DIURNAL STUDY IN LAKE PEPIN NAVIGATION CHANNEL

Arthur L. Howard 1, Robert Burdis 2, and M. A. Engen 1.
1 Department of Chemistry, Winona State University, Winona, MN  55987; and 2 
Minnesota Department of Natural Resources, 1801 South Oak Street, Lake City, MN 
55041.  

Lake Pepin serves as a recreational and commercial use waterway on the Upper 
Mississippi River.  Various agencies have ongoing river-monitoring programs that 
collect data weekly or bi-weekly primarily during daylight hours on Lake Pepin.  The 
existing research programs and data collection procedures do not support the 
gathering of data during a complete 24-hour period on Lake Pepin.  The Minnesota 
DNR in Lake City worked in conjunction with Winona State University collecting data 
hourly during a 13-day period in August of 1999 at Upper Mississippi River mile 
771.2.  Dissolved oxygen and temperature profiles at 1-meter intervals were sampled 
hourly each day.  Surface and bottom water chemistry samples were also taken twice 
a day.  Diurnal fluctuations, stratification, chemical, and physical relationships are 
examined.

Keywords:  Mississippi River, diurnal, dissolved oxygen, dissolved inorganic mixture, 
soluble reactive phosphorus, flourometric chlorophyll
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