Ottawa-Carleton Geosciences Center and Department of Earth Sciences, Carleton University, Ottawa, Ontario, Canada.
Research and Collections, Canadian Museum of Nature, Ottawa, Ontario, Canada.
PeerJ. 2023 Mar 8;11:e14847. doi: 10.7717/peerj.14847. eCollection 2023.
Meromictic Crawford Lake, located in SW Ontario, Canada is characterized by varved sediments, making it suitable for high-resolution paleoecological studies. Freeze cores, the only coring method available that reliably preserves the fragile laminations representative of seasonal deposition in the lake, were used to document siliceous diatom and chrysophyte community structure at an annual resolution from 1930-1990CE. Stratigraphically constrained cluster analysis identified major assemblage changes that are believed to have been caused by local, regional and possibly global anthropogenic impacts. The assemblage changes within the siliceous algae are attributed to regional weather and increased industrial emissions and related effects of acid deposition on the lake's catchment associated with the Great Acceleration -the massive economic, industrial, and demographic expansion beginning in the mid-20th century. Observed increases in spheroidal carbonaceous particles (SCPs) in varved lake sediment dating to the early 1950s record rapidly expanding steel production without emission controls around 30 km upwind of the lake. The findings reported here reflect major changes in earth systems that the Anthropocene Working Group recommends for a proposed epoch to be termed the Anthropocene, providing support for the laminated sediments from Crawford Lake as a potential Global boundary Stratotype Section and Point (GSSP).
位于加拿大安大略省西南部的梅尔米奇克克劳福德湖以纹层沉积物为特征，非常适合进行高分辨率的古生态学研究。为了记录 1930 年至 1990 年期间每年的硅质硅藻和金藻群落结构，使用了唯一一种可靠地保存了代表湖泊季节性沉积的脆弱纹层的冷冻芯，这是一种可行的取芯方法。受限于地层的聚类分析确定了主要的组合变化，这些变化被认为是由当地、区域和可能的全球人为影响造成的。硅质藻类中的组合变化归因于区域天气和工业排放增加，以及与大加速相关的酸沉降对湖泊集水区的影响——这是 20 世纪中叶开始的大规模经济、工业和人口扩张。可追溯到 20 世纪 50 年代早期的纹层湖沉积物中球形碳质颗粒（SCP）的观测增加记录了在湖的上风 30 公里处没有排放控制的钢铁生产的迅速扩张。这里报告的发现反映了地球系统的重大变化，人类世工作组建议将一个拟议的时代称为人类世，为克劳福德湖的纹层沉积物提供了作为潜在全球边界层型剖面和点（GSSP）的支持。
