Expanding environmental monitoring campaigns: Contaminants of emerging concern are also present in “unimpacted” watersheds

Academic Research Topics in Environmental Measurement and Monitoring
Oral Presentation

Prepared by , K. He

Contact Information: blaney@umbc.edu; 410-455-8608


The objective of this work was to explore the presence of contaminants of emerging concern (CECs) in an urban watershed that is not impacted by upstream wastewater treatment plants or animal feeding operations. This study was focused on the Gwynns Falls watershed (Maryland), which has a population of approximately 350,000 people in Baltimore County/City. We conducted separate 10-week sampling campaigns in summer and winter 2016. Samples were analyzed for a large suite of CECs: 45 antibiotics from the fluoroquinolone, macrolide, sulfonamide, and tetracycline classes; 5 UV-filters, which are organic sunscreen agents; and, 3 estrogenic hormones. All CECs were quantified using solid-phase extraction liquid chromatography with tandem mass spectrometry. A number of antibiotics were frequently detected. For example, erythromycin, meclocycline, and sulfamethoxazole were detected in 36%, 28%, and 23%, respectively, of the summer samples. Note that erythromycin is the only antibiotic present on the EPA Candidate Contaminant List. The tetracycline antibiotics, doxycycline and meclocycline, were both detected at concentrations higher than 100 ng/L. At least two UV-filters were detected in every sample; furthermore, oxybenzone and octinoxate concentrations showed clear trends across the rural-to-urban flow gradient of the watershed. Estrone was the most frequently detected estrogenic hormone with concentrations in the 1-10 ng/L range. Although the synthetic hormone, 17α-ethinylestradiol, was not detected in water samples, we did detect it in select sediment and biota from the sampling sites. In general, the occurrence and concentration of CECs was greater for downstream, urban sites. Since wastewater exfiltration can be as high as 10-20% of dry-weather flow, the source of these diverse CECs in the Gwynns Falls watershed may stem from leaking sewers. In this manner, CEC monitoring campaigns in unimpacted watersheds will not only yield important water quality data, but may also serve as a useful forensics tool to locate sewer leaks.