Mercury Concentrations and Methylation Rate Potentials in Lake Mendota, Wisconsin, USA: 2020-2021

This dataset describes mercury (Hg) concentrations and methylation rate potentials that were measured in Lake Mendota, Wisconsin, US in 2020 and 2021. This work is a collaboration between the University of Wisconsin, University of California-Davis, and the U.S. Geological Survey. Samples were collected to examine the linkages between Hg methylation, biogeochemical conditions, and microbial community abundance during lake stratification (September and October). Samples were collected at depths ranging from 0-23 meters, exact values vary per sampling event and are detailed in the corresponding tables. Total Hg (THg) concentrations increased with depth across the anoxic hypolimnion and slightly increased from September to October but exhibited comparable concentrations between both sampling years. Filter-passing MeHg increased with depth across all four sampling dates. Across all incubations, the formation of MeHg under ambient conditions, quantified using a 198Hg(II) tracer, varied widely based on incubation depth and subsequent redox state and the methylation rate potential (Kmet) ranged from 0.001 day-1 to 0.165 day-1. Demethylation rates (Kdem) were quantified using a Me204Hg tracer. The filtered control incubations showed increasing Kdem values with increasing sulfide, leveling off to approximately 0.2 day-1. Concentration and methylation rate potential data were compared to metagenomics and transcripnomics measurements conducted by the University of Wisconsin and further detailed in the corresponding journal article (Peterson et al. 2025, DOI:10.1021/acs.est.4c12759).

本数据集记录了2020年与2021年在美国威斯康星州门多塔湖（Lake Mendota）测得的汞（Hg）浓度与甲基化速率潜能数据。本研究由威斯康星大学、加州大学戴维斯分校与美国地质调查局（U.S. Geological Survey）联合开展。本次采集样本旨在探究湖泊分层期（9月与10月）内汞甲基化、生物地球化学环境与微生物群落丰度之间的关联。采样深度范围为0至23米，具体数值因采样事件而异，详细信息见对应附表。全湖缺氧湖下层（anoxic hypolimnion）中，总汞（Total Hg, THg）浓度随深度增加而升高，且9月至10月间略有上升，但两年采样期内浓度水平相当。四次采样中，过滤态甲基汞（Filter-passing MeHg）浓度均随深度增加而升高。所有孵化培养实验中，以198Hg(II)示踪剂定量测得的原位环境下甲基汞生成量，随孵化深度与后续氧化还原状态差异呈现显著波动；甲基化速率潜能（methylation rate potential, Kmet）的取值区间为0.001 day⁻¹至0.165 day⁻¹。脱甲基化速率（demethylation rate, Kdem）采用Me204Hg示踪剂进行定量。过滤对照组孵化实验显示，脱甲基化速率随硫化物浓度升高而增加，最终趋于约0.2 day⁻¹。本数据集的浓度与甲基化速率潜能数据，已与威斯康星大学开展的宏基因组学（metagenomics）与转录组学（transcriptomics）测量结果进行对比，详细信息见对应期刊论文（Peterson等，2025年，DOI:10.1021/acs.est.4c12759）。