Controls on emerging contaminants in UK rivers

The presence of emerging contaminants in river systems, such as pesticides, surfactants, flame retardants, and particularly pharmaceuticals, is an increasing environmental concern. In the UK, pharmaceuticals are widely detected in rivers, yet the processes controlling their distribution remain poorly understood. Contaminants enter rivers from multiple sources; for example, pharmaceuticals enter rivers from farm sources, including agricultural land (both grassland and cropland), wastewater treatment plants (WWTPs), and combined sewer overflows. The influence of these sources depends not only on their spatial distribution but also on factors such as population demographics, treatment infrastructure, and land use.  A combination of hydrological processes, including runoff generation, flow pathways, and groundwater-surface water interactions, determines when and how these sources connect to rivers.

This project will use two national water quality datasets: the Environment Agency’s Water Quality Archive (2000–present), covering surface and groundwater contamination, and the Chemical Investigation Programme dataset (2015–2022), which includes measurements of emerging contaminants upstream of and within WWTP effluent. These data will be analysed alongside catchment characteristics from the CAMELS-GB dataset, which provides detailed information on climate, topography, hydrology, land cover, soils, and human influences across 671 UK catchments.

By combining these datasets, the study will investigate how spatial and temporal patterns of emerging contaminant occurrence relate to catchment properties and hydrological behaviour, including comparisons between similar catchments using the Catchment Matcher Tool.

Possible research questions include:

How does hydrological connectivity influence the spatial distribution of pharmaceuticals in UK rivers?

Which catchment characteristics best explain variability in emerging contaminant concentrations?

To what extent do WWTPs versus diffuse agricultural sources control contaminant patterns?

Do catchments with similar characteristics exhibit different contamination signatures, and why?

Lead supervisors and email addresses

Dr. Laura Turnbull-Lloyd (laura.turnbull@durham.ac.uk)

Prof Sim Reaney (sim.reaney@durham.ac.uk)

Key references 

Coxon, G., Addor, N., Bloomfield, J. P., Freer, J., Fry, M., Hannaford, J., Howden, N. J. K., Lane, R., Lewis, M., Robinson, E. L., Wagener, T., and Woods, R. (2020) CAMELS-GB: hydrometeorological time series and landscape attributes for 671 catchments in Great Britain, Earth Syst. Sci. Data, 12, 2459–2483. https://doi.org/10.5194/essd-12-2459-2020

Folorunsho, O., Bogush, A., Kourtchev, I. (2025). Occurrence of emerging and persistent organic pollutants in the rivers Cam, Ouse and Thames, UK, Science of the Total Environment 962. https://doi.org/10.1016/j.scitotenv.2025.178436

Yang, Z., Worrall, F., & Knapp, J. (2025). The Impact of Sewage Treatment Plant Discharges on the Water Quality of Receiving Rivers. Ecohydrology, 18(5), Article e70087. https://doi.org/10.1002/eco.70087