AbstractChemicals in the environment are of growing concern as this presence is increasing alongside human population and use. There is increasing evidence that these contaminants of emerging concern (CECs) could drastically impact the environment, despite regulation and legislation in many countries across the world to monitor and limit them.
Current literature concludes there is a need for analytical methods sensitive enough to quantify chemicals from a wide range of classes, e.g. pharmaceuticals, industrial chemicals and pesticides, in various environmental matrices. However, current studies are limited by a small range of chemicals, low method sensitivity and being focussed on aqueous matrices only.
This work captures the development and validation of a highly sensitive ultra-performance liquid chromatography coupled with tandem mass spectrometry method for the analysis of five environmentally relevant matrices. This method has method quantification limits of 0.004 ng L-1 (bisphenol A in surface water) to 3,118 ng L-1 (creatinine in wastewater influent) and method accuracy and precision of 107.0% and 13.4% for 142 compounds covering 33 different classes. This method was then applied to 5 wastewater treatment works (WwTWs) within the same river catchment in South-West England, providing a detailed high-resolution picture of the levels of chemical contamination and the contribution from the local population.
Within this catchment it was found that raw wastewater entering the WwTWs contained 169.3 kg d-1 of CECs, the majority of which was found in the liquid phase, with only 1.4 kg d-1 found adsorbed to suspended particulate matter. The population normalised load was very consistent across the catchment with 154 ± 12 mg d-1 inhabitant-1. Although the WwTWs removed most of the CECs from the liquid phase, there was variation between the WwTWs, with WwTW A only discharging 0.19 kg d-1 and 7.3 kg d-1 at WwTW E. However, this did correlate highly with the contributing population. Whether the CECs were completely degraded, adsorbed to the solid phase or transformed is unknown, future work should consider the use of untargeted analysis and further sampling of the solid matrices during treatment processes to determine the final fate. Analysis of the solid phases showed a preference for antifungals and antidepressants to adsorb to the matrix. Analysis of the surface water showed many CECs were ubiquitous through the catchment with daily loads ranging from 0.005 g d-1 (ketamine) to 1890.3 g d-1 (metformin).
This data was then combined with existing ecotoxicity data to provide an environment risk assessment (ERA) of these CECs in this catchment. Overall, it was found that there was minimal risk from individual CECs, however similarly acting chemicals in the same group may pose a much higher risk. It also showed increasing levels of CECs and environmental risk as the river flowed through higher populated urban areas.
A novel ecotoxicity test using the protozoa, Tetrahymena Thermophila, was also developed. This test allows smaller quantities of contaminants to be tested but is also highly sensitive and has showed critical evidence of stereospecific ecotoxicity.
Further work should include the use of HR (high-resolution)-MS, analysis of metabolites and transformation products, and the further combination of both chemical and biological approaches.
|Date of Award||24 Jun 2020|
|Supervisor||Barbara Kasprzyk-Hordern (Supervisor), Tom Arnot (Supervisor) & Ruth Barden (Supervisor)|