Abstract
Sustained eutrophication in low-phosphorus (P < 1 μM and phosphate (PO43⁻) <0.2 μM) lakes poses a challenge to understanding P cycling in stratified lakes. Conventional P concentration and low vertical-resolution phosphate oxygen isotope data (δ18OP) cannot solve this problem. Here, we measured high-resolution δ18OP profiles in two typically low-P, eutrophic, thermally stratified lakes (Lake Hongfeng and Lake Aha, China) via a newly developed ESI-Orbitrap-MS technique. The lakes showed high δ18OP values (19.3‰−19.8‰) at the surface (0–2 m), but low values (13.4‰−13.7‰) at thermocline. A one-dimensional concentration-δ18OP coupled diffusion model constrains an apparent kinetic isotope effect of 0.9932 and 0.9906 for biological surface uptake and thermocline remineralization, respectively. The results suggest that eutrophication was sustained by a rapid PO43– uptake by algae at surface and remineralization of organic P at depth. This study provides isotope evidence for P cycling dynamics in low-P natural lakes with excessive algae growth.
Data availability
All data generated for figures in this study have been deposited in figshare: https://doi.org/10.6084/m9.figshare.31566028.
Code availability
All custom R code used in this study is freely available without restriction on Zenodo at https://doi.org/10.5281/zenodo.19031192.
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Acknowledgements
This study was supported by the National Natural Science Foundation of China (W2441015, 42494851, 42273032), Fundamental Research Funds for the Central Universities, including the General Program (0206/14380232, 0206/14380918), and additional grants (0206/14380204, 0206/14380150, 0206/14380185, and 0206/14380174), as well as startup fund from Nanjing University to HB.
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Z.W. and H.B. conceived the research idea and design. Z.W. collected water samples and Lake-water chemistry data with the assistance from B.W., Z.W., Y.S., and H.Y., Z.W., and L.Z. conducted the Orbitrap-MS-based δ18OP analyses. Z.W., H.Y., and H.B. analyzed the results. Z.W. and Y.W. assisted in the 1-D data modeling. Z.W. and H.B. wrote the paper with all co-authors contributed to the revisions.
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Wei, Z., Wang, B., Yan, H. et al. Phosphorus cycling dynamics in stratified low-phosphorus lakes. Commun Earth Environ (2026). https://doi.org/10.1038/s43247-026-03472-5
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DOI: https://doi.org/10.1038/s43247-026-03472-5
