Abstract

MKOMA, Stelyus L.; DA ROCHA, Gisele O.  and  DE ANDRADE, Jailson B.. Determination of Carboxylic Acids and Water-soluble Inorganic Ions by Ion Chromatography in Atmospheric Aerosols from Tanzania. S.Afr.j.chem. (Online) [online]. 2014, vol.67. ISSN 1996-840X.

Atmospheric aerosol samples of PM_2,5 and PM₁₀ were collected in April-May 2011 from a rural site in Tanzania and analyzed for water-soluble inorganic ions and low molecular weight carboxylic acids using ion chromatography. PM_2,5 and PM₁₀ low-volume samplers with quartz fibre filters were deployed and aerosol collections on a 24 h basis were made for each sampler. All samples were analyzed for carboxylates and inorganic ions by using ion chromatography. The results showed that mean mass concentration of PM_2,5 and PM₁₀ were 13 ± 3.5 µg m^-3 and 16 ± 2.3 µg m^-3, respectively. Mean concentrations of the total carboxylates were 23.7 ± 6.5 ng m^-3 in PM_2.5 and 36.4 ± 12 ng m^-3 in PM₁₀ whereas total water-soluble inorganic ions were 448 ± 88 ng m^-3 and 646 ± 214 ng m^-3, respectively. Oxalate and malonate in PM₂₅ and acetate in PM₁₀ were most abundant carboxylates accounting for 64 % and 62 % of total acids, respectively. Mg²⁺ was most important cation in PM₂₅ and PM₁₀ accounting for 44 % and 24 % of total water-soluble ions, respectively, whereas SO₄^2- was the main anionic component accounting for 23 % of total ions species in PM₂₅ and 37 % in PM₁₀. Using source indicators, we found photochemical activities, biogenic and biomass burning could possibly be important source types for aerosols in Tanzania.

Keywords : PM_2.5; PM₁₀; aerosol particles; organic acids; sources; Tanzania.

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