Anthropocene climate warming enhances autochthonous carbon cycling in an upland Arctic lake, Disko Island, West Greenland
Anthropocene climate warming enhances autochthonous carbon cycling in an upland Arctic lake, Disko Island, West Greenland
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DOI：
10.5194/bg-18-2465-2021
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发表时间：
2021-04
期刊：
影响因子：
4.9
通讯作者：
M. Stevenson;S. McGowan;E. Pearson;George E. A. Swann;M. Leng;V. Jones;Joseph J. Bailey;Xianyu Huang;E. Whiteford
中科院分区：
文献类型：
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作者：
M. Stevenson;S. McGowan;E. Pearson;George E. A. Swann;M. Leng;V. Jones;Joseph J. Bailey;Xianyu Huang;E. Whiteford
抽象的。北极正在迅速变化，扰乱了生物地球化学循环和碳(C)在相互关联的陆地-水生系统中的加工、输送和沉积。在这项调查中，我们将集水区土壤、沉积物和植物的水文地貌评估与最近的湖泊沉积物序列相结合，以了解位于低北极-高北极过渡带以南的迪斯科岛上三个北极高地湖泊集水区的有机碳的来源和质量。这种多种多样的永久冻土景观暴露了高海拔地区植被覆盖较少的土壤，湖泊获得了不同数量的冰川融水输入。我们为高纬度地区的古植被研究提供了改进的同位素和生物标志物来源识别，这些地区的陆地植被处于或接近其北纬和海拔范围的界限。集水区土壤发育不良，导致湖水中溶解有机碳含量较低(≤为1.5mg·L，−：1)。沉积碳氮比(C/N)、有机质碳同位素组成(δ13Corg)和生物标志物比值(正构烷烃、正构烷醇、正构烷酸和甾醇)表明，这些湖泊的沉积有机质(OM)主要来自水生来源(藻类和大型植物)。我们使用了一个210Pb年代的沉积物岩心来确定近几个世纪以来湖泊集水系统(DISKO 2)中的碳循环是如何变化的。自小冰期(LIA∼1860年CE)结束以来的最近变暖，在约1950年后加速，导致冰川冰和永久冻土融化，向湖泊释放营养物质和DOC，并刺激显著的水生藻类生产，β-胡萝卜素增加了10倍，表明制度发生了重大转变。我们还证明，最近集水区陆地植被覆盖率的增加对原地响应起到了促进作用。我们的发现突出表明，在集水区植被和土壤稀少发育的北极湖泊中，与广泛植被覆盖的低北极系统相比，最近人类世变暖导致湖内碳加工发生显著变化，并沉积了更多活性更强的、主要是原生的碳。
Abstract. The Arctic is rapidly changing, disrupting biogeochemical cycles and the processing, delivery and sedimentation of carbon (C), in linked terrestrial–aquatic systems. In this investigation, we coupled a hydrogeomorphic assessment of catchment soils, sediments and plants with a recent lake sediment sequence to understand the source and quality of organic carbon present in three Arctic upland lake catchments on Disko Island, located just south of the low–high Arctic transition zone. This varied permafrost landscape has exposed soils with less vegetation cover at higher altitudes, and lakes received varying amounts of glacial meltwater inputs. We provide improved isotope and biomarker source identifications for palaeolimnological studies in high-latitude regions, where terrestrial vegetation is at or close to its northerly and altitudinal range limit. The poorly developed catchment soils lead to lake waters with low dissolved organic carbon (DOC) concentrations (≤1.5 mg L−1). Sedimentary carbon/nitrogen (C/N) ratios, the C isotope composition of organic matter (δ13Corg) and biomarker ratios (n-alkanes, n-alkanols, n-alkanoic acids and sterols) showed that sedimentary organic matter (OM) in these lakes is mostly derived from aquatic sources (algae and macrophytes). We used a 210Pb-dated sediment core to determine how carbon cycling in a lake–catchment system (Disko 2) had changed over recent centuries. Recent warming since the end of the Little Ice Age (LIA∼1860 CE), which accelerated after ca. 1950, led to melt of glacier ice and permafrost, releasing nutrients and DOC to the lake and stimulating pronounced aquatic algal production, as shown by a >10-fold increase in β-carotene, indicative of a major regime shift. We also demonstrate that recent increases in catchment terrestrial vegetation cover contributed to the autochthonous response. Our findings highlight that in Arctic lakes with sparsely developed catchment vegetation and soils, recent Anthropocene warming results in pronounced changes to in-lake C processing and the deposition of more reactive, predominately autochthonous C, when compared with extensively vegetated low-Arctic systems.