Re-estimating China's lake CO₂ flux considering spatiotemporal variability

The variability of lake partial carbon dioxide pressure (pCO₂) introduces uncertainty into CO₂ flux estimates. Knowing the variation pattern of pCO₂ is important for obtaining an accurate global estimation.

In an article published in Environmental Science and Ecotechnology, researchers examined seasonal and trophic variations in lake pCO₂ based on 13 field campaigns conducted in Chinese lakes from 2017 to 2021. They found significant seasonal fluctuations in pCO₂, with decreasing values as trophic states intensify within the same region.

These pCO₂ dynamics resulted in variable CO₂ emissions, with lakes exhibiting different trophic states, and saline lakes differing from freshwater lakes (−23.1 ± 17.4 vs. 19.3 ± 18.3 mmol m⁻² d⁻¹). These spatiotemporal pCO₂ variations complicate total CO₂ emission estimations.

Using area proportions of lakes with varying trophic states and salinity in China, the researchers estimate China's lake CO₂ flux at 8.07 Tg C yr⁻¹. In future studies, the importance of accounting for lake salinity, seasonal dynamics, and trophic states must be used to enhance the accuracy of large-scale carbon emission estimates from lake ecosystems in the context of climate change.

The study indicated that the current annual total CO₂ fluxes from lakes in China might be overestimated when lake trophic states and salinity are ignored.

To improve the accuracy of regional and large-scale estimations of carbon emissions and carbon budgets in lake ecosystems affected by seasons, salinity, and trophic states, further investigations into CO₂ emissions from lakes in other parts of the world are warranted.