Sediment resuspension in the Lake Erie nearshore

A decline in water quality in Lake Erie during the last decade, despite increased efforts to limit nutrient loading, may be better understood by examining internal processes in the lake. We employed Be-7, Pb-210 and Cs-137 measurements of suspended matter in tributaries, in the lake water column, in atmospheric precipitation, in sediment traps and in bottom sediments collected in June and August/September 2011 to estimate the fraction of the suspended matter that is resuspended from the bottom. Mass balances on Be-7 and Pb-210 using sediment trap material indicated that at the nearshore site similar to 83-94% of suspended matter in the water column was resuspended bottom sediment, while, offshore, resuspended sediment made up only similar to 62-75%. A mass balance using the Be-7/Pb-210 ratio for each sediment source indicated that resuspension of bottom sediment accounted for 52-97% of the suspended material in the nearshore and from 53 to 86% of the suspended matter in the offshore and was greater after the fall overturn. The amount of nutrients delivered to the water column by resuspension indicates that the resuspension loading of particle-bound P to the lake is about the same as the tributary loading, although the resuspended P is likely to be significantly less bioavailable. (C) 2014 International Association for Great Lakes Research. Published by Elsevier B.V. All rights reserved.