Event Title
Impacts of Excess Chloride on Phosphorus in an Urban Eutrophic Lake
Location
Hager-Lubbers Exhibition Hall
Description
PURPOSE: Excess chloride concentrations from road salt runoff can negatively impact the biological, chemical, and physical properties of freshwater ecosystems. Currently, there are few studies on how freshwater salinization may interact with other ecological stressors such as eutrophication. My research aims to understand how excess chloride from road deicers may impact nutrient processes in lakes. METHODS AND MATERIALS: Water quality surveys were conducted at a lake in Grand Rapids, MI over the course of 18 months. At each sampling event, we measured water quality parameters in situ with a multiparameter sonde. We collected water samples throughout the water column for analysis of total phosphorus (TP), soluble reactive phosphorus (SRP), and chloride. We collected sediment cores from the lake bottom for an experimental study and measured sediment phosphorus release under varying oxygen and chloride treatments over the course of 25 days. ANALYSES: Sediment cores from the experiment were analyzed in R using a multiway ANOVA with three factors. RESULTS AND CONCLUSIONS: Hypolimnetic chloride concentrations in the lake consistently exceeded the EPA chronic toxicity threshold, at times reaching 324 mg/L. Chloride-induced stratification has caused permanent hypoxia near the lake bottom, leading to TP concentrations over 6,000 µg/L in the hypolimnion, suggesting sediment release of phosphorus. Sediment cores exposed to the anoxic/high chloride treatment had the highest mean maximum TP release, suggesting that elevated road salt concentrations exacerbate internal phosphorus loading. Results from the study will shed light on how excess chloride impacts lake nutrient processes and ultimately help inform lake management and remediation strategies.
Impacts of Excess Chloride on Phosphorus in an Urban Eutrophic Lake
Hager-Lubbers Exhibition Hall
PURPOSE: Excess chloride concentrations from road salt runoff can negatively impact the biological, chemical, and physical properties of freshwater ecosystems. Currently, there are few studies on how freshwater salinization may interact with other ecological stressors such as eutrophication. My research aims to understand how excess chloride from road deicers may impact nutrient processes in lakes. METHODS AND MATERIALS: Water quality surveys were conducted at a lake in Grand Rapids, MI over the course of 18 months. At each sampling event, we measured water quality parameters in situ with a multiparameter sonde. We collected water samples throughout the water column for analysis of total phosphorus (TP), soluble reactive phosphorus (SRP), and chloride. We collected sediment cores from the lake bottom for an experimental study and measured sediment phosphorus release under varying oxygen and chloride treatments over the course of 25 days. ANALYSES: Sediment cores from the experiment were analyzed in R using a multiway ANOVA with three factors. RESULTS AND CONCLUSIONS: Hypolimnetic chloride concentrations in the lake consistently exceeded the EPA chronic toxicity threshold, at times reaching 324 mg/L. Chloride-induced stratification has caused permanent hypoxia near the lake bottom, leading to TP concentrations over 6,000 µg/L in the hypolimnion, suggesting sediment release of phosphorus. Sediment cores exposed to the anoxic/high chloride treatment had the highest mean maximum TP release, suggesting that elevated road salt concentrations exacerbate internal phosphorus loading. Results from the study will shed light on how excess chloride impacts lake nutrient processes and ultimately help inform lake management and remediation strategies.