Study Reveals Important Role of Iron Oxides in Global Soil Carbon Stabilization and Stocks

Soil organic carbon (SOC) is a critical component for the Earth's carbon cycle, and iron oxides (Fed, Feo, Fep) play a crucial role in SOC accumulation and storage.

To better understand the iron-bound organic carbon (OC-Fe) in terrestrial ecosystems, a research team led by Prof. ZENG Fanjiang from the Xinjiang Institute of Ecology and Geography (XIEG) of the Chinese Academy of Sciences, investigated the global distribution, formation mechanisms, and saturation states of OC-Fe in terrestrial ecosystems. Their findings have been published in Nature Communications.

The researchers created a global dataset based on 3,395 soil profiles and used machine learning methods to quantify the stock of OC-Fe, assess its saturation, and identify the main pathways of OC-Fe formation.

The global OC-Fe stock is approximately 232.9 Pg, accounting for 33.5% of the SOC and 52.3% of the mineral-associated organic carbon (MAOC) stock, the study found. Moreover, wetlands were found to exhibit the highest saturation, while forests to have the greatest potential for increased storage of OC-Fe in future.

In addition, researchers identified co-precipitation as the primary pathway for the formation of OC-Fe in terrestrial soils, rather than adsorption or the promotion of soil aggregate formation.

"These findings can help us understand more about the mechanisms of soil carbon stability, and predict global carbon stocks," said LI Lei, corresponding author of this study.

This study has underscored the importance of OC-Fe in the stability of soil organic carbon, and can provide data support for carbon cycle models which incorporate mineral factors.

Article link: https://doi.org/10.1038/s41467-024-54832-8

Modelled global patterns of OC-Fe at soil depths ranging from 0 to 30 cm. (Image by XIEG)

Contact

LONG Huaping

Xinjiang Institute of Ecology and Geography

E-mail: longhp@ms.xjb.ac.cn

Web: http://english.egi.cas.cn