Background air pollution measurements

(Mária Kiss, László Horváth)

Sampling of NO₂ by impregnated
sintered glass filters in glass bulbs

One of the main tasks of the Hungarian Meteorological Service is the monitoring of chemical composition of atmosphere and precipitation, which is performed by means of the analyses of air and precipitation samples, as well as by direct, in-situ measurements. The purpose is the monitoring of background air pollution and providing data for European-scale transport modelling studies. Local scale (urban) air pollution measurements is not a part of the activity of HMS. For monitoring of background air pollution a network of five stations is operated (K-puszta, Hegyhátsál, Farkasfa, Nyirjes, Hortobágy), which is completed with an additional precipitation-sampling site (Siófok). The data are also provided for international organizations and research programs, therefore, both sampling and analytical methods as well as the data evaluation procedures comply with the recommendations of EMEP (European Monitoring and Evaluation Program) and WMO (World Meteorological Organization). The data reporting obligations for EMEP and WMO GAW (Global Atmosphere Watch) are fulfilled by the data measured at K-puszta and Hegyhátsál.

Sampling procedures:

Precipitation sampling is performed by means of a "wet-only" sampler (open only during precipitation events) at each stations.

Gases and aerosol particles are sampled by means of a three-stage filter pack. Aerosol particles for a SO₄^2-, NO₃^-, NH₄⁺, Na⁺, K⁺, Ca²⁺, Mg²⁺ analyses are collected on the surface of the first Teflon filter while gas components (SO₂, HNO₃, NH₃) are absorbed by chemical reactions on the second and third filters.

Heavy metals are sampled by means of separated precipitation samplers. Samples require special treatment because of the low concentrations. For the same reason, heavy metal content of the atmosphere is also sampled by a separated filter pack and collected on a Teflon filter. The samples are analysed for Pb and Cd at the moment.

Nitrogen dioxide (NO₂) is sampled on impregnated sintered glass filters by chemical reaction.

Analytical methods:

Measurements of metal content
of precipitation and aerosol
samples by flame atomic
absorption spectrophotometry

Both air and precipitation samples are analyzed in the same way, differences are only in the pre-analytical treatment of the samples.
Precipitation:
no pre-analytical preparation is applied, components are determined directly from the precipitation water.
Gas components:
determination after chemical transformation (oxidation, forming a colored compound).
Aerosol particles:
sampling filters are leached by de-ionized water, solution is analyzed by the same methods as for precipitation water.
Lead and cadmium:
determination after acid extraction.
Nitrogen dioxide:
determination after chemical transformation (forming a colored compound).

The following analytical methods are applied in the laboratory:

Direct, in-situ measurements:

Ozone near surface level concentration measurements are performed by means of gas analyzers based on UV-photometry.

At Hegyhátsál station CO₂, CH₄, N₂O, SF₆, CO and H₂ content of the atmosphere is determined by means of in-situ IR-photometry (CO₂) and gas chromatography (CH₄, N₂O, SF₆, CO). Independent samples taken in glass flasks and analyzed by US NOAA, are used for quality control.