Researchers at the University of Cambridge and Trent University, Canada have developed a new water quality analysis technique that can identify the source of pollutants in rivers and freshwater lakes. By using high-resolution mass spectrometry to analyze water samples, the approach can detect microparticles from car tyres, pesticides from farmers’ fields, and toxins from harmful algal blooms. This allows researchers to understand the impact these chemicals are likely to have in a particular river or lake, as well as point to the origin of specific organic matter dissolved in the water based on its composition.
Chemodiversity, the diversity of organic matter dissolved in water, plays a significant role in determining water quality. The thousands of different dissolved organic compounds present in freshwater ecosystems can either help to keep the ecosystem healthy or contribute to their decline, depending on the mixture that is present. This new approach provides a simple and comprehensive overview of the organic molecules present in a particular river or lake, allowing researchers to quickly understand the state of the water and identify sources of pollution.
By reviewing studies of dissolved organic matter in freshwater samples from rivers and lakes across Europe and northern Canada, the research team was able to gain insights into what drives chemodiversity in these ecosystems. For example, analyzing water samples from Lake Erie in Canada revealed high levels of phosphorus pollution, which was identified as originating from agricultural activities rather than wastewater effluent. This new approach allows researchers to use the unique molecular fingerprint of different sources of pollution in freshwater to pinpoint their origin, providing a more accurate understanding of water quality.
Traditional approaches to monitoring water quality involve separately measuring various indicators of ecosystem health, such as organic nutrients and pollutants like nitrogen. These measurements can indicate the condition of the water, but do not provide insight into why this condition has arisen. Dissolved organic matter is a complex mixture consisting of thousands of individual molecules, each with unique properties that influence processes in rivers and lakes such as nutrient cycling, carbon storage, light absorption, and food web interactions – all of which determine ecosystem function.
Sources of dissolved organic matter in freshwater include urban runoff, agricultural runoff, aerosols, and wildfires. Monitoring the health of freshwater through the diversity of compounds present can provide valuable insights into the state of the ecosystem, and the new approach developed by the researchers is being rolled out across the UK. Moving forward, the team plans to apply this technique to analyze water samples from farmland drainage ditches in the Fens as part of a project to understand freshwater health in this agricultural landscape, showcasing the potential impact of this innovative approach on water quality analysis.
