近日，美国加州大学伯克利分校Ronald Amundson团队揭示了忽略垂直迁移会导致低估土壤碳动态。相关论文于2025年12月8日发表在《自然—地球科学》杂志上。

土壤有机碳(C)的放射性碳含量反映了碳的生物反应性。大的土壤放射性碳年龄被解释为意味着碳对环境扰动（如变暖对土壤微生物碳分解率的影响）的反应缓慢。

研究组表明，土壤C的向下平流输送是影响土壤C年龄的重要过程，即使分解速率保持不变，放射性碳年龄也不可避免地随深度增加。因此，C的放射性碳年龄随深度的增加并不直接意味着C的反应性随深度的变化而相应降低。在理论和对土壤C分解率的独立评估的基础上，计算了美国3000多个土壤的放射性碳剖面（以及给定深度的含量），并将其与基于土壤放射性碳测量的观测结果进行了比较。两种完全不同的方法之间的一阶一致性表明了输运的基本重要性，并暗示土壤C分解速率常数可能随深度相对不变。这些见解可能有助于减少目前与观测到的土壤C的深度模式或其放射性碳含量不匹配的地球系统模型的偏差。

附：英文原文

Title: Neglecting vertical transport leads to underestimated soil carbon dynamics

Author: Amundson, Ronald, Sanderman, Jonathan, Yoo, Kyungsoo, Chitsaz, Maedeh, Abramova, Anna, Georgiou, Katerina

Issue&Volume: 2025-12-08

Abstract: The radiocarbon content of soil organic carbon (C) is assumed to reflect the carbon’s biological reactivity. Large soil radiocarbon ages are interpreted to mean that the C will have a slow response to environmental perturbations such as the effects of warming on the soil microbial C decomposition rate. Here we show that downward advective transport of soil C is an important process affecting soil C ages, leading to an inevitable increase in radiocarbon age with depth even if the decomposition rates remain constant. Thus, the increasing radiocarbon ages of C with depth do not directly imply a corresponding decrease in C reactivity as a function of depth. On the basis of theory and an independent assessment of soil C decomposition rates, the radiocarbon profiles (and content for a given depth) were calculated for over 3,000 soils in the USA and were compared to observational results based on measured soil radiocarbon. The first-order coherence between the two entirely differing approaches suggests the fundamental importance of transport and the implication that the soil C decomposition rate constant may be relatively invariant with depth. These insights may serve to reduce biases in Earth system models that presently do not match the observed depth patterns in soil C or its radiocarbon content.

DOI: 10.1038/s41561-025-01846-6

Source: https://www.nature.com/articles/s41561-025-01846-6