Sulphate reduction and anaerobic methane oxidation in sediments of Lake Grevelingen

在季节性分层和缺氧的沿海咸水湖中，人类活动增加的营养输入几十年来一直支持着较高的初级生产力。这导致沉积物中积累了大量的有机物质。由于大多数氧气已经在沉积物的上部毫米中损失，因此大多数有机物目前在缺氧条件下通过硫酸盐还原（SR）和甲烷生成而降解。硫酸盐还原在硫酸盐-甲烷-过渡区（SMTZ）厌氧氧化去除向上扩散的甲烷中也起着关键作用。甲烷的不完全氧化导致向上拖尾的甲烷配置文件和扩大的SMTZ与硫酸盐和甲烷是目前在一个广泛的深度间隔。负责这样一个广泛的SMTZ，这也是在其他系统的沉积物中观察到的过程，仍然没有完全理解。在这里，我们将扩大现有的孔隙水数据集的硫酸盐和甲烷的动力学在湖Grevelingen沉积物中的SR和甲烷的厌氧氧化（AOM）的速率测量，以进一步了解SMTZ的分布和程度的两个过程。此外，还将研究铁、锰和磷的沉积动力学以及AOM对其源和汇行为的影响。该研究将有助于更好地了解海洋沉积物中甲烷厌氧氧化的过程及其对其他生物地球化学循环的影响。

In seasonally stratified and hypoxic coastal saline Lake Grevelingen anthropogenically enhanced nutrient input has supported a high primary production already for several decades. This has resulted in the accumulation of large amounts of organic matter in the sediments. Because most oxygen is already lost in the upper millimetres of the sediment, most of this organic matter is currently degraded under anoxic conditions by sulphate reduction (SR) and methanogenesis. Sulphate reduction also plays a key role in removing upward diffusing methane through anaerobic oxidation in the sulphate-methane-transition zone (SMTZ). Incomplete oxidation of methane leads to an upward tailing of the methane profile and a broadening of the SMTZ with both sulphate and methane being present over a wide depth interval. The processes responsible for such a broad SMTZ, which is also observed in sediments of other systems, are still incompletely understood. Here, we will expand the existing pore water data set on sulphate and methane dynamics in sediments of Lake Grevelingen with rate measurements of SR and anerobic oxidation of methane (AOM) to obtain further insight into the distribution and extent of both processes in the SMTZ. Furthermore, the sedimentary dynamics of iron, manganese and phosphorus and the impact of AOM on their source and sink behaviour will be studied. This study will contribute to a better understanding of the processes leading to anaerobic oxidation of methane in marine sediments and the impact on other biogeochemical cycles.