Sedimentary processes in the Great Lakes

Sediments in the Great Lakes are subject to four general categories of processes: input, transport, deposition, and postdepositional alteration. Sedimentary input is from coastal erosion (64%), riverine input (26%), atmospheric transport (3%), and several lesser sources (7%). Once in the lake, sediments are transported to their place of deposition along the bottom and/or in suspension depending upon grain size and density. The rate of deposition in the Great Lakes is variable and ranges from zero in some areas to over 6000 g m−2 yr−1 in the eastern basin of Lake Erie. After deposition, sediments undergo bioturbation, dissolution of carbonate and opal, remobilization of many metals followed by reprecipitation within the surficial oxidized layer, and degradation of organic compounds.