The University Scholars Program

Radiogenic 87Sr is preferentially leached over the non-radiogenic Sr isotopes (84,86,88Sr) during the initial weathering of fresh bedrock and sediments in glacial terrains. Therefore, the magnitude of the difference between 87Sr isotope values of water and bedrock provides valuable information about the extent of chemical weathering, which in turn, controls the fluxes of radiogenic isotopes of Sr from continents to the oceans. Variations in these fluxes are recorded in marine sediments, which may allow reconstruction of the timing of the advance and retreat of continental glaciers. The intensity of weathering differs among the various types of drainage systems near continental glaciers, including pro-glacial streams and de-glaciated watersheds, and this proposed work aims to assess the relative flux of radiogenic Sr from these different watersheds that are exposed as the Greenland Ice Sheet retreats. As of now, no studies have examined 87Sr fluxes from the different types of glacial watersheds to the oceans, so their effects on marine records are not known. Consequently, I will investigate the 87Sr composition of surface water samples collected from Western Greenland in order to determine the extent of chemical weathering in pro-glacial and de-glaciated watersheds. The separation of dissolved strontium from the water samples will be carried out by cation-exchange chromatography and analysis will be done by mass spectrometry. Understanding the relationship between chemical weathering and the fluxes of radiogenic isotopes of Sr from continents to the oceans is vital to the interpretation of marine records. This project will also help determine the variation of weathering intensity in different watershed environments, which will become more important as glaciers recede and expose more ground surface to differential weathering.