Effects of Cadmium on Superoxide Dismutase Activity in Reed Leaves

Industrial polluted water has become an important water source for irrigation in the majority of constructed wetlands or even natural wetlands in China. The shortage of clean water resources has raised concerns about the potential accumulation of heavy metals, such as cadmium. Plants stressed by high levels of cadmium can increase the activity of superoxide dismutase. We have identified a positive correlation between the superoxide dismutase activity and the cadmium content of reed leaves in the wetland. Regression analysis confirmed that the superoxide dismutase activities fit a logistic curve. The logistic model was then applied to describe the superoxide dismutase activity, estimating parameters under different levels of cadmium stress. According to the findings, higher cadmium concentrations would cause the superoxide dismutase activity to increase at a higher intrinsic rate, have a lower environmental capacity k, and have lower inflection points. The dynamic model predicted an acceptable cadmium concentration of less than 3mg.kg-1. At this concentration, reeds could develop and grow satisfactorily in the presence of cadmium. Therefore, the concentration of cadmium in the irrigated water of polluted water in mine sites, papermaking wastewater, or other industrial wastewater should be less than or equal to 3mg.kg-1 to ensure the normal growth of reeds in related wetlands.