Pollution of a River Basin Impacted by Acid Mine Drainage in the Iberian Pyrite Belt (Sw Spain)

Abstract

Abstract. The Iberian Pyrite Belt (IPB) is one of the most famous sulfide mining regions in the world. Mining activity in the IPB dates back to prehistoric times, and though today there is no active mining, the pollution continues to generate. The result is acidic drainage containing elevated concentration of sulfate and heavy metals. This is responsible for the pollution and degradation of the Odiel River basin in south-western Spain. In this work we have conducted a study along the entire Odiel basin. During the years 2002 and 2003 we have collected water samples at 69 points in order to characterize and quantify the pollutants that the Odiel River receives as a consequence of the AMD inputs within its watershed. The contaminant load transported by the Odiel River into the Huelva Estuary has also been calculated. Due to the great quantity of samples and analyses, the use of statistical multivariate techniques (Principal Component Analysis) was used to interpret the results. PCA of the samples showed strong interrelationships between the generation of acid by sulfide mineral weathering and metal loads. In downstream reaches, the rock forming elements (K, Ca, Na, Mg, etc.) dominate as the acidic waters dissolve the rocks in the stream bed. The contaminant load transported by the Odiel River to the Huelva Stuary is dominated by SO 4 2-, Al and Fe, with lesser quantities of Zn, Cu, Cd, etc. Additional Key words:Odiel River, acid drainage, metal pollution.

Natural attenuation processes in two water reservoirs receiving acid mine drainage

“…1). In these streams the range of pH is between 2.6-3.5, 13-106 mg/l Al, 2-13 mg/l Cu, 12-338 mg/l Fe, 3-307 mg/l Zn, 448-3158 mg/l SO4 2and maximum concentration of 1095 µg/l of Co, 229 µg/l of As, 962 µg/l of Ni, 611 µg/l of Cd, 789 µg/l of Pb, etc., can be found (Sarmiento et al, 2006;Sarmiento, 2008).…”

“…Values of pH around 2.6 and concentration about 1 g/L of Al, 2 g/L of Fe, 412 mg/l of Zn, 167 mg/l of Cu, 3.6 mg/l of As, 0.9 mg/l of Pb, 6.4 mg/l of Ni, etc. can be found in the streams draining these mines (Sarmiento et al, 2006;Sarmiento, 2008).…”

“…Pyrite, sphalerite, galena and chalcopyrite are the main mineral phases that make up these deposits, which also contain accessory amounts of As, Cd, Co, Ni, Cr, etc. As a consequence of the oxidative dissolution of the sulphides exposed in the surface associated to mining activities, acid mine drainage pollution is an important processes in the Odiel basin (Sanchez-España et al, 2005;Sarmiento et al, 2006;Sarmiento 2008). Near its mouth, the Odiel River has a very low pH and high concentrations of metals and metalloids (Cánovas et al, 2007;Olías et al, 2004;Sarmiento et al, 2004).…”

Environmental Impact of Mining Activities in the Southern Sector of the Guadiana Basin (SW of the Iberian Peninsula)

“…Quite recently, a number of investigations have been completed on the Odiel river basin Sarmiento et al 2004Sarmiento et al , 2006Sarmiento et al , 2008 among others, in which the contamination load from the river into the estuary and its impact on the water quality during the dry and wet seasons was estimated. Therefore, the environmental problem derived from acid mine drainage into the Odiel and Tinto rivers in the Huelva area is well known.…”

Mobilization and natural attenuation of arsenic in acid mine drainage ( AMD )

“…tailings) where oxidation of sulfides occurs. As a result, the area is totally degraded and the Tinto and Odiel rivers are currently two of the most polluted rivers in Spain (Olías et al, 2004;Sarmiento et al, 2006;Nieto et al, 2007;Sarmiento et al, 2009) owing to the longevity of the contamination processes of AMD (Younger, 1997). In these massive sulfide deposits, arsenic can be found in arsenical pyrite (with up to 0.4% of As), and in some accessory minerals such as arsenopyrite and marcasite.…”