Neutron activation analysis of samples taken from the Lake Milton bed and various surrounding tributaries

Abstract

Lake Milton, through which the Mahoning River flows, was a recreational facility for many years, until the lake was drained in 1986. After the lake was drained, soil samples were cored from 31 locations along the dry lake bed and from surrounding tributaries. The samples were oven dried, crushed and weighed, and then analyzed by neutron activation analysis (NAA), a sensitive analytical method for determining trace elements, at the Ohio State University Nuclear Reactor Laboratory (OSU-NRL) in Columbus, Ohio. From preliminary results, nine of the 31 sites were chosen for further analysis. The choice of sites was based on the concentrations of the following elements, which may be pollutants: As, Al, V, Ti, Co, Cr, Zn, and Ni. For the nine selected sites, the cored samples were divided into three portions, top, middle, and bottom. Thirty two elements (Mn, V, Ti, Na, Sc, Cr, Co, Rb, Ba, La, Sm, Yb, Lu, Th, Nd, U, As, Zn, Cs, Sb, Ca, Fe, Al, Eu, Tb, Se, Sr, Zr, Hf, Ta, Ce, and Ni) were determined by NAA for each of the 27 samples (nine sites, three portions per site). Attempts were made to relate the results to the history and geography of the lake. Many sites near inhabited areas and sites near or on the banks of the Mahoning River, contained elevated concentrations of various elements. Eight elements (Ti, Fe, As, Ba, Co, Cr, Cs, and V) were found in elevated concentrations in samples taken from the lake bed. Four samples taken from Canyon Park area contained elevated concentrations of these elements. However, due to the limited sampling of such a large area as Lake Milton, no definite conclusions can be drawn from the data concerning possible pollution or contamination.