The Relative Importance of Groundwater and its Ecological Implications in Diverse Glacial Wetlands

Abstract

Abstract The hydrogeomorphic approach, which assesses a wetland's geomorphic setting, water sources, and hydrodynamics, has proven to be a useful framework for characterizing wetlands. Yet, estimating wetland water sources quantitatively across more than a few study sites remains impractical for larger comparative studies due to the time-intensive measurements required. In this research we tested the efficacy of using dissolved magnesium (Mg2+) as a semiconservative tracer of wetland water sources in southern Lower Michigan. Because concentrations of magnesium in groundwater are high due to equilibrium with dolomite in the glacial deposits, dissolved magnesium distinguished the relative importance of groundwater vs. precipitation as wetland water sources. We examined a set of 24 wetlands to consider relationships between a wetland's water sources and its geomorphic setting, water level variation, and biogeochemistry. Fens and swamps were generally groundwater-dominated, whereas wetlands dominated by Sphag...