Mineralogy and origin of atmospheric particles in the industrial area of Huelva (SW Spain)

The mineralogy of atmospheric particles at the confluence of the Tinto and Odiel rivers, south of Huelva (a highly industrialized city in the SW Spain), was characterized in view to identify source origins. In spite of the small amount of sample collected, mineralogical characterization was performed by X-ray diffraction, polarized light microscopy and scanning electron microscopy with EDS analysis system, using an adequate sample preparation methodology. Sedimentable (SP) and aerosols particles were sampled an one-week basis every two months for one year. Quartz, calcite and feldspars were found to be the major minerals in both fractions, and phyllosilicates, dolomite and gypsum were also identified in lower content. Minor mineral particles included barite, apatite, sphalerite and pyrite. SEM studies revealed the additional presence of chalcopyrite in both SP and aerosols, and of chalcocite–covellite, halite and sylvite in the latter. Siderite, hematite and ankerite were only detected in the SP fraction. The concentrations of the previous minerals increased in summer by effect of the limited rain and the resulting scarcity of atmosphere washing. Non-mineral particles detected by SEM in SP and aerosol fractions included spherical, biological and compositionally complex particles. The main source of mineral particles was found to be the soil suspension in addition to the metallurgical and fertilizer production industries in the area.