Iron dynamics in eutrophic systems were studied in the laboratory utilizing gas-water-Sediment phase sealed microcosms. Sediments from Hyrum Reservoir (2.4 percent iron by weight) were placed in the dark to simulate the hypolimnetic regions of a eutrophic impoundment. Iron both chemically and physically was readily available to microorganisms of the aqueous phase because iron in these systems was soluble. In the light microcosms, which simulated shallow littoral regions of eutrophic impoundments, iron was found in higher aqueous phase concentrations than was predicted chemically and physically; this was rationalized through biological mechanisms. The experiment was conducted in two phases: Phase I lasted 189 days (0 and 0.300 mg NO3–N/1 inputs) and phase II lated 175 days (10mg NO3-N/1 imput). Average light microcosm effluent iron concentrations increased from 0.092 mg FE/1 (Phase I) to 0.246 mg Fe/1 (Phase II) given higher inorganic nitrogen inputs. In Phase II, when nitrogen input into the microcosms ceased (nitrogen perturbations, day 115), aqueous phase iron concentrations in the dark microcosms increased dramatically (0.011 to 0.624 mg Fe/1).
Cowan, Peter A.; Adams, V. Dean; and Porcella, Donald B., "Iron Dynamics in a Gas-Water-Sediment Microcosm" (1976). Reports. Paper 522.