Mineralogy of atmospheric dust impacting the Rio Tinto mining area (Spain) during episodes of high metal deposition

Abstract

This study is the first to investigate the mineral composition of the atmospheric particulate matter deposited at Rio Tinto, Spain, an historical mining district of world-class importance, with emphasis on metal-bearing particles and their environmental implications. The dustfall is composed of quartz, feldspars, phyllosilicates (mica, chlorite and/or kaolinite) and a variety of accessory heavy minerals, the most common being primary sulfides (pyrite, chalcopyrite with minor galena, sphalerite and bornite) and their oxidation products (notably goethite, hematite and jarosite). This mineral assemblage suggests a local source of wind-blown dust and it is consistent with the large deposition levels of sulfide-related elements (As, Bi, Cd, Cu, Pb, Sb and Zn) registered at the sampling site adjacent to the mine waste dumps. However, the generation of potentially harmful dust particles is not restricted to mine wastes. Anthropogenic metallic compounds arising from a nearby hazardous waste disposal centre can make a relevant additional contribution to the metal deposition, particularly for Fe, Ni, Cr and Mn. Atmospheric fallout is a major mechanism for metal input to soils and plants around or near the mining area.