Bacteriohopanepolyols record stratification, nitrogen fixation and other biogeochemical perturbations in Holocene sediments of the central Baltic Sea
Bacteriohopanepolyols record stratification, nitrogen fixation and other biogeochemical perturbations in Holocene sediments of the central Baltic Sea
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DOI：
10.5194/bg-10-2725-2013
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发表时间：
2013-01-01
期刊：
影响因子：
4.9
通讯作者：
Thiel, V.
中科院分区：
文献类型：
--
作者：
Blumenberg, M.;Berndmeyer, C.;Thiel, V.
波罗的海是世界上最大的咸海盆地之一，大约 17 000 至 15 000 年前斯堪的纳维亚半岛冰川消融后形成。在波罗的海多变的历史中，大约8000年前，最初的淡水系统与北海相连，并建立了现代的咸水海洋环境（利托里纳海）。如今，由于盐度差异，深盆水体已形成相对稳定的分层。分层只是偶尔被混合事件打断，它控制着营养物质的可用性以及特别适应的微生物和藻类的生长。我们研究了波罗的海中部（哥特兰深海）沉积物核心中的细菌藿烷多元醇 (BHP)（特定细菌群的脂质），发现波罗的海历史的不同阶段之间存在显着差异。一些单独的 BHP 结构表明，来自未知的氧化还原素特异性细菌（细菌藿四醇异构体）、甲烷氧化菌（35-氨基细菌藿四醇）、蓝细菌（细菌藿四醇环醇醚异构体）和土壤细菌（腺苷藿烷）通过 Littorina 海侵后的异地输入做出了贡献，而核心中其他 BHP 的起源仍有待确定。在咸海 Littorina 阶段的沉积物中观察到了显着高的 BHP 丰度，特别是在层状沉积物层中。由于这些沉积物记录了稳定水柱分层的时期，因此专门适应这些条件的细菌可能占 BHP 的大部分。额外和/或伴随的来源可能是固氮（氰基）细菌，BHP 丰度与 C-org 和 delta N-15 呈正相关表明了这一点。
The Baltic Sea, one of the world's largest brackish-marine basins, established after deglaciation of Scandinavia about 17 000 to 15 000 yr ago. In the changeable history of the Baltic Sea, the initial freshwater system was connected to the North Sea about 8000 yr ago and the modern brackish-marine setting (Littorina Sea) was established. Today, a relatively stable stratification has developed in the water column of the deep basins due to salinity differences. Stratification is only occasionally interrupted by mixing events, and it controls nutrient availability and growth of specifically adapted microorganisms and algae. We studied bacteriohopanepolyols (BHPs), lipids of specific bacterial groups, in a sediment core from the central Baltic Sea (Gotland Deep) and found considerable differences between the distinct stages of the Baltic Sea's history. Some individual BHP structures indicate contributions from as yet unknown redoxcline-specific bacteria (bacteriohopanetetrol isomer), methanotrophic bacteria (35-aminobacteriohopanetetrol), cyanobacteria (bacteriohopanetetrol cyclitol ether isomer) and from soil bacteria (adenosylhopane) through allochthonous input after the Littorina transgression, whereas the origin of other BHPs in the core has still to be identified. Notably high BHP abundances were observed in the deposits of the brackish-marine Littorina phase, particularly in laminated sediment layers. Because these sediments record periods of stable water column stratification, bacteria specifically adapted to these conditions may account for the high portions of BHPs. An additional and/or accompanying source may be nitrogen-fixing (cyano) bacteria, which is indicated by a positive correlation of BHP abundances with C-org and delta N-15.