The impact of freeze-thaw history on soil carbon response to experimental freeze-thaw cycles

This dataset contains data used for the paper "The impact of freeze-thaw history on soil carbon response to experimental freeze-thaw cycles". The Related References field will be updated with a full citation when available. Freeze-thaw is a disturbance process in cold regions where permafrost soils are becoming vulnerable to temperature fluctuations above 0˚C. Freeze-thaw alters soil physical and biogeochemical properties with implications for carbon persistence and emissions in Arctic landscapes. We examined whether different freeze-thaw histories in two soil systems led to contrasting biogeochemical responses under a laboratory-controlled freeze-thaw incubation. We investigated controls on soil organic matter (SOM) composition through Fourier-transform ion cyclotron resonance mass spectroscopy (FT-ICR-MS) to identify nominal carbon oxidation states and relative abundances of aliphatic-type carbon molecules in both surface and subsurface soils. Soil cores (~ 60 cm-depth) were sampled from two sites in Alaskan permafrost landscapes with different in situ freeze-thaw characteristics: Healy (>40 freeze-thaw cycles annually) and Toolik (<150 freeze-thaw cycles annually). FT-ICR-MS was coupled with in situ temperature data and soil properties (i.e., soil texture, mineralogy) to assess (1) differences in SOM composition associated with previous freeze-thaw history and (2) sensitivity to experimental freeze-thaw in the extracted cores. Control (freeze-only) samples showed greater carbon oxidation in Healy soils compared with Toolik, even in lower mineral horizons where freeze-thaw history was comparable across both sites. Healy showed the most loss of carbon compounds following experimental freeze-thaw in the lower mineral depths, including a decrease in aliphatics. Toolik soils responded more slowly to freeze-thaw as shown by intermediary carbon oxidation distributed across multiple carbon compound classes. Variations in the response of permafrost carbon chemistry to freeze-thaw is an important factor for predicting changes in soil function as permafrost thaws in high northern latitudes. This dataset contains a compressed (.zip) archive of the data and R scripts used for this manuscript. The dataset includes files in .csv format, which can be accessed and processed using MS Excel or R. This archive can also be accessed on GitHub at https://github.com/Erin-Rooney/FTC-FTICR (DOI 10.5281/zenodo.6533064).

本数据集包含支撑论文《冻融历史对土壤碳响应实验冻融循环过程的影响》的相关数据，相关参考文献字段在获取完整引用后将予以更新。
冻融是寒冷地区的一类扰动过程，当前多年冻土（permafrost）土壤正愈发易受0℃以上温度波动的影响。冻融作用会改变土壤物理与生物地球化学特性，进而对北极景观中的碳固存与碳排放产生影响。本研究通过实验室可控的冻融培养实验，探究两种土壤系统中不同的冻融历史是否会引发迥异的生物地球化学响应。
研究借助傅里叶变换离子回旋共振质谱（Fourier-transform ion cyclotron resonance mass spectroscopy, FT-ICR-MS）分析土壤有机质（Soil Organic Matter, SOM）组成，以识别表层与地下土壤的名义碳氧化态，以及脂肪族类碳分子的相对丰度。我们从阿拉斯加多年冻土景观的两个采样点采集了深度约60cm的土芯，两处点位的原位冻融特征存在差异：希利（Healy）站点年均冻融循环超过40次，图利克（Toolik）站点年均冻融循环不足150次。
研究将FT-ICR-MS分析结果与原位温度数据及土壤属性（包括土壤质地、矿物学特征）相结合，以评估两大目标：(1) 与既往冻融历史相关的土壤有机质组成差异；(2) 提取土芯对实验性冻融的敏感性。
实验结果显示，仅冻融处理的对照组样本中，希利土壤的碳氧化程度高于图利克土壤，即便在两处站点冻融历史相当的低矿物层位亦是如此。在矿物下层土壤中，希利土壤经实验性冻融后出现了最为显著的碳化合物损失，其中包括脂肪族化合物的减少。而图利克土壤对冻融的响应更为缓慢，其特征表现为中间碳氧化态分布于多种碳化合物类别中。
多年冻土碳化学对冻融的响应差异，是预测高北纬地区多年冻土融化后土壤功能变化的重要影响因素。
本数据集包含支撑该论文的实验数据与R脚本的压缩（.zip）归档文件。数据集包含.csv格式文件，可通过Microsoft Excel或R语言进行访问与处理。该归档文件亦可在GitHub平台获取，链接为https://github.com/Erin-Rooney/FTC-FTICR，DOI为10.5281/zenodo.6533064。