Characterization of Dissolved Organic Matter in Aquatic Systems

Dissolved organic matter (DOM) represents a vast and chemically diverse assemblage of organic molecules in freshwater and marine environments. Its composition reflects inputs from terrestrial vegetation, microbial production and photochemical transformation, and its fate influences global carbon cycling, water quality and contaminant transport. Characterisation of DOM relies on complementary high-resolution analytical tools—such as mass spectrometry, spectroscopy and fluorescence techniques—to resolve molecular formulae, structural motifs and reactive intermediates. These insights underpin models of DOM lability, photoreactivity and microbial utilisation, yielding practical applications in biogeochemistry, water treatment and climate feedback assessment. Advances in understanding DOM assembly, persistence and reactivity continue to reveal universal patterns and site-specific adaptation, thereby strengthening predictions of ecosystem responses to environmental change.

Research from Nature Portfolio

Recent studies have employed advanced spectroscopic and spectrometric approaches to unravel DOM structure and processing pathways. One investigation used multiplicity-edited 13C nuclear magnetic resonance (NMR) to characterise DOM from major tropical rivers and boreal lakes, identifying oxidative dearomatisation (ODA) of polyphenolic precursors as a key driver of structural diversity. This mechanism generates unusual tetrahedral quaternary carbons and promotes formation of oxygenated aliphatic frameworks at early stages of DOM processing. Another study combined ultrahigh-resolution mass spectrometry with microbial sequencing in permafrost-affected lakes to demonstrate that photo-produced aromatic compounds, rather than low-molecular-weight aliphatics, accelerate biodegradation of dissolved organic carbon. These findings highlight the interplay of photochemical and biological pathways in regulating carbon turnover under changing light regimes.

Characterization of Dissolved Organic Matter in Aquatic Systems publication trend

The graph below shows the total number of articles in characterization of dissolved organic matter in aquatic systems across all publications each year (not limited to Nature Index journals).

Technical terms

Dissolved organic matter (DOM): Broad array of organic compounds dissolved in aquatic environments, including humic substances, carbohydrates and lipids.

Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS): Ultra-high resolution mass spectrometric technique for resolving complex organic mixtures at molecular level.

Nuclear magnetic resonance (NMR) spectroscopy: Analytical method using magnetic fields to elucidate structural features of organic molecules.

Oxidative dearomatisation (ODA): Reaction mechanism converting aromatic rings into oxygen-containing aliphatic structures, enhancing molecular diversity.

Chromophoric dissolved organic matter (CDOM): Fraction of DOM that absorbs light, driving photochemical reactions in surface waters.

Recalcitrant DOM: Subset of DOM resistant to microbial and photochemical degradation, persisting for decades to millennia.

References

1. Dearomatization drives complexity generation in freshwater organic matter. Nature (2024).
2. Photo-produced aromatic compounds stimulate microbial degradation of dissolved organic carbon in thermokarst lakes. Nature Communications (2023).
3. An ultrahigh‐resolution mass spectrometry index to estimate natural organic matter lability. Rapid Communications in Mass Spectrometry (2015).
4. Triplet state dissolved organic matter in aquatic photochemistry: reaction mechanisms, substrate scope, and photophysical properties. Environmental Science Processes & Impacts (2016).
5. Turnover time of fluorescent dissolved organic matter in the dark global ocean. Nature Communications (2015).
6. Universal molecular structures in natural dissolved organic matter. Nature Communications (2018).