Tropospheric mercury vertical profiles between 500 and 10 000 m in central Europe
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 f...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-03-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/16/4135/2016/acp-16-4135-2016.pdf |
| Summary: | 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, SO<sub>2</sub>, CO, O<sub>3</sub>, NO, and NO<sub>2</sub>, 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.<br><br>
No vertical gradient was found inside the well-mixed boundary layer
(variation of less than 0.1 ng m<sup>−3</sup>) at different sites, with GEM
varying from location to location between 1.4 and 1.6 ng m<sup>−3</sup> (standard temperature and pressure, STP: <i>T</i> = 273.15 K, <i>p</i> = 1013.25 hPa). At all
locations GEM dropped to 1.3 ng m<sup>−3</sup> (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<sup>−3</sup> (STP). |
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| ISSN: | 1680-7316 1680-7324 |