Origin-specific molecular signatures of dissolved organic matter in the Lena Delta
Origin-specific molecular signatures of dissolved organic matter in the Lena Delta
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DOI：
10.1007/s10533-014-0049-0
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发表时间：
2015-03-01
期刊：
影响因子：
4
通讯作者：
Koch, B. P.
中科院分区：
文献类型：
--
作者：
Dubinenkov, I.;Flerus, R.;Koch, B. P.
大型北冰洋河流向北冰洋排放大量溶解有机物质(DOM)。我们采集了Lena河、Buor-Khaya Bay(拉普特夫海)、永久冻土融水小溪、冰川融水小溪和一个湖泊的天然水样本。这项研究的目的是描述Lena三角洲内不同水体的DOM分子组成。我们的目标是识别来源特定的DOM分子标记及其对不同来源的DOM的相对贡献。采用傅立叶变换离子回旋共振质谱(FT-ICR-MS)对固相萃取DOM进行了分子表征。原始样品中溶解有机碳的平均浓度为490+/-A75A moL C L-1,399+/-A115A moL C L-1(多年冻土融水小溪)。与河流和海湾(均为13.2+/-A2.6A mU/N L-1)相比，多年冻土融化水中的TdN平均浓度(19.7+/-A7.1Au·moL N·L-1)要高。FT-ICR MS和统计工具表明，Lena三角洲DOM的起源系统地反映在其分子组成上。根据MS数据计算的幅度加权参数(O/C-Wa、H/C-Wa、C/N-Wa)突出了初步的样品区分。融水小溪中DOM的H/C-Wa最高，为1.315，而河流和海湾中DOM的H/C-Wa分别为1.281和1.230。在海湾样品中，我们观察到更高比例的富氧成分，反映在O/C-Wa比为0.445，而河流和小溪分别为0.425和0.427。从最南端到海湾，氮分子标记物相对枯竭，氧化的DOM组分相对丰富。小溪对氮的贡献最大，C/N-Wa为104，而河流和海湾的C/N-Wa分别为143和176。使用主成分分析和指标值分析在分子式水平上研究了这些观察结果。结果表明，在水来源方面存在系统差异，并构成了更好地从机制上理解不断变化的北极河流中DOM转化的重要基础。
Large Arctic rivers discharge significant amounts of dissolved organic matter (DOM) into the Arctic Ocean. We sampled natural waters of the Lena River, the Buor-Khaya Bay (Laptev Sea), permafrost melt water creeks, ice complex melt water creeks and a lake. The goal of this study was to characterize the molecular DOM composition with respect to different water bodies within the Lena Delta. We aimed at an identification of source-specific DOM molecular markers and their relative contribution to DOM of different origin. The molecular characterization was performed for solid-phase extracted DOM by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Average dissolved organic carbon concentrations in the original samples were 490 +/- A 75 A mu mol C L-1 for riverine and bay samples and 399 +/- A 115 A mu mol C L-1 for permafrost melt water creeks. Average TDN concentrations were elevated in the permafrost melt waters (19.7 +/- A 7.1 A mu mol N L-1) in comparison to the river and the bay (both 13.2 +/- A 2.6 A mu mol N L-1). FT-ICR MS and statistical tools demonstrated that the origin of DOM in the Lena Delta was systematically reflected in its molecular composition. Magnitude weighted parameters calculated from MS data (O/C-wa, H/C-wa, C/N-wa) highlighted preliminary sample discrimination. The highest H/C-wa of 1.315 was found for DOM in melt water creeks in comparison to 1.281 for river and 1.230 for the bay samples. In the bay samples we observed a higher fraction of oxygen-rich components which was reflected in an O/C-wa ratio of 0.445 in comparison to 0.425 and 0.427 in the river and creeks, respectively. From the southernmost location to the bay a relative depletion of nitrogenous molecular markers and an enrichment of oxidized DOM components occurred. The highest contribution of nitrogenous components was indicative for creeks reflected in a C/N-wa of 104 in comparison to 143 and 176 in the river and bay, respectively. These observations were studied on a molecular formula level using principal component and indicator value analyses. The results showed systematic differences with respect to water origin and constitute an important basis for a better mechanistic understanding of DOM transformations in the changing Arctic rivers.