Determination of Carboxylic Acids and Water-soluble Inorganic Ions by Ion Chromatography in Atmospheric Aerosols from Tanzania
Atmospheric aerosol samples of PM2.5 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. PM2.5 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 PM2.5 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 inPM2.5 and acetate in PM10 were most abundant carboxylates accounting for 64% and 62 % of total acids, respectively. Mg2+ was most important cation in PM2.5 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 inPM2.5 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.