Assessment of heavy metal accumulation potential of aquatic plants for bioindication and bioremediation of aquatic environment

This study is devoted to assessing the potential for accumulating heavy metals (Fe, Mn, Cu, Zn) of nine species of aquatic and coastal plants growing in the water area of the Okhta River (St. Petersburg, Russian Federation). The list of studied species included the following: hornwort (Ceratophyllum demersum L.), water soldier (Stratiotes aloides L.), yellow water-lily (Nuphar lutea (L.) Sm.), arrowhead (Sagittaria sagittifolia L.), broadleaf cattail (Typha latifolia L.), water arum (Calla palustris L.), acute sedge (Carex acuta L.), reed canary grass (Phalaris arundinacea L.), and meadowsweet (Filipendula ulmaria (L.) Maxim.). The values of the bioconcentration factor for particular plant tissues were calculated. It has been established that the concentrations of metals in plant tissues can be thousands and tens of thousands of times higher than their content in water. At the same time, the ability of plants to accumulate metals varies greatly and depends on a number of factors, such as environmental conditions, the growing season, the type and ecological group of the plant. The study also attempts to determine the spatial and temporal dynamics of the content of heavy metals in higher aquatic plants. The main difficulties in data interpretation are indicated. The data obtained show the different significance of the study macrophyte species both for bioindication purposes and for use in wastewater treatment. The possibility of using such species as Sagittaria sagittifolia L., Typha latifolia L., Ceratophyllum demersum L., and Calla palustris L. for bioremediation is substantiated.