Glaciers and ice sheets cover over 10 % of Earth's land surface area and store a globally significant amount of dissolved organic matter (DOM), which is highly bioavailable when exported to proglacial environments. Recent rapid glacier mass loss is hypothesized to have increased fluxes of DOM from these environments, yet the molecular composition of glacially derived DOM has only been studied for a handful of glaciers. We determine DOM composition using ultrahigh resolution mass spectrometry from a diverse suite of Arctic glacial environments, including time series sampling from an ice sheet catchment in Greenland (Russell Glacier) and outflow from valley glaciers in catchments with varying degrees of glacial cover in Svalbard. Samples from the Greenland outflow time series exhibited a higher degree of similarity than glacier outflow between glaciers in Svalbard; however, supraglacial meltwater samples from Greenland and Svalbard were more similar to each other than corresponding glacial outflow. Outflow from Russell Glacier was enriched in polyphenolic formulae, potentially reflecting upstream inputs from plants and soils, or inputs from paleosols overridden by the ice sheet, whereas Svalbard rivers exhibited a high level of molecular richness and dissimilarity between sites. When comparing DOM compositional analyses from other aquatic systems, aliphatic, and peptide‐like formulae appear particularly abundant in supraglacial meltwater, suggesting the DOM quickly metabolized in previous incubations of glacial water originates from energy‐rich supraglacial sources. Therefore, as glaciers lose mass across the region, higher‐quality fuel for microbial degradation will increase heterotrophy in coastal systems with ramifications for carbon cycling.

中文翻译：

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斯瓦尔巴特群岛和格陵兰岛冰川溶解的有机物质的分子标记

冰川和冰盖覆盖了地球陆地面积的10％以上，并存储了全球相当数量的溶解有机物（DOM），当将其出口到冰川环境时，这些生物具有很高的生物利用率。据推测，近来冰川的快速质量损失使来自这些环境的DOM通量增加，但是，仅针对少数冰川研究了冰川衍生DOM的分子组成。我们使用超高分辨率质谱仪从一系列北极冰川环境中确定DOM组成，包括从格陵兰（Russell Glacier）的一个冰盖流域进行时间序列采样，以及在斯瓦尔巴特群岛具有不同程度的冰川覆盖度的流域中的山谷冰川流出。格陵兰岛流出时间序列的样本与斯瓦尔巴特群岛冰川之间的冰川流出相比，具有更高的相似度。但是，格陵兰岛和斯瓦尔巴群岛的冰川上融水样品彼此之间的对应关系要比相应的冰川流出更为相似。罗素冰川的流出物中富含多酚类物质，可能反映了植物和土壤的上游输入，或被冰盖覆盖的古土壤的输入，而斯瓦尔巴特河则表现出较高的分子富集度和站点之间的相似性。当比较来自其他水生系统的DOM成分分析时，在冰川上融水中脂肪和类肽的配方显得特别丰富，这表明在先前的冰水温育中快速代谢的DOM来源于能量丰富的冰川上来源。