Investigating levels and behaviour of pharmaceutical and personal care products (PPCPs) in freshwater sediment

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Dawood, Abdalkarim Mohamed A. ORCID: https://orcid.org/0009-0005-4149-0151 (2023). Investigating levels and behaviour of pharmaceutical and personal care products (PPCPs) in freshwater sediment. University of Birmingham. Ph.D.

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Abstract

Pharmaceuticals and personal care products (PPCPs) have received increasing scientific interest as emerging pollutants that have the potential to harm the environment and human health. While sediment has been identified as a major sink for several legacy chemical pollutants, very little is known on the concentrations and profiles of PPCPs in sediment, particularly in the freshwater environment.

In this thesis, an analytical method was optimised for determination of 30 widely used PPCPs in sediment samples using ultraperformance liquid chromatography (UPLC), coupled to high resolution mass spectrometry (HRMS). The average concentrations of Σ30PPCPs in sediment samples from the River Tame, Coventry Canal, River Severn, and Birmingham & Worcester Canal, were 129, 79, 62, and 110 ng/g, respectively. Investigation into the distribution of PPCPs between sediment and water revealed a significant positive correlation between LogKOW of the studied compounds and their experimentally measured sediment–water distribution coefficient (LogKP). Amoxicillin, caffeine, and 17-α-ethinylestradiol had estimated risk quotients (RQ) higher than 1 in the four study locations, raising concern over the risk of these chemicals to freshwater biota.

Over the course of a year, large seasonal variations were observed in the concentrations of target 30 PPCPs in sediment samples collected monthly from the River Sowe, River Tame, River Severn, and Worcester & Birmingham Canal (with coefficients of variation (%) of 116 %, 119 %t, 120 %, and 133 %, respectively). Highest PPCPs concentrations in all locations were recorded in summer, while the lowest concentrations were measured in winter. This could be partially explained by the lower flowrates and reduced rain fall in summer, which may facilitate the partitioning of PPCPs from water to sediment. Principle component analysis (PCA) revealed the observed variance in results may be attributed to various sources of different PPCPs to the studied waterways, including run-off from agricultural land, sewage discharge, and veterinary applications of some PPCPs in livestock farming and aquaculture. Moreover, Σ30PPCPs concentrations in sediment downstream of WWTPs in the studied rivers were significantly higher (P < 0.05) than those measured in upstream samples. This confirms the role of WWTPs as major input sources of PPCPs to freshwater sediments due to inefficient removal of these contaminants by traditional wastewater treatment processes.

Globally, the concentrations and profiles of 30 target PPCPs were measured and compared in sediment samples collected from rivers and freshwater lakes from 13 countries. Concentrations of Σ30PPCPs in African sediment samples were significantly higher than those from other continents. The Klang River sediment in Malaysia had the highest Σ30PPCPs concentration of (459 ng/g), while the Detriot River in the United States had the lowest concentration (159 ng/g). PPCPs profiles in sediment were correlated with their usage profiles in the studied countries, highlighting trends of extensive usage of antibiotics in Africa and Asia, as well as increasing consumption of anxiolytic drugs in Europe and North America to mitigate the negative impact of COVID-19 lockdown measures on mental health.

Overall, the results of this thesis provide important information on baseline concentrations of PPCPs in freshwater sediment from the UK and worldwide, as well as highlighting their potential risk to aquatic biota. While available literature focuses mainly on PPCPs in water, further research is required to fully understand the fate and risk of PPCPs in sediment.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):