ABSTRACT
All fluorescein samples were analyzed at the field site using a Kontron Spectrofluorometer (Model SFM-23) with an excitation wavelength of 491 nm and an emission wavelength of 513 nm. A detection limit of approximately 1 mg/L was achieved using this method. Se(VI) and Se(IV) concentrations were measured at an in-house laboratory using hydride generation atomic absorption spectrometry. Se(IV) was measured directly, while Se(VI) was determined from the difference between a sample digested to determine total selenium and Se(IV). The digestion procedure consisted of boiling equal amounts of sample with 5 mL of concentrated HC1 for 10 minutes. A detection limit for Se(Vl) of 2 /xg/L was achieved using this procedure. Se(IV) levels remained at or below the detection level of approxi mately 1 /xg/L during the entire test, and therefore, are not discussed further. Nitrate-N concentrations were measured at a commercial laboratory using cad mium reduction method (Clesceri et al., 1989). Detection limits were either 0.2 mg/L (for well 1) or 0.02 mg/L (for all other wells).
