M. Santistebán

Characterisation of AMD Pollution in the Reservoirs of the Iberian Pyrite Belt

Abstract A number of water-supply dams have been built in the semi-arid Iberian Pyrite Belt (SW Spain) in a fluvial network affected by acid mine drainage (AMD). There are almost a hundred mines, most of which are closed, which emit low pH leachates with high metal and sulphate loads to reservoirs intended for urban supply. The Iberian Pyrite Belt contains 23 of these reservoirs spread along the Tinto and Odiel river basins, which are the main water courses affected by AMD, and the Chanza and the Guadiamar river basins, which are affected to a lesser extent. We characterised the degree of pollution in the various reservoirs that receive AMD-affected waters; this will eventually allow the development of a risk map of the overall extent of the problem in reservoirs in the Iberian Pyrite Belt.ZusammenfassungIm semi-ariden Iberischen Pyrit-Gürtel (Südwest Spanien), einem durch saure Grubenwässer (AMD) beeinträchtigten Flusssystem, wurde eine Reihe von Talsperren für die Wasserversorgung errichtet. Es gibt dort fast einhundert Bergwerke, zumeist stillgelegt, die Wasser mit niedrigen pH-Werten und hohen Metall- und Sulfatfrachten letztlich an Talsperren abgeben, die für die kommunale Wasserversorgung gedacht sind. Im Iberischen Pyrit-Gürtel gibt es 23 solcher Talsperren, verteilt in den Einzugsgebieten von Rio Tinto und Rio Odiel, die die durch AMD beeinträchtigten Hauptflüsse sind, und von Rio Chanza und Rio Guadiamar, die durch AMD weniger betroffen sind. Es wurde der Grad der Verunreinigung der verschiedenen Talsperren charakterisiert, die durch AMD beeinträchtigte Wässer erhalten. Das wird die Entwicklung einer Risikokarte für das Gesamtausmaß des Problems in den Talsperren im Iberischen Pyrit-Gürtel ermöglichen.ResumenDiques para suministro de agua se han construido en el cinturón pirítico ibérico (sudoeste de España) en una red fluvial afectada por drenaje ácido de minas (DAM). Casi un centenar de minas, la mayoría cerradas, producen lixiviados de bajo pH y con alta carga de metales y sulfatos que llegan a reservorios destinados para suministro urbano. El cinturón pirítico ibérico contiene 23 de estos reservorios a lo largo de las cuencas de los ríos Tinto y Odiel que son los principales cursos de agua afectados por el DAM, y las cuencas de los ríos Chanza y Guadiamar que son afectados en menor extensión. Hemos caracterizado el grado de contaminación en varios reservorios que reciben las aguas afectadas por DAM; esto eventualmente permitirá el desarrollo de un mapa de riesgo sobre la extensión global del problema en los reservorios del cinturón pirítico ibérico.抽象伊比利亚黄铁矿带(Iberian Pyrite Belt)位于半干旱的西班牙西南地区,沿该区河网修建了大量市政供水水坝。河网内河水已为酸性废水(AMD)污染,100多个矿井(多数已经关闭)将富含金属和硫酸盐的酸性废水最终排向了供水水库。在伊比利亚黄铁矿带内,Tinto和Odiel流域的23个水库受酸性废水(AMD)污染严重,而Chanza和Guadiamar流域水库受酸性废水污染较轻。评价了伊比利亚黄铁矿带内各水库的酸性废水(AMD)污染程度,绘制了水库的污染风险评估图。

Statistical Contrast Analysis of Hydrochemical Parameters Upstream of the Tidal Influence in Two AMD-Affected Rivers

The Iberian Pyrite Belt (IPB), SW Spain, has been exploited since ancient times, and previous studies have compared different parameters in the Tinto and Odiel Rivers, the principal rivers that cross the IPB. We used classical statistics to draw contrasts between the two rivers. Samples were collected at two sites, one in the Tinto River, and the other in the Odiel, immediately upstream of tidal influence. Both rivers are strongly contaminated by acid mine drainage (AMD). However, the results suggest a distinctive, although somewhat parallel, geochemical behavior. The pattern of affinity between parameters differs because in addition to AMD, the Odiel River receives important contributions from non-contaminated catchments, while the Tinto River is the main receptor of drainage from the Rio Tinto mine. The applied statistical approach revealed that pH and electrical conductivity present a similar temporal evolution, which point to an identical geochemical signature; this indicates that both systems are similarly affected by contamination from the same pyritic area.ZusammenfassungDer Iberische Pyrit-Gürtel (Iberian Pyrite Belt, IPB) in Südwest-Spanien wird seit historischen Zeiten bergbaulich genutzt. Schon viele Untersuchungen beschäftigen sich mit Parametervergleichen zwischen den Hauptvorflutern im IBP, dem Rio Tinto und dem Rio Odiel. Wir nutzen klassische statische Methoden, um Unterschiede zwischen beiden Flusssystemen aufzuzeigen. Beide jeweiligen Untersuchungsstandorte im Rio Tinto und im Rio Odiel befanden sich oberstromig des Gezeiteneinflusses. In beiden Flüssen ist ein Einfluss vom AMD nachweisbar. Jedoch können an den Untersuchungsstandorten jeweils charakteristische und z. T. parallel verlaufende geochemische Verhältnisse erkannt werden. Die Ähnlichkeit zwischen den gemessenen Parametern differiert aufgrund des unterschiedlichen AMD-Einflusses. Während dem Rio Odiel maßgebliche Anteile aus nicht kontaminierten Einzugsgebieten zufließen, ist der Rio Tinto der Hauptvorfluter für Abflussanteile der Rio Tinto Bergwerke. Die statistische Auswertung macht deutlich, dass die pH-Werte und die elektrischen Leitfähigkeiten zeitlich ähnliche Entwicklungen aufzeigen und somit auf identische geochemische Signaturen hinweisen. Dieses zeigt, dass beide Flusssysteme durch die gleiche Pyritzone beeinflusst werden.ResumenLa faja pirítica ibérica (IPB), SO España, ha sido explotada desde tiempos remotos; estudios previos han comparado diferentes parámetros en los Ríos Tinto y Odiel que son los principales ríos que atraviesan la IPB. En este trabajo hemos usado estadística clásica para mostrar los contrastes entre los dos ríos. Las muestras fueron colectadas en dos sitios, uno en el Río Tinto y el otro en el Río Odiel inmediatamente río arriba de la zona de influencia de las mareas. Ambos ríos están fuertemente contaminados por AMD. Sin embargo, los resultados sugieren un diferente, aunque en alguna medida semejante, comportamiento geoquímico. El patrón de afinidad entre parámetros difiere porque el Río Odiel recibe importantes contribuciones desde afluentes no contaminados mientras que el Rio Tinto es el principal receptor del drenaje proveniente de la mina Río Tinto. La aproximación por estadística aplicada reveló que el pH y la conductividad eléctrica presentan una evolución temporal similar, que señala idénticas características geoquímicas; esto indica que ambos sistemas están afectados en forma similar por la contaminación proveniente de la misma área pirítica.抽象西班牙西南部的伊利比亚黄铁矿带(IPB)开采历史悠久,以往研究曾对比了横穿伊利比亚黄铁矿带(IPB)的Tinto河与Odiel河的水化学参数。本文采用传统统计学方法对比了两条河流水的水化学特征。研究分别于Yinto河与Odiel河受潮汐影响的上游取样。这两条河流都被酸性矿井水严重污染。但是,两种水样却显示出一种明显不同却有点类似的地球化学行为。由于除了AMD之外,Odiel河还接收大量未受污染流域来水,Tinto河水主要源于Rio Tinto矿井排水,两水样水化学参数之间关系明显不同。应用统计学的方法揭示,pH值和电导率呈现相似的时间演化过程,两水样具有相同的地球化学特征,表明两条河流经受着同一黄铁矿区的污染。

Hydrochemical characterization of an acid mine drainage-affected reservoir: the Sancho Reservoir, Huelva, southwest Spain

Abstract The objectives of this study were to discover the relationship between variables in a water reservoir and the hydrochemical variations related to acid mine drainage (AMD), and to describe the horizontal stratification related to vertical salinity and variations in metals present in the region. The information obtained may be used for establishing risk evaluation criteria and to design future remediation strategies, which could be useful for new dams. The hydrochemical characterization was based on a sampling campaign performed in October 2011. A total of 28 samples, at 1-m-deep intervals, were obtained. The hydrogeochemical study of the polluted reservoir shows that the dilution effect is not sufficient to neutralize AMD contributions from mining activity. Sampling carried out from the surface water to the deepest points reveals stratification of the reservoir that allows it to be included in the group of monomictic and holomitic lakes. Editor D. Koutsoyiannis; Associate editor M.D. Fidelibus Citation Cerón, J.C., Grande, J.A., de la Torre, M.L., Borrego, J., Santisteban, M., and Valente, T., 2014. Hydrochemical characterization of an acid mine drainage-affected reservoir: the Sancho Reservoir, Huelva, southwest Spain. Hydrological Sciences Journal, 59 (6), 1213–1224. http://dx.doi.org/10.1080/02626667.2013.834341

Polonium behaviour in reservoirs potentially affected by acid mine drainage (AMD) in the Iberian Pyrite Belt (SW of Spain).

The province of Huelva is one of the areas most affected by acid mine drainage (AMD) in the world, which can produce big enhancements and fractionations in the waters affected by AMD. There are very few studies on this issue, and none on polonium-210. Twenty-two water reservoirs were sampled, and the (210)Po was measured in both dissolution and particulate phases. The (210)Po concentrations in the waters were in the same order of magnitude to those ones for unperturbed systems, although the data published to particulate matter are very scarce. A mean value and standard uncertainty for (210)Po of 0.25 ± 0.03 mBq L(-1) in the dissolved matter, and 62 ± 9 mBq g(-1) in the particulate matter can be established as base line for the reservoirs of the Huelva area. The distribution coefficients (kd) range from 10(4) to 10(6) L kg(-1), in agreement to the found ones by other authors for the case of neutral waters, but being the lowest values for the more acidic reservoirs. It has been also found that (210)Po has a high tendency to be associated to the particulate matter for neutral-alkaline waters, however, under extreme acid conditions (pH < 3), increases the Po tendency to be associated to the dissolved phase. Therefore, the main conclusion obtained in this work is that AMD has no a significant influence on the total activity concentration of (210)Po in the waters of reservoirs, but the acidity has a clear influence on its distribution between both dissolved and the particulate phases.

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

ABSTRACT This paper presents hydrochemical data of an AMD stream, Poderosa Creek, in the Iberian Pyrite Belt, obtained between its source, in the Poderosa Mine portal, and its confluence with the Odiel River. The main objective is to establish potential interdependent relationships between sulphate and metal loads and the following physico-chemical variables: pH, electrical conductivity (EC), redox potential (EH) and dissolved oxygen (DO). All the parameters show an overall increasing tendency from the tunnel exit to the confluence at the Odiel River. The TDS and EC are two relevant exceptions. They behave similarly, showing a decreasing trend and a strong inflection that describes a minimum immediately after the discharging point. Spatial analysis combined with statistical tools reveal typical AMD processes and the respective physico-chemical implications. Inputs with distinctive hydrochemical signatures impose relevant modifications in the Poderosa Creek waters. This indicates low hydrochemical inertia and high vulnerability to external stimuli. Editor D. Koutsoyiannis; Associate editor not assigned

Hydrogeochemical variables regionalization – applying cluster analysis for a seasonal evolution model from an estuarine system affected by AMD

This study describes the spatial evolution of the hydrogeochemical parameters which characterise a strongly affected estuary by Acid Mine Drainage (AMD). The studied estuarine system receives AMD from the Iberian Pyrite Belt (SW Spain) and, simultaneously, is affected by the presence of an industrial chemical complex. Water sampling was performed in the year of 2008, comprising four sampling campaigns, in order to represent seasonality. The results show how the estuary can be divided into three areas of different behaviour in response to hydrogeochemical variables concentrations that define each sampling stations: on one hand, an area dominated by tidal influence; in the opposite end there is a second area including the points located in the two rivers headwaters that are not influenced by seawater; finally there is the area that can be defined as mixing zone. These areas are moved along the hydrological year due to seasonal chemical variations.

Negative pH values in an open-air radical environment affected by acid mine drainage. Characterization and proposal of a hydrogeochemical model

This paper presents the finding of a singular environment polluted by acid mine drainage in the Iberian Pyrite Belt. This situation is regulated by particular conditions, thus the analysed values can be considered as extreme, not only because of the high concentrations of toxic elements, but also due to the extreme low pH, reaching an average negative pH of -1.56, never found before in open-air environments contaminated by acid mine drainage. Concentrations up to 59 g/L of Fe, 2.4 g/L of Al, 740 mg/L of As, 4.3 mg/L of Co, 5.3 mg/L of Ge, 4.8 mg/L of Sb, inter alia, can be found dissolved in these polluted waters. The main aims of the present work are the physicochemical characterization and the toxicity assessment of these radical polluted waters. In addition, a hydrogeochemical model of the system will be proposed, which justifies the extreme pH value and the extraordinarily high concentrations of toxic elements, even for acid mine drainage polluted environments. Extreme acidity and metal and sulphate concentrations in the Radical Environment are due to several processes of different nature, mainly driven by the geochemistry of the minerals presents in the endorheic character of the basin. The extremely acidic nature of these waters control the Fe species present in them, being FeHSO4+ the mainly Fe specie representing 94% of total. High toxicity of these waters has been detected due to the absence of any diatoms species.

The paradigm of Circular Mining in the world: the Iberian Pyrite Belt as a potential scenario of interaction

Water is one of the receptors most affected by the impacts caused, especially in the case of mining sulphides and, to a lesser extent, of coal. Acid Mine Drainage (AMD) is the main problem associated with these mining operations, producing extremely high impacts, and in many cases irreversible impacts, until now. A new concept of mining can make this activity compatible with the environmental preservation and also to the recovery of the environment affected by the old mining operations that today are in the process of reopening. This new concept implicates the paradigm of Circular Mining as a derivative of the concept of Circular Economy, considered as a strategy that aims to reduce both the entry of materials and the production of virgin waste, closing the “loops” or economic and ecological flows of resources. The present work discusses the paradigm of Circular Mining, focused on the Iberian Pyrite Belt, one of the most paradigmatic metallogenetic regions in the world. Based on some examples, expeditious calculations show the possibility of recovering base metals as well as strategic elements from acid mine drainage, thus obtaining important economic assets.

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

The Sancho Reservoir (Iberian Pyrite Belt, SW Spain) is nourished by the waters of the river Meca, which is affected by acid mine drainage (AMD) processes from the abandoned Tharsis mine. The aim of the present work is to study the hydrochemical variations in this reservoir, in order to define potential stratification processes in metal load and sulphates. A stratified sampling from the surface, with one meter deep intervals to the bottom of the dam, was performed. The results show a clear stratification of temperature, pH, electric conductivity, dissolved oxygen, metal and sulphate loads associated with depth. There is an increase of metal loads at the bottom of the reservoir, though previous studies only detect iron. The proximity between pH and aluminium suggests that water chemistry is strongly influenced by aluminium precipitation processes. This indicates the buffer effect that aluminium exercises, which precipitates as amorphous or low crystalline phases, introducing hydrogen ions to the system, while alkalinity input tends to raise pH.