Accumulation of trace metals by aquatic macrophytes and their possible use in phytoremediation techniques

Abstract

The aim of the performed research was to obtain knowledge on the ability of aquatic plants naturally growing at a site to absorb trace metals contained in bottom sediments and surface water. Furthermore, we compared differences in the accumulation of trace metals by the individual groups of aquatic plants (submerged and emergent) and assessed a possible use of the individual plant species in phytoremediation techniques. Representative samples of water, sediments and aquatic macrophytes were taken from three anthropogenically loaded streams in six monitoring cycles in several collection profiles differing in the distance from a source of contamination. The samples were analysed for the total content of selected trace metals (As, Cd, Pb, Al, Hg, Zn, Fe, Mn, Cr, Ni and Cu). For comparison, one profile at an unloaded site was sampled as well. The obtained results were subjected to multivariate statistical analysis of data. Increased contents of Fe, Al, Mn, Cr and Zn were detected in sediments and plant biomass at loaded sites, namely 2–3× higher than at the comparing site. The contents of metals in surface water samples were altogether below the detection limit of the analytical method. When evaluating the individual plant species, we can state that the lowest contents of metals were detected in shore species (reed canary grass Phalaroides arundinacea, wood club-rush Scirpus silvaticus and red dock Rumex aquaticus); plant species growing in the very water current (water star-wort Callitriche sp. and flote-grass Glyceria fluitans) exhibited mean contents of metals. In species forming mats (Fontinalis antipyretica and Cladophora sp.), these contents were several times higher as compared to the previous species. The results of the performed research show that one of important factors, which influence the accumulation of trace metals in plants, is their ecological group (emergent – submerged) affiliation and the species classification within this group. Based on the evaluated data, we can recommend species of moss and algae that form mats eventually species growing in the very water flow for the future use in phytoremediation techniques.

Keywords

• trace metals
• freshwater ecosystems
• aquatic macrophytes
• sediment
• contamination