Use of aquatic macrophytes as a bioassay method to assess relative toxicity,uptake kinetics and accumulated forms of trace metals

Floating aquatic macrophytes such as the Lemnaceae have many attributes which commend their use in laboratory and field investigations to assess both the toxicity of substances and the quality of freshwater systems. As well as their more well known advantages of small size, relative structural simplicity, rapid growth and vegetative reproduction and genetically homogenous populations, they are also excellent accumulators of a number of metallic elements. This raises the possibility of the use of these aquatic macrophytes in water quality monitoring and also as laboratory bioassays for toxicity and uptake studies. Results are presented of a study of the comparative toxicity, uptake kinetics and accumulated forms of thallium and cadmium in the duckweed, Lemna minor and the role of this methodology in water quality monitoring and hazard evaluation are discussed.