Presence of Pharmaceuticals and Personal Care Products in Sinkhole Lakes in West-Central Florida

Graduation Year

2024

Document Type

Dissertation

Degree

Ph.D.

Degree Name

Doctor of Philosophy (Ph.D.)

Degree Granting Department

School of Geosciences

Major Professor

Philip van Beynen, Ph.D.

Committee Member

Laurent Calcul, Ph.D.

Committee Member

Jeffrey Cunningham, Ph.D.

Committee Member

Mark Rains, Ph.D.

Committee Member

Kamal Alsharif, Ph.D.

Keywords

Rainfall, Organic compounds, LC-MS/MS, Seasonality, Septic Tanks

Abstract

Pharmaceuticals and personal care products (PPCPs) are essential for human health, improving quality of life, and extending life expectancy. However, many of these chemicals have become significant environmental pollutants, particularly in lentic (lake) environments. One unintended source of PPCPs in natural environments is onsite wastewater treatment systems (OWTS), commonly known as septic tanks.

This study examines whether the seasonal variability of rainfall and soil saturation affects the assemblages and concentrations of PPCPs in a residential lake. The general premise of the dissertation was that with the onset of the wet season, PPCPs that had collected in the drainfields of the OWTS would be flushed into the lake as soils became saturated. Target PPCPs for this study were theophylline, caffeine, cotinine, acetaminophen, sulfamethoxazole, methylparaben, DEET, carbamazepine, propylparaben, testosterone, ibuprofen, fluoxetine, atorvastatin, and octocrylene. In addition, the environmental risk quotient (RQ) was calculated for maximum and mean concentrations to determine the potential stress on aquatic organisms.

The site for this study was a residential lake located in Riverview, Hillsborough County, Florida. This lake was selected because it fulfilled many of the requirements needed to conduct the research: 1) lake surrounded by OWTSs, 2) no input of water into lake from nearby streams, 3) the presence of PPCPs had already been established, 4) a nearby lake located within a nature preserve provided a “control” for the study.

Weekly water sample collections from both the residential and natural lakes commenced during the last few months of the dry season (starting April 30th) to well into the wet season (August 30th). These water samples were then subjected to solid-phase extraction to isolate the PPCPs from the water. The resulting samples were then analyzed using a LC-MS/MS to determine the exact concentrations of the PPCPs in the sampled water. Of all the PPCPs detected, only DEET concentrations were significantly higher in the wet season compared to the dry season. In contrast, caffeine, cotinine, and testosterone concentrations decreased during the wet season. Overall, more compounds were detected during the wet season, with highly hydrophobic PPCPs (fluoxetine, atorvastatin, and octocrylene) only present during this period.

The RQmax values varied between seasons, with more PPCPs showing higher RQ values in the wet season. Caffeine posed the highest environmental risk across all three trophic levels: fish, daphnia, and algae. Testosterone had a higher RQ for daphnia in the dry season. The RQ calculated on mean PPCP concentrations showed that the RQmean was higher in the dry season.

The purpose of the natural lake was to determine whether PPCPs occurred in a very similar area, but that was not impacted directly by OWTS. Surprisingly, PPCPs were present in this lake. The FAS had no direct connection, nor was well water being used on the property. The only possible source was a community 200 m south of the lake in which the homes used OWTS.

Overall, the results underscore the significant presence of PPCPs in lentic environments. The absence of some compounds at specific sampling locations indicates that sampling only once at a single location during the hydrological year in a septic-fed lake may lead to incorrect conclusions. Therefore, the findings of this study emphasize the importance of consistent monitoring, which is crucial to understanding the processes occurring in lentic environments and making informed decisions about environmental protection.

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