In situ produced branched glycerol dialkyl glycerol tetraethers in suspended particulate matter from the Yenisei River, Eastern Siberia
In situ produced branched glycerol dialkyl glycerol tetraethers in suspended particulate matter from the Yenisei River, Eastern Siberia
复制标题
DOI：
10.1016/j.gca.2013.10.031
复制
发表时间：
2014-01-15
影响因子：
5
通讯作者：
Damste, Jaap S. Sinninghe
中科院分区：
文献类型：
--
作者：
De Jonge, Cindy;Stadnitskaia, Alina;Damste, Jaap S. Sinninghe
海洋河流扇沉积物中土壤衍生的支链甘油二烷基甘油四醚（brGDGTs）具有确定河流流域土壤年平均温度（MAT）和pH变化的潜在用途。在与海洋沉积物结合之前，这些化合物由河流输送到海洋系统。然而，新出现的证据表明，淡水系统中的brGDGTs可以来自土壤径流和原位生产。河流系统中brGDGT的产生会使传递给海洋系统的brGDGT信号的解释复杂化。因此，我们研究了叶尼塞河悬浮颗粒物（SPM）中brdgt脂质的分布。色谱改进使得最近描述的六甲基化brGDGT异构体得以定量，其特征是在6/6 ‘而不是5/5 ’位置上有两个甲基，这是第一次在环境数据集中。该新化合物是叶尼塞SPM中最丰富的brGDGT。它的分数丰度与六甲基化brGDGT的6-甲基异构体的分数丰度相关良好，其中含有一个环戊烷部分。叶尼塞河流域由于跨越较大的纬度范围（46-73°N），因此具有较大的MAT差异（bb0 - 11°C），这将反映在其土壤的brGDGT分布中。然而，其SPM中的brGDGT分布变化不大。此外，重建的pH值比流域土壤pH值高。因此，我们假设叶尼塞河SPM中的brGDGTs主要是原位产生的，而不是主要来自土壤侵蚀。这解释了温度信号没有变化的原因，因为河水温度更稳定。利用湖泊定标，重建的温度值与记录的夏季平均温度（MST）一致。因此，叶尼塞河在这个季节向海洋输送的brGDGTs不是来自土壤的，这可能使brGDGTs在海洋沉积物中用于古气候重建的使用复杂化。(C) 2013年作者。Elsevier Ltd.出版。版权所有。
Soil-derived branched glycerol dialkyl glycerol tetraethers (brGDGTs) in marine river fan sediments have a potential use for determining changes in the mean annual temperature (MAT) and pH of the river watershed soils. Prior to their incorporation in marine sediments, the compounds are transported to the marine system by rivers. However, emerging evidence suggests that the brGDGTs in freshwater systems can be derived from both soil run-off and in situ production. The production of brGDGTs in the river system can complicate the interpretation of the brGDGT signal delivered to the marine system. Therefore, we studied the distribution of brGDGT lipids in suspended particulate matter (SPM) of the Yenisei River. Chromatographic improvements allowed quantification of the recently described hexamethylated brGDGT isomer, characterized by having two methyl groups at the 6/6 ' instead of the 5/5 ' positions, in an environmental dataset for the first time. This novel compound was the most abundant brGDGT in SPM from the Yenisei. Its fractional abundance correlated well with that of the 6-methyl isomer of the hexamethylated brGDGT that contains one cyclopentane moiety. The Yenisei River watershed is characterized by large differences in MAT (>11 degrees C) as it spans a large latitudinal range (46-73 degrees N), which would be expected to be reflected in brGDGT distributions of its soils. However, the brGDGT distributions in its SPM show little variation. Furthermore, the reconstructed pH values are high compared to the watershed soil pH. We, therefore, hypothesize that the brGDGTs in the Yenisei River SPM are predominantly produced in situ and not primarily derived from erosion of soil. This accounts for the absence of a change in the temperature signal, as the river water temperature is more stable. Using a lake calibration, the reconstructed temperature values agree with the mean summer temperatures (MST) recorded. The brGDGTs delivered to the sea by the Yenisei River during this season are thus not soil-derived, possibly complicating the use of brGDGTs in marine sediments for palaeoclimate reconstructions. (C) 2013 The Authors. Published by Elsevier Ltd. All rights reserved.