Abstract
An oxygenated atmosphere changed life on Earth but it also provided a negative feedback to organic matter accumulation by increasing decomposition rates. Nonetheless, dissolved organic carbon (DOC) is a huge carbon pool (> 750 Pg) and it can accumulate to high concentrations (20–100 mg C L−1) in some freshwater aquatic systems, yet it is not clear why. Here, we examine DOC in several Greenland lakes with varying DOC concentrations and identify processes that could alter its composition to make it increasingly recalcitrant. Δ14C aging of DOC corresponded with increased DOC concentrations, slower degradation rates, changes in isotope ratios and optical properties, all suggesting that photochemical and microbial degradation processes contributed to recalcitrance. Young DOC degradation was stimulated by phosphorus, but older DOC was not, suggesting an important role for nutrients early in degradation. Photochemical processing coupled with decreased habitat diversity in hydrologically isolated systems may enable recalcitrant DOC to accumulate with important implications for Earth's carbon and oxygen cycles.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 401-409 |
| Number of pages | 9 |
| Journal | Limnology And Oceanography Letters |
| Volume | 7 |
| Issue number | 5 |
| DOIs | |
| State | Published - Oct 2022 |
Bibliographical note
Funding Information:We received support for this work from the US National Science Foundation (JBC: OCE‐0527196) and the UK Natural Environment Research Council (NJA NE/K000349/1 and NE/J021474/1); CO received support from the North Carolina State University Office of Global Engagement Internationalization and NJA received support from NERC. Meghan Funke provided technical assistance for long‐term DOM degradation assays. Stephen Richardson and Roxane Bowden provided technical support to CO and Chris Barry provided inspiration and field assistance.
Publisher Copyright:
© 2022 The Authors. Limnology and Oceanography Letters published by Wiley Periodicals LLC on behalf of Association for the Sciences of Limnology and Oceanography.