Source, transport and fate of soil organic matter inferred from microbial biomarker lipids on the East Siberian Arctic Shelf
Source, transport and fate of soil organic matter inferred from microbial biomarker lipids on the East Siberian Arctic Shelf
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DOI：
10.5194/bg-13-4899-2016
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发表时间：
2016-09-06
期刊：
影响因子：
4.9
通讯作者：
Talbot, Helen M.
中科院分区：
文献类型：
--
作者：
Bischoff, Juliane;Sparkes, Robert B.;Talbot, Helen M.
西伯利亚北极地区含有全球重要的有机碳（OC）库，容易受到河流和海岸侵蚀过程的加剧变暖和随后释放的影响。然而，人们对释放速度、其在北冰洋的行为以及对再矿化的脆弱性知之甚少。在这里，我们结合联合收割机新的测量微生物biohopanoids，包括adenosylhopane，脂质与土壤微生物群落，与已发表的甘油二烷基甘油四醚（GDGT）和散装三角洲C-13测量，以提高知识的命运OC运输到东西伯利亚北极大陆架（ESAS）。微生物hopanoid为基础的土壤有机碳代理R '（土壤）的范围从0.0到0.8整个ESAS，最高值近岸和近海减少。在整个大陆架上，R '（土壤）显示出与大量δ C-13测量值的负线性相关（r（2）=-0.73，p = < 0：001）。当比较GDGT为基础的OC代理，分支和异戊二烯四醚（BIT）指数，脱钩（非线性）的行为在货架上观察到，特别是在Buor-Khaya湾，其中R '（土壤）显示有限的变化，而BIT指数显示快速下降移动远离勒拿河流出通道。这反映了不同来源的OC的交付和移除之间的平衡。hopanoid和散装陆地信号之间的良好相关性表明，广泛的hopanoid来源，河流和通过海岸侵蚀，而GDGT似乎主要来源于河流运输。冰复合沉积物（ICDs）的分析显示，平均R '（土壤）为0.5的Lena三角洲，相当于Buor-Khaya湾沉积物，而ICDs从更远的东部显示更高的值（0.6-0.85）。虽然R '（土壤）与散装有机碳比BIT更密切相关，但我们对该系统端元的理解显然仍然不完整，不同的东西伯利亚北极地区之间的变化可能反映了环境条件（例如温度，pH值）的差异，但在嗜冷条件下微生物bacteriohopanepolyol（BHP）生产的其他生理控制尚不清楚。
The Siberian Arctic contains a globally significant pool of organic carbon (OC) vulnerable to enhanced warming and subsequent release by both fluvial and coastal erosion processes. However, the rate of release, its behaviour in the Arctic Ocean and vulnerability to remineralisation is poorly understood. Here we combine new measurements of microbial biohopanoids including adenosylhopane, a lipid associated with soil microbial communities, with published glycerol dialkyl glycerol tetraethers (GDGTs) and bulk delta C-13 measurements to improve knowledge of the fate of OC transported to the East Siberian Arctic Shelf (ESAS). The microbial hopanoid-based soil OC proxy R'(soil) ranges from 0.0 to 0.8 across the ESAS, with highest values nearshore and decreases offshore. Across the shelf R'(soil) displays a negative linear correlation with bulk delta C-13 measurements (r(2) = -0.73, p = < 0 : 001). When compared to the GDGT-based OC proxy, the branched and isoprenoid tetraether (BIT) index, a decoupled (non-linear) behaviour on the shelf was observed, particularly in the Buor-Khaya Bay, where the R'(soil) shows limited variation, whereas the BIT index shows a rapid decline moving away from the Lena River outflow channels. This reflects a balance between delivery and removal of OC from different sources. The good correlation between the hopanoid and bulk terrestrial signal suggests a broad range of hopanoid sources, both fluvial and via coastal erosion, whilst GDGTs appear to be primarily sourced via fluvial transport. Analysis of ice complex deposits (ICDs) revealed an average R'(soil) of 0.5 for the Lena Delta, equivalent to that of the Buor-Khaya Bay sediments, whilst ICDs from further east showed higher values (0.6-0.85). Although R'(soil) correlates more closely with bulk OC than the BIT, our understanding of the endmembers of this system is clearly still incomplete, with variations between the different East Siberian Arctic regions potentially reflecting differences in environmental conditions (e.g. temperature, pH), but other physiological controls on microbial bacteriohopanepolyol (BHP) production under psychrophilic conditions are as yet unknown.