The carbonate system geochemistry of shallow groundwater-surface water systems in temperate glaciated watersheds (Michigan, USA): Significance of open-system dolomite weathering

Abstract

Research Article| May 01, 2007 The carbonate system geochemistry of shallow groundwater–surface water systems in temperate glaciated watersheds (Michigan, USA): Significance of open-system dolomite weathering Erika L. Williams; Erika L. Williams 1Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA Search for other works by this author on: GSW Google Scholar Kathryn J. Szramek; Kathryn J. Szramek 1Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA Search for other works by this author on: GSW Google Scholar Lixin Jin; Lixin Jin 1Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA Search for other works by this author on: GSW Google Scholar Timothy C.W. Ku; Timothy C.W. Ku 2Department of Earth and Environmental Sciences, Wesleyan University, Middletown, Connecticut 06459, USA Search for other works by this author on: GSW Google Scholar Lynn M. Walter Lynn M. Walter 3Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Erika L. Williams 1Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA Kathryn J. Szramek 1Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA Lixin Jin 1Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA Timothy C.W. Ku 2Department of Earth and Environmental Sciences, Wesleyan University, Middletown, Connecticut 06459, USA Lynn M. Walter 3Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA Publisher: Geological Society of America Received: 13 Jan 2006 Revision Received: 29 Sep 2006 Accepted: 04 Dec 2006 First Online: 08 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 GEOLOGICAL SOCIETY OF AMERICA GSA Bulletin (2007) 119 (5-6): 515–528. https://doi.org/10.1130/B25967.1 Article history Received: 13 Jan 2006 Revision Received: 29 Sep 2006 Accepted: 04 Dec 2006 First Online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Erika L. Williams, Kathryn J. Szramek, Lixin Jin, Timothy C.W. Ku, Lynn M. Walter; The carbonate system geochemistry of shallow groundwater–surface water systems in temperate glaciated watersheds (Michigan, USA): Significance of open-system dolomite weathering. GSA Bulletin 2007;; 119 (5-6): 515–528. doi: https://doi.org/10.1130/B25967.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract We present here a field geochemical study of controls on carbonate weathering within rapidly circulating, shallow groundwater–surface water systems in the glaciated mid-continent region. Groundwaters and surface waters in three watersheds spanning the Upper to Lower Peninsulas of Michigan consist of Ca2+-Mg2+-HCO3− solutions derived from the open-system dissolution of calcite and dolomite in soils developed on mixed mineralogy glacial drift. The thermodynamic stabilities of calcite and dolomite both decrease with decreasing temperature, with dolomite more strongly affected. Thus, the low mean annual temperature of these temperate weathering environments maximizes the absolute solubility of dolomite as well as its solubility relative to calcite. Many groundwaters in the study area approach equilibrium with respect to the more soluble dolomite and are moderately supersaturated with respect to calcite. Groundwaters in each watershed have distinct and relatively narrow ranges of carbon dioxide partial pressure (PCO2) values, which increase significantly from north to south (log PCO2 of −3.0 to −2.2 atm), suggesting that there are landscape-level differences in carbon transformation rates in soil weathering zones. Increases in weathering-zone PCO2 values produce HCO3− concentrations that vary by a factor of five, but the Mg2+/Ca2+ and Mg2+/HCO3− ratios of all groundwaters are similar, suggesting relatively constant weathering input ratios of calcite and dolomite. Although surface waters commonly are between 2 and 10 times supersaturated with respect to calcite, the Mg2+/HCO3− ratios of surface waters are very close to initial groundwater values, suggesting that back precipitation of calcite is not a significant process in these systems. The enhanced solubility of dolomite at low temperatures coupled with the landscape-level differences in carbon cycling suggest that temperate-zone weathering reactions in glaciated terrains are significant contributors to continent-scale fluxes of both Mg2+and HCO3−. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.