Peatlands store carbon in the form of dead organic residues. Climate change and human impact impose risks on the sustainability of the peatlands carbon balance due to increased peat decomposition. Here, we investigated molecular changes in the upper peat layers (0–40 cm), inferred from high-resolution vertical depth profiles, from a boreal peatland using two-dimensional ¹H–¹³C nuclear magnetic resonance (NMR) spectroscopy, and comparison to δ¹³C, δ¹⁵N, and carbon and nitrogen content. Effects of hydrological conditions were investigated at respective sites: natural moist, drainage ditch, and natural dry. The molecular characterization revealed preferential degradation of specific side-chain linkages of xylan-type hemicelluloses within 0–14 cm at all sites, indicating organic matter losses up to 25%. In contrast, the xylan backbone, galactomannan-type hemicelluloses, and cellulose were more resistant to degradation and accumulated at the natural moist and drainage site. δ¹³C, δ¹⁵N, and carbon and nitrogen content did not correlate with specific hemicellulose structures but reflected changes in total carbohydrates. Our analysis provides novel insights into peat carbohydrate decomposition and indicates substantial organic matter losses in the acrotelm due to the degradation of specific hemicellulose structures. This suggests that variations in hemicellulose content and structure influence peat stability, which may have important implications with respect to climate change.

中文翻译：

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泥炭的有机化学表征表明特定半纤维素结构的分解是 Acrotelm 中有机质损失的主要原因

泥炭地以死有机残留物的形式储存碳。由于泥炭分解增加，气候变化和人类影响给泥炭地碳平衡的可持续性带来了风险。在这里，我们使用二维¹ H– ¹³ C 核磁共振 (NMR) 光谱从北方泥炭地的高分辨率垂直深度剖面推断出上层泥炭层 (0–40 cm) 的分子变化，并进行比较到 δ ¹³ C, δ ¹⁵N，以及碳和氮的含量。在各个地点调查了水文条件的影响：自然潮湿、排水沟和自然干燥。分子表征显示，木聚糖型半纤维素的特定侧链键在所有位点的 0-14 厘米范围内优先降解，表明有机物损失高达 25%。相比之下，木聚糖主链、半乳甘露聚糖型半纤维素和纤维素更耐降解，并在自然潮湿和排水部位积累。δ ¹³ C, δ ¹⁵N、碳和氮含量与特定的半纤维素结构无关，但反映了总碳水化合物的变化。我们的分析提供了对泥炭碳水化合物分解的新见解，并表明由于特定半纤维素结构的降解，acrotelm 中大量有机物质损失。这表明半纤维素含量和结构的变化会影响泥炭的稳定性，这可能对气候变化具有重要意义。