DECIPHERING THE GEOCHEMICAL HISTORY OF LAKE WABAN, WELLESLEY, MASSACHUSETTS

Lake Waban (Wellesley, Mass.) sediment appears to preserve a geochemical record of the Charles River watershed's complex history. Located downstream of a regional paint factory, the lake acted as an effluent depository for Cr and Pb from 1848 to 1928. This study attempts to unravel the industrial history of Lake Waban through elemental and isotopic analyses of freeze cores from the deepest portion of the lake. Chemical analyses of sediments are conducted using X-ray fluorescence. Sediments are dated using gamma spectroscopy with ²¹⁰Pb, ¹³⁷Cs, ⁷Be, and ²³⁴Th radionuclide tracers and Pb sources are “fingerprinted” using ²⁰⁷Pb/²⁰⁶Pb and ²⁰⁶Pb/²⁰⁸Pb isotopic ratios. Preliminary analyses show elevated Pb levels in surface sediment and a maximum in Pb accumulation possibly during the years of peak pigment production. Sediment sampling at the inlet and outlet examines present-day mobility and transport of Pb. Lake Waban's sediment profile reflects direct inputs from upstream activity, diffusion within sediments and advection in the water column.