CHANGE OF CONCENTRATIONS OF HEAVY METALS IN THE COMPONENTS OF A SMALL RIVER (ON THE EXAMPLE OF DRAINAGE RECLAMATION)

Abstract

The relevance of the research lies in the need to assess such components of watercourse ecosystem as bottom sediments and aquatic plants that are able to accumulate various pollutants from the catchment area and can serve as indicators of the ecological state of pollution of the surface watercourse. The aim of the work is an environmental assessment of small rivers of the Middle Amur Lowland under the influence of drainage reclamation according to the content of heavy metals. Objects: surface water, bottom sediments and aquatic plants susceptible to drainage reclamation. Methods: filtering water samples through membrane filters with a pore diameter of 0,45 μm for the separate determination of dissolved and suspended forms of heavy metals;sampling of bottom sediments with a Gr-91 rod-type dredger at a depth of 25 cm from the bedding surface;acid decomposition of samples of bottom sediments and vegetation in the «Mars-6» microwave system, grinding in a «Pulverisette 6» planetary mill, determination of heavy metals by atomic absorption spectrometry on a «Solaar 6M» spectrometer. Results.In surface waters, there is an increase in gross concentrations of heavy metals, especially iron and lead, exceeding the maximum permissible concentrations by 3 times. The accumulation of various pollutants takes place in the bottom sediments, however, when the chemical and hydrological parameters of the environment change, they again pass into the watercourse, thereby being a source of secondary pollution. The most intense deposition processes were calculated for Fe (lgК=5,06), Pb (lgК=4,76), as well as for Zn (lgК=4,60). The average character of sedimentation can be traced for Mn and Cu (lgК=3,36). For Ni, the coefficient has a minimum value (lgК=2,82), which indicates metal reverse migration from bottom sediments to water. Under the influence of drainage, an increase in concentration of heavy metals in macrophytes occurs.

Keywords

• middle amur lowland
• small rivers
• aquatic vegetation
• heavy metals
• bottom sediments
• drainage reclamation