Dissolved organic matter could be used to track and improve the health of freshwaters

The dissolved organic matter (DOM) from hundreds of plant and animal remains could be used to track and possibly restore the health of freshwater bodies, Andrew J. Tanentzap and Jérémy A. Fonvielle write in this Perspective. The broad range of compounds, or chemodiversity, of DOM has multiple effects in freshwaters, including providing nutrients to support food web productivity, reducing or enhancing contamination from pollutants, and influencing the metabolism of microorganisms important to the biogeochemical cycle. DOM may also reduce the heat that reaches the deeper, cooler waters that helps to offset some of the impacts of climate warming. Tanentzap and Fonvielle say that high-resolution mass spectrometry can be used to assess freshwater chemodiversity in a way that allows researchers to better pinpoint pollution sources, including those in drinking water, and monitor changes in DOM that could affect freshwater ecosystem health. In one example provided by the authors, DOM chemodiversity analysis was used to determine that a major tributary of Lake Erie shared nearly 30% more organic phosphorus compounds with cropland drainage than with wastewater effluent, leading to the conclusion that inorganic fertilizers were the main source of phosphorus pollution.