Ultrahigh- and high-resolution mass spectrometry (UHRMS/HRMS) is rapidly reshaping how scientists read the “molecular handwriting” of dissolved organic matter (DOM)—a complex mixture that influences water quality, ecosystem functioning, and how pollutants move through aquatic environments. In a new Review, researchers argue that these advanced instruments are opening a once “black-box” link between DOM composition and a world that is changing through human activity and climate stress.
The authors emphasize that UHRMS can resolve molecular complexity with sufficient detail to detect both direct anthropogenic signatures and indirect, anthropogenic-driven transformations. Instead of treating DOM as a bulk pool, the approach aims to map its molecular formulae and compound classes, revealing patterns tied to land use and environmental perturbations.
A central theme is how human pressures alter DOM’s elemental makeup. Changes in heteroatom content—especially nitrogen and sulfur (N,S)—and shifts in compound families can be traced to specific stressors such as agriculture, urbanization, wildfire regimes, and climate change. These signals act as molecular fingerprints, allowing researchers to distinguish between natural variability and human-influenced chemistry.
Beyond cataloging molecules, the Review connects molecular indicators to processes occurring across catchments and waterways. Agricultural inputs, for instance, can reshape nutrient-driven DOM formation pathways, while urban and industrial activities may introduce or transform S- and N-bearing compounds. Fire and climate-related changes further modify the chemical pathways that generate and degrade DOM.
The Review also highlights a technical frontier: bridging composition-level information with structural identification. UHRMS can suggest what molecules might be present through accurate mass and formula predictions, but converting that into unambiguous structures remains challenging. The authors call for analytical strategies that integrate molecular tracers with stronger structural characterization.
Practical recommendations focus on standardization and data transparency, two requirements for making molecular indicators comparable across studies and instruments. Without shared workflows and accessible datasets, pattern recognition—crucial for identifying anthropogenic impacts—can become fragmented.
Taken together, the work positions UHRMS as a powerful tool for monitoring and interpreting anthropogenic influence in aquatic systems. With improved methods, reproducible protocols, and better linking of molecular data to structure, the technique could move from descriptive chemistry toward a more diagnostic environmental science.
Finally, the Review stresses that progress depends on opening the analytical “window” wider—connecting high-dimensional mass spectral data to clearer mechanistic interpretations. Such advances could help researchers evaluate how human activities are reshaping DOM at the molecular level, and how those changes propagate through aquatic ecosystems over time.
DOI: https://doi.org/10.1038/s44221-026-00682-1
Article Title: The use of ultrahigh- and high-resolution mass spectrometry to examine the anthropogenic signature of dissolved organic matter in aquatic systems.
Article References: Spencer, R.G.M., Remucal, C.K., Borch, T. et al. The use of ultrahigh- and high-resolution mass spectrometry to examine the anthropogenic signature of dissolved organic matter in aquatic systems. Nat Water (2026). https://doi.org/10.1038/s44221-026-00682-1
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