline pyrophosphatase activity in the three aquatic plants. The plant species have tolerance capacity to the heavy metals applied.