Macrophytes as Bioindicators of Heavy Metal Pollution in Belarusian Rivers

Abstract

Macrophytes are well-known for accumulating a large number of various substances, including metals, and they may consequently serve as biogeochemical indicators of aquatic system pollution. In general, the sequence of analyzed metal accumulation in river macrophytes is as follows (mg/kg): Mn (141) > Cu (2.53) > V (0.89) > Cr (0.70) > Pb (0.68) > Ni (0.23). Submersed species are conspicuous for their increased metal accumulation capacity, with statistically significant differences compared to other ecological groups. Among the aquatic plant genera examined (Potamogéton, Ceratophýllum, Elodea, Núphar, Butomus, Glycéria, and Spargánium), an increased capacity to accumulate Mn, Cu, and Pb is observed in all submersed macrophytes, while Cr, V, and Ni are particularly accumulated by Ceratophýllum and Elodea. Potamogéton has the largest range of V, Cr, Mn, Ni, and Cu variations. The overall bioaccumulation capability evaluated by the metal accumulation index was ordered as follows: Núphar (6.94) > Potamogéton (5.53) > Butomus (3.48) > Glycéria (2.86) > Spargánium (2.62) > Elodea (2.33) > Ceratophýllum (1.98). Bio-accumulation factors (BAFs) (macrophytes/sediment) vary depending on the metal and macrophyte ecological groups. For submersed macrophytes, the sequence of BAFs is Mn > Cu > Ni > Pb > Cr > V. In the submersed plants of watercourses taken at the anthropogenic impact sites, the accumulation of Ni, V, Mn, Pb, and Cu is statistically significantly higher compared to those in natural conditions. Compositional data analysis has revealed such biogeochemical signatures of the anthropogenic impact as the formation of the anthropogenic Cr–Ni association, which is associated with the identified multivariate anomalies, as well as an increase in Cu variability and a decrease in Mn.