College of Forest, Sichuan Agricultural University, Soil and Water Conservation and Desertification Control Key Laboratory of Sichuan Province, Chengdu 611130, China.
College of Forest, Sichuan Agricultural University, Soil and Water Conservation and Desertification Control Key Laboratory of Sichuan Province, Chengdu 611130, China.
Sci Total Environ. 2021 Jan 20;753:141933. doi: 10.1016/j.scitotenv.2020.141933. Epub 2020 Aug 24.
Mountain ecosystems store a large amount of soil organic carbon (SOC) sensitive to global climate change. The SOC associated with Al and Fe minerals is important for SOC retention because of the ubiquitous nature and highly reactive surface properties of these minerals. Topography is also known to impact the distribution and transformation of SOC by creating different microclimates. However, the effect of topography on the distribution of organo-mineral associations has seldom been reported. This study uses a selective dissolution method to quantify the soil carbon (C) fractions associated with Al and Fe minerals in alpine shrub-meadow soil. Na-pyrophosphate (PP), HCl-hydroxylamine (HH) and dithionite-HCl (DH) were used to quantify organo-metal complexes, SOC associated with short-range order (SRO) phases and crystalline phases, respectively. Results suggest that the Al and Fe mineral-associated C accounted for a small proportion of SOC (less than 30%) in each extraction. A higher concentration coupled with a lower percentage of SOC was found in the A horizon compared to the B horizon. A significant correlation was observed between Fe and C in PP and HH extractions, whereas Al was significantly correlated with C in DH extractions. Elevation and slope aspect strongly influenced soil biotic and abiotic parameters, as well as organo-mineral associations. The C fractions extracted by PP and HH were significantly higher in the NE slope aspect than the SW slope aspect. These fractions were positively correlated with soil water content and negatively correlated with soil pH. The C fractions extracted using DH decreased with increasing elevation and were positively correlated with DH extractable Al. Our results highlight the role of topography on the distribution of organo-mineral associations, which should be considered during the assessment of SOC stability in alpine soils.
高山生态系统储存了大量对全球气候变化敏感的土壤有机碳 (SOC)。与 Al 和 Fe 矿物结合的 SOC 对于 SOC 保持很重要，因为这些矿物具有普遍存在的性质和高度反应性的表面特性。地形也通过创造不同的小气候而影响 SOC 的分布和转化。然而，地形对有机-矿物结合物分布的影响很少有报道。本研究使用选择性溶解方法来量化高山灌丛-草地土壤中与 Al 和 Fe 矿物结合的土壤碳 (C) 分数。使用焦磷酸钠 (PP)、盐酸羟胺 (HH) 和连二亚硫酸钠-盐酸 (DH) 分别定量有机金属络合物、与短程有序 (SRO) 相和结晶相结合的 SOC。结果表明，Al 和 Fe 矿物结合的 C 仅占各提取物中 SOC 的一小部分（小于 30%）。与 B 层相比，A 层中 SOC 的浓度更高，而百分比更低。在 PP 和 HH 提取物中观察到 Fe 和 C 之间存在显著相关性，而在 DH 提取物中 Al 与 C 之间存在显著相关性。海拔和坡度方位强烈影响土壤生物和非生物参数以及有机-矿物结合物。在 NE 坡度方位提取的 PP 和 HH 提取的 C 分数明显高于 SW 坡度方位。这些分数与土壤水分含量呈正相关，与土壤 pH 值呈负相关。使用 DH 提取的 C 分数随海拔升高而降低，与 DH 可提取 Al 呈正相关。我们的研究结果强调了地形对有机-矿物结合物分布的作用，在评估高山土壤中 SOC 稳定性时应考虑这一作用。
