A COMPARISON OF δ18O AND δ2H AND BULK WATER CHEMISTRY ANAYLSES OF SPRINGS IN THE SHENADOAH VALLEY

The Shenandoah Valley has long been recognized for its high density of springs, which is known to be due to the unique geologic history and extensive karstic nature of the area. These spring waters are also known to exhibit a very diverse hydrochemistry. We propose to add to the understanding of the geochemical origin and fate of these spring waters by studying the their oxygen (δ¹⁸O) and deuterium (δ²H) isotopic composition and comparing these values to the Global Meteoric Water Line (GMWL) (Craig,1961), in addition to bulk water chemistry (specific conductance, temperature, pH, Eh, alkalinity, K⁺, Na⁺, Ca²⁺, Mg²⁺, Fe(tot), F^-, NO₃^-, SO₄^2-, Cl^-, and PO₄^3-).

Premilinary data indicate that these waters vary widely geochemically from Ca+Mg: HCO₃+CO₃ to Na+K+Ca+Mg: Cl +SO₄. Most of these waters are minimally fractionated from the GMWL, meaning that they are likely to be meteoric in origin.

Additional sampling and chemical/isotopic analysis is being conducted to further describe these variations in water chemistry as well as relate the variability to the depth of origin and geologic controls (faulting, folding, etc.) that might also be controlling the various types of water chemistries.