Quantifying the distribution of phosphorus fractions in sediment of Chequamegon Bay, Lake Superior

Session: Poster session

Marisa Ulman, Northland College, Burke Center for Freshwater Innovation, [email protected]
Christopher McNerney, Northland College, [email protected]
Matthew Hudson, Northland College, Mary Griggs Burke Center for Freshwater Innovation, [email protected]
Matthew Cooper, Northland College, Mary Griggs Burke Center for Freshwater Innovation, [email protected]

Abstract

Chequamegon Bay (CB) is one of the shallowest, most isolated, and warmest bays in Lake Superior. Recent data collected by researchers at Northland College indicates episodic events contribute significant tributary loads of total phosphorus to CB. The CB region is predicted to warm in response to climate change, potentially leading to an increase in water temperature and the potential for increased eutrophication driven by internal phosphorus loading from conditions in the hypolimnion. For this reason, it is important to understand the concentration and distribution of phosphorus in sediments of the Bay. We collected a series of spatially-distributed sediment samples from 11 sites in CB using a ponar dredge. The samples are being analyzed for total, metal-bound, and unbound phosphorus and grain size distribution. The effort is aimed at evaluating the relationship between sediment grain size and phosphorus distribution and understanding potentially available phosphorus concentrations at the sediment-water interface in CB. Preliminary results indicate clay and silt-sized particles are concentrated in the southwest and northwest regions of CB, suggesting these areas would have the greatest sediment phosphorus concentrations. We will present results from sediment phosphorus analysis and describe its relationship to known tributary loading patterns and particle size distribution in CB.

1. Keyword
phosphorus

2. Keyword
Lake Superior

3. Keyword
sediments

4. Additional Keyword
Chequamegon Bay