Eutrophication may be weakening one of lakes’ long-term carbon-burial pathways
WHAT THE EVIDENCE SAYS
Reactive iron oxide-bound organic carbon (Fe–OC) accounted for about 16% of total organic carbon in the study synthesis and was estimated to bury roughly 14 Mt C per year in lakes globally. Bloom-prone lakes had lower Fe–OC content and contribution than non-bloom-prone lakes. Field observations and incubation experiments indicated that bloom-driven redox fluctuations and low-aromaticity algal organic matter accelerated Fe–OC turnover and reduced organic-carbon loading on iron minerals, with experimental Fe–OC losses reaching about 68%.
WHY IT MATTERS / OUR READ
Eutrophication is usually managed through nutrients, blooms and oxygen, but this work points to another process: whether sediment carbon remains mineral-protected. If the mechanism generalizes, reducing bloom pressure could affect not only water quality but also the persistence of buried carbon. That is a reason to measure sediment carbon forms rather than infer carbon storage from total organic carbon alone.
CAVEATS / UNCERTAINTY
The global burial estimate is an extrapolation from available lake datasets, while the proposed mechanism is supported by field observations and incubations rather than a global experiment. Fe–OC is one carbon pool, not the whole lake carbon balance, and carbon lost from mineral protection is not automatically emitted to the atmosphere.
SOURCE
Communications Earth & Environment — primary study
View original evidence ↗
Bloom-prone lakes held less iron-bound organic carbon; field and incubation work linked bloom-driven redox swings and algal inputs to losses of mineral-protected carbon.
Read the Wild Lands assessment →