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首页> 外文期刊>Lakes & Reservoirs >Anthropogenic and climatic influences over the past three centuries on characteristics of an Adirondack lake, Eastern North America
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Anthropogenic and climatic influences over the past three centuries on characteristics of an Adirondack lake, Eastern North America

机译：在过去三个世纪中，人为和气候影响对北美东部阿迪朗达克湖的特征

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Fourth Lake is a drainage lake at 43°N, 74°W, from which a 37-cm long mud-water interface core was recovered. ~(210)Pb dating indicates the core spans ≈ 340 years, from the Little Ice Age through modern global warming. Diatom accumulation responds to anthropogenic watershed disturbances, declining slightly up-core until a peak in the late-1800s attributable to sediment and nutrient influx from logging and enlargement of the outlet dam. A dramatic decrease occurs ≈1900 as logging and lake filling ceased, and a smaller peak ≈1960 accompanies residential development. Similar changes occur in organic carbon accumulation, which ranges from 0.0038-0.024 mg cm~(-2) year~(-1), with generally decreasing values up-core, punctuated by maximum values in the late-1800s. Expressing diatoms as concentration, however, reveals a doubling up-core that positively correlates with changes extending beyond the watershed, including Northern Hemisphere temperature, atmospheric CO_2 concentration and solar irradiance (R = 0.627, 0.675 and 0.400, respectively). A >50% increase in % organic carbon, from 3.8% to 5.9%, also positively correlates with these larger-scale environmental conditions (R= 0.828, 0.830 and 0.832), while negative correlations with the extrabasinal records are exhibited by magnetic susceptibility (R = -0.654, -0.496, and -0.660) and clay (R = -0.770, -0.762, and -0.737). These changes are consistent with decreased sediment influx and reduced dilution of biogenous sedimentary components. In contrast to total diatoms, the accumulation of planktonic genus Asterionella displays a long-term increase up-core. Potential explanations include increasing duration of the ice-free season or a shift in the timing of the spring bloom and a mismatch with abundance of predator(s). Asterionella also increases as a percentage of total diatoms, being positively correlated with extrabasinal conditions (R = 0.827, 0.774 and 0.674). This change occurs at the expense of many benthic genera and, over the past century, at the expense of tychoplanktonic genus, Aulacosiera. Heavily silicified, Aulacosiera requires strong mixing to remain within the epilimnion. Thus, its decline might result from increasing stratification caused by warming.
机译：第四湖是北纬43°，南纬74°的排水湖，从中回收了37厘米长的泥水界面核心。 〜（210）Pb测年表明从小冰期到现代全球变暖的核心跨度约为340年。硅藻的积累对人为的流域扰动作出响应，在中心向上略有下降，直到1800年代后期达到峰值，这归因于出口大坝的伐木和扩建导致沉积物和养分涌入。随着伐木和湖泊填充的停止，约1900年急剧下降，伴随住宅开发的约1960年出现了一个较小的高峰。有机碳积累发生了类似的变化，范围从0.0038-0.024 mg cm〜（-2）年〜（-1），总体上呈下降趋势，最高点在1800年代后期被破坏。但是，将硅藻表示为浓度时，显示出倍增的上核，与越过分水岭的变化呈正相关，包括北半球温度，大气CO_2浓度和太阳辐照度（分别为R = 0.627、0.675和0.400）。有机碳百分比从3.8％增加到5.9％> 50％，也与这些较大规模的环境条件呈正相关（R = 0.828、0.830和0.832），而磁化率与基外记录呈负相关关系（ R ＝ -0.654，-0.496和-0.660）和粘土（R ＝ -0.770，-0.762和-0.737）。这些变化与减少的泥沙涌入和减少的生物源性沉淀成分的稀释是一致的。与总硅藻相反，浮游藻类Asterionella的积累显示了长期的上调。可能的解释包括无冰季节持续时间的延长或春季开花时间的变化，以及与捕食者的丰富性不匹配。 Asterionella占硅藻总数的百分比也增加，与基底外条件呈正相关（R = 0.827、0.774和0.674）。这种变化是以许多底栖生物属为代价的，而在过去的一个世纪中，是以浮游动物属Aulacosiera为代价的。重硅化后，Aulacosiera需要强烈混合才能保留在上斜物中。因此，其下降可能是由于变暖引起的分层增加。

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