COMPREHENSIVE CONTAMINANT PROFILING OF GROUNDWATER AT CAPE COD BY LIQUID CHROMATOGRAPHY/MASS SPECTROMETRY/MASS SPECTROMETRY AND ACCURATE MASS

Both liquid chromatography/mass spectrometry/mass spectrometry (LC/MS-MS) and liquid chromatography/quadrupole-time-of-flight mass spectrometry (LC/Q-TOF-MS) were used to identify trace levels of pharmaceuticals and corrosion agents in groundwater samples from a sand and gravel aquifer on Cape Cod. The sampling site was from an original infiltration bed at the Otis Air Base wastewater treatment plant. The wastewater has not been applied to the infiltration bed since 1995; thus, it gives nearly 20 years of freshwater recharge and groundwater flow to dilute the former effluent. Pharmaceuticals were found at trace levels, ng/L concentrations, at Well S469 at six depths. The lowest depths, which contained the lowest levels of dissolved organic carbon (DOC), had the least amount of pharmaceuticals and corrosion agents, while the shallowest depths had the highest concentrations of pharmaceuticals and DOC. The pharmaceuticals found included: atenolol, sulfamethoxazole, trimethoprim, carbamazepine, cotinine, diphenhydramine, metoprolol, and propranolol. This list includes blood pressure medications, antibiotics, and anxiety medications all at trace levels. The pesticide, diuron, and the anticorrosives, the benzotriazoles, were also present at trace levels. These results, when compared to today’s wastewater effluents, indicate that the majority of the pharmaceutical contaminants have been removed by dilution and degradation. These results suggest that natural attenuation is at work at the infiltration beds. Finally, these results will be interpreted with respect to their depth and oxic conditions within the infiltration beds and show the value of comprehensive contaminant profiling by accurate mass analysis and tandem mass spectrometry.