Resumen de Caracterización química y mineralógica del material particulado atmosférico de un episodio de calima sobre las Islas Canarias
Sonia Castillo Fernández, José Andrés Alastuey Urós, Xavier Querol Carceller, A. Ávila, E. Cuevas, C. Estarellas, C. Torres, P.M. Romero, F. Exposito, O. García, J.P. Diaz, R. van Dingenen, J.P. Putaud
An intense African dust outbreak episode affecting the Canary Islands from 28 to 31/07/02 has been characterized at two stations in Tenerife Island (the Izaña Observatory in the free troposphere, FT, and an urban background site in Sta. Cruz de Tenerife, into the marine boundary layer, MBL). This African episode intrudes into de FT, increasing considerably the levels of the particulate matter (PM) at Izaña, but affecting indirectly by deposition at Sta. Cruz. A complete chemical and mineralógicaI characterization of total suspended particles (TSP) and particles <2.5pm (PM2.5) was performed at both sites in order to investigate the composition of the dust and the possible interaction with locally emitted atmospheric pollutants. The results obtained demonstrated that African dust mainly consists of clays (illite, kaolinite, clinochlore, palygorskite) quartz, feldspars and calcite, with minor amounts of fresh water diatoms and pollen particles from North Africa. Chemically, Saharan dust is characterized by high levels of AI, Fe, Ca, K, Ti, like major elements, but also relative high levels of As, Ba, Cr, Li, Mn, Ni, Sr, and Zn were also recorded. Quantitative data on the proportions of mineral dust, marine aerosols and anthropogenic load in ambient air TSP and PM2.5 are reported. Finally, the interaction of Ca- and K-bearing mineral compounds with S02 and NO-, derived emissions are also evidenced at Sta. Cruz, giving rise to the formation of Ca-Na nitrate and sulfate phases.
