We developed vertically resolved soil biogeochemistry (carbon and nitrogen) module and implemented it into a land surface model, ISAM. The model captures the vertical heterogeneity of the northern high latitudes permafrost soil organic carbon (SOC). We also implemented Δ¹⁴C to estimate SOC turnover time, a critical determinant of SOC stocks, sequestration potential, and the carbon cycle feedback under changing atmospheric CO₂ concentration [CO₂] and climate. ISAM accounted for the vertical movement of SOC caused by cryoturbation and its linkage to frost heaving process, oxygen availability, organo‐mineral interaction, and depth‐dependent environmental modifiers. After evaluating the model processes using the site and regional level heterotrophic respiration, SOC stocks, and soil Δ¹⁴C profiles, the vertically resolved soil biogeochemistry version of the model (ISAM‐1D) estimated permafrost SOC turnover time of 1,443 years, which is about 3 times more than the estimation based on the without vertically resolved version of ISAM (ISAM‐0D). ISAM‐1D‐simulated SOC stocks for permafrost regions was 319 Pg C in the top 1 m soil depth by the 2000s, about 80% higher than the estimates based on ISAM‐0D. ISAM‐1D SOC stock and turnover time were compared well with the observations. However, the longer SOC turnover time preserves less SOC stocks due to the lower carbon use efficiency (CUE) for SOC than ISAM‐0D and thus respires more SOC than being transferred downward by cryoturbation. ISAM‐1D simulated reduced SOC sequestration (3.7 Pg C) compared to ISAM‐0D (4.8 Pg C) and published Earth system models (ESMs) over the 1860s–2000s, due to weaker [CO₂]‐carbon cycle and stronger climate‐carbon cycle feedbacks, highlighting the importance of the vertically heterogeneous soil for understanding the permafrost SOC sinks.

中文翻译：

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利用具有垂直非均质性的多年冻土的土地表面模型估算多年冻土的SOC储量和周转时间

我们开发了垂直解析的土壤生物地球化学（碳和氮）模块，并将其实施到陆地表面模型ISAM中。该模型捕获了北部高纬度多年冻土土壤有机碳（SOC）的垂直非均质性。我们还实施Δ ¹⁴ C至估计SOC周转时间，SOC股的关键决定因素，封存潜力，并在变化的大气CO碳循环反馈₂浓度[CO ₂]和气候。ISAM解释了由低温扰动引起的SOC的垂直运动及其与霜冻过程，氧的可利用性，有机矿物质的相互作用以及与深度有关的环境调节剂的联系。使用本网站和区域层面异养呼吸，SOC股票，土壤评估模型过程Δ后¹⁴C剖面，该模型的垂直解析土壤生物地球化学版本（ISAM-1D）估算的多年冻土SOC转换时间为1,443年，这比基于无垂直解析版本的ISAM（ISAM-0D）的估算大约高3倍。ISAM-1D模拟的多年冻土区域的SOC存量在2000年代前1 m土深中为319 Pg C，比基于ISAM-0D的估计高约80％。ISAM-1D SOC库存和周转时间与观察值进行了很好的比较。但是，由于SOC的碳使用效率（CUE）比ISAM-0D低，因此更长的SOC转换时间可以保留更少的SOC库存，因此比通过低温扰动向下转移所释放的SOC多。与ISAM-0D（4.8 Pg C）和已发布的地球系统模型（ESM）相比，ISAM-1D在1860到2000年代模拟了减少的SOC隔离（3.7 Pg C），₂ ]-碳循环和更强的气候-碳循环反馈，突出了垂直非均质土壤对于了解多年冻土SOC汇的重要性。