Skip to main content
SLU publication database (SLUpub)

Research article2021Peer reviewed

Algal Organic Matter Drives Methanogen-Mediated Methylmercury Production in Water from Eutrophic Shallow Lakes

Lei, Pei; Zhang, Jin; Zhu, Jinjie; Tan, Qiaoguo; Kwong, Raymond W. M.; Pan, Ke; Jiang, Tao; Naderi, Mohammad; Zhong, Huan

Abstract

Algal blooms bring massive amounts of algal organic matter (AOM) into eutrophic lakes, which influences microbial methylmercury (MeHg) production. However, because of the complexity of AOM and its dynamic changes during algal decomposition, the relationship between AOM and microbial Hg methylators remains poorly understood, which hinders predicting MeHg production and its bioaccumulation in eutrophic shallow lakes. To address that, we explored the impacts of AOM on microbial Hg methylators and MeHg production by characterizing dissolved organic matter with Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) and three-dimensional excitation-emission matrix (3D-EEM) fluorescence spectroscopy and quantifying the microbial Hg methylation gene hgcA. We first reveal that the predominance of methanogens, facilitated by eutrophication-induced carbon input, could drive MeHg production in lake water. Specifically, bioavailable components of AOM (i.e., CHONs such as aromatic proteins and soluble microbial byproduct-like materials) increased the abundances (Archaea-hgcA gene: 438-2240% higher) and activities (net CH4 production: 16.0-44.4% higher) of Archaea (e.g., methanogens). These in turn led to enhanced dissolved MeHg levels (24.3-15,918% higher) for three major eutrophic shallow lakes in China. Nevertheless, our model results indicate that AOM-facilitated MeHg production could be offset by AOM-induced MeHg biodilution under eutrophication. Our study would help reduce uncertainties in predicting MeHg production, providing a basis for mitigating the MeHg risk in eutrophic lakes.

Keywords

methylmercury; organic matter; methanogens; eutrophication; lake

Published in

Environmental Science & Technology
2021, Volume: 55, number: 15, pages: 10811-10820 Publisher: AMER CHEMICAL SOC

    Sustainable Development Goals

    SDG6 Clean water and sanitation

    UKÄ Subject classification

    Environmental Sciences

    Publication identifier

    DOI: https://doi.org/10.1021/acs.est.0c08395

    Permanent link to this page (URI)

    https://res.slu.se/id/publ/113491