State Key Laboratory of Tibetan Plateau Earth System Science (LATPES), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China; Polar Oceans Research Group, Sheridan, MT 59749, USA.
Polar Oceans Research Group, Sheridan, MT 59749, USA; Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, CA 94550, USA.
Sci Total Environ. 2022 Oct 1;841:156639. doi: 10.1016/j.scitotenv.2022.156639. Epub 2022 Jun 10.
Glaciers can accumulate and release organic matter affecting the structure and function of associated terrestrial and aquatic ecosystems. We analyzed 18 ice cores collected from six locations in Taylor Valley (McMurdo Dry Valleys), Antarctica to determine the spatial abundance and quality of organic matter, and the spatial distribution of bacterial density and community structure from the terminus of the Taylor Glacier to the coast (McMurdo Sound). Our results showed that dissolved and particulate organic carbon (DOC and POC) concentrations in the ice core samples increased from the Taylor Glacier to McMurdo Sound, a pattern also shown by bacterial cell density. Fluorescence Excitation Emission Matrices Spectroscopy (EEMs) and multivariate parallel factor (PARAFAC) modeling identified one humic-like (C1) and one protein-like (C2) component in ice cores whose fluorescent intensities all increased from the Polar Plateau to the coast. The fluorescence index showed that the bioavailability of dissolved organic matter (DOM) also decreased from the Polar Plateau to the coast. Partial least squares path modeling analysis revealed that bacterial abundance was the main positive biotic factor influencing both the quantity and quality of organic matter. Marine aerosol influenced the spatial distribution of DOC more than katabatic winds in the ice cores. Certain bacterial taxa showed significant correlations with DOC and POC concentrations. Collectively, our results show the tight connectivity among organic matter spatial distribution, bacterial abundance and meteorology in the McMurdo Dry Valley ecosystem.
冰川可以积累和释放有机物，影响相关陆地和水生生态系统的结构和功能。我们分析了从南极麦克默多干谷泰勒谷的六个地点采集的 18 个冰芯，以确定有机物的空间丰度和质量，以及从泰勒冰川末端到海岸（默多海峡）的细菌密度和群落结构的空间分布。我们的结果表明，冰芯样本中的溶解态和颗粒态有机碳（DOC 和 POC）浓度从泰勒冰川到默多海峡逐渐增加，细菌细胞密度也呈现出同样的模式。荧光激发发射矩阵光谱（EEMs）和多元平行因子（PARAFAC）建模在冰芯中鉴定出一个类腐殖质（C1）和一个类蛋白（C2）成分，其荧光强度均从极地高原向海岸增加。荧光指数表明，从极地高原到海岸，溶解有机物质（DOM）的生物可利用性也降低了。偏最小二乘路径模型分析显示，细菌丰度是影响有机物数量和质量的主要正向生物因素。海洋气溶胶对冰芯中 DOC 的空间分布的影响大于下降风。某些细菌类群与 DOC 和 POC 浓度呈显著相关。总的来说，我们的结果表明，在麦克默多干谷生态系统中，有机物空间分布、细菌丰度和气象之间存在紧密的联系。
