Evidences of different meteorological patterns governing ⁷Be and ²¹⁰Pb surface levels in the southern Iberian Peninsula

⁷Be, ²¹⁰Pb and PM₁₀ 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 PM₁₀ 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 PM₁₀ concentration levels in both sampling sites. On the other hand, component F2 detaches the ⁷Be, ²¹⁰Pb and PM₁₀ 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.