Abstract.At a cropland and a grassland site field scale ammonia (NH 3 ) emissions from slurry application were determined simultaneously by two approaches based on (i) eddy covariance (EC) flux measurements using high temperature Chemical Ionisation Mass Spectrometry (HT-CIMS) and on (ii) backward Lagrangian Stochastic (bLS) dispersion modelling using concentration measurements by three optical open path Fourier Transform Infrared (FTIR) systems. Slurry was spread on the fields in sequential tracks over a period of one to two hours. In order to calculate field emissions, measured EC/HT-CIMS fluxes were combined with flux footprint analysis of individual slurry spreading tracks to parameterise the NH 3 volatilisation with a bi-exponential time dependence. Accordingly, track-resolved concentration footprints for the FTIR measurements were calculated using bLS. A consistency test with concentrations measured by impingers showed very low systematic deviations for the EC/HT-CIMS results (<8 %) but larger deviations for the bLS/FTIR results. For both slurry application events, the period during fertilisation and the subsequent two hours contributed by more than 80 % to the total field emissions. Averaged over the two measurement methods, the cumulated emissions of the first day amounted to 17 ± 3 % loss of applied total ammoniacal nitrogen over the cropland and 16 ± 3 % over the grassland field.

At a cropland and a grassland site field scale ammonia (NH₃) emissions from slurry application were determined simultaneously by two approaches based on (i) eddy covariance (EC) flux measurements using high temperature Chemical Ionisation Mass Spectrometry (HT-CIMS) and on (ii) backward Lagrangian Stochastic (bLS) dispersion modelling using concentration measurements by three optical open path Fourier Transform Infrared (FTIR) systems. Slurry was spread on the fields in sequential tracks over a period of one to two hours. In order to calculate field emissions, measured EC/HT-CIMS fluxes were combined with flux footprint analysis of individual slurry spreading tracks to parameterise the NH₃ volatilisation with a bi-exponential time dependence. Accordingly, track-resolved concentration footprints for the FTIR measurements were calculated using bLS. Comparison of concentrations calculated from the parameterised fluxes with concentrations measured by impingers showed that the EC/HT-CIMS emissions on the two fertilisations corresponded to the impinger concentrations within 10 % while the bLS/FTIR results showed larger deviations. For both events, the period during fertilisation and the subsequent two hours contributed by more than 80 % to the total field emissions. Averaged over the two measurement methods, the cumulated emissions of the first day amounted to 17 ± 3 % loss of applied total ammoniacal nitrogen over the cropland and 16 ± 3 % over the grassland field

A Raman polychromator system is described which makes use of a concave grating, two objectives with f-numbers lower than 1, and a multichannel detector. The system provides a very large optical throughput and should be suitable for analysis of gaseous and liquid samples -especially in cases where the concentration of the compounds investigated is rapidly varying. This is demonstrated by measurements at automobile exhaust gases and by an on -line detection of high -pressure liquid chromatography (HPLC)-fractions. Keywords: Raman spectroscopy; linear Raman spectroscopy; multichannel spectrometer; automobile exhaust gases; on -line high-pressure liquid chromatography (HPLC) /Raman. Optical Engineering 22(3), 308 -313 (May /June 1983). Keywords: Raman spectroscopy; linear Raman spectroscopy; multichannel spectrometer; automobile exhaust gases; on-line high-pressure liquid chromatography (HPLQ/Raman. Optical Engineering 22 (3), 308-313 (May/June 1983).

Quantitative analysis of automotive emissions gives detailed information about a motor's combustion behavior and gives information about the contribution from traffic to air pollution. Following the introduction, which discusses the problems of exhaust gas analysis, section 2 covers the basics of the physical effects, that the different spectroscopic systems are based on. These physical effects are discussed especially with respect to gas analysis. Section 3 describes the functioning of different spectroscopic systems, the measuring procedures and different examples of exhaust gas analysis. Simple examples are used to illustrate the functioning of Fourier transform infrared (FTIR) and diode laser (DL) systems. The construction of a completely home‐made Raman polychromator is described in detail. Specific problem areas are pointed out. Selected examples of exhaust gas analysis show typical applications of the particular methods. Section 4 discusses the present and future potential of the systems described.

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