Pollutant Sources, Depositional Environment, and the Surficial Sediments of Onondaga Lake, New York

Abstract

AbstractA physical and chemical characterization of the surficial sediments of polluted, hypereutrophic Onondaga Lake, New York is presented. Seventy samples were analyzed for a suite of parameters: particle size, moisture content, volatile solids, calcium carbonate, clastics, N, P, chemical oxygen demand, and inorganic and organic C. The lake's sediments are enriched in calcium carbonate (averaging 66% dry weight, DW), at least in part due to an industrial discharge of Ca2+. Enrichment with calcium carbonate serves to dilute other sediment constituents, yielding concentrations of N, P, and organic matter (volatile solids) unusually low for a hypereutrophic system. The distribution of sediment constituents is strongly influenced by lake morphometry: fine sediments (Φ = 4.6) relatively high in N (0.45% DW), P (0.12% DW), and volatile solids (10.7% DW) are characteristic of low energy, deep‐water depositional environments and coarse (Φ = 1.7), calcium carbonate‐rich (83% DW) sediments are typical of shallow, high energy nearshore sites. The location of tributary and point source inputs and the lake's predominant circulation pattern also influence the distribution of clastics, organic matter, and P. Cluster analysis was used to identify regions of common sediment character: (1) nearshore sediments rich in calcium carbonate, (2) shallow water sediments directly influenced by tributary and point source discharges, and (3) deep‐water sediments rich in N, P, and organic matter. The deep‐water sediment type was further subdivided in recognition of the high chemical oxygen demand characteristic of the deepest portions of the depositional basin.