PRELIMINARY HYDROGEOCHEMICAL INVESTIGATION OF A RECONSTRUCTED VERNAL POOL, EASTERN CONNECTICUT

The hydrogeochemistry of a reconstructed vernal pool is being investigated as one approach to assessing the success of the reconstruction. Vernal pools are unique temporary wetlands found throughout the world that fill with water for at least two months a year and dry up yearly. Because vernal pools dry up, they are free of predatory fish and provide important habitats for amphibians and invertebrate communities. Only recently has the role of vernal pools in preserving biological diversity been recognized and efforts made to reconstruct them. The purpose of this study is to investigate the hydrogeochemistry of one reconstructed vernal pool in a glaciated terrain.

The reconstructed vernal pool at Gay City State Park, Hebron, CT, is located in an isolated depression in glacial till deposited during the Pleistocene. Direct precipitation and some runoff from surrounding uplands are the only sources of water to the vernal pool. Water is lost from the pool via evapotranspiration and leakage into the subsurface. The water chemistry of the pool is primarily the result of the precipitation chemistry, geologic materials/soil, and biological activity. As with all wetlands, pH and mineral and nutrient content influence biological activity and diversity.

Preliminary results indicate that the vernal pool water chemistry is significantly different from precipitation, the main source of water to the pool. Acid precipitation (pH 4-5) is buffered in the pool yielding pH values more conducive to biological activity (pH 6-7). Although both precipitation and pool water are dilute, the pool water exhibits slightly higher electrical conductivity, indicating an increase in dissolved solid content likely due to chemical interactions with geologic materials. Decreased values of dissolved oxygen in the pool relative to precipitation indicate that oxygen is being consumed in the pool as would be expected with biological activity. Water samples for major cation and anion content are being analyzed to investigate seasonal variations in vernal pool water chemistry and the hydrogeochemical reactions occurring within the pool.