Contribution of mine wastes to atmospheric metal deposition in the surrounding area of an abandoned heavily polluted mining district (Rio Tinto mines, Spain)

摘要

The present study seeks to estimate the impact of abandoned mine wastes on the levels and chemical profile of total atmospheric deposition in one of the oldest and largest mining districts in Europe (Rio Tinto mines, Iberian Pyrite Belt), on the basis of a complete geochemical characterization of paniculate matter samples periodically collected in five sampling stations located around the mining district between March 2009 and February 2011.The annual levels of total bulk deposition (soluble and insoluble fractions) registered in the Rio Tinto Mining District ranged between 18 and 43 g/m2 depending on the distance from the sampling station with regard to the mine waste deposits. As a general pattern in the area, high mass levels of Zn and Cu were deposited in a range of 9-62 mg/m~2 not only in the insoluble but also in the soluble fraction. Other potentially toxic trace elements such as As, Sb, Ba, Pb, Sn and Bi showed greater deposition fluxes in the locations closest to the mine waste deposits. A principal component analysis with a Multilinear Regression Analysis certifies the presence of two common sources in the mining area: 1) a mineral factor composed mainly of elements derived from silicate minerals (Al, Ca, Sr, Ti, Li, Mg, Mn, K, Na and Fe), mixed with other anthropogenic species (NH_4~+, SO_4~(2-), NO_3~-) within the village closest to the mine; and 2) a marine factor composed of Na, Cl, Mg, SO_4~(2-) and Sr. In addition, a mine waste factor made up of toxic elements (Cu, Zn, Ga, As, Sb, Ba, Pb, Sn, Cd and Bi) has been recognized in the sampling sites exposed to dust-bearing winds downwind of the mining area, suggesting that mine wastes are a relevant source of heavy-mineral particles with potentially adverse environmental effects to surrounding soils, plants and humans.