Mine Drainage Residual Additions to Lake Sediments Alter Phosphorus and Trace Metal Distributions

Abstract A greenhouse microcosm study investigated the impacts of recovered iron oxyhydroxide mine drainage residuals (MDRs) on phosphorus (P) and trace metal distributions at sediment layer/water column interface in Grand Lake o’ Cherokees, a large reservoir receiving waters impacted by both historic mining current agricultural land uses. Each mesocosm included 5 kg lake 20 L on-site groundwater. Three treatments were examined triplicate: control (C) with no additions, low MDR (LM) 0.3 added MDR, high (HM) 0.9 MDR. In first 10 days, aqueous soluble reactive phosphorous (SRP) concentrations decreased likely due to colonizing biomass uptake significant differences among three treatments. LM HM showed delayed peaks dissolved oxygen (DO) lesser chlorophyll-a (Chl-a) compared C treatment, indicating addition may suppress growth. During days 11 138, treatment demonstrated increasing pH, decreasing ORP, decay resulting significantly increased SRP concentrations. treatments, sufficient P sorption maintained Although MDRs are derived from metal-rich waters, all below hardness-adjusted acute chronic criteria, except for Pb regard criterion. Metal sediments Tri-State Mining District (TSMD)–specific Sediment Quality Guidelines (SQGs). additions serve as stable long-term sinks prevent release dead biomass, decrease internal cycling rates, mitigate eutrophication, limited concern release.