Atmospheric mercury (Hg) concentrations are quantified primarily through preconcentration on gold (Au) cartridges through amalgamation and subsequent thermal desorption into an atomic fluorescence spectrometry detector. This procedure has been used for decades, and is implemented in the industry-standard atmospheric Hg analyzer, the Tekran 2537. There is ongoing debate as to whether gaseous elemental mercury (Hg) or total gaseous mercury (TGM, Hg + Hg) is measured using Au cartridges. The raw Hg signal processing algorithms for the Tekran 2537 analyzer have also been questioned. The objective of this work was to develop a better understanding of what forms of Hg are collected on gold cartridges through the use of permeation tube-based calibrators, that release known amounts of Hg and Hg. The potential differences between different Tekran analyzer models (i.e., 2537B versus 2537X) Hg signal processing algorithms, and Hg calibration methods were also investigated. Experiments were performed using Hg and Hg permeation calibrators. Validation tests showed that the Hg calibrator produced a reproducible and stable Hg permeation rate (2.2 ± 0.2 pg min). Results of Hg sampling and analysis using Au amalgamation showed the gold cartridges measured up to 75 % Hg, with the value at the beginning of the Hg measurement being much lower (as low as 10 %) due to Hg adsorption on analyzer surfaces and the Tekran particulate filter. Furthermore, thermal desorption of Hg from Au reduced only 80 % of Hg to Hg, resulting in additional Hg that was not measured by the analyzer. By adding a thermolyzer upstream of the analyzer, 97 % of Hg was measured as Hg. Additionally, Hg measurements using Tekran 2537 B and X models using a newly developed signal processing algorithm, different peak integration methods, and two Hg sources were compared. Results showed the 2537X model was not affected by the integration type, while the 2537B model was. Bell jar calibration based on the Dumarey equation resulted in 6 % ± 7 % (mean ± SD) underestimation of measured Hg concentrations compared to the calibration with a permeation calibrator. Gold cartridges measured an atmospheric Hg fraction somewhere between Hg and TGM due to Hg adsorption and inefficient reduction of Hg to Hg during thermal desorption from Au. Since Hg in ambient air can be 25 % of total Hg, distinguishing between Hg and TGM is important. The use of a thermolyzer or a cation exchange membrane upstream of gold cartridges is recommended to enable TGM or Hg measurements, respectively. Observations showed that traceable multipoint calibrations of atmospheric Hg measurements are needed for Hg quantification, and that different Hg calibration methods can produce significantly different results for measured atmospheric Hg concentrations.

中文翻译：

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使用金进行大气汞采样的局限性和见解


大气中汞 (Hg) 浓度的定量主要通过金 (Au) 筒上的混汞和随后的热解吸到原子荧光光谱检测器中进行预富集。该程序已使用数十年，并在行业标准大气汞分析仪 Tekran 2537 中实施。关于测量气态元素汞 (Hg) 还是总气态汞（TGM，Hg + Hg）一直存在争论使用金墨盒。 Tekran 2537 分析仪的原始汞信号处理算法也受到质疑。这项工作的目的是更好地了解通过使用基于渗透管的校准器在金盒上收集什么形式的汞，该校准器释放已知量的汞和汞。还研究了不同 Tekran 分析仪型号（即 2537B 与 2537X）汞信号处理算法和汞校准方法之间的潜在差异。使用汞和汞渗透校准器进行实验。验证测试表明，汞校准器可产生可重复且稳定的汞渗透率 (2.2 ± 0.2 pg min)。使用金汞齐化的汞采样和分析结果显示，金筒测得的汞含量高达 75%，由于分析仪表面和 Tekran 上的汞吸附，汞测量开始时的值要低得多（低至 10%）颗粒过滤器。此外，Hg 从 Au 中热解吸仅将 80% 的 Hg 还原为 Hg，导致分析仪无法测量到额外的 Hg。通过在分析仪上游添加热解器，97% 的汞被测量为汞。 此外，还对使用 Tekran 2537 B 和 X 型号的汞测量进行了比较，其中使用了新开发的信号处理算法、不同的峰积分方法和两个汞源。结果显示，2537X 型号不受集成类型的影响，而 2537B 型号则受到影响。与使用渗透校准器的校准相比，基于杜马雷方程的钟罩校准导致测得的汞浓度低估了 6% ± 7%（平均值 ± 标准差）。由于汞吸附以及金热解吸过程中汞还原为汞的效率低下，金盒测量到的大气汞分数介于 Hg 和 TGM 之间。由于环境空气中的汞可能占总汞的 25%，因此区分汞和 TGM 很重要。建议在金盒上游使用热解器或阳离子交换膜，以分别进行 TGM 或 Hg 测量。观测结果表明，汞定量需要对大气汞测量进行可追溯的多点校准，并且不同的汞校准方法可能会产生明显不同的大气汞浓度测量结果。