Waples, J. T. Great Lakes WATER Institute, University of Wisconsin-Milwaukee, jwaples@uwm.edu
Klump, V. T. Great Lakes WATER Institute, University of Wisconsin-Milwaukee, vklump@uwm.edu
Edgington, D. N. Great Lakes WATER Institute, University of Wisconsin-Milwaukee, dnedge@uwm.edu
MacKenzie, R. Great Lakes WATER Institute, University of Wisconsin-Milwaukee, ram@uwm.edu
Szmania, D. Great Lakes WATER Institute, University of Wisconsin-Milwaukee, sd@uwm.edu
Robbins, J. A. Great Lakes Environmental Reseach Laboratory, robbins@glerl.noaa.gov
Eadie, B. J. Great Lakes Environmental Reseach Laboratory, eadie@glerl.noaa.gov

 
TH-234 INVENTORIES IN NEARSHORE ENVIRONMENTS OF LAKE MICHIGAN
 
The activity of Th-234 (half-life 24.1 days), and its departure from secular equilibrium with its U-238 parent (100 +/- 5 fCi/L) has been measured within the water column of nearshore Lake Michigan. Th-234 activities, both in solution (< 0.45 um) and bound to particles, have been measured on a bi-monthly basis throughout the southern basin of the lake in water depths from 10 to 40 meters. These represent the first activity measurements in freshwater for both soluble and particulate Th-234. Particle concentrations within the coastal margin of Lake Michigan vary dramatically in response to episodic sediment resuspension events, and Th-234 activities reflect time dependent fluctuations in particle loadings, particle settling rates, and particle surface geochemistry. The utility of Th-234 as a tracer for measuring the residence time/behavior of particles has been established by marine scientists. The use of particle reactive tracers, however, has been unexploited by limnologists.
 
Day: Thursday, Feb. 4
Time: Poster
Location: Sweeney Center
 
Code: SS52TH1137S