The end-Permian extinction (EPE) (∼251.9 Ma) is considered the most severe biotic crisis in Earth’s history. Rapid climatic change and oceanic acidification triggered by Siberian Traps volcanism culminated in a widely documented mass extinction in the marine realm, but the event’s impact on terrestrial ecosystems, particularly plant communities, is less well understood. While the existence of a floral mass extinction at the Permian-Triassic Boundary (PTB) is still debated, there is mounting evidence for pervasive mutagenesis among various plant lineages, as expressed by the high incidence of aberrant spores and pollen grains. Previous studies have proposed a causal relationship between increased UV-B flux and plant mutagenesis across the PTB, yet the role of volcanically derived heavy metals as a contributing factor has received considerably less attention. Here we present the results of a high-resolution palynological, sedimentological, and geochemical analysis of a continuous and previously unstudied PTB section from the Norwegian Arctic. The study reveals an abrupt increase in the levels of heavy metals across the EPE negative carbon isotope excursion (CIE). Palynological analysis indicates disruption, and a phased transition of plant communities at the PTB, without a significant turnover in species or decrease in diversity. However, the abrupt appearance and elevated abundance of aberrant palynomorphs coincides with increased concentrations of As, Co, Hg, and Ni, which is interpreted as compelling evidence for heavy metal-induced stress and genetic disturbance in plant communities during the EPE. We hypothesise that biomagnification of these elements may have been a significant driver for the end-Permian biotic crisis. Our findings are correlated via biostratigraphy and chemostratigraphy with other circum-Arctic PTB sections described in the literature, demonstrating the isochroneity and facies independence of these widespread palaeoecological changes.

中文翻译：

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二叠纪末大规模灭绝期间的火山汞和植物突变：盘古大陆北部的古生态扰动


二叠纪末灭绝（EPE）（∼251.9 Ma）被认为是地球历史上最严重的生物危机。西伯利亚陷阱火山活动引发的快速气候变化和海洋酸化最终导致了广泛记录的海洋领域大规模灭绝，但该事件对陆地生态系统，特别是植物群落的影响却鲜为人知。虽然二叠纪-三叠纪边界（PTB）是否存在花卉大规模灭绝仍然存在争议，但越来越多的证据表明各种植物谱系之间存在普遍的诱变，如异常孢子和花粉粒的高发生率所表明的那样。先前的研究提出了 UV-B 通量增加与 PTB 植物诱变之间存在因果关系，但火山衍生重金属作为影响因素的作用却很少受到关注。在这里，我们展示了对挪威北极地区连续且之前未经研究的 PTB 剖面进行高分辨率孢粉学、沉积学和地球化学分析的结果。研究表明，在 EPE 负碳同位素偏移 (CIE) 范围内，重金属含量突然增加。孢粉学分析表明，PTB 植物群落发生了破坏和阶段性转变，但物种没有显着更替或多样性下降。然而，异常孢粉型的突然出现和丰度的增加与砷、钴、汞和镍浓度的增加相一致，这被解释为EPE期间重金属引起的植物群落胁迫和遗传干扰的有力证据。我们假设这些元素的生物放大作用可能是二叠纪末生物危机的重要驱动因素。 我们的研究结果通过生物地层学和化学地层学与文献中描述的其他环北极 PTB 剖面相关联，证明了这些广泛的古生态变化的等时性和相独立性。