Water depth and transparency drive the quantity and quality of organic matter in sediments of Alpine Lakes on the Tibetan Plateau
Water depth and transparency drive the quantity and quality of organic matter in sediments of Alpine Lakes on the Tibetan Plateau
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DOI：
10.1002/lno.12180
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发表时间：
2022-07
影响因子：
4.5
通讯作者：
YingXun Du;Chunyan Luo;Feizhou Chen;Qiaoying Zhang;Yongqiang Zhou;Kyoung-Soon Jang;Yibo Zhang;
中科院分区：
文献类型：
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作者：
YingXun Du;Chunyan Luo;Feizhou Chen;Qiaoying Zhang;Yongqiang Zhou;Kyoung-Soon Jang;Yibo Zhang;
确定调节气候敏感型高山湖泊中沉积有机物（OM）数量和质量的主要环境驱动因素对于了解高山湖泊在温室气体排放和地球气候系统中的作用至关重要。本文对青藏高原20个高山湖泊的有机质进行了分析，包括表层沉积物中的有机质、水溶性有机质和碱提有机质，以及表层水中的溶解有机质（DOM）。沉积物中总有机碳（TOC）含量较低（< 3%），TOC的δ 13 C和C：N比值表明外源碳输入有限。沉积物水溶性有机质和碱提取有机质均以低分子量、低芳香性化合物为主，陆源腐殖物质的贡献较低，这表明沉积物可沥滤有机质主要受湖内来源和过程的调节。Redundancy分析表明，水深，水透明度，总磷浓度在水柱解释约50%的沉积物体积和可沥滤的OM的变化，证实了本地来源和初级生产力在调节沉积OM的数量和质量的重要性。与湖泊表层水DOM相比，沉积物水溶性和碱提性有机质中陆源类腐殖物质的比例较高，表明沉积物中有外来物质优先保存。我们的研究结果是第一次证明了西藏湖泊的物理属性和沉积有机质之间的明确联系。相关关系预测，在气候变暖和降水增加的情景下，湖泊扩大将增加沉积物中有机质和自生碳的总量，这可能会放大西藏湖泊的温室气体排放。
Identifying primary environmental drivers mediating the quantity and quality of sedimentary organic matter (OM) in climate‐sensitive alpine lakes is crucial to understanding the role of alpine lakes in greenhouse gas emissions and Earth's climate system. Here, we characterized various pools of OM of 20 alpine lakes across the Tibetan Plateau, including bulk OM, water‐soluble OM and alkaline‐extracted OM from surface sediments, and dissolved OM (DOM) from surface water. The total organic carbon (TOC) content in sediments was low (< 3%), and δ13C of TOC and C : N ratios indicated limited allochthonous carbon inputs. Sedimentary water‐soluble OM and alkaline‐extracted OM were both dominated by low‐molecular‐weight, low‐aromaticity compounds with low contributions of terrestrial humic substances, suggesting that sedimentary leachable OM was primarily regulated by in‐lake sources and processes. Redundancy analysis showed that water depth, water transparency, and total phosphorus concentration in water column explained ~ 50% variance of sedimentary bulk and leachable OM, substantiating the importance of autochthonous sources and primary productivity in regulating the quantity and quality of sedimentary OM. Compared with lake surface water DOM, water‐soluble OM and alkaline‐extracted OM from sediments had higher proportions of terrestrial humic‐like substances, suggesting preferential preservation of allochthonous materials in sediments. Our results are the first to demonstrate a clear link between physical attributes and sedimentary OM in Tibetan lakes. The associated relations predict that the amount of total OM and autochthonous carbon preserved in sediments would increase due to the lake enlargement under the scenarios of climate warming and precipitation enhancement, which may amplify greenhouse gas emissions from Tibetan lakes.