Project: Pathways of chemicals into freshwaters and their ecological impacts (PACIFIC)
Timescale: Nov 2022-Oct 2026
Funder: UKRI Natural Environment Research Council
Principal investigator: Dr Daniel Read, UK Centre for Ecology & Hydrology

The challenge

We need to investigate how human-made chemicals make their way into freshwater ecosystems and what impacts they have, with a particular focus on freshwater microbes, which are essential to wider freshwater ecosystem health.


Manufactured chemicals such as pharmaceuticals, pesticides, and personal care products are used to maintain public health, food production, and quality of life. The use of these compounds throughout society has led to increasing concentrations and chemodiversity in the environment.

While there has been a focus on understanding the impacts of chemicals on a subset of freshwater biodiversity (particularly invertebrates and fish), we understand less about how chemical pollution impacts freshwater microbes. These microbial communities (the 'microbiome') number in the millions to billions of cells per millilitre of water or gram of sediment and form the most biodiverse and functionally important component of freshwater ecosystems.

Project overview

The PACIFIC project will investigate the relationship between predicted diffuse and point source chemical pathways and measured chemical concentrations in water and sediments at locations across the Thames and Bristol Avon catchments, chosen to represent gradients of diffuse pollution sources. These locations will coincide with Wastewater Treatment Works (WwTWs) to understand how sewage effluent contributes to chemical burden across these gradients. 

Chemical groups proven and suspected to impact freshwater ecology will be profiled and samples from each location measured using a variety of laboratory techniques including liquid chromatography, mass spectrometry and DNA sequencing to identify the impact of chemical exposure.

We will perform experimental microcosm exposures on freshwater microbial communities to determine ecological exposure thresholds and explore exposures in more realistic but controlled settings.

Models of diffuse and point source chemical pollution pathways will be combined with novel thresholds developed from the lab and field exposures to determine chemical threats to freshwater microbes, supporting the development of tools for the better management of the risks of chemical pollution to freshwater ecosystem health.

These will be combined with future hydrological, climate, and socio-economic scenarios, informed by responses in our experiments and co-developed with project collaborators, the Environment Agency, to explore future threats to microbial freshwater ecosystems and wider ecosystem health.




UKCEH people

Acting Science Area Head - Soils & Land Use / Group leader - Molecular Ecology
Principal investigator