Accumulation and release of elements during the decomposition of Myriophyllum spicatum L. biomass in the Yenisei River stretch subjected to human impacts

An in-situ experiment was conducted within the limits of the city of Krasnoyarsk, at the dammed part of the Yenisei River, which is affected by the activities of a fish farm and water discharged by the thermal power plant. The aim of the experiment was to study possible secondary contamination of the aquatic ecosystem by heavy metals (HMs) and nutrients during decomposition of a submerged macrophyte – Myriophyllum spicatum L. The rate of decomposition of M. spicatum biomass was determined. Release and accumulation of macro elements and trace elements, including HMs, were studied using inductively coupled plasma atomic emission spectrometry (ICP–AES), and nitrogen and carbon were determined using high-temperature catalytic combustion. Throughout the experiment, Al, Be, Cu, Fe, Ga, Li, Mo, Ti, and V were accumulated in the decaying M. spicatum biomass, and In, K, Mg, Mn, Na, P, Pb, S, Tl, N, and C were released from it. The study showed that decomposition of M. spicatum biomass is a probable source of the secondary contamination of the ecosystem by HMs and nutrients (C, N, P).