The paper contains the comparative assessment of content levels and the revealed patterns of total and mobile forms of metals (Cd, Pb, Co, Cu, Ni, Zn, Cr, Mn, Fe) distribution in the bottom sediments of natural (Volga-Kama Nature Reserve) and urbanized (Kazan) territories of the Republic of Tatarstan. The changes in absolute metals content in sediments of urban lakes, as well as their ratio, breaking the Oddo-Harkins rule, caused by the forms of their release to the aquatic environment from technogenic sources are shown. Environment reaction and particle size composition of sediments are the factors determining the mobility of cationogenic metals in water bodies of natural and urbanized areas. It was found that the active layer of sediments, in which processes of biogeochemical transformation of natural and technogenic metals compounds occur, is a surface layer with capacity up to 50 cm.