Transformations of aquatic mercury species by the diatom Cyclotella meneghiniana

IF 7.6 2区环境科学与生态学 Q1 ENVIRONMENTAL SCIENCES

Environmental Pollution Pub Date : 2025-04-12 DOI:10.1016/j.envpol.2025.126248

João P. Santos , Javier Garcia-Calleja , Emmanuel Tessier , Séverine Le Faucheur , Zoyne Pedrero , David Amouroux , Vera I. Slaveykova

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Abstract

Phytoplankton are traditionally viewed as simple bioaccumulators and key entry points for mercury (Hg) into aquatic trophic chain. However the more recent findings suggest that they can function as dynamic biological systems capable of enhancing Hg cycling reactivity and altering its speciation. Nevertheless, the role of phytoplankton species in mercury transformations remains largely overlooked. The present study examined inorganic mercury (Hg(II)) methylation, monomethylmercury (MeHg) demethylation, and the production of dissolved gaseous mercury (Hg(0)) following exposure to sub-nanomolar concentrations Hg(II) or MeHg, representative of contaminated environments. Diatom Cyclotella meneghiniana was selected as a representative phytoplankton species due to its widespread presence in diverse aquatic ecosystems. To track transformation pathways, isotopically labeled Hg species were used to distinguish between methylation and demethylation processes. The results demonstrated rapid accumulation of both Hg(II) and MeHg in the diatom cells. A cellular demethylation of MeHg into Hg(II), primarily occurring within the cell debris fraction, but no detectable Hg(II) methylation was observed. The reduction of Hg(II) to Hg(0) was found to be biologically mediated and independent of the photosynthetic system. No significant production of Hg(0) after MeHg exposure was determined. Overall, these findings imply that phytoplankton species could actively contribute to mercury cycling in aquatic environments through cellular transformation processes, including MeHg demethylation and Hg(II) reduction.

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水生汞物种在硅藻Cyclotella meneghiniana中的转化

传统上，浮游植物被认为是简单的生物蓄积器，是汞进入水生营养链的关键入口。然而，最近的研究结果表明，它们可以作为一种动态的生物系统，能够增强汞的循环反应性并改变其形态。然而，浮游植物在汞转化中的作用在很大程度上仍然被忽视。本研究考察了无机汞（Hg(II)）甲基化、单甲基汞（MeHg）去甲基化以及暴露于亚纳摩尔浓度汞（II）或甲基汞（MeHg）后产生的溶解气态汞（Hg(0)），这些都是污染环境的代表。由于meneghiniana硅藻环藻广泛存在于各种水生生态系统中，因此被选为具有代表性的浮游植物。为了追踪转化途径，使用同位素标记的汞物种来区分甲基化和去甲基化过程。结果表明，汞（II）和甲基汞在硅藻细胞中快速积累。甲基汞的细胞去甲基化为汞（II），主要发生在细胞碎片碎片中，但未观察到可检测到的汞（II）甲基化。Hg（II）到Hg(0)的还原被发现是生物介导的，独立于光合系统。MeHg暴露后未发现显著的Hg(0)产生。总的来说，这些发现表明浮游植物物种可以通过细胞转化过程，包括甲基汞的去甲基化和汞（II）的还原，积极促进水生环境中的汞循环。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Environmental Pollution 环境科学-环境科学

CiteScore

16.00

自引率

6.70%

发文量

2082

审稿时长

2.9 months

期刊介绍： Environmental Pollution is an international peer-reviewed journal that publishes high-quality research papers and review articles covering all aspects of environmental pollution and its impacts on ecosystems and human health. Subject areas include, but are not limited to: • Sources and occurrences of pollutants that are clearly defined and measured in environmental compartments, food and food-related items, and human bodies; • Interlinks between contaminant exposure and biological, ecological, and human health effects, including those of climate change; • Contaminants of emerging concerns (including but not limited to antibiotic resistant microorganisms or genes, microplastics/nanoplastics, electronic wastes, light, and noise) and/or their biological, ecological, or human health effects; • Laboratory and field studies on the remediation/mitigation of environmental pollution via new techniques and with clear links to biological, ecological, or human health effects; • Modeling of pollution processes, patterns, or trends that is of clear environmental and/or human health interest; • New techniques that measure and examine environmental occurrences, transport, behavior, and effects of pollutants within the environment or the laboratory, provided that they can be clearly used to address problems within regional or global environmental compartments.