The effect of three types of aquatic plants on water purification and removal of cadmium under different salinity conditions in northwestern Iran

Abstract

Phytoremediation is a high-performance and cost-effective approach to clean up contaminated water. This study aimed to investigate the rate of cadmium (Cd) uptake and changes in absorption of other elements using different plants at different cadmium concentrations under salinity conditions. This study was performed as a factorial experiment in a completely randomized design with three replications at Zanjan University located in northwestern Iran. For this purpose, three aquatic plants, Azolla Caroliniana, Watercress, and Duckweed, were used. In these experiments, different levels of Cd (0, 5, 10, 20, 40, and 80 mg L−1) in the nutrient solution as well as different NaCl concentrations (0, 10, 20, 40 and 80 mM L−1) were employed. After producing nutrient solutions with salinity and different Cd concentrations, three plants were grown in them for 30 days. The absorption of different elements such as Cd, Fe, Mn, Zn, Cu, N, P, K, Ca, Mg, and Na was measured in the plants. The results showed that the studied plants absorbed high concentrations of Cd. It was also concluded that the salinity of nutrient solution directly relates to Cd concentration in the plant tissues. The highest concentration of Cd in Azolla Caroliniana in 40 mg Cd and 80 mM NaCl was obtained with an average of 3,470.8 mg kg−1. In general, the results showed that the use of all three plants is suitable for purifying Cd-contaminated water.