Impact of sea-land breezes on 210Pb in southern Iberian Peninsula e Feasibility study on using submicron-sized aerosol particles to analyze 210Pb hourly patterns

Özet

This work addresses the impact of mesoscale circulations on 210Pb concentrations in southwesternIberian Peninsula by analysing the 210Pb database at El Arenosillo station during 2004e2011 (128 periodswith a time scale of 48 h).The analysis of surface winds during each one of these periods has revealed the positive impact of thetwo sea-land breeze patterns (pure and non-pure), previously identified in this region, on 210Pb activityconcentrations. An average value of 0.80 ± 0.09 mBq m3 was obtained for the pure pattern (34 periods),0.54 ± 0.09 mBq m3 for the non-pure pattern (23 periods) and 0.46 ± 0.04 mBq m3 for the rest (71periods).The analysis of one representative period of each sea-land breeze patterns is also presented. Toperform this analysis we have used: hourly surface wind observations, surface wind fields simulated bythe WRF mesoscale model and the hourly database of sub-micron-particle size range in the accumulationmode (NACC). The use of this type of particles to investigate the hourly temporal variability of 210Pb isbased on the high correlation, obtained in the present work, between 210Pb activity and particles in theaccumulation mode (R ¼ 0.90).The analysis reveals that the highest concentrations of NACC, and hence, 210Pb, are obtained when thesampling area is under the influence of the pure breeze, due to it favours the accumulation of particlespreviously transported by Mediterranean flows along the Guadalquivir valley. In the case of the non-purepattern, the increase in the concentration of particles is related to the arrival of background synopticwinds from the continental areas of western Iberian Peninsula. In the latest, the increment of NACC isfaster and around 400 particles cm-3, while in the case of the pure pattern, it is progressive up to 1400 particles cm-3