ATMOSPHERIC MERCURY SPECIES IN THE ARCTIC: MEASUREMENTS AND MODELLING

Torunn Berg¹, Jerzy Bartnicki², John Munthe³,Heikki Lattila⁴, Jaroslaw Hrehoruk⁵ and Andrzej Mazur⁵.

1: Norwegian Institute for Air Research, P.O. Box 100, N-2007 Kjeller, Norway

torunn.berg@nilu.no

2: Norwegian Meteorological Institute,

3: Swedish Environmental Research Institute,

4: Finnish Meteorological Institute,

5: Institute for Meteorology and Water Management, Poland

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Concentrations of different species of mercury in arctic air and precipitation have been measured at Ny-Ålesund (Svalbard) and Pallas (Finland) during 1996 and 1997.

Vapor phase mercury was sampled by amalgamation on manual gold traps. Particulate mercury was collected on filters using both low- and high volume samplers, whereas precipitation was sampled using bulk samplers. Analysis was performed using CV-AFS. Typical concentrations for gaseous mercury measured at the two stations were in the range of 0.7-2 ng m-3 (Fig. 1). Particulate mercury were below 5 pg m-3 (Fig. 2). Total mercury in precipitation were in the range 3-30 ng l-1 (Fig. 3).

Fig. 1: Time series of monthly averaged vapour phase mercury at Ny-Ålesund and Pallas, 1996-1997.

Fig. 2: Mercury associated with particles (pg/m3) at Ny-Ålesund and Pallas during four measurement campaigns 1996-1997.

Fig 3: Total mercury in precipitation at Ny-Ålesund and Pallas, 1996-1997.

In order to evaluate the transport and deposition of mercury to the arctic from European anthropogenic sources, the Eulerian transport model HMET was modified and extended to also include mercury species. A scheme for chemical conversion of elemental mercury and deposition of different mercury species was included in the model. European emission inventories for three different forms of Hg (Hg⁰, HgCl₂ and Hg(p)) were implemented in the numerical grid system for the HMET model. Without background values for gaseous and particulate mercury, the model underestimate the concentrations for gaseous mercury and particulate mercury with 2 (Fig. 4) and 1 orders of magnitude, respectively.

Fig. 3: Annual mean concentrations of Hg° in the mixing layer, 1996.

The results indicate that direct atmospheric transport of mercury from source areas in central and northern Europe to the Arctic is negligible. In order to assess the impact of European mercury emissions on the Arctic environment, models need to take into account re-emission processes occurring over land and water. Furthermore, the regional scale models (Europe-Arctic) need to be coupled with hemispheric or global scale models in order to take into account the long-term cycling mercury in the atmosphere. Obviously, this approach also requires detailed information on emissions (both natural and anthropogenic) on the same scale.