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Explore the impact of phosphorus levels in the Great Lakes and the changing regulations. Find out how agricultural practices and water quality initiatives are addressing the issue.
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Phosphorus in the Great Lakes: The Rules Have Changed Harvey Bootsma
Great Lakes Water Quality Agreement Total Phosphorus Target Concentrations: Lake Superior = 5 mg / L Lake Michigan = 7 mg / L Lake Huron = 5 mg / L Lake Erie = 10 / 15 mg / L Lake Ontario = 10 mg / L
P loading trends in the Great Lakes Dolan and Chapra, 2012
Lake Erie Algal Bloom NOAA / NASA
Phosphorus Concentrations in Lake Erie EPA, Great Lakes National Program Office
More P is in dissolved reactive form P. Richards, Heidelberg College
Hypoxia in Lake Erie Stuart Ludsin, The Ohio State University Tom Johengen, U. of Michigan CILER
Factors favoring toxin-forming cyanobacteria (blue-green algae) 1. High dissolved phosphorus concentrations. 2. Warm temperatures. 3. Calm conditions. 4. Selective grazing by zebra mussels and quagga mussels. 5. Alteration of nitrogen : phosphorus ratio by mussels.
P in Wisconsin Cropland Average [P] (ppm) 2000- 04 Soil P Storage Change (kg ha-1) Bundy and Sturgul(2001)
P in New York Cropland Ketterings et al. (2005)
Long-term Influence of Soil P on Lake P Soil P inputs reduced after year 250 Soil [P] Sediment [P] P Inputs to Soil (g m-2 y-1) Phosphorus Density (g m-2) We are here Water [P] at current input Water [P] Net P Input to soil Year Source: S.R. Carpenter, 2005, Proc Nat. Acad. Sci. 102:10002-10005.
Milwaukee River Transect, April 2005 SRP (mg L-1)
Phosphorus Loading (g P m-2 year-1) Mean Depth (m) Vollenweider (1968 Horne & Goldman (1983)
Annual P Load Total P in Lake (metric tons) (metric tons) Huron 3,000 8,843 Michigan 3,000 14,760
River load: 120 mg P m-2 Mussel Excretion: 506 mg P m-2 Cladophora zone 10 km 10 km Milwaukee region Nearshore Phosphorus loads, May – July 2006 Milwaukee R. Menomonee R. Kinnickinnic R.
Pelagic prey fish: lakewide fall survey (9-110 m) USGS-GLSC bottom trawl survey
Management Challenge: • The Phosphorus Conundrum • Will a reduction in P loading fix the Cladophora problem? • Will a reduction in P loading exacerbate the problem of low plankton production offshore? • The rules of the game have changed. We need to determine the P loading “sweet spot” for each lake. • Linking agricultural and water quality management.
MMSD 2020 Water Quality Initiative MMSD Greenseams Program
Lake Whitefish Condition Madenjian et al. 2002
UK water company Thames Water is now extracting phosphate from sewage waste
Graph showing world phosphate rock production, 1900–2012, reported by US Geological Survey