**4. Conclusion**

PM2.5 and PM10 aerosols samples were collected from a rural site Morogoro, Tanzania and analysed for low molecular weight carboxylates and water-soluble inorganic ions. Oxalate and malonate were dominant species in PM2.5 while acetate was most prominent species in PM10 aerosols followed by oxalate. Of the ionic components, SO42−, K+, and Mg2+ in PM2.5 and SO42−, Na+, and Mg2+ in PM10 made lager contribution to total water-soluble inorganic aerosol mass. Various ratios and correlations between carboxylates and ions used for possible source identification suggest that primary emissions, secondary formation, and to a slightly extent sea spray and biomass burning could be the sources for the aerosols at this site. The ratio of acetate to formate was used to distinguish primary and secondary sources of these carboxylates and was found to be close to reported value for secondary reactions, indicating dominance of secondary sources. Substantial concentration of carboxylates and water-soluble ions observed in the Morogoro atmosphere suggest that it was urgent to study the characteristics and sources of these species to better understand their roles in the Tanzania environment. However, more work is needed to determine longer-chain (high) molecular weight carboxylic acids and related organic compounds and their seasonal variations in other urban and rural sites in Tanzania.

Characteristics of Low-Molecular Weight

Carboxylic Acids in PM2.5 and PM10 Ambient Aerosols From Tanzania 215

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