Effects of the presence of nutrients in the removal of high concentrations of Cr(III) by Typha domingensis

Abstract

The aim of this work was to study the influence of nutrients on the tolerance, removal efficiency and accumulation of high concentration of Cr(III) by Typha domingensis. This species was exposed to the following Cr(III) treatments, arranged in triplicate: 200 mg L−1 Cr; 600 mg L−1 Cr; 200 mg L−1 Cr + 50 mg L−1 P + 50 mg L−1 N; 600 mg L−1 Cr + 50 mg L−1 P + 50 mg L−1 N; without metal or nutrient additions (control 1); 50 mg L−1 P + 50 mg L−1 N, without metal addition (control 2). In order to simulate extreme events, the concentrations studied were higher than the concentrations commonly found in constructed wetlands. Cr and nutrient concentrations in water decreased in all treatments along time. Nutrient addition did not affect Cr removal for the two concentrations studied. In tissues, the highest Cr concentrations were observed in roots in all treatments. The mass balance showed that sediment showed the highest accumulation of Cr. Metals caused growth inhibition and a decrease in chlorophyll concentration. Despite these sublethal effects, T. domingensis demonstrated that it could accumulate Cr. These results confirm the high tolerance of this species ensuring the survival plant and wetland efficiency in time.