Determination of Carboxylic Acids and Water-soluble Inorganic Ions by Ion Chromatography in Atmospheric Aerosols from Tanzania

Abstract

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 ngm^–3 in PM2.5 and 36.4 ± 12 ngm^–3 in PM₁₀ whereas total water-soluble inorganic ions were 448±88 ngm^–3 and 646± 214 ngm^–3, respectively. Oxalate and malonate inPM_2.5 and acetate in PM₁₀ were most abundant carboxylates accounting for 64% and 62 % of total acids, respectively. Mg²⁺ was most important cation in PM_2.5 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 inPM_{2.5 and 37 % in PM10. Using source indicators, we found photochemical activities, biogenic and biomass burning could possibly beimportant source types for aerosols in Tanzania.}

_{KEYWORDS: PM2.5, PM10, aerosol particles, organic acids, sources, Tanzania.}