Hydrophilic freshwater DOM biodegrades fastest
Across a Swedish stream and two lakes, the most water-loving DOM fractions lost 12–25% of DOC in 150 days versus 6–15% for hydrophobic fractions.
Source
Hydrophilic Species Are the Most Biodegradable Components of Freshwater Dissolved Organic Matter
What they did
Split DOM from a humic stream, a clearwater lake, and a eutrophic lake on C18 by hydrophobicity, then incubated fractions 150 days and tracked DOC loss and composition.
What they found
Hydrophilic fractions (U and 1) were most labile; hydrophobic fractions were most refractory; the pattern held at all three sites; pooling fractions did not show a strong priming effect.
The limits
What it doesn't show
Three Uppland waters cannot represent all inland waters, and MS still under-samples the most hydrophilic molecules.
Key terms
- DOM
- Dissolved organic matter, a major aquatic carbon pool.
- Hydrophilicity
- Affinity for water; polar molecules stay dissolved more readily.
- Reactivity continuum
- DOM as a mix of many decay rates rather than one exponential.
- Dilution hypothesis
- Idea that tiny concentrations of many similar compounds limit microbial use.
- Priming effect
- One DOM constituent speeding or slowing decay of others.
- C18 separation
- Chromatography that retains hydrophobic organics more than hydrophilic ones.
Flashcards
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Hydrophilic DOC loss by day 150:
Common questions
Sites?
Three inland waters in Uppland, Sweden.
Hydrophilic DOC loss at day 150?
12–25%.
Hydrophobic loss?
6–15%.
Incubation length?
150 days.
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