Abstract Jacques O, Pienitz R, Ibrahim G. 2020. Paleolimnological assessment of long-term changes in a boreal recreational lake of the Fermont mining region (subarctic Quebec, Canada). Lake Reserv Manage. 36:314–334. Lac Carheil is a boreal recreational lake located near Fermont, a remote town of subarctic Quebec built in the 1970s to support iron ore mining activities. Harmful cyanobacterial blooms were recently observed at its surface, suggesting that it suffered from eutrophication. However, long-term water quality data were lacking to properly understand its current condition. We therefore undertook a paleolimnological study to investigate past limnological changes in the lake based on the multiproxy analysis of sediment cores. The cores retrieved from Lac Carheil were marked by numerous distinct laminae representing past episodes of high-energy events in the lake catchment. Furthermore, diatom assemblages of the sediments revealed that the limnological conditions of the lake had been relatively stable for more than a thousand years before beginning to change around 1840 AD. This was mainly evidenced by the emergence of species indicative of nutrient enrichment (e.g., Aulacoseira subarctica, Fragilaria crotonensis), which suggested an early eutrophication potentially attributable to climate change. The period of modern settlement (1971–2015) was characterized by a decrease in the carbon to nitrogen ratio (C/N) of the sediments, and marked increases in their organic matter content, diatom total abundance, and diatom-inferred total phosphorus concentrations, which indicated an enhanced primary production. Nevertheless, our results suggested that the disturbance level of the lake was weak and that its prospect for recovery is good. Our study provides valuable reference data to assist the management of Lac Carheil, and reveals first insights into the sedimentological and limnological history of the Fermont mining region.

中文翻译：

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Fermont 矿区（亚北极魁北克，加拿大）北方休闲湖泊长期变化的古湖泊学评估

摘要 Jacques O、Pienitz R、Ibrahim G. 2020。Fermont 矿区（加拿大魁北克省亚北极地区）北方休闲湖泊长期变化的古湖泊学评估。湖泊保护区管理。36:314-334。Lac Carheil 是一个北方休闲湖泊，位于 Fermont 附近，Fermont 是魁北克亚北极地区的一个偏远小镇，建于 1970 年代，用于支持铁矿石开采活动。最近在其表面观察到有害的蓝藻水华，表明它遭受了富营养化。然而，缺乏长期水质数据来正确了解其当前状况。因此，我们进行了一项古湖沼学研究，以基于对沉积物核心的多重代理分析来调查湖泊过去的湖沼学变化。从 Lac Carheil 取回的岩心上有许多不同的薄层，它们代表了过去湖泊集水区高能事件的发生。此外，沉积物的硅藻组合表明，在公元 1840 年左右开始发生变化之前，湖泊的湖沼条件已经相对稳定了 1000 多年。这主要通过指示营养丰富的物种的出现（例如，Aulacoseira subarctica、Fragilaria crotonensis）来证明，这表明可能归因于气候变化的早期富营养化。现代聚落时期（1971-2015）的特征是沉积物碳氮比（C/N）降低，有机质含量、硅藻总丰度和硅藻推断总磷浓度显着增加, 这表明初级生产增加。尽管如此，我们的研究结果表明，该湖的干扰程度较弱，恢复前景良好。我们的研究提供了宝贵的参考数据来协助 Lac Carheil 的管理，并揭示了对 Fermont 矿区沉积学和湖沼学历史的初步见解。