Chiang Mai Journal of Science

     In this study, effect of salinity on growth was examined together with cadmium (Cd) and nickel (Ni) accumulation capacity of coontail a free-fl oating hydrophyte (Ceratophyllum demersum L.) under controlled conditions. Different saline waters (EC = 2.8, 5.5 and 9.5 dS m^-1) were made with the base of farm drainage water (EC = 13.2 dS m^-1). A total of four concentrations of Ni(NO₃)₂ and CdCl₂ (0, 1, 2, 4 mg L^-1) were added to these. The results showed that there was a decrease in the growth rate as the water salinity level increased. The biomass production was also inhibited with the increase in salinity. At 9.5 dS m^-1 salinity level growth rate was the lowest (0.81 ± 0.05 g FW d^-1) among the treatments. This decrease was accelerated by metal contaminations. High salinity levels decreased the removal of nickel. Highest removal was recorded as R= 86% (Ni = 1 mg L^-1, EC = 5.5 dS m^-1). The lowest cadmium removal was observed as R = 35% (Cd = 4 mg L^-1, EC = 2.8 dS m^-1) in the lowest salinity medium. In general, phytoremediation effi ciency of coontail decreased with enhancing nickel concentrations, but increased when cadmium concentration increased. An increase in the salinity levels of water lead towards a parallel increase in the removal effi ciency of coontail. It was concluded that this fl oating hydrophyte has a good potential for phytoremediation of cadmium and nickel from a saline aquatic environment.