Arctic wetlands are a globally significant store of soil organic carbon. They are often characterized by ice-wedge polygons, which are diagnostic of lowland permafrost, and which greatly influence wetland hydrology and biogeochemistry during summer. The degradation of ice-wedge polygons, which can occur in response to climate change or local disturbance, has poorly understood consequences for biogeochemical processes. We therefore used geochemical analyses from the active layer and top permafrost to identify and compare the dominant biogeochemical processes in high-centered (degraded) and low-centered (pristine) polygons situated in the raised beach sediments and valley-infill sediments of Adventdalen, Central Svalbard. We found similar organic-rich sediments in both cases (up to 38 dry wt.%), but while low-centered polygons were water-saturated, their high-centered counterparts had a relatively dry active layer. Consequently, low-centered polygons showed evidence of iron and sulfate reduction leading to the precipitation of pyrite and siderite, whilst the high-centered polygons demonstrated more oxidizing conditions, with decreased iron oxidation and low preservation of iron and sulfate reduction products in the sediments. This study thus demonstrates the profound effect of ice-wedge polygon degradation on the redox chemistry of the host sediment and porewater, namely more oxidizing conditions, a decrease in iron reduction, and a decrease in the preservation of iron and sulfate reduction products.

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斯瓦尔巴湿地低中心和高中心冰楔多边形的生物地球化学

北极湿地是全球重要的土壤有机碳储存库。它们通常以冰楔多边形为特征，这是低地永久冻土的诊断，并且极大地影响夏季湿地水文和生物地球化学。冰楔多边形的退化可能是由于气候变化或局部扰动而发生的，但人们对其对生物地球化学过程的影响知之甚少。因此，我们利用活动层和顶部永久冻土的地球化学分析来识别和比较位于中部 Adventdalen 的凸起海滩沉积物和山谷填充沉积物中的高中心（退化）和低中心（原始）多边形的主要生物地球化学过程。斯瓦尔巴特群岛。我们在这两种情况下都发现了类似的富含有机物的沉积物（干重高达 38%），但虽然低中心多边形是水饱和的，它们的高中心对应物具有相对干燥的活性层。因此，低中心多边形显示出铁和硫酸盐还原的证据，导致黄铁矿和菱铁矿沉淀，而高中心多边形则显示出更多的氧化条件，铁氧化减少，沉积物中铁和硫酸盐还原产物的保存率较低。因此，这项研究证明了冰楔多边形退化对宿主沉积物和孔隙水的氧化还原化学的深远影响，即更多的氧化条件、铁还原的减少以及铁和硫酸盐还原产物的保存的减少。低中心多边形显示出铁和硫酸盐还原导致黄铁矿和菱铁矿沉淀的证据，而高中心多边形显示出更多的氧化条件，铁氧化减少，沉积物中铁和硫酸盐还原产物的保存率较低。因此，这项研究证明了冰楔多边形退化对宿主沉积物和孔隙水的氧化还原化学的深远影响，即更多的氧化条件、铁还原的减少以及铁和硫酸盐还原产物的保存的减少。低中心多边形显示出铁和硫酸盐还原导致黄铁矿和菱铁矿沉淀的证据，而高中心多边形显示出更多的氧化条件，铁氧化减少，沉积物中铁和硫酸盐还原产物的保存率较低。因此，这项研究证明了冰楔多边形退化对宿主沉积物和孔隙水的氧化还原化学的深远影响，即更多的氧化条件、铁还原的减少以及铁和硫酸盐还原产物的保存的减少。