随着分子生物学的发展,微生物的作用改变了科学界对土壤有机碳(SOC)形成和固持的认知。土壤微生物残体与矿物结合形成矿质结合态有机碳(mineral-associated organic carbon, MAOC)加深了对SOC固存的理解。MAOC是以土壤微生物残体C为主的SOC组分,主要由分子量相对较低且可识别的微生物残体与矿物表面结合而成。由于MAOC对草地和农田生态系统土壤C库的贡献超过50%,且周转时间较长(百年-千年尺度),研究其形成过程和稳定机制已成为碳中和背景下土壤碳汇的焦点。现阶段的研究明确指出,MAOC的形成和稳定不仅与微生物残体C密切相关,还与土壤矿物有着非常紧密的联系。基于此,聚焦土壤微生物"碳泵"调控SOC形成这一前沿科学问题,围绕土壤微生物残体贡献MAOC形成这一科学构架进行概述,旨在揭示不同来源LMW-DC(溶解态低分子量C底物)对MAOC形成的贡献,探讨土壤矿物对LMW-DC选择性吸附机理,探究MAOC贡献稳定C库的影响因素。并对该研究领域未来的发展进行展望,以期能从分子水平出发,探究不同生态系统、土壤类型及土层深度微生物的调控差异,为土壤有机碳固持的研究提供理论参考,为丰富土壤C源/汇功能提供科学依据。
With the development of molecular biology, the role of soil microorganisms has changed the scientific understanding of formation and sequestration of soil organic carbon (SOC). Microbial residue combined with soil minerals to form mineral-associated organic carbon (MAOC), which has improved our understanding of soil organic carbon sequestration. MAOC is a fraction of soil organic carbon dominated by soil microbial residue carbon. It is mainly composed of identifiable microbial residue with low molecular weight bound to the mineral surface. As MAOC contributes more than 50% to soil organic carbon pool of grassland and agricultural ecosystems and has a long turnover time (centennial-millennial scale), the study of MAOC formation process and stabilization mechanism has become the focus of soil carbon sink in the context of carbon neutrality. Recent studies clearly indicate that the formation and stability of MAOC are not only mainly related to microbial residue carbon, but also closely associated with soil minerals. Based on this, we focus on the cutting-edge scientific issue of microbial carbon pump regulating soil organic carbon and provide an overview of the scientific framework on soil microbial residue contribution to MAOC. The aim is to reveal the contribution of LMW-DC (low molecular weight dissolved carbon substrate) from different sources to MAOC formation, and to explore the mechanism of selective adsorption of LMW-DC by soil minerals. Meanwhile, the relevant factors affecting the contribution of MAOC to stabilizing carbon pools are also discussed. It also provides an outlook on the future development of this research field, with a view to exploring the differences in the regulation of soil microorganisms in different ecosystems, soil types and soil depths from the molecular level, so as to provide a theoretical reference for the research on soil organic carbon sequestration and a scientific evidence for enriching soil carbon source/sink functions.
薛志婧, 李霄云, 焦磊, 杨阳, 窦艳星, 王宝荣, 黄倩, 刘春晖, 屈婷婷, 周正朝, 安韶山.土壤矿质结合态有机碳形成及稳定机制的研究进展[J].水土保持学报,2023,37(5):12~23复制