Accumulation and vertical distribution of heavy metals in sapropel of Gryaznoe lake (Medvezhe'gorsk district, Republic of Karelia)

The results of studying sapropel sediments and clay underlying sapropel of Gryaznoe Lake (the Medvezh'egorsk district, Republic of Karelia) have been considered. Analysis of the small stock published literature and fund sources on reserves and quality of sapropel of this region gives an indication of the importance of studying this type of natural resources. This research focuses on studying heavy metal content in the sapropel to assess the ecological status of the water body and the prospect of using it sapropel deposits for practical purposes. The modern precision methods of research material have been used. The chemical analysis of the sediments of Gryaznoe Lake has been measured using X-ray fluorescence spectrometer ARL ADVANT'X and mass spectrometer XSeries-2 ICP-MS, and the particle-size distribution of the lake sediments has been determined using the multifunction particles' analyzer LS13 Series 320. Thus the results of studying particle-size distribution and content of the major components of Gryaznoe Lake as well as basic correlation patterns calculated from the data have been given. The studied sediments' column of this lake is 3,4 m, where the thickness of the sapropel layer is 3,1 m. The content of organic substance of sapropel of Gryaznoe Lake is from 55,2 to 70,2 %. According to the literature the studied sapropel sediments comply for the type of reddish-brown sapropels widespread in Karelia and suitable to various kinds of practical use. The content of heavy metals in entire thickness of sapropel of the lake does not exceed the established norms. A comparison of levels of heavy metals' accumulation in the sediments of Gryaznoe Lake and Lamba Lake located within the city of Petrozavodsk has been carried out. The negative impact of human activities on the urban areas on the deterioration of useful properties of sapropel deposits of small Karelian lakes has been clearly illustrated.