Collaborative Research: Refining and Testing Methods for Identifying and Quantifying Gaseous Oxidized Mercury in Air

大气中的汞（Hg）以多种形式存在，其中一些比其他形式毒性更大。汞的最大成分，气态单质汞（GEM）是相对惰性的，但它会氧化成气态氧化汞（GOM）或转化为具有活性和毒性的颗粒结合汞（PBM）。因此，准确监测这些不同形式的汞是至关重要的。由美国国家科学基金会资助的研究人员过去的工作表明，商业Tekran系统（广泛用于监测活性汞并被视为标准）容易出现大错误和系统性偏差。具体来说，基于Tekran的反应性GOM和RGM显示出持续的低偏倚，这对我们目前对汞毒性和暴露的理解提出了质疑。该项目将在全球部署一套新的仪器，在全球范围内提供可靠和校准良好的活性汞测量数据，以提高我们对汞及其对人类健康风险的预测知识。该项目将开发和部署一套新的稳定和敏感的仪器，用于在传统Tekran系统运行的网络现场校准特定的活性汞测量。它建立在NSF支持的初步有希望的结果的基础上。这些仪器包括一个由该团队开发的新的活性GOM系统，该系统可以收集阳离子交换膜和尼龙膜上的GOM，然后分析它们的活性汞。两种截然不同的收集和分析方法将证实没有来自物种形成或大气采样条件（例如高湿度或臭氧）的潜在偏差。这种方法已被证明是高度选择性的，没有来自大量存在的GEM的干扰。此外，研究人员将部署自动化GOP和GEM校准器进行常规现场验证。最后，将在多个地点共同部署气相色谱/质谱系统来分离和鉴定各种氧化汞化合物。这10个核心站点将横跨全球，涵盖广泛的大气条件和排放情况。将分析统一的无偏倚、化学成分丰富的全球汞数据，为汞建模和评估研究界奠定坚实的观测基础。这里开发的系统将商业化，并提供给更广泛的社区，用于可靠的特定汞测量。

Atmospheric mercury (Hg) occurs in many forms some of which are more toxic than others. The largest component of Hg, gaseous elemental mercury (GEM) is relatively inert but it oxidizes to gaseous oxidized mercury (GOM) or converts to particle bound mercury (PBM) that are reactive and toxic. Therefore, it is critical to monitor these distinct forms of mercury accurately. The investigators' past work sponsored by NSF has shown that the commercial Tekran systems, which are used widely to monitor reactive mercury and accepted as the standard, are prone to large errors and systematic biases. Specifically, Tekran based reactive GOM and RGM show a persistent low bias and call into question our current understanding of mercury toxicity and exposure. The project will deploy a new suite of instruments globally to provide robust and well-calibrated measurements of reactive mercury globally to improve our predictive knowledge of mercury and its health risks for humans.The project will develop and deploy a suite of new stable and sensitive instruments for calibrated speciated reactive mercury measurements at a network field sites where conventional Tekran systems have been operating. It builds on preliminary promising results that were supported by NSF. The instruments include a new active GOM system developed by the team that collects GOM on cation exchange and nylon membranes and then analyzes them for reactive mercury. The two-distinct collection and analysis methods will confirm the absence of potential biases from speciation or atmospheric sampling conditions (e.g. high humidity or ozone). This method has been shown to be highly selective with no interference from GEM that is present in much larger amounts. Furthermore, the investigators will deploy an automated GOP and GEM calibrator for routine field verification. Finally, a gas chromatography/mass spectrometry system to separate and identify various oxidized mercury compounds will be co-deployed at multiple sites. The 10 core sites will span the globe and cover a wide range of atmospheric conditions and emission cases. The harmonized bias-free chemically rich global mercury data on mercury will be analyzed to lay a solid observational foundation for the mercury modeling and assessment research community. The systems developed here will be commercialized and made available to the wider community for reliable speciated mercury measurements.