Water resources in the vicinity of municipalities on the Eastern Mesabi Iron Range and the Vermilion Iron Range, northeastern Minnesota

Cotter, R.D.; Young, H. L.; Petri, L.R.; Prior, C.H.

doi:10.3133/ofr6322

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“…Recent published data for dissolved iron and manganese concentrations within the lake and surrounding groundwater are lacking, but data from the early 1960s are available in a USGS water-survey report (Cotter et al 1965). Iron and manganese were found to be 0.10 and 0.00 ppm (respectively) in lake surface water.…”

Section: General Geology and Limnologymentioning

confidence: 97%

Freshwater Ferromanganese Stromatolites from Lake Vermilion, Minnesota: Microbial Culturing and Environmental Scanning Electron Microscopy Investigations

Sommers¹,

Dollhopf²,

Douglas³

2002

Geomicrobiology Journal

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Lacustrine ferromanganese oxide nodules have been discovered in Lake Vermilion, northern Minnesota, USA. They occur as two morphotypes: laminated discs growing around or on cobbles ("reef-type"), and ovoid nodules on muddy gravel ("oncoidtype"). Nodules have only been found within a depth-range of »1 to 7 m, and no nodules were found on or in ne mud sediments. Oxide coatings on recent litter allowed estimates of growth rates between 2.3 to 3.5 ¹m/yr. X-ray diffraction, energy dispersive X-ray spectroscopy, and thin section and environmental scanning electron microscopy of the nodules showed microorganisms, chie y bacteria but also including cyanobacteria, diatoms, and other protozoans, mineralized by X-ray amorphous ferromanganese oxyhydroxide compounds and forming porous granular layers. ESEM examination also revealed solid-appearing layers, with no microorganism remains. Bacterial culturing experiments were carried out using lake water, sediment, and nodule swabs and pieces as the inocula. All resulted in the growth of bacteria that reduce and/or oxidize iron and manganese, showing that metal oxidizing and reducing bacteria are ubiquitous within the lake habitats. The culturing experiments also demonstrate that the bacteria can cause the formation of solid metal oxides. The combination of culturing and ESEM

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Section: General Geology and Limnologymentioning

confidence: 97%