『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⁺-HO3^- 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^-.

keywords: carbon; groundwaters; Michigan; carbonate saturation; dolomite dissolution; carbon dioxide.』

Introduction
Hydrogeologic framework of field study sites
Methods
　Field sampling
　Laboratory analyses
　Thermodynamic modeling and aqueous speciation
Results and interpretations
　Elemental stoichiometries and mineral-water reactions
　Carbonate speciation and carbonate mineral equilibria
　Mass balancing dissolution and precipitation: Mg²⁺/HCO3^- as conservative tracer
　Comparisons with North American drainage: Divalent cation and inorganic carbon budgets
Summary and conclusions
Acknowledgments
References cited