Condensed organic matters (COM) with black carbon-like structures are considered as long-term carbon sinks because of their high stability. It is difficult to distinguish COM from general organic matter by conventional chemical analysis, thus the contribution by and interaction mechanisms of organo-mineral complexes in COM stabilization are unclear and generally neglected. Molecular markers related to black carbon-like structures, such as benzene polycarboxylic acids (BPCAs), are promising tools for the qualitative and quantitative analysis of COM. In this study, one natural soil and two cultivated soils with 25 y- or 55 y-tillage activities were collected and the distribution characteristics of BPCAs were detected. All the investigated soils showed similar BPCA distribution pattern, and over 60% of BPCAs were detected in clay fraction. The extractable BPCA contents were substantially increased after mineral removal. The ratios of BPCA contents before and after mineral removal indicate the extent of COM-mineral particle interactions, and our results suggested that up to 73% COM were protected by mineral particles, and more stronger interactions were noted on clay than on silt. The initial cultivation dramatically decreased COM-clay interactions, and this interaction was recovered only slowly after 55-y cultivation. Kaolinite and muscovite are important for COM protection. But a possible negative correlation between BPCAs and reactive iron oxides of the cultivated soils suggested that iron may promote COM degradation when disturbed by tillage activities. This study provided a new angle to study the stabilization of COM and emphasized the importance of organo-mineral complexes for COM stabilization.

具有黑碳状结构的冷凝有机物（COM）由于具有很高的稳定性而被认为是长期的碳汇。通过常规化学分析很难将COM与一般有机物区分开，因此有机-矿物配合物在COM稳定中的作用和相互作用机理尚不清楚，而且通常被忽略。与黑碳样结构相关的分子标记物，例如苯多元羧酸（BPCA），是对COM进行定性和定量分析的有前途的工具。在本研究中，收集了25种耕作活动或25种耕作活动的天然土壤和2种耕作土壤，并检测了BPCAs的分布特征。所有调查的土壤均显示了类似的BPCA分布模式，并且在粘土级分中检测到超过60％的BPCA。去除矿物质后，可提取的BPCA含量显着增加。矿物去除前后BPCA含量的比值表明COM-矿物颗粒之间相互作用的程度，我们的结果表明，高达73％的COM受矿物颗粒保护，并且在粘土上的相互作用比在粉砂上更强。最初的培养显着降低了COM与粘土的相互作用，而这种相互作用在培养55年后才缓慢恢复。高岭石和白云母对于COM保护很重要。但是BPCA与耕作土壤中的反应性氧化铁之间可能存在负相关关系，这表明当耕作活动受到干扰时，铁可能促进COM降解。