(Table) Bacterial counts and Fe, Mn and SO4 content in sediments and pore waters of two cores from Lake Baikal

Sediments at the bottom of Lake Baikal are mostly oxidized at their surface, and the oxidized sedimentary deposits are enriched in Fe and Mn hydroxides. The thickness of the oxidized zone of the pelagic sediments averages at 5 cm and locally reaches 10-15, occasionally exceeding 20 cm. Both the thickness of the oxidized layer and the degree of its enrichment in iron and manganese hydroxides are controlled by the depth to which oxygen can penetrate into the sedimentary deposits, which is, in turn, closely related to the sedimentation conditions in the lake (which broadly vary). The sedimentation rate far off the shores of Lake Baikal ranges from <0.02 mm/year to 1.5 mm/year, and the content of organic matter buried in the sediments varies from 0.1 to >4%. The variability of the sedimentation process makes Lake Baikal very convenient to study its diagenetic processes related to redox reactions in sediments, first of all, processes responsible for the redistribution of Fe and Mn compounds. […]

贝加尔湖湖底沉积物表层多呈氧化状态，氧化沉积层富铁（Fe）、锰（Mn）氢氧化物。远洋沉积物（pelagic sediments）的氧化带平均厚度为5厘米，局部可达10~15厘米，偶尔可超过20厘米。氧化层厚度及其铁、锰氢氧化物的富集程度，均由氧气向沉积层渗透的深度所调控；而该渗透深度反过来又与湖内沉积环境紧密相关，且这类沉积环境存在广泛差异。贝加尔湖远岸区域的沉积速率介于0.02毫米/年以下至1.5毫米/年之间，沉积物中埋藏的有机质含量介于0.1%至4%以上。沉积过程的多样性使得贝加尔湖成为研究沉积物内氧化还原反应相关成岩作用的理想研究对象，其中尤以调控铁、锰化合物再分配的作用过程为首要研究重点。[…]