Treatment and Analysis of Glacial Sediments Using Low-precision Instrumentation

Subsurface glacial sediments play an important role in the health and treatment of water sources in Minnesota. Having a greater understanding of the composition and origin of these sediments would aid in dealing with issues associated with water sources. Typically, geomorphology analysis is performed in an attempt to determine the source of these glacial materials. Unfortunately, this method often relies on surface features, which are not preserved in buried sediments. This study sought to circumvent these issues by using geochemical analysis to more accurately characterize these sediments, and in turn, determine their origin. The main issue with analysis in this area is that most samples are very rich in carbonate. By digesting these samples in acetic acid, it was throught that strong carbonate signals would be reduced. Sediment samples were analyzed using x-ray diffraction and x-ray fluorescence spectroscopy which gave information about the compositional map of the minerals found in these sediment samples. The sediment samples were then digested in a pH=4 acetic acid/sodium acetate buffer at a 20:1 (buffer/sample) ration for a 48-hour period in a 90°C water bath. Previous methods were successful in removing acid prone sources of carbonate, but had difficulty removing the acid resistant mineral, dolomite. However, the results from the initial analysis of these sediment samples provided a methodology for easily obtaining compositional data using low precision instruments