The content of trace elements in higher aquatic plants of the Volga Delta and the Northern Caspian
Higher aquatic plants play an important role among the biotic components of aquatic ecosystems. They act as ideal indicators for comparing the trace element composition between different reservoirs. This article compares the content of heavy metals in higher aquatic vegetation (Potamogeton lucens and Potamogeton perfoliatus, Zostera marina, Myriophyllum spicatum and Polysiphonia) in the Volga Delta and in the Northern Caspian. The method of atomic absorption spectrometry was used, according to the methodology, GOST 30178-96 to determine the concentration of heavy metals (copper, zinc, manganese, lead, cobalt, nickel, iron, chromium, cadmium). As a result of the study, the data were obtained on the concentrations of trace elements in the aquatic organisms under consideration, their content was analyzed, patterns in the accumulation of trace elements by aquatic plants were revealed. Decreasing series of heavy metal concentrations were compiled for the Volga Delta and the Northern Caspian. Moreover, the author determined the metals accumulating in aquatic plants more than others, namely iron, manganese and zinc. It is concluded that the trace element composition of Myriophyllum spicatum concentrates heavy metals to a greater extent than other higher aquatic plants which is due to its specific features. The comparison of the trace element composition of higher aquatic plants, namely Zostera marina and Myriophyllum spicatum, growing both in the Volga Delta and in the Northern Caspian Sea was made. The study found that marine plants, unlike those growing in the delta, accumulate more zinc, copper, cadmium and cobalt. River hydrophytes concentrate more manganese. The peculiarities of the accumulation of such elements as chromium and lead are related to the specific features of the plants under consideration.