Calibration Sources for Gaseous Oxidized Mercury: A Review of Source Design, Performance, and Operational Parameters

Abstract

Mercury is a neurotoxin that, unlike many localized industrial pollutants, spreads globally through atmospheric transport. Mercury in the atmosphere is operationally partitioned into gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), and particulate-bound mercury (TPM). Although GOM makes up only a small fraction of Hg in the free troposphere under normal conditions, its role in the dry and wet deposition of mercury makes GOM a significant species for understanding the transport and fate of mercury in the atmosphere. Although instruments for atmospheric mercury speciation are commercially available, significant uncertainty is associated with the current speciation methods, from sample collection to calibration, for GOM measurements. This paper examines the custom-made calibration sources that have been developed for GOM measuring instruments, evaluates the factors influencing the source performance, and synthesizes recommendations for the design and operation of GOM calibration sources in the future.

Keywords:

• Calibration source
• diffusion cell
• gaseous oxidized mercury
• permeation tube

Acknowledgements

We thank the anonymous reviewers for their thoughtful comments for the improvement of this paper.

Author contributions

MD investigated and wrote the manuscript. JL conceptualized and supervised this project.

Conflicts of interest

There are no conflicts to declare.

Additional information

Funding

Natural Sciences and Engineering Research Council of Canada (NSERC) for financial support to Julia Lu.