Pharmaceuticals and Personal Care Products in the Tidal Freshwater Potomac River
Date
2019
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Abstract
It is believed that the principal source of pharmaceuticals and personal care products (PPCPs) in rivers and streams is directly linked to the high consumption rate of drugs in our society. As such, PPCPs and their metabolites are inadvertently released into the rivers and streams through reclaimed water and waste treatment plant (WTP) discharge. Understanding the sources, emissions, and effects of PPCPs in surface waters is essential to managing public health and enlightening our society about the environmental implications of overprescribed drug therapy. The goals of the present study were to (i) characterize the presence, spatial distribution, and temporal variability in the concentrations of PPCPs in water and sediments throughout the tidal freshwater Potomac River (TFWPR), (ii) evaluate the interfacial dynamics of PPCPs in the TFWPR through the quantification of sediment-water fluxes along a downstream transect near a high capacity waste treatment facility, and (iii) investigate the burial profiles of PPCPs in river sediments. PPCPs (96 individual constituents) were analyzed in river samples using solid phase (water) and solvent extraction (QuEChERS) techniques coupled with liquid chromatography-mass spectrometry (LC-MS/MS). Approximately 42 PPCPs were quantified in river samples by LC-MS/MS at 14 individual sampling sites. Spatial analysis revealed that PPCP export from the TFWPR exceeded input, showing that the major WTPs markedly increase river concentrations. In addition, the greatest PPCP concentrations were generally found nearest the WTP outfalls. Seasonality in PPCP water concentrations was directly related to use patterns. Determination of PPCP sediment-water distribution constants indicated that mineral sorption likely plays a significant role sediment uptake. Results from sediment-water fluxes showed that bed sediments near the WTP outfalls were accumulating PPCPs, and that fluxes reversed direction further downstream. It was determined that sediment can serve as either a sink or a source of PPCPs into the water column depending upon the location and distance from the outfall studied. In addition, it was found that bioturbation had a significant role in overall fluxes. Lastly, the study also determined the nature of sediment burial and historical deposition profiles of PPCPs present in a sediment core taken from a location downstream of a high-capacity WTP in the Gunston Cove region. It was concluded that PPCPs have a significantly different historical depth profile when compared to other legacy micropollutants such as organochlorine pesticides because of the differences in their deposition rates, degradation processes, and different physical and chemical properties. Furthermore, the depth profiles suggested that PPCPs do not persist in sediments. The present study demonstrated that understanding the sources, emissions, and effects of PPCPs in surface waters is essential to managing public health and enlightening our society about the environmental implications of overprescribed drug therapy. In addition, valuable information concerning the presence, spatial distribution, and temporal variability in the concentrations of PPCPs in water and sediments, the interfacial dynamics of PPCPs, and the burial profiles of PPCPs in river sediments was obtained as part of the effort to understand these matters.