Niemi, Gerald JHarriss, Donald K2023-11-092023-11-091985https://hdl.handle.net/11299/258084The year given (1985) is an estimate.Water samples were analyzed from 40 sites at three depths (surface, middle, and 1 m above bottom) and sediment samples from 28 sites for amphibole and chrysotile asbestos fibers. Two analytical methods were used: x-ray diffraction (XRD) was used to estimate mass concentration of amphibole minerals and electron microscopy (EM) to estimate the actual number of fibers. The concentration of fibers was highest in samples collected from the western end of Lake Superior where water samples had concentrations that ranged up to 68 million fibers/1 and sediment samples up to 9.6 million fibers/mg of sediment. Amphibole fiber concentrations were moderate to low in the northern section of Lake Superior where water samples ranged from below detection up to 8.5 million fibers/1 and sediment samples ranged from below detection up to 0.5 million fibers/mg of sediment. Amphibole fiber concentrations in the eastern end of Lake Superior were much lower than in the western end. Generally, water concentrations ranged from below detection up to 1.6 million fibers/I and sediment concentrations from below detection up to .36 million fibers/mg of sediment. The origin of all fibers throughout Lake Superior cannot be determined, but the higher concentrations and the elemental composition of fibers in the western end of Lake Superior suggests that the Reserve Mining taconite facility was the major contributor.enNatural Resources Research InstituteUniversity of Minnesota DuluthReport