Origin of observed high 7Be and mineral dust concentrations in ambient air on the Island of Tenerife

Abstract

Temporal series of atmospheric PM1 and PM10 matter (particulate matter with aerodynamic diameter below 1 and 10μm) as well as 40K and 7Be concentrations in aerosol filters, collected in the Island of Tenerife from 30 June 2003 until 17 January 2005, were analysed here to: (1) study the variability of 7Be in the atmosphere at this site and (2) to identify the origin of high 7Be events and check their possible connection with the transport of Saharan dust to Tenerife.A complex relationship was observed between PM10 matter and 7Be concentrations in the measured aerosol filters. Due to this fact, the analysed atmospheric events had to be grouped in: (I) high 7Be and high PM10 matter events; (II) low 7Be and high PM10 matter events; and (III) high 7Be and low PM10 matter events. The low 7Be and low PM10 matter events were not considered in this study. The results indicated that four times during the study period significant concentrations of 7Be were observed with the arrival of suspended material from the African continent. An enhanced scavenging effect of the 7Be available in the aerosol transport zone by the re-suspended material is believed to have caused these detected increments in local atmospheric concentrations. Seventy-two hours forecasts created with the Dust Regional Atmospheric model (DREAM model) for these events, also, seem to support this hypothesis.