Sedimentation rates in Western Nipigon Bay, Lake Superior using the 210Pb method

Abstract

210Pb, 226Ra and 137Cs profiles have been measured for sediment cores from three locations in western Nipigon Bay, Lake Superior, Canada. Compaction of the sediment with depth of burial was taken into account in calculating recent sedimentation rates and age profiles at these locations from the excess 210Pb profiles. The rates at two of the locations were 0.85±0.03 mmy −1 (16.7 mg cm −2 y −1) and 1.39±0.12 mmy −1 (29.5 mg cm −2 y −1). The third core had an anomaly in the 210Pb profile below a depth of 3.5 cm corresponding to the time that the outfall of a nearby pulp mill was relocated. The 137Cs profiles of the two undisturbed cores were in accord with the corresponding age/depth curves derived from the 210Pb measurements.