A study of alkalinity in aerosols collected in Gran Canaria, Spain during 2011

Abstract

The solubility and bioavailability of aerosol elements that play an important role in the biogeochemistry in the ocean may be influenced by atmospheric process during transport and the presence of acidic and basic components. In this work, we studied the chemical characterization of particulate aerosols collected at Pico de La Gorra station, (1930 m altitude and located in Gran Canaria, Spain) during 2011, focusing primarily in the acid and basic components (pH, total alkalinity, and soluble NO3−, SO2−4, Ca and Mg). In addition, other major ion concentrations (like F−, Cl−) and soluble and total trace metal concentrations (Al, Fe, Ca, Na, K, Mg, Zn Co, Cu, Cr, Ni, Cd, Pb, V) were determined. Total suspended particles (TSP) were collected on cellulose filters (WH 41) using high volume samplers and were sub- divided into 8 equal parts for analysis. Using soluble Ca and Mg as indicators of carbonate concentrations (CaCO3 and MgCO3), some variations in total alkalinity were detected between anthropogenic and African aerosols. In African dust outbreaks with TSP concentrations higher than 26 µg m−3 (2 µg Al m−3), the relative concentration of these elements were lower compared with values for less dust load. In the anthropogenic aerosol group, despite high concentrations of acidic species (such as NO3− and SO24−), relatively high carbonate concentrations appear to be acting to reduce the acidity of these aerosols.