Soil organic carbon (SOC) enrichment in aeolian sediments and SOC loss by dust emission in the desert steppe, China

Authors: DU, HEQIANG - Chinese Academy Of Sciences; LI, SEN - Chinese Academy Of Sciences; WEBB, NICHOLAS - New Mexico State University; ZUO, XIAOAN - Chinese Academy Of Sciences; LIU, XUYANG - Chinese Academy Of Sciences

Submitted to: Science of the Total Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/17/2021
Publication Date: 7/29/2021
Citation: Du, H., Li, S., Webb, N., Zuo, X., Liu, X. 2021. Soil organic carbon (SOC) enrichment in aeolian sediments and SOC loss by dust emission in the desert steppe, China. Science of the Total Environment. 798:Article 149189. https://doi.org/10.1016/j.scitotenv.2021.149189.
DOI: https://doi.org/10.1016/j.scitotenv.2021.149189

Interpretive Summary: Dust emissions due to wind erosion influence the movement of soil organic carbon (SOC) across landscapes and into the atmosphere. Measurements of the SOC content of dust show that dust is enriched in carbon relative to eroding soils. In order to understand how much carbon is moved by wind erosion and blowing dust, it is important to quantify SOC enrichment rates and identify approaches to estimating SOC enrichment and the quantity of SOC moved in dust. This research sought to measure how much SOC is associated with different soil and dust particle sizes and evaluate how this information could be used to inform dust and carbon cycle modeling. We found that the SOC content of dust can be estimated with knowledge of how SOC is distirbuted across eroding soil particle size classes. A dust emission model was used to estimate SOC dust emissions and losses across the desert steppe of Inner Mongolia, China. The modeling approach simplifies earlier approaches to estimate SOC enrichment in dust emissions and will enable global evaluation of the influence of wind erosion and dust emissions on carbon cycling and carbon sequestration.

Technical Abstract: Dust emission is an important mechanism for carbon exchange between terrestrial and atmospheric carbon pools. However, undetermined soil organic carbon (SOC) enrichment in aeolian sediment limits the accurate estimation of SOC loss induced by wind erosion. Herein, we examined wind erosion and SOC loss measurements in the desert steppe of Inner Mongolia, China. By testing the particle size distributions (PSDs) and SOC contents across different particle size groups of the soil samples and aeolian sediments, we found that the finer soil particles generally had higher SOC contents. According to the measured results, we recognized that the mechanism of SOC enrichment in aeolian sediment is the inconstant distribution of SOC across the different soil particle size groups and the differences between the PSDs of soils and aeolian sediments. Based on the mechanism, we proposed a method to calculate the SOC content in aeolian sediment, and the calculated results are highly consistent with the measured results. Compared with the previous method, our calculation method provided a more precise result. Integrating our method for estimating SOC content in dust (diameter less than 50 µm) and a dust emission model, we simulated the SOC loss induced by wind erosion in this region by a wind erosion model, and the results show SOC loss induced by dust emissions ranging from 0 to 39 g/m2/y during the period of 2001 to 2017. We believe the study method of dust SOC content calculation we proposed could be interested by the scholars in the field of carbon cycling, and the simulated results of SOC loss could provide robust data for the estimation of carbon budget in the desert steppe.