Bioaccumulation of Al,Cu and Zn in coontail ceratophyllum demersum L. after experimental exposure to a metal cocktail pollution

Abstract

Metal pollution is of major concern because metals can be bioaccumulated in aquatic organisms and have high toxicity. Metal concentrations can be increased along the food chain and could potentially threaten environmental and human health. As the coontail (Ceratophyllum demersum L.) is rootless, it is advantageous for use in laboratory bioassays as this would eliminate the complication of soil-rootcontinuum and shoot-root metal partitioning. It thus has the potential to be a suitable model for investigating metal stress in plants. The research objective was to determine the degree of Al, Cu and Zn bioaccumulationin C. emersum L. after exposure to a metal cocktail in a simulated “pollution event” under laboratory conditions over a five week exposure period. Plants were divided into four experimental treatment groups, each with different exposure concentrations of Al (AlSO4), Cu (CuSO4) and Zn (ZnSO4) in mixture. A fifth uncontaminated group of plants served as the control. Aluminium, Cu and Zn concentrations were determined in water and plant samples by means of nitric acid digestion and ICPMS analysis. This macrophyte proved highly effective in the accumulation of these metals at all four exposure concentrations. The results showed that concentrations of the metals in the water varied in all treatments over time with no specific patterns emerging amongst the treatment groups. The metal bioaccumulation in C. demersum was also variable between consecutive weeks per treatment and between consecutive treatments per week. This may be due to C. demersum being able to regulate Al, Cu, and Zn throughout the exposure period. The plant accumulated metals in the order: Zn>Al>Cu.