Lake and catchment response to Holocene environmental change: spatial variability along a climate gradient in southwest Greenland
Lake and catchment response to Holocene environmental change: spatial variability along a climate gradient in southwest Greenland
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DOI：
10.1007/s10933-012-9616-3
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发表时间：
2012-06-01
影响因子：
2.1
通讯作者：
Jones, M. D.
中科院分区：
文献类型：
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作者：
Anderson, N. J.;Liversidge, A. C.;Jones, M. D.
格陵兰岛西南部的康克鲁斯瓦格地区是一个湖泊丰富的地区，它覆盖了一个气候梯度：一个更海洋性、更凉爽、更潮湿的沿海地区与干燥的内陆地区形成鲜明对比。对海岸和峡湾顶部的配对湖泊的放射性碳定年沉积物序列（覆盖范围类似于11,200-8,300 cal年）进行了岩石地层变量（有机质含量、体积密度、Ti、Ca）分析。对比了4个湖泊的成矿速率和碳积累速率，以确定流域和湖泊对全新世气候变率的响应。海岸的集水区侵蚀主要是冰冻过程，由于有限的植被覆盖和暴露的岩面，产生了大量的沉积物。在5800 - 4000 cal year BP期间，其中一个站点（AT4）的成矿沉积物输入量很高(> 1 gDW cm(-2) year(-1))，这可能反映了东北面斜坡的低温过程加剧并迅速向湖泊输送。由于流域地势较低，在附近的高海拔地区（AT1）没有观察到这一时期的侵蚀活动；相反，在大约5800 cal year BP时，碳和成矿聚集速率急剧下降。内陆站点的沉积物积累速率要低得多（< 0.005 gDW cm（-2）年），反映了更大的流域稳定性（更广泛的植被覆盖）、更低的地形和更少的降水，但从1200到1000 cal year BP的矿物积累速率同步增加可能反映了与区域冷却和局部干旱相关的风蚀。两个内陆站点的碳积累速率剖面相似，在全新世早期高于平均水平（类似于6-8 g C m（-2）年（-1）），随后在大约6000 cal year BP后下降。在内陆湖泊，矿物和碳积累速率都与气候表现出更强的联系，受到有效降水和区域风成活动趋势的驱动。流域差异（地形、海拔）导致海岸侵蚀历史和湖泊生产力的个人主义记录。
The Kangerlussuaq area of southwest Greenland is a lake-rich landscape that covers a climate gradient: a more maritime, cooler and wetter coastal zone contrasts with a dry, continental interior. Radiocarbon-dated sediment sequences (covering similar to 11,200-8,300 cal year) from paired lakes at the coast and the head of the fjord were analysed for lithostratigraphic variables (organic-matter content, bulk density, Ti, Ca). Minerogenic and carbon accumulation rates from the four lakes were compared to determine catchment and lake response to Holocene climatic variability. Catchment erosion at the coast was dominated by cryonival processes, with considerable sediment production due to the limited vegetation cover and exposed rock faces. Input of minerogenic sediment at one site (AT4) was high (> 1 gDW cm(-2) year(-1)) during the period 5,800-4,000 cal year BP, perhaps reflecting intensification of cryogenic processes on northeast-facing slopes and rapid delivery to the lake. This period of erosional activity was not observed at the nearby, higher elevation site (AT1) due to the lower catchment relief; instead, there was an abrupt decline in carbon and minerogenic accumulation rates at similar to 5,800 cal year BP. Sediment accumulation rates at the inland sites were much lower (< 0.005 gDW cm(-2) year(-1)) reflecting greater catchment stability (more extensive vegetation cover), lower relief and substantially lower precipitation, but synchronous increases in mineral accumulation rates from similar to 1,200 to 1,000 cal year BP may reflect wind erosion associated with regional cooling and local aridity. Carbon-accumulation-rate profiles were similar at the two inland sites, with higher-than-average accumulation (similar to 6-8 g C m(-2) year(-1)) during the early Holocene and a subsequent decline after similar to 6,000 cal year BP. At the inland lakes, both mineral and carbon accumulation rates exhibited a stronger link to climate, driven by trends in effective precipitation and regional aeolian activity. Catchment differences (relief, altitude) lead to more individualistic records in both erosion history and lake productivity at the coast.