1. Walter Dean, USGS, Denver, CO
The Significance of Groundwater-Surface Water Interactions to the Accumulation of Iron and Manganese in the Sediments of Lakes in North-Central Minnesota: A Geological Perspective  
Walter Dean, USGS, Denver, CO 1

8. Parts per million
Parts per billion 10 9 3 6

10. 2 of the springs that occur around entire shoreline with onshore and offshore discharges

11. Lucite block Peeper before covering with dialysis membrane
Sediment porewater sampler
“Peeper”
Lucite block Peeper
before covering with
dialysis membrane
water
sediment
Two-component
mixing model
Distilled water

14. Tom Winter’s Well-Field of Dreams
meters
They didn’t come

16. years
years

17. OC OC
CaCO3
CaCO3

18. conclusions
Most of the Fe and Mn in the sediments of at least three, and probably most of the lakes in the Shingobee Rivers Headwaters Area is derived from endogenic precipitation of X-ray amorphous oxyhydroxides during fall and spring overturn; little is derived from detrital clastic material.
The amounts of Fe and Mn oxyhydroxides that ultimately are buried in the lake sediments is a balance between the rate at which they are produced during fall and spring overturn and the rate at which they are dissolved in the sediments during summer stratification.
A deep till aquifer is the source of most of the dissolved Fe and Mn in ground and surface waters.