Soil erosion induced by runoff is a main hydrological pathway for lateral transport of carbon in terrestrial landscapes. More information about how water erosion influences the carbon gains and losses at different erosional and depositional landform positions is critical, especially in fragile agroecosystems with a variety of land uses and ephemeral hydrological and sedimentological pulses, typical of Mediterranean environments. The purpose of this study is to characterize the lateral mobilization of soil organic and inorganic carbon (SOC and SIC) along topographically driven transects over a period of four decades in a sub-humid karstic area in northern Spain. The 137Cs inventories and the characterization of terrain attributes of the study area were used to identify whether erosional or depositional processes have been predominant in the 58 sampling sites. Average soil losses and gains varied between -4 and +4 mm ha-1 yr-1, and the carbon patterns obtained are discussed in the context of the dominant hydrological processes in the study area. Results indicate that SOC and SIC losses were related to an increase in water flow accumulation, while the highest SOC gains were recorded at concave positions. Soil erosion processes and the content of SOC and SIC in soils are the two main factors controlling carbon budgets. The topographical and geomorphological characteristics of the transects, the spatial distribution of land uses and the presence of landscape linear elements such as terraces or paths, affect runoff and determine the sediment connectivity and carbon dynamics along the slopes. The combined use of 137Cs and the perceptual model provides reliable SDR estimates benefiting the appraisals of the redistribution of eroded carbon. The knowledge of processes involved in the lateral carbon movement induced by runoff along karstic hillslopes provides a better understanding of the role of soil erosion as carbon source or sinks in the global carbon cycle.

中文翻译：

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沿岩溶斜坡的径流引起的土壤碳的横向动员。

径流引起的土壤侵蚀是陆地景观中碳横向运输的主要水文途径。有关水蚀如何影响不同侵蚀和沉积地形位置的碳损益的更多信息至关重要，尤其是在脆弱的农业生态系统中，其土地使用多种多样，并且具有短暂的水文和沉积脉动，这是地中海环境的典型特征。这项研究的目的是描述在西班牙北部一个半湿润的岩溶地区，在长达四十年的时间里，土壤有机碳和无机碳（SOC和SIC）沿地形驱动样带的横向运动特征。使用137Cs清单和研究区域的地形属性来确定在58个采样点中侵蚀或沉积过程是否占主导地位。平均土壤损失和增加在-4和+4 mm ha-1 yr-1之间变化，并且在研究区域的主要水文过程的背景下讨论了获得的碳模式。结果表明，SOC和SIC的损失与水流蓄积的增加有关，而最高的SOC增益记录在凹处。土壤侵蚀过程以及土壤中SOC和SIC的含量是控制碳收支的两个主要因素。样带的地形和地貌特征，土地利用的空间分布以及景观线性元素（例如阶地或路径）的存在，影响径流并确定沿斜坡的沉积物连通性和碳动力学。137Cs和感知模型的组合使用可提供可靠的SDR估算值，从而有助于评估侵蚀碳的重新分配。对径流沿着岩溶山坡引起的横向碳运动所涉及的过程的了解，可以更好地了解土壤侵蚀作为全球碳循环中碳源或汇的作用。