The present study reports the capacity of the aquatic macrophyte Lemna minor to remediate combinations of Cu(II), Pb(II) and Cr(III) from a simulated natural environment. The effect of these metal mixtures on the growth of L. minor was also investigated using growth rate and biomass inhibition calculations. L. minor was successful in removing Cr and Pb from the water, and it remained an effective remediation agent when both metals were present in the environment. However, a relatively low absorption capacity was observed for Cu, increasing concentrations of which were associated with significant decreases in growth rate. No statistically significant difference was found between the 24 h and 7 days absorption rates of Cu, Pb and Cr, suggesting that, at the concentrations tested, equilibrium occurs within 24 h of metal exposure.Keywords Biomass inhibition Á Bioremediation Á Growth rate Á Phytoremediation Metals are some of the most common pollutants in the ecosystem, and their tendency to readily accumulate in food chains renders them an important health hazard.Consequently, a wide variety of physical, chemical and biological methods have been developed to remove metals from the environment, and the use of live or processed plants for the sorption of metals from aquatic ecosystems has received considerable attention in recent decades. However, most phytoremediation experiments focus separately on the removal of each individual metal, as it is difficult to account for interrelations between the accumulations of different elements in plant tissue. Such an experimental setup may not necessarily reflect a metal-contaminated natural environment, where many metals are often present in high concentrations (Horvat et al. 2007). As such, further research is necessary to fully elucidate how multiple metals affect the uptake and metabolization of each other.Lemna minor (duckweed) is an aquatic macrophyte commonly utilized in toxicology research, and it has been suggested as a potential phytoremediation agent due to its high reproductive rate, ease of culturing and capacity to absorb a variety of metals (Elmacı et al. 2009). However, the effects of multiple metal exposure on the biosorption and metal retention rates of L. minor are largely unknown. As such, we aim to elucidate the interplay between the uptake mechanisms of different metals in this aquatic plant by observing the biosorption of Cr, Pb, Cu mixtures in different concentrations by L. minor in a simulated natural environment. We also describe the toxicity of those metals, alone or in conjunction with each other, to estimate how the presence of multiple metals may alter the growth of L. minor in multi-element contaminated environments.
Materials and MethodsAll studies were carried out in a semi-controlled environment, if applicable. L. minor culture conditions were
