Aquatic macrophytes as indicators for element distribution in river water in the Mulde River (central Germany)

The sediments of the Mulde River are well studied and provide insight into the long-term material development within the river catchment area. While studies of aquatic plants enable additional time and location-specific elemental insights to be gained, little data on aquatic plant species in the Mulde River are available. Little is known in the relevant literature and herbaria about the colonization of the Mulde by aquatic seed plants. The sampling of aquatic plants requires little effort in comparison to the sampling of sediments, as it does not require the transport of parts of the sample with the flowing water. Samples of aquatic plants were taken along the Freiberger Mulde, Zwickauer Mulde and at their confluence, the Mulde River, identified, and analyzed with respect to their elemental contents. The most widespread aquatic species were found to be representatives of the genera Elodea, Myriophyllum, and Ranunculus. The elemental contents of the aquatic macrophytes reflect the elemental distribution determined for the water, suspended matter and sediment of the Mulde River. The Freiberger Mulde River is characterized by elevated levels of lead, cadmium, and silver; the Zwickauer Mulde River is characterized by the presence of uranium and nickel. The Mulde River represents the mixing of the partial flows. Clear trends in the distribution of elemental contents between plant species could be identified for aluminum, lead, chromium, calcium, iron, potassium, molybdenum, nickel, and uranium.