Evaluation of ammonia fluxes into the free atmosphere over Western Germany

• Published in: Tellus 1980-02, Vol.32 (1), p.48-55
• Main Authors: LENHARD, ULRICH, GRAVENHORST, GODE
• Format: Article
• Language: English
• ISSN: 0040-2826; 2153-3490
• DOI: 10.1111/j.2153-3490.1980.tb01721.x

ABSTRACT The upward flux densities of gaseous ammonia and particulate ammonium through a layer 400 m above ground were determined by aircraft measurements over a rural area in Western Germany. The flux densities were calculated according to the gradient method. The fluxes amounted to 118 ± 49 μg/m2h NH3‐N and 93 ± 47 μg/m2h NH+4‐N in summer and to 7 ± 14 μg/m2h NH3‐N and 23 ± 34 μg/m2h NH+4‐N in winter. When integrated over a year, the sum of these ammonia fluxes can be maintained by NH3 volatilization from domestic animal excrements. The NH3 liberation from mineral fertilizer and natural soils contributes only a small amount to the overall production rate. Most of the NH3 and NH+4 diffusing upwards into the middle troposphere will eventually be incorporated in rain. For the conversion of gaseous NH3 to particulate NH+4 in the first 400 m of the atmosphere a lower limit for a pseudo first‐order reaction rate constant of 1–2 × 10−5 s−1 was deduced from flux density considerations.