Corrigendum to: “Real-time measurements of ammonia, acidic trace gases and water-soluble inorganic aerosol species at a rural site in the Amazon Basin" published in Atmos. Chem. Phys., 4, 967–987, 2004

Abstract

A detailed description of the WAD/SJAC and the analytical procedures is given elsewhere (Slanina et al., 2001; Wyers et al., 1993). A simplified sketch of the sampling system is shown in Fig. 2. The air flow through the instrument (∼17 l min−1, STP) was generated by a scroll pump outside the wooden house and could be adjusted with a needle valve. The flow was measured continuously (1 min time resolution) with a mass flow meter (Bronkhorst, F-112ACHA-55-V). After the sample air passed the steel elbow and/or pre-impactor and the PFA Teflon tubing, it entered a horizontally aligned WAD that scavenges soluble gaseous species. Trace gases (such as NH3, HNO3, HNO2, HCl and SO2) were collected in a 10−4 M NaHCO3 absorption solution. The liquid input was controlled automatically by an infrared sensor and a switching valve and the liquid was continuously pumped out of the denuder at a flow rate of 0.5– 0.6 ml min−1 by a peristaltic pump. The liquid effluent was collected in a sample reservoir (“gas sample”, see Fig. 2). Artifacts due to evaporation of aerosol phase species in the WAD can be excluded because the characteristic time for formation/evaporation of NH4NO3 is >10 s (Dlugi, 1993), while the mean residence time of the sample air in the WAD is ∼0.002 s (annulus volume: 0.0018 l, flow rate: ∼17 l min−1). After the WAD, the air entered a reservoir where it was mixed with steam of highly purified water. The supersaturation causes aerosol particles to grow rapidly (within 0.1 s) into droplets of at least 2μm diameter. These droplets, containing the dissolved aerosol species were then collected in a cyclone (Khlystov et al., 1995). The cyclone effluent (“aerosol sample”) was transferred into the sample reservoir by a peristaltic pump at a flow rate of 0.5–0.6 ml min−1.