Figure 1: Mean probable effect concentration quotients (mPECQs) calculated for the four primary metals of interest, copper, cadmium, lead, and zinc (top panel), and for the eight metals commonly calculated to express potential effects for mixtures of metals in sediments, arsenic, cadmium, chromium, copper, lead, mercury, nickel, and zinc (bottom panel; [30]). Treatments included artificial sediment (CTRL), reference sediments from Lower Arrow Lake (LALL) and Genelle (GE), and site sediments from Deadman’s Eddy (DE), Northport (NP), Little Dallas (LD), Upper Marcus Flats (UMF) and Lower Marcus Flats (LMF).