Quantifying the upper limit of stable soil carbon storage is essential for guiding policies to increase soil carbon storage. One pool of carbon considered particularly stable across climate zones and soil types is formed when dissolved organic carbon sorbs to minerals. We quantified, for the first time, the potential of mineral soils to sorb additional dissolved organic carbon (DOC) for six soil orders. We compiled 402 laboratory sorption experiments to estimate the additional DOC sorption potential, that is the potential of excess DOC sorption in addition to the existing background level already sorbed in each soil sample. We estimated this potential using gridded climate and soil geochemical variables within a machine learning model. We find that mid- and low-latitude soils and subsoils have a greater capacity to store DOC by sorption compared to high-latitude soils and topsoils. The global additional DOC sorption potential for six soil orders is estimated to be 107 ±\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\pm$$\end{document} 13 Pg C to 1 m depth. If this potential was realized, it would represent a 7% increase in the existing total carbon stock.

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通过吸附可以向土壤中添加多少碳？

量化稳定土壤碳储量的上限对于指导增加土壤碳储量的政策至关重要。当溶解的有机碳吸附到矿物质上时，就会形成一个被认为在不同气候带和土壤类型中特别稳定的碳库。我们首次量化了矿质土壤吸附六个土壤等级的额外溶解有机碳 (DOC) 的潜力。我们编制了 402 个实验室吸附实验来估计额外的 DOC 吸附潜力，即除了每个土壤样品中已经吸附的现有背景水平之外的过量 DOC 吸附的潜力。我们使用机器学习模型中的网格气候和土壤地球化学变量来估计这种潜力。我们发现，与高纬度土壤和表土相比，中低纬度土壤和底土通过吸附存储 DOC 的能力更大。六个土壤订单的全球附加 DOC 吸附潜力估计为 107 ±\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \ usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\pm$$\end{document} 13 Pg C 至 1 m 深度。如果这一潜力得以实现，现有总碳储量将增加 7%。六个土壤订单的全球附加 DOC 吸附潜力估计为 107 ±\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \ usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\pm$$\end{document} 13 Pg C 至 1 m 深度。如果这一潜力得以实现，现有总碳储量将增加 7%。六个土壤订单的全球附加 DOC 吸附潜力估计为 107 ±\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \ usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\pm$$\end{document} 13 Pg C 至 1 m 深度。如果这一潜力得以实现，现有总碳储量将增加 7%。