Ecological state assessment of recreational areas in Nizhny Novgorod on heavy metal soil pollution and bioindication indicators of Betula pendula Roth leaves

In this paper the ecological state of recreational areas in Nizhny Novgorod was assessed by the level of soil contamination with heavy metals (HM) and the values of bioindication indicators of the birch (Betula pendula Roth). The objects of the study were 4 recreational areas. The forest park «Shelokovsky Farm» located far from pollution sources was chosen as a control site. The excess of normative indicators (in multiplicities of normative indicators) on gross content of HM was observed in soils only for nickel: in the park «Switzerland» in 1,3 times, in «Raspberry Ridge» - in 2,3 times. The soils with the pollution category «moderately dangerous» were the most polluted by HM according to the total indicator of pollution: in the protected area «Crimson Ridge» and in the park «Oaks». Bioindication indicators of a birch leaf deviated from the conventional norm in a number of studied areas. The quality of the environment, estimated by fluctuating asymmetry of birch leaves in «Shelokovsky Farm» and the park «Oaks», correspond to 2 points (a slight deviation from the norm), in the Park «Switzerland» - to 3 points (the average deviation from the norm), and in «Crimson Ridge» - to 4 points (a significant deviation from the norm). In the two most contaminated sites («Oaks» and «Crimson Ridge»), a decrease of chlorophyll content in birch leaves relative to the control («Shelokovsky Farm») was observed.