Imprint of past and present environmental conditions on microbiology and biogeochemistry of coastal Quaternary sediments
Imprint of past and present environmental conditions on microbiology and biogeochemistry of coastal Quaternary sediments
复制标题
DOI：
10.5194/bg-8-55-2011
复制
发表时间：
2011-01-01
期刊：
影响因子：
4.9
通讯作者：
Engelen, B.
中科院分区：
文献类型：
--
作者：
Beck, M.;Riedel, T.;Engelen, B.
迄今为止，北海潮滩沉积物已深入研究海底以下 5 m 的深度 (mbsf)。然而，人们对深层硫酸盐还原剂和产甲烷菌的生物地球化学、微生物丰度和活性知之甚少。在这项研究中，从德国西北部斯皮科罗格岛的潮坪地区取回了两个 20 m 长的岩心。钻探地点的选择距离很近，为 900 m，可以比较两种沉积环境：首先是充满全新世沉积物的古河道，其次是主要是更新世沉积序列。通过分析这些核心，我们想要测试古环境印记在多大程度上被当前的过程叠加。一般来说，细菌16S rRNA基因的数量比古细菌高一到两个数量级。硫酸盐还原和产甲烷关键基因（dsrA 和 mcrA）的丰度与硫酸盐和甲烷分布相对应。这些关键基因在硫酸盐-甲烷界面上的协方差和增强的异位 AOM 速率表明这些层中可能发生甲烷的厌氧氧化。微生物和生物地球化学剖面相对于同一研究区域较浅沉积物的 5 m 深岩心垂直拉伸，但与深海沉积物相比仍然显得压缩。我们的跨学科分析表明，与更新世沉积物相比，全新世的微生物丰度和代谢率有所升高。然而，这主要是由于目前的环境条件，例如孔隙水流量和有机质可用性。古环境印记仍然可见，但被这些过程叠加。
To date, North Sea tidal-flat sediments have been intensively studied down to a depth of 5 m below seafloor (mbsf). However, little is known about the biogeochemistry, microbial abundance, and activity of sulfate reducers as well as methanogens in deeper layers. In this study, two 20 m-long cores were retrieved from the tidal-flat area of Spiekeroog Island, NW Germany. The drill sites were selected with a close distance of 900 m allowing to compare two depositional settings: first, a paleo-channel filled with Holocene sediments and second, a mainly Pleistocene sedimentary succession. Analyzing these cores, we wanted to test to which degree the paleo-environmental imprint is superimposed by present processes.In general, the numbers of bacterial 16S rRNA genes are one to two orders of magnitude higher than those of Archaea. The abundances of key genes for sulfate reduction and methanogenesis (dsrA and mcrA) correspond to the sulfate and methane profiles. A co-variance of these key genes at sulfate-methane interfaces and enhanced ex situ AOM rates suggest that anaerobic oxidation of methane may occur in these layers. Microbial and biogeochemical profiles are vertically stretched relative to 5 m-deep cores from shallower sediments in the same study area, but still appear compressed compared to deep sea sediments. Our interdisciplinary analysis shows that the microbial abundances and metabolic rates are elevated in the Holocene compared to Pleistocene sediments. However, this is mainly due to present environmental conditions such as pore water flow and organic matter availability. The paleo-environmental imprint is still visible but superimposed by these processes.