Articles | Volume 16, issue 6
Atmos. Chem. Phys., 16, 4135–4146, 2016

Special issue: Global Mercury Observation System – Atmosphere...

Atmos. Chem. Phys., 16, 4135–4146, 2016

Research article 30 Mar 2016

Research article | 30 Mar 2016

Tropospheric mercury vertical profiles between 500 and 10 000 m in central Europe

Andreas Weigelt1,a, Ralf Ebinghaus1, Nicola Pirrone2, Johannes Bieser1,3, Jan Bödewadt1, Giulio Esposito2, Franz Slemr4, Peter F. J. van Velthoven5, Andreas Zahn6, and Helmut Ziereis3 Andreas Weigelt et al.
  • 1Helmholtz-Zentrum Geesthacht (HZG), Institute of Coastal Research, Geesthacht, Germany
  • 2National Research Council (CNR), Institute of Atmospheric Pollution Research, Rende, Italy
  • 3Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institute of Atmospheric Physics, Oberpfaffenhofen, Germany
  • 4Max-Planck-Institute for Chemistry (MPI-C), Department of Atmospheric Chemistry, Mainz, Germany
  • 5Royal Netherlands Meteorological Institute (KNMI), Chemistry and Climate Division, De Bilt, the Netherlands
  • 6Karlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research, Karlsruhe, Germany
  • anow at Federal Maritime and Hydrographic Agency (BSH), Hamburg, Germany

Abstract. The knowledge of the vertical distribution of atmospheric mercury (Hg) plays an important role in determining the transport and cycling of mercury. However, measurements of the vertical distribution are rare, because airborne measurements are expensive and labour intensive. Consequently, only a few vertical Hg profile measurements have been reported since the 1970s. Besides the Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container (CARIBIC) observations, the latest vertical profile over Europe was measured in 1996. Within the Global Mercury Observation System (GMOS) project, four vertical profiles were taken on board research aircraft (CASA-212) in August 2013 in background air over different locations in Slovenia and Germany. Each vertical profile consists of at least seven 5 min horizontal flight sections from 500 m above ground to 3000 m a.s.l. Gaseous elemental mercury (GEM) and total gaseous mercury (TGM) were measured with Tekran 2537X and Tekran 2537B analysers. In addition to the mercury measurements, SO2, CO, O3, NO, and NO2, basic meteorological parameters (pressure, temperature, relative humidity) have been measured. Additional ground-based mercury measurements at the GMOS master site in Waldhof, Germany and measurements onboard the CARIBIC passenger aircraft were used to extend the profile to the ground and upper troposphere respectively.

No vertical gradient was found inside the well-mixed boundary layer (variation of less than 0.1 ng m−3) at different sites, with GEM varying from location to location between 1.4 and 1.6 ng m−3 (standard temperature and pressure, STP: T  =  273.15 K, p  =  1013.25 hPa). At all locations GEM dropped to 1.3 ng m−3 (STP) when entering the free troposphere and remained constant at higher altitudes. The combination of the vertical profile, measured on 21 August 2013 over Leipzig, Germany, with the CARIBIC measurements during ascent and descent to Frankfurt Airport, Germany, taken at approximately the same time, provide a unique central European vertical profile from inside the boundary layer (550 m a.s.l) to the upper free troposphere (10 500 m a.s.l.) and show a fairly constant free-tropospheric TGM concentration of 1.3 ng m−3 (STP).

Short summary
We show the first mercury profile measurements over Europe since 1996. Besides gaseous elemental mercury (GEM) and total gaseous mercury (TGM), the gases CO, SO2, NOx, and O3 were measured from aboard a research aircraft over four European locations. Compared to the boundary layer, the concentration of GEM and TGM in the free troposphere was 10–30% lower. Inside the individual layers no vertical gradient was apparent. Combined with CARIBIC data, a unique profile from 0.4 to 10.5 km is provided.
Final-revised paper