Evaluating pharmaceuticals and other organic contaminants in the Lac du Flambeau Chain of Lakes using risk-based screening techniques
Matthew A. Pronschinske ,Steven R. Corsi,Celeste Hockings
Abstract
In an investigation of pharmaceutical contamination in the Lac du Flambeau Chain of Lakes (hereafter referred to as “the Chain”), few contaminants were detected; only eight pharmaceuticals and one pesticide were identified among the 110 pharmaceuticals and other organic contaminants monitored in surface water samples. This study, conducted in cooperation with the Lac du Flambeau Tribe’s Water Resource Program, investigated these organic contaminants and potential biological effects in channels connecting lakes throughout the Chain, including the Moss Lake Outlet site, adjacent to the wastewater treatment plant lagoon. Of the 6 sites monitored and 24 samples analyzed, sample concentrations and contaminant detection frequencies were greatest at the Moss Lake Outlet site; however, the concentrations and detection frequencies of this study were comparable to other pharmaceutical investigations in basins with similar characteristics. Because established water-quality benchmarks do not exist for the pharmaceuticals detected in this study, alternative screening-level water-quality benchmarks, developed using two U.S.
Introduction
Pharmaceuticals are recognized as aquatic contaminants of emerging concern (CECs) because they have been detected in surface waters around the world and sometimes occur at concentrations which may negatively impact aquatic life [1, 2]. Pharmaceuticals are used daily around the world and are typically designed to have highly specific effects, such as antibiotics that target bacterial infections and anticonvulsants that are designed to treat seizures. Although pharmaceuticals have targeted effects, they often persist beyond their intended targets and are passed through the digestive systems of human or domestic animal targets into waste which retains the potential for eliciting biological activity if not effectively treated [3–5].
Material and methods
Sampling design and collection
For this study, surface water samples were collected quarterly for one year (1: August 2020, 2: November 2020, 3: February 2021, and 4: May 2021) at six sites along the Lac du Flambeau Chain of Lakes (Fig 1). Study site locations were selected in channels between lakes to characterize the water flowing through the Chain before it empties into the Bear River at Flambeau Lake Outlet, the most downstream sampling site. A geographic information system was used to determine the drainage area and land cover of each of the sampling sites; further methodological details are included in the Supplemental Information.
Results
Occurrence and magnitude
In this study, only 9 contaminants (8 pharmaceuticals and 1 pesticide) were detected from among the 110 analytes monitored in 24 samples (S2 Table), and sample data can be accessed using the Nation Water Information System [31]. The number of contaminants detected at each site ranged from 1 to 6 (Crawling Stone Lake Outlet, 1; Fence Lake Outlet and Long Lake Outlet, 2; Pokegama Lake Outlet and Flambeau Lake Outlet, 4; Moss Lake Outlet, 6). The quarterly samples collected in May 2021 had the greatest number of detections (17) whereas the fewest chemicals (4) were detected in November 2020 quarterly samples. Four contaminants were detected only once: acetaminophen, fluconazole, methocarbamol, and thiabendazole.
Discussion
Occurrence and magnitude
In general, the detection frequencies and concentration levels for the sites and contaminants monitored in this study were low. The influence of the WWTP lagoon was not quantified in this study, but Moss Lake Outlet stands out as having substantially greater contaminant detection frequencies and concentrations than other sites. The elevated concentrations at Moss Lake Outlet indicate that contaminants could be leaching from the municipal wastewater treated by the facultative lagoon into this lake. However, even the elevated Moss Lake Outlet sample concentrations are comparable to sample results from two similar studies which are described in further detail below [16, 25]. The relatively low degree of influence exhibited by the WWTP lagoon adjacent to this Chain may be due in part to dilution and potential infiltration from the wetland which the lagoon discharges into before entering the lake [46]. Further, the pharmaceutical concentrations observed in this study may be the result of residual contamination from wastewater treated before the system was upgraded in October 2020. The upgraded treatment system and processes (further described in the Supplemental Information) may result in even fewer pharmaceutical detections and/or lower concentrations than those observed in this study.
Conclusion
Pharmaceuticals were not prevalent at most sites in this study, with more than 60% of samples containing no contaminants other than atrazine (a pesticide included within the analytical schedule). Only 9 of the 110 contaminants monitored in this study were detected: 8 pharmaceuticals (acetaminophen, caffeine, carbamazepine, fluconazole, gabapentin, metformin, methocarbamol, thiabendazole) and 1 pesticide (atrazine). Contaminant detections seemed to exhibit a seasonal pattern with peak concentrations in May 2021 and minimum concentrations during November 2020. The water chemistry results from this study had comparable concentration magnitudes and detection frequencies to those of similar studies of analogous watersheds. In the current study, pharmaceuticals were most frequently detected and had the greatest concentrations in samples from Moss Lake Outlet, suggesting that this site may be influenced by the adjacent WWTP lagoon which contains municipal wastewater from the Lac du Flambeau community.
Acknowledgments
The authors gratefully acknowledge A. Virden, J. De Vries, B. Cook, J. Wilber, K. Hanson, and D. Allen for assistance in the collection and processing of samples. Thanks to S. Valliere and the Indian Health Service for assistance with revisions to the manuscript. Thanks to the analysts at the U.S. Geological Survey’s National Water Quality Laboratory for all chemical analyses. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
Citation: Pronschinske MA, Corsi SR, Hockings C (2023) Evaluating pharmaceuticals and other organic contaminants in the Lac du Flambeau Chain of Lakes using risk-based screening techniques. PLoS ONE 18(6): e0286571. https://doi.org/10.1371/journal.pone.0286571
Editor: Xiaoshan Zhu, Tsinghua University, CHINA
Received: September 28, 2022; Accepted: May 18, 2023; Published: June 2, 2023
This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.
Data Availability: All relevant data are within the paper and its Supporting information files, and water chemistry data are also available online at https://waterdata.usgs.gov/nwis.
Funding: CH received a grant on behalf of the Lac du Flambeau Band of Lake Superior Chippewa Indians (URL: https://www.ldftribe.com/). The grant was awarded by the U.S. Environmental Protection Agency (URL: https://www.epa.gov/) under agreement number AA00E02790. MP also received support from US Geological Survey through cooperative matching funds (URL: https://www.usgs.gov/mission-areas/water-resources/science/usgs-cooperative-matching-funds). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
