Tinto Versus Odiel: Two A.M.D. Polluted Rivers and an Unresolved Issue. An Artificial Intelligence Approach

Abstract

The Iberian Pyrite Belt (SW Spain) is a highly relevant source of Acid Mine Drainage contamination on a global scale. Although the Tinto and Odiel Rivers, which cross the Iberian Pyrite Belt, have been widely studied by various authors, an issue is still pending: the study of the metal load distribution undergone by each of these rivers and, hence, the establishment of cause-effect relationships between the transported load in the final sections of both rivers, upstream of the tidal influence limits, and the characteristics of the input in each of the basins. To solve this, a water sampling campaign was conducted on both rivers on a daily basis from mid September 2007 to the end of May 2008, where pH, conductivity, redox potential, As, Cd, Fe, Cu, Zn, Mn and sulfate were analyzed. The results were treated with the PreFurGe tool, which is based on Fuzzy Logic. This showed that the order of abundance for the parameters analyzed for the Odiel River is SO 4 >Zn>Mn>Fe>Cu>Cd>As, whereas for the Tinto River it is SO 4 >Fe>Cu>Zn>Mn>Cd>As. This last pattern coincides with the order of abundance of elements in Pyrite. In the Tinto River, the metal with the highest rate is Fe, which presents mean values of 361.1 mg/L, whereas in the Odiel River iron mean concentration is 5.34 mg/L. This difference is due to higher precipitation of oxyhydroxysulfates of iron in the Odiel River as a result of the higher intensity of neutralization processes.

Stratification of Metal and Sulphate Loads in Acid Mine Drainage Receiving Water Dams – Variables Regionalization by Cluster Analysis

“…The AMD and ARD processes that affect the regional drainage network have been extensively described by several authors (Aroba et al, 2007;Borrego, 1992: Borrego et al, 2002Borrego et al, 2011;Carro et al, 2011;Braungardt et al, 1998;Davis et al, 2000;de la Torre et al, 2009;de la Torre et al, 2010;de la Torre et al, 2011;Elbaz-Poulichet et al, 1999;Elbaz-Poulichet et al, 2000;Elbaz-Poulichet et al, 2001;Grande, 2011;Grande et al, 2000;Grande et al 2003a;Grande et al, 2003b;Grande et al, 2005a;Grande et al, 2005b;Grande et al, 2007;Grande et al, 2010a;Grande et al, 2010b;Grande et al, 2010c;Grande et al, 2010d;Grande et al, 2010e;Grande et al, 2011a;Grande et al, 2011b;Jiménez et al, 2009;Leblanc et al, 2000;Sáinz et al, 2002;Sáinz et al, 2003a;Sáinz et al, 2004;Sáinz et al, 2005).…”

Physico-Chemical Influence of Surface Water Contaminated by Acid Mine Drainage on the Populations of Diatoms in Dams (Iberian Pyrite Belt, SW Spain)

“…AMD occurs when sulfurous minerals are exposed to atmospheric [1], hydrological (oxygen, water) or biological weathering (chemoautotrophic bacteria) and they become oxidized, resulting in sulfuric acid (low pH), dissolved metal ions, elevated sulfate content [2], low alkalinity and high conductivity. The AMD process is widely described in the scientific literature because globally, it is one of the most serious and widespread contamination problems, affecting a large number of water resources in five continents (e.g., [3,4,5]).…”

Spatial evolution of an AMD stream in the Iberian Pyrite Belt: process characterization and control factors on the hydrochemistry

“…Presently, the Poderosa tunnel allows the output of water that is undergoing AMD contamination inside the galleries and open pits, which have been interconnected for over 2000 years (Pinedo Vara 1963). The water flows down to the Odiel River, which is widely described in the AMD literature (Borrego 1992, Sáinz 1999, Sáinz et al 2002, 2003a, Borrego et al 2002, López-Fernández et al 2003, 2003b, 2011a, Sainz et al 2003b, Sarmiento and Nieto 2003, Sarmiento et al 2004a, 2004b, Cánovas et al 2005, Casiot et al 2005, Sánchez-España et al 2005, 2006a, 2006b, Jiménez et al 2009, De La Torre et al 2010.…”