Air Quality Research Division, Science and Technology Branch, Environment and Climate Change Canada, Toronto, Ontario M3H 5T4 Canada.
Environ Sci Technol. 2017 Jan 17;51(2):855-862. doi: 10.1021/acs.est.6b04926. Epub 2016 Dec 23.
Gaseous oxidized mercury (GOM) measurement uncertainties undoubtedly impact the understanding of mercury biogeochemical cycling; however, there is a lack of consensus on the uncertainty magnitude. The numerical method presented in this study provides an alternative means of estimating the uncertainties of previous GOM measurements. Weekly GOM in ambient air was predicted from measured weekly mercury wet deposition using a scavenging ratio approach, and compared against field measurements of 2-4 hly GOM to estimate the measurement biases of the Tekran speciation instruments at 13 Atmospheric Mercury Network (AMNet) sites. Multiyear average GOM measurements were estimated to be biased low by more than a factor of 2 at six sites, between a factor of 1.5 and 1.8 at six other sites, and below a factor of 1.3 at one site. The differences between predicted and observed were significantly larger during summer than other seasons potentially because of higher ozone concentrations that may interfere with GOM sampling. The analysis data collected over six years at multiple sites suggests a systematic bias in GOM measurements, supporting the need for further investigation of measurement technologies and identifying the chemical composition of GOM.
气态氧化汞（GOM）测量不确定性无疑会影响对汞生物地球化学循环的理解；然而，对于不确定性的大小，尚未达成共识。本研究提出的数值方法为估算先前 GOM 测量不确定性提供了一种替代方法。使用清除比方法，根据每周测量的汞湿沉降来预测环境空气中的每周 GOM，并与 2-4 小时 GOM 的现场测量结果进行比较，以估算 13 个大气汞网络（AMNet）站点上 Tekran 形态分析仪器的测量偏差。多 年平均 GOM 测量结果表明，在六个站点上的测量值偏低，偏差超过 2 倍，在另外六个站点上的偏差在 1.5 到 1.8 倍之间，在一个站点上的偏差低于 1.3 倍。预测值与观测值之间的差异在夏季比其他季节明显更大，可能是因为臭氧浓度更高，可能会干扰 GOM 采样。在多个站点上收集的六年分析数据表明，GOM 测量存在系统偏差，这支持进一步研究测量技术和确定 GOM 的化学组成的必要性。
