Bioaccumulation, Growth and Photosynthetic Response of a New Found in Bulgaria Invasive Species Lemna minuta and L. valdiviana to Heavy Metal Pollution

ABSTRACT: Heavy metals can meet in the surrounding environment as natural ingredients or from agricultural, industrial and chemical industries. The study was conducted in order to trace the potential of the aquatic plant L. minuta and L. valdiviana for the bioaccumulation of Cu, Cd, and Pb from contaminated water at low levels of these elements. Each of the duckweed species was treated separately with CuSO4.5H2O, CdSO4, Pb SO4 (Valerus, Bulgaria) at 0.5 and 1 mg L-1 concentrations of for 96 hours. After conducting the experiments, relative growth rate (RGR), bioconcentration factor (BCF), tolerant index (Ti) and photosynthetic pigments of two Lemna species were studied. The solution with higher metal concentration more inhibits the growth of macrophytes. The BCF of the metals on the two species were in decreasing order: Cu > Pb > Cd. Our study showed that L. minuta and L. valdiviana at a concentration of 0.5 mg L-1 copper have better affected on the photosynthetic apparatus compared to the control. Better bioaccumulation ability was established in L. minuta compared to L. valdiviana.