A field intercomparison of three passive air samplers for gaseous mercury in ambient air

Abstract

Abstract. Passive air samplers (PASs), which provide time-averaged concentrations of gaseous mercury over the timescale of weeks to months, are promising for filling a gap in the monitoring of atmospheric mercury worldwide. Their usefulness will depend on their ease of use and robustness under field conditions, their availability and affordability, and most notably, their ability to provide results of acceptable precision and accuracy. Here we describe a comparative evaluation of three PASs with respect to their ability to precisely and accurately record atmospheric background mercury concentrations at sites in both southern Italy and southern Ontario, Canada. The study includes the CNR-PAS with gold nanoparticles as a sorbent, developed by the Italian National Research Council, the IVL-PAS using an activated carbon-coated disk, developed by the Swedish Environmental Research Institute, and the MerPAS® using a sulfur-impregnated activated carbon sorbent, developed at the University of Toronto and commercialized by Tekran. Detection limits are deduced from the variability in the amount of mercury quantified in more than 20 field blank samples for each PAS. Analytical and sampling precision is quantified through 22 triplicate deployments for each PAS, ranging in duration from 2 to 12 weeks. Accuracy and bias are assessed through comparison with gaseous elemental mercury concentrations recorded by Tekran 2537 automated mercury analyzers operating alongside the PASs at both locations. The performance of the PASs was significantly better in Italy, with all of them providing concentrations that are not significantly different from the average concentrations of the Tekran 2537 instruments. In Canada, where weather conditions were much harsher and more variable during the February through April deployment period, there are differences amongst the PASs. At both sites, the MerPAS® is currently the most sensitive, precise, and accurate among the three PASs. A key reason for this is the larger size and the radial configuration of the MerPAS®, which results in lower blank levels relative to the sequestered amounts of mercury when compared to the other two PASs, which rely on axial diffusion geometries. Since blank correction becomes relatively smaller with longer deployments, performance tends to be closer amongst the PASs during deployments of 8 and 12 weeks.

Using Passive Air Samplers to Quantify Vertical Gaseous Elemental Mercury Concentration Gradients Within a Forest and Above Soil

“…In summary, the QA/QC measures taken during these three field studies yielded numerical performance indicators that are largely consistent with earlier reports relying on this PAS (McLagan et al., 2016; McLagan, Hussain, et al., 2018; Naccarato et al., 2021). Specifically, the measured air concentrations were always higher than the LOQ, confirming the PAS's capability to record background air concentrations of GEM during deployments lasting 1 months and longer.…”

Pocket Mercury-Vapour Detection System Employing a Preconcentrator Based on Au-TiO2 Nanomaterials

“…To collect and accumulate a considerable amount of mercury vapour on the PreHG, we directed our attention to a nanostructured adsorbent material [7,24], already widely tested and studied by our team in previous works, with applications in mercury vapour passive air samplers (PASs) [25]. The adaptability of this adsorbent material is given by its possibility to be used both in passive samplers (for slow samplings and long period of expositions) and in active sampling systems for short term samplings [26].…”

Mercury in air and soil on an urban-rural transect in East Africa

“…[18][19][20][21] A recent comparison determined the PAS developed and tested on a global scale by McLagan et al 22,23 to be the most accurate and precise PAS for GEM at the present time. 24 Besides the atmosphere, soil is also an important environmental compartment for Hg, as it represents the largest Hg reservoir. 25 On a large scale, the terrestrial environment acts as a sink of Hg in the Southern Hemisphere.…”

“…18–21 A recent comparison determined the PAS developed and tested on a global scale by McLagan et al 22,23 to be the most accurate and precise PAS for GEM at the present time. 24…”