Bicarbonate content of groundwater in carbonate rock in eastern North America

Abstract

In carbonate-rock terrane the most effective solution occurs where soil and vegetative cover facilitate biogenic production and storage of CO 2 in the soil until part of it is carried downward in percolating water. Bicarbonate data for groundwater in eastern North America are examined in the light of these conditions, of the CO 2 content of soil gas, and of the timing of groundwater recharge relative to seasonal changes in soil temperature. There appears to be no well-marked relation between latitude and bicarbonate content of groundwater in this region. Interplay of all the factors listed above, and of lithology and soil types, is evidently such that under optimum conditions the amount of solution of carbonate rock is roughly comparable, per unit of groundwater recharge, over the region from Ohio to Florida (and, perhaps, to Puerto Rico and Yucatan). Relatively low HCO 3 concentrations observed in much of the southern United States are attributed to low production and storage of CO 2 in sandy soil that is poor in organic matter. On the other hand, concentrations observed in Ontario, New York and Michigan are markedly higher than is to be expected from interrelations of the factors considered. These high values, apparently anomalous, are attributed in part to solution of granular glacial drift derived largely from carbonate rock.