Internal Phosphorus Storage in Two Headwater Agricultural Streams in the Lake Erie Basin.

Internal phosphorus (P) in sediments plays an important role in the nutrient dynamics of lakes, sometimes long after external loads have been reduced. Similarly, internal P sources may drive the nutrient dynamics of small agricultural streams that drain to larger rivers and lakes, despite best management practices intended to reduce external P loads from adjacent fields. Here, internal P concentrations were measured with sequential extraction on cores collected in spring and summer from two small agricultural streams in the drainage basin of Lake Erie, a large, eutrophic lake experiencing increasing SRP loads.

Copper and nickel partitioning with nanoscale goethite under variable aquatic conditions.

Metal contaminated sediments can be toxic to aquatic organisms and are common in human-dominated ecosystems, which results in metals being a leading cause of ecosystem impairment. Bioavailability of metals is influenced by their affinity for dissolved and solid-phase ligands, including iron (Fe) oxyhydroxides, which have been hypothesized to reduce metal toxicity in sediments. The authors examined the adsorption kinetics of copper (Cu) and nickel (Ni) with goethite (α-FeOOH) and characterized the influences of solute metal concentration, pH, ionic strength, and humate concentration on steady-state partitioning of the metals with goethite under conditions representative of natural aquatic environments.