Geochemistry and source contribution of fugitive phosphogypsum particles in Huelva, (SW Spain)

Abstract

The present study has estimated the impact of fugitive phosphogypsum (PG) particles on the bulk atmospheric deposition (soluble and insoluble species) of a nearby urban area (Huelva, SW Spain). The work is based on the geochemical characterization of bulk atmospheric samples collected from April 2014 to March 2017 in a huge PG pond and at increasing distances (0.5 km, 1.5 km and 54 km). Furthermore, a high resolution sampling, using flat-plate model, of deposited particles was performed at 0.5 km during 4 months of 2017 for ESEM-EDS analysis.The deposition of fugitive PG particles causes acidification, especially for wet deposition which is caused by high concentrations of F−, SO42− and PO43− in the soluble fraction, which decreases with increasing distance from the PG pond. F− levels decrease 10 times at 0.5 km, 40 times at 1.5 km and 90 times at 54 km. Besides, U, V, and REE are enriched in the insoluble fraction.Source contribution analysis shows three sources derived from the PG deposit: PG, layered salts and gypsum + impurities (REE and U). The last source reaches the city under SW-S-SE winds accounting for a 6% of bulk atmospheric deposition. The fugitive PG particles reaching the city are <10 μm size, composed by Ca ± S ± P, gypsum, fluoride particles and complex mixtures. This study supports the need of surveillance strategies during the future restoration in order to prevent the PG impact on the city.