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Abstract: On 28 and 29 November 2005, the tropical storm Delta struck the Canary Islands (Spain) and the western shores of Morocco. Gravimetric and radiometric measurements carried out in atmospheric aerosol and water samples, collected after the storm, showed increased levels of total suspended particles (TSP) in the atmosphere and gross alpha, gross beta as well as 90Sr activities in both the atmosphere and drinking water. These variations were most likely produced by local re-suspension of soil material. However, 210Pb and 7Be activities, measured in atmospheric aerosols, did not increase until a week after the storm had passed. 40K and 137Cs activities, also measured in atmospheric aerosols, did not vary significantly with respect to previous weeks indicating that the slightly higher levels of TSP, measured during the week when the storm occurred, were not produced by the long-range transport of re-suspended aerosols from the African continent, as it has been observed in other occasions at this site. Gross alpha, gross beta, 40K and 90Sr levels in drinking water samples increased after the storm over their average values by approximately 245%, 245%, 130% and 440%, respectively. These results indicate how important the local re-suspension and later deposition/scavenging of aerosols may be on the water supply in Tenerife. [Copyright &y& Elsevier]

Tenerife (Canary Islands) is often affected by Saharan mineral dust outbreaks. These events result in high PM10 concentrations in ambient air, well above the limiting values adopted by the European Union (Directive EU/1999/30). To comply with the EU Air Quality Directive, a quantitative proxy for the characterisation of high PM10 events is required. Furthermore, this proxy must be capable of differentiating natural sources (as defined by the Directive), such as Saharan mineral dust outbreaks, from other anthropogenic sources. In this study, we have analysed the time series of 137Cs, 40K and PM10 recorded at the island of Tenerife (2000–2006) in the Marine Boundary Layer (MBL), to test the possible usefulness of the two mentioned radiotracers as markers of Saharan mineral dust events. The results of the analysis showed that this is indeed the case for 137Cs and that there are, at least, two different sources of 40K concentrations in the collected atmospheric aerosol filters. While the detection of 137Cs in atmospheric aerosol filters could be directly associated with the arrival of low altitude (<2000m.a.s.l.) dust intrusions to the study site, 40K concentrations could be associated, in most cases, with either low or high altitude (>2000m.a.s.l) dust intrusions. Moreover, two different mechanisms of aerosol loading in the MBL were, also, identified with the mentioned radiotracers. Good correlations (R 2 >0.6) were found between the three parameters when all the compiled data was considered. The correlation values increased to nearly 0.8 when only those samples that had 137Cs above detection limits were considered. The highest concentrations of 137Cs, 40K and PM10 were recorded in March 2004 in connection with a very intense low altitude Saharan dust intrusion. The results of this study, also, indicated that the 137Cs/40K ratio could be potentially useful to differentiate low from high altitude dust intrusions at this site. [Copyright &y& Elsevier]

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. [Copyright &y& Elsevier]