State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, CAS, Guiyang 550081, China; University of Chinese Academy of Sciences, Beijing 100049, China.
State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, CAS, Guiyang 550081, China; Laboratory of Land Resources Evaluation and Monitoring in Southwest China of Ministry of Education, Sichuan Normal University, Chengdu 610066, China.
Environ Res. 2022 Nov;214(Pt 1):113767. doi: 10.1016/j.envres.2022.113767. Epub 2022 Jun 27.
Soils in glacier forefields have a significant capacity for atmospheric CH uptake, but this pattern could be changed by high soil water content (SWC). The Hailuogou Glacier in SW China is a typical temperate monsoon glacier on siliceous bedrock, where a forefield soil chronosequence has developed with progressive glacier recession. To understand CH dynamics and their potential regulatory factors, we measured the concentrations and stable carbon (C) isotope compositions of CH and CO soil physicochemical properties, and perfromed a high-throughput sequencing. Among nine sampling sites, soil CH concentrations of six sites were below atmospheric levels and δC-CH values were similar to atmospheric levels. The average value was approximately -48.6‰ and without obvious fractionation. The soil CH concentrations exceeded atmospheric levels for the remaining three sites, and the δC-CH values were more enriched with increasing soil CH concentration. We calculated the soil-atmosphere CH flux (J) using the concentration gradient method based on the soil CH concentration, sampling depth, and soil porosity. J ranges from -0.08 to -0.52 mg m d, acting as an atmospheric CH sink. It also shows that the correlation with soil exposure age or vegetation succession was insignificant. But the CH emission shows a larger variation changing from 0.05 to 1.8 mg m d, which could result from local CH production differences catalyzed by aceticlastic methanogens. The results showed that not all sites acted as a net CH sink. SWC may have an important influence on CH dynamics in the Hailuogou Glacier forefield (HGF).
冰川前缘土壤具有很大的大气 CH 吸收能力，但高土壤含水量 (SWC) 可能会改变这种模式。中国西南的海螺沟冰川是一种典型的温带季风冰川，位于硅质基岩上，随着冰川后退，形成了一个前缘土壤时间序列。为了了解 CH 动态及其潜在的调节因素，我们测量了 CH 和 CO 土壤理化性质的浓度和稳定碳 (C) 同位素组成，并进行了高通量测序。在九个采样点中，有六个采样点的土壤 CH 浓度低于大气水平，δC-CH 值与大气水平相似。平均值约为-48.6‰，没有明显的分馏。其余三个采样点的土壤 CH 浓度超过大气水平，δC-CH 值随着土壤 CH 浓度的增加而更加富集。我们使用基于土壤 CH 浓度、采样深度和土壤孔隙度的浓度梯度法计算了土壤-大气 CH 通量 (J)。J 的范围为-0.08 至-0.52 mg m d，作为大气 CH 的汇。它还表明，与土壤暴露年龄或植被演替的相关性不显著。但是，CH 排放的变化更大，从 0.05 到 1.8 mg m d，这可能是由于乙酸营养型产甲烷菌催化的局部 CH 产生差异造成的。结果表明，并非所有站点都作为净 CH 汇。SWC 可能对海螺沟冰川前缘（HGF）的 CH 动态有重要影响。
