Selective Leaching of Dissolved Organic Matter From Alpine Permafrost Soils on the Qinghai‐Tibetan Plateau
Selective Leaching of Dissolved Organic Matter From Alpine Permafrost Soils on the Qinghai‐Tibetan Plateau
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DOI：
10.1002/2017jg004343
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发表时间：
2018-03
期刊：
影响因子：
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通讯作者：
Yinghui Wang;Yunping Xu;R. Spencer;P. Zito;A. Kellerman;D. Podgorski;Wenjie Xiao;D. Wei;H. Rashid;Yuanhe Yang
中科院分区：
文献类型：
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作者：
Yinghui Wang;Yunping Xu;R. Spencer;P. Zito;A. Kellerman;D. Podgorski;Wenjie Xiao;D. Wei;H. Rashid;Yuanhe Yang
持续的全球气温上升导致青藏高原多年冻土严重融化和退化。有机物从永冻土到水生系统的沥滤是非常复杂的，并且难以在实验室环境中重现。我们从QTP上的高山沼泽草甸的活动层和永久冻土层的天然渗出物中收集样品，通过结合光学测量，高分辨率傅里叶变换离子回旋共振质谱，放射性碳（14 C）和固态13 C核磁共振光谱来阐明流动的溶解有机物（DOM）的组成。我们的研究结果表明，即使活动层土壤中含有大量的蛋白质和碳水化合物，有选择性释放的芳香族成分，而在深层冻土层，碳水化合物和蛋白质成分在解冻过程中优先浸出。鉴于这些不同的化学特性的动员DOM，我们假设，光矿化作用有助于显着的损失DOM是从季节性解冻的表层。然而，随着持续变暖，生物降解将变得更加重要，因为蛋白质和碳水化合物等生物不稳定物质优先从深层永久冻土中释放出来。DOM渗滤液源和相关化学成分的这种转变对QTP的下游河流网络产生了影响，特别是在碳和相关通量的处理方面。
Ongoing global temperature rise has caused significant thaw and degradation of permafrost soils on the Qinghai‐Tibetan Plateau (QTP). Leaching of organic matter from permafrost soils to aquatic systems is highly complex and difficult to reproduce in a laboratory setting. We collected samples from natural seeps of active and permafrost layers in an alpine swamp meadow on the QTP to shed light on the composition of mobilized dissolved organic matter (DOM) by combining optical measurements, ultrahigh‐resolution Fourier transform ion cyclotron resonance mass spectrometry, radiocarbon (14C), and solid‐state 13C nuclear magnetic resonance spectroscopy. Our results show that even though the active layer soils contain large amounts of proteins and carbohydrates, there is a selective release of aromatic components, whereas in the deep permafrost layer, carbohydrate and protein components are preferentially leached during the thawing process. Given these different chemical characteristics of mobilized DOM, we hypothesize that photomineralization contributes significantly to the loss of DOM that is leached from the seasonally thawed surface layer. However, with continued warming, biodegradation will become more important since biolabile materials such as protein and carbohydrate are preferentially released from deep‐layer permafrost soils. This transition in DOM leachate source and associated chemical composition has ramifications for downstream fluvial networks on the QTP particularly in terms of processing of carbon and associated fluxes.