Characterization and Quantification of Atmospheric Mercury Sources Using Passive Air Samplers

Abstract

The Minamata Convention on Mercury (Hg) requires improved atmospheric Hg monitoring and characterization of Hg sources. Here we demonstrate how a network of passive air samplers (PASs) can be used cost effectively to determine the spatial distribution of gaseous Hg and estimate atmospheric Hg emissions at contaminated sites. Gaseous Hg concentrations were mapped around a former Hg mine in the Monte Amiata district in Italy using simultaneous deployments of PASs across local and regional spatial scale grids. The concentration maps help visualize with great detail and precision the dispersal of gaseous Hg from a contaminated site, revealing even subtle effects of wind, season, and minor sources. Emissions estimated from the empirical data (80 ± 40 and 150 ± 75 kg/year for October and July, respectively) were robust to changes in the most uncertain parameters (excess Hg in the air above the mine and advection rate) and compared well to previous estimates for this and other closed Hg mines. This PAS‐based approach has a number of advantages: (i) concurrent deployments of multiple samplers constrain concentration changes to spatial variability only, (ii) time‐averaged data over longer periods negate biases related to short‐term, infrequent measurements, (iii) more spatially representative estimates of Hg distributions and emissions can be made at a fraction of the cost, and (iv) use is easy, especially in difficult terrain. Time‐averaged data across a broad area are also most pertinent for assessing chronic human exposure, especially in terms of the inhalation of Hg by workers and residents living close to contaminated sites.

Application of the Passive Sampler Developed for Atmospheric Mercury and Its Limitation

“…The rather low adsorption capacity of the sampler is likely associated with the selected adsorbent, the gold-coated beads. Previous studies using the same diffusive body with S-impregnated activated carbon [12] revealed higher adsorption capacities, for deployment of a year and above. Also, in Zhang et al (2012) [8], the amount of Hg adsorbed by the passive sampler using polyethylene diffusion tube with S-impregnated activated carbon attained 22 ng.…”

“…This requires the development of a passive sampler that is inexpensive, easily deployed, and does not need electricity.Because a passive sampler is able to identify concentrations at a fine spatial resolution, it has been widely used for certain pollutants including persistent organic pollutants and carbon dioxide [7]; however, nearly all Hg research studies have relied on an active sampler until recently. Many previous studies using an Hg passive sampler did not provide satisfactory results [7], and only a few groups suggested the reliable data [8][9][10][11][12]. For an Hg passive sampler, a diffusive body including radial [10,13], axial [8], box [14], and two-bowl [15] types has been tested.…”

Monitoring of Airborne Mercury: Comparison of Different Techniques in the Monte Amiata District, Southern Tuscany, Italy

“…Traditionally, the monitoring of atmospheric Hg has been accomplished by instrumental techniques, like Light Detection and Ranging (LIDAR; [4]), and compact analyzers, such as Tekran®and Lumex®instruments [5]. These methods are excellent to characterize point sources [6]. However, they lack spatial resolution and provide only short-term information on Hg contamination [6,7].…”

“…These methods are excellent to characterize point sources [6]. However, they lack spatial resolution and provide only short-term information on Hg contamination [6,7].…”

“…A recently developed technique for Hg monitoring is represented by manufactured passive air samplers (PASs), where a bituminous coal-derived, sulfur-impregnated, activated carbon is employed as sorbent for Hg species [19]. Passive sampling, either by employing living organisms or manmade products, is a more sustainable and ecologically relevant approach to monitor Hg for longer periods of time [20][21][22] and allows a better detection of nonpoint sources of Hg and better spatial resolution [6,7].…”