Mercury bioaccumulation induces oxidative stress and toxicity to submerged macrophyte Potamogeton crispus l

The bioaccumulation of mercury in the submerged macrophyte, Potamogeton crispus L., was investigated, along with Hg-induced modification of malondialdehyde content, potassium leakage, and total chlorophyll, protein, cysteine, and nonprotein thiol contents. The Hg exposure concentrations were 0, 0.1, 0.25, 0.5, 1.0, 5.0, and 10.0 mu M. Results showed that the Hg uptake potential of the plant was correlated positively with the concentration in nutrient solution, with the Hg concentration in the plant increasing significantly with increasing concentration and exposure time. A significant increase in malondialdehyde content was observed at Hg concentrations of 0.1 mu M and higher, and K leakage was found at these concentrations, as well as a significant decrease in total chlorophyll content. Mercury up to 0.25 mu M had a significant stimulatory effect on protein content, but protein content decreased at higher Hg concentrations. The activity of nitrate reductase was stimulated significantly at Hg concentrations less than 0.5 mu M up to 72 h of exposure, but at longer exposure periods, relatively low levels of stimulation were recorded. Mercury exposure increased nonprotein thiol content, except at the highest Hg concentration, which was paralleled somewhat by cysteine content.