Speciation and bioavailability of particulate phosphorus in forested karst watersheds of southern Ontario during rain events |
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Affiliation: | 1. Department of Civil & Environmental Engineering, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931, United States;2. Department of Civil & Environmental Engineering and Great Lakes Research Center, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931, United States;3. Upstate Freshwater Institute, 224 Midler Park Drive, Syracuse, NY 13206, United States;4. O''Brien and Gere, 333 West Washington Street, Syracuse, NY 13202, United States |
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Abstract: | Understanding riverine phosphorus (P) dynamics, its transport, and transformation mechanisms from sources in the watersheds to receiving water bodies are essential for the development of effective strategies to decrease excess P loading and reduce eutrophication. Karst watersheds are thought to be especially vulnerable to P pollution due to their geomorphological features. In this study, we investigated the dynamics of particulate P (PP) chemical phases in two karst watersheds from a Great Lakes Area of Concern in southern Ontario (Bay of Quinte, Canada). Suspended solids were collected during different hydrological regimes representing storm events with low and high discharge, and particulate P binding forms were measured using extraction techniques. Our results show that in these karst watersheds, particulate P is dominated by chemical species that are likely to be highly bioavailable and contribute 62–75% to total PP. Concentrations of these bioavailable P binding forms in suspended solids increase two- to three-fold on dry mass basis during periods of high river flow. Electron microprobe and energy dispersive X-ray spectroscopy suggest that the primary carriers of particulate P are aggregates of Fe oxyhydroxides and Al-silicates. Our results underscore the influence of particulate P sources on the ongoing eutrophication in the Bay of Quinte Area of Concern. |
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Keywords: | Particulate phosphorus Catchment Bay of Quinte Karst watersheds Extreme rain event Bioavailable phosphorus |
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