基于热解技术的大气颗粒物形态汞同位素组成分析方法

Analysis of Isotopic Compositions of Mercury Species in Atmospheric Particulates Based on Thermo-Desorption Technique

汞是一种有毒重金属,其在大气中的传输、沉降和循环对生态系统和人类健康构成严重危害。大气颗粒物是汞相态转化的重要载体,在全球汞循环中起着至关重要的作用。汞同位素常被用于追踪大气汞的来源和迁移转化过程,但现有研究仅局限于大气颗粒物总汞同位素,难以深入理解大气汞转化机制和生态效应。本研究旨在建立一种基于热解技术的形态汞同位素分析方法,用以分离大气颗粒物中不同汞形态并进行同位素组成检测,为深入研究颗粒态汞(PBM)在大气中的行为和源汇特性奠定基础。本研究通过自主搭建的热解装置对大气颗粒物样品进行汞形态分离,判定了天津市实际大气PBM中主要的形态为有机结合态汞(Hg-OM)、β-硫化汞(β-HgS)和α-硫化汞(α-HgS),同时测试分析了各形态汞同位素组成。结果表明,热解方法能有效区分PBM中不同汞形态并进行同位素分析,为进一步揭示大气中汞的源-汇过程和迁移转化机制开辟了新的视野。

Mercury is a global environmental pollutant,its atmospheric transport,deposition,and cycling posing significant threats to ecosystems and human health.Atmospheric particulate matter serves as a crucial carrier for the phase transformation of mercury.Isotopes of particulate-bound mercury(PBM)are commonly utilized in studying the sources and transformation of atmospheric mercury.However,existing research has been limited to composition of total mercury isotope,lacking a comprehensive understanding of species-specific isotope signature and of atmospheric mercury behavior and transformation mechanisms.This study aims to establish a thermal decomposition method to separate different mercury forms in atmospheric particulate matter for accurate analysis of their isotopic compositions.This study employed a self-constructed pyrolysis apparatus to separate mercury species in atmospheric particulate matter samples.It identified the major forms of mercury in the actual atmospheric particulate matter(PBM)in Tianjin as organic-bound mercury(Hg-OM),β-mercury sulfide(β-HgS),and α-mercury sulfide(α-Hgs).Additionally,the isotopic composition of different mercury species was analyzed.Results demonstrated the effectiveness of this method in discerning isotopic characteristics of various mercury forms in PBM,offering a new avenue for understanding the source-sink processes and environmental behavior of atmospheric mercury.