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Abstract 7Be, 210Pb and PM 10 levels in surface air have been simultaneously measured at two sampling sites in the southern Iberian Peninsula for a period of two years. Each site covers one different meteorological area of the Guadalquivir valley, from the mouth (Huelva) to the middle point (Cordoba). The objective of the present study is to analyse the spatial variability of both natural radionuclides, and to identify and characterise the meteorological patterns associated with similar and different surface concentration levels in this complex region. Concentrations are similar in both sampling sites. 7Be level is in the 0.6–15.5 mBq m−3 range in Huelva and 1.2–13.3 mBq m−3 in Córdoba, 210Pb activity concentrations are between 0.04 and 2.30 mBq m−3 in Huelva, and between 0.03 and 1.2 mBq m−3 in Cordoba, and PM 10 concentrations are found to be in the 5.1–81.3 μg m−3 range in Huelva, and 8.2–76.3 μg m−3 in Cordoba, respectively. A linear regression analysis indicates more regional variability for 210Pb than for 7Be between simultaneous measurements. Principal components analysis (PCA) is applied to the datasets and the results reveal that aerosol behaviour is mainly represented by two components, which explain 82% of the total variance. The analysis of surface measurements and meteorological parameters revealed that component F1 groups sampling periods in which the influence of similar meteorological conditions over the region lead to similar 7Be, 210Pb and PM 10 concentration levels in both sampling sites. On the other hand, component F2 detaches the 7Be, 210Pb and PM 10 concentration levels between monitoring sites, and the meteorological analysis shows how surface concentrations within this component are associated with the development of different mesoscale circulations in each part of the valley. The identification of sampling periods characterised by differences in surface concentrations and wind patterns between stations suggests that the valley could not be considered as one single unit for certain meteorological scenarios. These results evidence how the understanding of wind characteristics within a complex terrain provide some essential knowledge in the regionalization and/or optimization of monitoring networks. Highlights • We provide simultaneous 7Be, 210 Pb and PM10 records for two sites (southern Spain) across a two-year period. • PCA was applied to the datasets and shows two main and different behaviors in the region;. • Strong dependence of 7Be and 210Pb specific activities on the air flow patterns;. • High and different values associated to the scenarios of mesoscale circulations. [ABSTRACT FROM AUTHOR]

The combined analysis of 222 Rn activity concentrations and mesoscale meteorological conditions at Huelva city (Spain) was addressed in this study to understand the potential impact of phosphogypsum piles on the 222 Rn activity concentrations registered at this area. Hourly mean data from April 2012 to February 2013 registered at two sampling sites (Huelva city and in the background station of El Arenosillo, located 27 km to the south-east) have been used in the study. The results of the present study showed a large difference in mean radon concentrations between the two stations during the sampling period, 6.3 ± 0.4 Bq m −3 at Huelva and 3.0 ± 0.2 Bq m −3 at El Arenosillo. The analysis has demonstrated that hourly 222 Rn concentrations at Huelva city above 22 Bq m −3 , with nocturnal peaks up to 50 Bq/m 3 , mainly coincided with the occurrence of a pure sea-land breeze cycle. Mesoscale circulations in this region are mainly characterized by two patterns of sea-land breeze, pure and non-pure, with the phosphosypsum piles directly upstream (south) of the city during the afternoon on pure sea-breeze days. The difference between mean 222 Rn activity concentrations at Huelva city were 9.9 ± 1.5 Bq m −3 for the pure pattern and 3.3 ± 0.5 Bq m −3 for the non-pure pattern, while in the background station concentrations were 3.9 ± 0.4 Bq m −3 and 2.8 ± 0.4 Bq m −3 respectively. Considering these large differences, a detailed analysis of composites and case studies of representative sea-land breeze cycles of both types and their impact on 222 Rn activity concentration was performed. The results suggested that the presence of the phosphogypsum piles was necessary in order to justify the high 222 Rn activity concentrations observed at Huelva compared with the background station in the afternoons on pure sea breeze days (1.5–2.0 Bq m −3 ). On the other hand, large night time differences between the two sites on these days were likely to be associated with a combination of shallow density currents travelling down the Guadalquivir valley and, again, the presence of phosphogypsum piles. The results have demonstrated a significant impact of the phosphogypsum piles on 222 Rn activity concentrations in Huelva city during the occurrence of pure sea breeze days. [ABSTRACT FROM AUTHOR]

Abstract: On 12 and 13 August 2006, an exceptional air pollution event occurred in the southwest of the Iberian Peninsula (western Andalusia). High concentrations of surface ozone, CO and PM10 were registered at several air quality stations, in some cases reaching record values. During the late afternoon and evening of these two dates, the information and alert thresholds of surface ozone at coastal stations were exceeded, with peaks of 270 μg m−3. Concentrations of CO and PM10 reached 1800 μg m−3 and 240 μg m−3. Surface meteorological observations, back trajectories computed with the HYSPLIT model and wind and specific humidity fields from the meso-meteorological WRF-ARW model have all been used to gain an understanding of the origin of this event. The results indicate that this event was caused by the long-range transport of air masses from the wildfires that had occurred in the northwest of the Iberian Peninsula (Galicia and northern Portugal) during the first two weeks of August 2006. Air masses loaded with pollutants were transported approximately 1000 km from north to south, over Portugal and the Atlantic Ocean, to reach the southwestern Iberian Peninsula, with the consequent negative high impact on the air quality of this region. [Copyright &y& Elsevier]

Abstract: High activity concentrations of several man-made radionuclides (such as 131I, 132I, 132Te, 134Cs and 137Cs) have been detected along the Iberian Peninsula from March 28th to April 7th 2011. The analysis of back-trajectories of air masses allowed us to demonstrate that the levels of manmade radionuclide activity concentrations in the southwest of the Iberian Peninsula come from the accident produced in the nuclear power plant of Fukushima. The pathway followed by the radioactive plume from Fukushima into Huelva (southwest of the Iberian Peninsula) was deduced through back-trajectories analysis, and this fact was also verified by the activity concentrations measured of those radionuclides reported in places crossed by this radioactive cloud. In fact, activity concentrations reported by E.P.A., and by IAEA, in several places of Japan, Pacific Ocean and United States of America are according to the expected ones from the air mass trajectory arriving at Huelva province. [Copyright &y& Elsevier]

Tropospheric ozone is considered one of the most significant air pollutants due to its negative effects on human health, agricultural crops, ecosystems and climate. The features of the southwest of the Iberian Peninsula (high temperatures and high solar radiation, the presence of the Guadalquivir basin and sources of precursors) favour the occurrence of episodes of high concentrations that cause exceedances of legal thresholds with relative frequency. Despite this, no study examining regional ozone episodes has been carried out in this region until now. In the present work a surface hourly ozone dataset (2003–2006) measured at 11 representative stations located in the southwest of the Iberian Peninsula (western Andalusia) was analysed in order to identify and characterise, for the first time, the regional ozone episodes that occur in this area. Using a statistical criterion, eight regional episodes were identified and analysed. The analysis of synoptic weather patterns revealed that these episodes occur in conjunction with two different synoptic conditions (high surface pressure either close to the British Isles or over the Atlantic Ocean). Both conditions generate weak isobaric surface pressure over the Iberian Peninsula, favouring the establishment of easterly winds at 500 m and the development of winds with two main prevailing directions (southwest-northwest, following the Guadalquivir basin) in the study area. During episodic days ozone follows a similar daily cycle to that observed on non-episode summer days, although the levels reached during the former are higher. In both cases, a direct relationship between the daily ozone cycle and the local wind regimen was not observed. This therefore seems to indicate that the daily cycle followed by ozone is mainly regulated by the precursor emissions produced in the environment, by the temperature changes taking place during the day and by the influence of the lower troposphere during anticyclonic weather conditions. [ABSTRACT FROM AUTHOR]