Interactions between organic carbon (OC) and minerals represent a critical mechanism for stabilizing organic matter in soils. Because both mineral weathering and plant productivity are negatively affected by soil erosion, mineral-associated organic carbon (MOC) chemistry is also expected to vary with erosion intensity. Here we show that MOC chemistry, determined by carbon X-ray absorption near-edge fine structure spectroscopy (XANES), exhibits little difference across a large (10-fold) gradient in erosion-derived soil turnover times. Mineral-associated OC chemistry further fails to explain the variation in radiocarbon-based MOC turnover times. Our results suggest that soil OC longevity is largely independent of organic matter chemistry in steep mountainous landscapes where soil development is constrained by erosion.

有机碳 (OC) 和矿物质之间的相互作用是稳定土壤有机质的关键机制。由于矿物风化和植物生产力都受到土壤侵蚀的负面影响，预计矿物相关有机碳 (MOC) 化学也会随着侵蚀强度而变化。在这里，我们展示了由碳 X 射线吸收近边缘精细结构光谱 (XANES) 确定的 MOC 化学，在侵蚀衍生的土壤周转时间的大（10 倍）梯度上几乎没有差异。矿物相关 OC 化学进一步无法解释基于放射性碳的 MOC 周转时间的变化。我们的研究结果表明，土壤有机碳寿命在很大程度上与陡峭山地景观中的有机物质化学无关，其中土壤发育受到侵蚀的限制。