Lehrstuhl für Bodenkunde, Department Ecology and Ecosystem Management, Center of Life and Food Sciences Weihenstephan, Technische Universität München, D-85350 Freising-Weihenstephan, Germany.
Institute of Soil Ecology, Helmholtz Zentrum München (GmbH), German Research Center for Environmental Health, D-85764 Neuherberg, Germany.
Nat Commun. 2014;5:2947. doi: 10.1038/ncomms3947.
The sequestration of carbon and nitrogen by clay-sized particles in soils is well established, and clay content or mineral surface area has been used to estimate the sequestration potential of soils. Here, via incubation of a sieved (<2 mm) topsoil with labelled litter, we find that only some of the clay-sized surfaces bind organic matter (OM). Surprisingly, <19% of the visible mineral areas show an OM attachment. OM is preferentially associated with organo-mineral clusters with rough surfaces. By combining nano-scale secondary ion mass spectrometry and isotopic tracing, we distinguish between new labelled and pre-existing OM and show that new OM is preferentially attached to already present organo-mineral clusters. These results, which provide evidence that only a limited proportion of the clay-sized surfaces contribute to OM sequestration, revolutionize our view of carbon sequestration in soils and the widely used carbon saturation estimates.
土壤中黏土颗粒对碳和氮的固定作用早已确立，而土壤的固碳潜力通常用黏土含量或矿物表面积来估算。在这里，我们通过将筛分（<2mm）后的表土与标记的凋落物进行培养发现，只有部分黏土大小的表面能够结合有机物质（OM）。令人惊讶的是，只有不到 19%的可见矿物面积显示出 OM 附着。OM 优先与具有粗糙表面的有机-矿物团聚体结合。通过结合纳米级二次离子质谱和同位素示踪技术，我们可以区分新标记的和预先存在的 OM，并表明新 OM 优先附着在已经存在的有机-矿物团聚体上。这些结果表明，只有一小部分黏土大小的表面有助于 OM 的固定，这彻底改变了我们对土壤中碳固定的看法，以及对广泛使用的碳饱和估计。
