The spatial distributions of Mn, Cu, Ni, Co, Cr, Zn, Pb, Mo, Ti, Zr, and Fe, as well as particle sizes and humus, in the surface horizon of soils in the Lokna River small watershed (Tula oblast) have been studied. The relationships of the studied parameters have been characterized by statistical methods. Little change in particle size distribution in the humus horizons of soils is revealed from the geomorphological elements of the watershed. An increase in the content of most metals is observed in soils on the convex slopes and the bottom of the watershed balka compared to the autonomous positions. Positive correlations have been found between the contents of Co, Mn, Zr, Mo, and, to a lesser degree, Zn and Pb and the sand and coarse silt fractions; no correlations of Ni, Cr, Ti, and Fe with the particle size fractions were revealed.

Statistical models relating the content of mobile heavy metals with their total forms, humus, Fe- and Mn-oxide content, and acid-base and redox conditions were developed and studied. A positive correlation was found between the total and exchangeable forms for Mn, Cr, and Ni and a negative correlation for Cu and Co; no correlation was discovered for Pb and Zn. Mobile Fe and Mn favor the accumulation of many heavy metals. In alkaline conditions, the activity of Zn, Pb, Ni, and Co decreases and that of Mn increases. In reducing conditions, Zn is more mobile and Mn, Cu, Pb, and Ni are less mobile than in oxidative conditions.