Evaluation of ammonia fluxes into the free atmosphere over Western Germany

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 k 49 pg/m2h NH,-N and 93 f 47 pg/m2h NH:-N in summer and to 7 k 14 pg/m2h NH,-N and 23 f 34 pg/m2h NHi-N in winter.When integrated over a year, the sum of these ammonia fluxes can be maintained by NH, volatilization from domestic animal excrements. The NH, liberation from mineral fertilizer and natural soils contributes only a small amount to the overall production rate. Most of the NH, and NH: diffusing upwards into the middle troposphere will eventually be incorporated in rain. For the conversion of gaseous NH, to particulate NH: in the first 400 m of the atmosphere a lower limit for a pseudo first-order reaction rate constant of 1-2 x s-I was deduced from flux density considerations.

Seasonal variation of gaseous HNO3 and NH3 at a Tropical Savannah site

“…In Jaribu, tropical Australia, Ayers and Gillet (1988) found lower concentrations of NH,; a mean value of 0.5 ppb (range 0.2-1.2 ppb) for nine 24 h surface samples was reported. It is also worth mentioning that the NH, concentrations found by us are comparable with the levels reported for rural areas of North America (Anlauf et al, 1985;Lewin et al, 1986;Cadle et al, 1982;Dawson and Farmer, 1984;Harward et al, 1982) and, in general, a little bit lower than the concentrations in rural Europe (Harrison and Pio, 1983;Erisman et al, 1988;Lenhard and Gravenhorst, 1980).…”

Estimation of the rate constant for the reaction of acid sulphate aerosol with NH3 gas from atmospheric measurements

“…It is thus a unique study which has generated results very comparable with those of experimental studies of NH, to NH: conversion based upon vertical gradients (Erisman et al, 1988;Lenhard and Gravenhorst, 1980) and upon data fitting in a numerical model (Asman and van Jaarsfeld, 1990). The use of ground-level concentration measurements ignores the existence of vertical gradients within the boundary layer, and will lead to some under-estimation of the true rate constant.…”

“…They calculated values of k, of 1 x 1O-4 SK' for daytime periods and 5 X 10-j C' for nighttime periods. A further interesting comparison is with the data of Lenhard and Gravenhorst (1980) who estimated for the rate constant, k, at a height of 400 m, a value of 1.2 x lop5 s-' in winter and 2.1 x 10P5 SC' in summer. They acknowledge that greater values for k may occur at lower levels.…”

A semi-continuous measurement of gaseous ammonia and particulate ammonium concentrations in PM2.5 in the ambient atmosphere

“…Harrison and Kitto (1992) determined the rate of conversion from ammonia to ammonium, which was between 4×10 −6 s −1 and 4.1×10 −4 s −1 . Also, it was 8×10 −5 s −1 for long-range transport air mass (Asman and Van Jaarsveld 1990), 10 −5 to 10 −3 s −1 in the atmospheric boundary layer under 100 m (Vermetten et al 1985), and 2.1×10 −5 s −1 at 400 m heights (Lenhard and Gravenhorst 1980). A linear correlation of daily average concentrations of ammonia and ammonium as shown in Fig.…”

“…The Spearman correlation coefficient was 0.90. The conversion rate of NH 3 to NH 4 + with acid gases (e.g., H 2 SO 4 HNO 3 , and/or HCl) has been calculated in previous studies (Lenhard and Gravenhorst 1980;Erisman et al 1988;Asman and Van Jaarsveld 1990;Harrison and Kitto 1992 conversion rates between ammonia and ammonium during daytime and nighttime were calculated to be 1×10 −4 s −1 and 5×10 −5 s −1 , respectively (Erisman et al 1988). Harrison and Kitto (1992) determined the rate of conversion from ammonia to ammonium, which was between 4×10 −6 s −1 and 4.1×10 −4 s −1 .…”