Beyond the tropopause hypothesis: Drivers of even mercury isotope fractionation unraveled by 3D modeling

IF 12.5 1区综合性期刊 Q1 MULTIDISCIPLINARY SCIENCES

Science Advances Pub Date : 2025-09-19 DOI:10.1126/sciadv.adx8401

Zhengcheng Song, Shaojian Huang, Peng Zhang, Tengfei Yuan, Xin Miao, Kaihui Tang, Guangyi Sun, Xuewu Fu, Ruoyu Sun, Wang Zheng, Jiubin Chen, Yanxu Zhang

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Abstract

Mercury (Hg) is a globally persistent contaminant with substantial health impact. The mass-independent fractionation of even mercury isotopes (even-MIF, denoted as Δ²⁰⁰Hg) is widely used to trace atmospheric Hg sources and fluxes. However, the chemical processes inducing even-MIF remain largely unknown. Here, we develop a three-dimensional atmospheric Hg isotope model linking Hg redox processes with even-MIF. The results show that the previous hypothesis of even-MIF occurring exclusively at the tropopause may not fully explain the global Δ²⁰⁰Hg patterns. We speculate OH-initiated reactions and photoreduction of Hg^II(p) as likely dominant drivers. Simulations show that even-MIF primarily originates in the free troposphere and propagates downward to surface air. Our results reveal distinct spatial Δ²⁰⁰Hg variations that were previously unaccounted for in tracing Hg sources. This study provides critical insights into even-MIF drivers and serves as a reference for using Δ²⁰⁰Hg to trace atmospheric Hg sources.

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超越对流层顶假说：甚至汞同位素分馏的驱动因素被3D模型揭开

汞是一种全球性的持久性污染物，对健康有重大影响。均匀汞同位素的质量无关分馏（even- mif，表示为Δ 200 Hg）被广泛用于追踪大气汞源和通量。然而，诱导- mif的化学过程在很大程度上仍然未知。在这里，我们建立了一个三维大气汞同位素模型，将汞氧化还原过程与均匀mif联系起来。结果表明，以前的假设甚至mif只发生在对流层顶，可能不能完全解释全球Δ 200 Hg模式。我们推测oh引发的反应和Hg II (p)的光还原可能是主要的驱动因素。模拟结果表明，even-MIF主要起源于自由对流层并向下传播到地面空气。我们的研究结果揭示了不同的空间Δ 200汞变化，这是以前在追踪汞源时未考虑到的。该研究提供了对甚至mif驱动因素的关键见解，并为使用Δ 200 Hg追踪大气汞源提供了参考。

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来源期刊

Science Advances 综合性期刊-综合性期刊

CiteScore

21.40

自引率

1.50%

发文量

1937

审稿时长

29 weeks

期刊介绍： Science Advances, an open-access journal by AAAS, publishes impactful research in diverse scientific areas. It aims for fair, fast, and expert peer review, providing freely accessible research to readers. Led by distinguished scientists, the journal supports AAAS's mission by extending Science magazine's capacity to identify and promote significant advances. Evolving digital publishing technologies play a crucial role in advancing AAAS's global mission for science communication and benefitting humankind.