Aquatic Sciences Meeting, Albuquerque 2001

SS31 Integrated Approaches to Drainage Basin Nutrient Inputs and Inland/Coastal Eutrophication (Science and Society Connections)

Date: Thursday, February 15, 2001, Time: 4:15:00 PM

Location: Cimarron

Pilgrim, K, M, University of Minnesota/Graduate Program in Water Resources Science, Minneapolis, USA, pilg0005@tc.umn.edu

Brezonik, P, L, University of Minnesota/Water Resources Center, St. Paul, USA, brezo001@tc.umn.edu

THE IMPORTANCE OF BIOLOGICALLY AVAILABLE PHOSPHORUS AND PARTICLE SETTLING FOR LAKE RESTORATION

The importance of biologically available phosphorus (BAP) and particle settling in urban stormwater was investigated for two pond/wetland systems. Settling experiments using stormwater from the McCarrons Lake watershed demonstrated complete removal of particulate BAP after 72 hrs of settling but the concentration of dissolved BAP was still high. Settling and was less complete (12 %) for water from the stormwater pond/wetland systems in the Fish Lake watershed. Analysis of P species in size fractions, >0.45 um, 0.45 um to 1000 MW, and <1000 MW, demonstrated the effect of stormwater detention on phosphorus sorption. Phosphorus entering the McCarrons Lake wetland system contained predominantly soluble phosphorus species while size analysis showed that most of this P is sorbed by suspended particles and converted to particulate P. Algal assays demonstrated a benefit to P sorption in the wetland. Experiments with alum demonstrated its practical application by removing up to 99 % of dissolved and particulate P forms and providing an additional algal growth reduction of 49 to 87 % over settling.

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Aquatic Sciences Meeting, Albuquerque 2001

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