Water chemistry and benthic pigments in the Lake Meretta wetlands, Resolute Bay, Nunavut

The Meretta wetlands are an extensive area of shallow lakes, ponds and streams that mostly drain into Meretta Lake, in the Resolute Bay area, on Cornwallis Island in the Canadian High Arctic. The terrain is polar desert, with extensive landform modifications due to airport and road construction activities from the 1950s onwards. At least some of the basins were created or modified to treat wastewater discharge from the airport, and although this pollution was halted finally in the 1980s, there are still legacy effects of this earlier enrichment (Smol 2023). All of the aquatic environments are underlain by benthic biofilms, typically dominated by cyanobacteria, but with diatoms, green algae and other taxa. The aim of this study was to characterize these benthic communities by HPLC pigment analysis, with associated chemical analysis of the overlying water. The study took place from 3 to 8 August 2021. The water for chemical analysis was obtained by grab samples near the shore, at the surface, and analyzed by standard methods at INRS, Québec. The benthic pigment samples were taken as 5 mm x 5 mm cores, that were then extracted as in Bonilla et al. (2005). Pigments were quantified in each extract by high-performance liquid chromatography (HPLC) as in Zapata et al. (2000). The biofilms sampled in this study have also been analyzed for bacterial community structure and antibiotic resistance genes (Provencher et al. 2024).梅雷塔湿地（Meretta wetlands）是一片广袤的浅湖、池塘与溪流群，其水体大多汇入加拿大高北极地区康沃利斯岛雷索卢特湾（Resolute Bay）区域的梅雷塔湖。该区域地表为极地荒漠，自20世纪50年代起，机场与道路建设活动已对地表形态造成广泛改造。至少有部分盆地系为处理机场废水排放而人工打造或改造而来；尽管该类污染已于20世纪80年代彻底终止，但此前的营养富集仍遗留有持续影响（Smol, 2023）。所有水生环境的底床均被底栖生物膜（benthic biofilms）覆盖，这类生物膜通常以蓝细菌为优势类群，同时包含硅藻、绿藻及其他分类单元。本研究旨在通过高效液相色谱（high-performance liquid chromatography, HPLC）色素分析，结合上层水体的化学分析，对这些底栖群落进行特征表征；研究于2021年8月3日至8日开展。用于化学分析的水样采用瞬时采样（grab samples）法获取，采集自近岸表层，并于魁北克省INRS研究所采用标准方法完成分析。底栖色素样品以5 mm×5 mm的岩芯形式采集，随后按照Bonilla等人（2005）的方法完成萃取。各萃取液中的色素均参照Zapata等人（2000）的方法，通过高效液相色谱（HPLC）进行定量分析。本研究中采集的生物膜还曾被用于分析细菌群落结构与抗生素抗性基因（Provencher et al., 2024）。