Measurements of Gaseous and Particulate Species in the Atmosphere Using Annular Denuder System

Abstract

Combination of annular denuders, and polytetrafluoroethylene (teflon), polyamide (nylon) and impregnated filters have been used for the collection and subsequent determination of gaseous SO₂, HNO₂, HNO₃, HCl and NH₃, and of aerosols SO₄^2-, NO₃^-, Cl^-, NH₄⁺, Na⁺, K⁺, Ca²⁺ and Mg²⁺ in the atmosphere. The efficiencies of collection of these gaseous and aerosol species by the denuders and filters were examined. The rate of loss of the species on the filters were also studied. The penetration rate of the species in the denuder tubes were theoretically and experimentally researched.
The technique was further applied to the sampling of the species at Nara Prefectural Institute of Public Health, Japan during a period between June 1994 to May 1995. The sampling has been conducted for consecutive five days in a month at sampling flow rate of 5l/min. The annual mean concentrations of the species were as follows ; SO₂ : 4.32, HNO₂ : 1.46, HNO₃ : 1.61, HCl : 1.66, NH₃ : 2.43, SO₄^2- : 4.27, NO₃^- : 2.09, Cl^- : 1.12, NH₄⁺ : 1.70, Na⁺ : 0.34, K⁺ : 0.31, Ca²⁺ : 0.22 and Mg²⁺ : 0.44 (μg/m³) . Seasonal variations of the concentrations were clearly observed for SO₂, HNO³, SO₄^2- and Cl^-. The concentration of HNO₂ was higher than the HNO₃ in winter, while, it was reverse in summer.