Deciphering the link between particulate organic matter molecular composition and lake eutrophication by FT-ICR MS...

Area of Science:

• Environmental Science
• Limnology
• Biogeochemistry

Background:

• Eutrophication is a major global lake issue, significantly influenced by particulate organic matter (POM) as a nutrient carrier.
• Understanding the source and molecular makeup of POM is crucial for deciphering lake eutrophication dynamics.

Purpose of the Study:

• To investigate the relationship between the source and molecular composition of POM in lakes with varying trophic states.
• To elucidate the molecular mechanisms driving lake eutrophication in the Yangtze River basin.

Main Methods:

• Characterization of POM from seven lakes across a trophic gradient using carbon and nitrogen stable isotopes.
• Analysis of POM molecular composition via Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS).

Main Results:

• POM primarily originated from autochthonous (62.7%) versus allochthonous (37.3%) sources, with autochthonous dominance increasing with trophic state.
• Phosphorus-containing (CHOP) formulas constituted the largest proportion (51.56%) of labile compounds, correlating positively with lake trophic status.
• Molecular properties like unsaturation, aromaticity, and oxidation decreased with increasing trophic states, while lipid and protein content rose.

Conclusions:

• Intensified lake eutrophication leads to increased autochthonous POM, particularly labile P-containing compounds, creating a positive feedback loop.
• Molecular-level analysis of POM provides critical insights into the mechanisms of lake eutrophication.
• Findings are significant for understanding POM fate and developing effective lake eutrophication control strategies.