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.

An Ionic Liquid-Based Biorefinery Approach for Duckweed Utilization

“…Although the effect on growth was not investigated, these results are further evidence of the ability of duckweed to uptake heavy metals in significant quantities and confirm that it has significant potential for phytoremediation of water. Some studies focusing on the physiological responses of duckweed to heavy metals over similar concentration ranges have shown negative impacts such as decreased photosynthetic pigments and decreased protein contents. ,,− It is worth noting, however, that for some metals conflicting findings have been reported on metal toxicity limits, likely due to differences in tolerance between strains, as well as increasing tolerance from higher nitrogen and phosphorus concentrations . Therefore, further work should be performed to establish clearer limits for the application of duckweed for metal removal.…”

Insights into the Mechanisms Involved in Lead (Pb) Tolerance in Invasive Plants—The Current Status of Understanding

“…Interestingly, some heavy metal-tolerant plants may exhibit metal deficiency symptoms when specific metals are absent from the soil. At low doses, these metals can even stimulate photosynthetic activity and pigment synthesis [20][21][22]. In this way, heavy metal-tolerant plants, including some invasive plants, may have a competitive advantage in habitats with low-level heavy metal contamination, such as Pb, which can facilitate their colonization.…”