Teresa Maria Fernandes Valente

The role of two acidophilic algae as ecological indicators of acid mine drainage sites

Acidic effl uents, emerging from four abandoned mines (Valdarcas, Carris, Adoria and Cerquido) in Northern Portugal were analyzed regarding physical-chemical, mineralogical and ecological characteristics. Such effl uents present distinct properties since they were mobilized from wastes of different primary ores and mining procedures. Results show that acidophilic algal colonization is dominated by Euglena mutabilis and Klebsormidium sp.. Abundance and distribution of both algae are related to different intensity of acid mine drainage (AMD) at each mining site. Mineral-alga interactions infl uence metal deposition at Valdarcas and probably contribute to iron mineral precipitation. Euglena mutabilis displayed a preference for schwertmannite-rich AMD precipitates, which may suggest a mineralogical control on algal colonization. Spatial distribution of E. mutabilis can be used to qualitatively assess water quality improvements along the effluent channel.

Geochemistry of rare earth elements in a passive treatment system built for acid mine drainage remediation

Rare earth elements (REE) were used to assess attenuation processes in a passive system for acid mine drainage treatment (Jales, Portugal). Hydrochemical parameters and REE contents in water, soils and sediments were obtained along the treatment system, after summer and winter. A decrease of REE contents in the water resulting from the interaction with limestone after summer occurs; in the wetlands REE are significantly released by the soil particles to the water. After winter, a higher water dynamics favors the AMD treatment effectiveness and performance since REE contents decrease along the system; La and Ce are preferentially sequestered by ochre sludge but released to the water in the wetlands, influencing the REE pattern of the creek water. Thus, REE fractionation occurs in the passive treatment systems and can be used as tracer to follow up and understand the geochemical processes that promote the remediation of AMD.

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。

Enrichment of trace elements in the clay size fraction of mining soils

Reactive waste dumps with sulfide minerals promote acid mine drainage (AMD), which results in water and soil contamination by metals and metalloids. In these systems, contamination is regulated by many factors, such as mineralogical composition of soil and the presence of sorption sites on specific mineral phases. So, the present study dedicates itself to understanding the distribution of trace elements in different size fractions (<2-mm and <2-μm fractions) of mining soils and to evaluate the relationship between chemical and mineralogical composition. Cerdeirinha and Penedono, located in Portugal, were the waste dumps under study. The results revealed that the two waste dumps have high degree of contamination by metals and arsenic and that these elements are concentrated in the clay size fraction. Hence, the higher degree of contamination by toxic elements, especially arsenic in Penedono as well as the role of clay minerals, jarosite, and goethite in retaining trace elements has management implications. Such information must be carefully thought in the rehabilitation projects to be planned for both waste dumps.

Widespread Environmental Contamination with Mycobacterium tuberculosis Complex Revealed by a Molecular Detection Protocol

Environmental contamination with Mycobacterium tuberculosis complex (MTC) has been considered crucial for bovine tuberculosis persistence in multi-host-pathogen systems. However, MTC contamination has been difficult to detect due to methodological issues. In an attempt to overcome this limitation we developed an improved protocol for the detection of MTC DNA. MTC DNA concentration was estimated by the Most Probable Number (MPN) method. Making use of this protocol we showed that MTC contamination is widespread in different types of environmental samples from the Iberian Peninsula, which supports indirect transmission as a contributing mechanism for the maintenance of bovine tuberculosis in this multi-host-pathogen system. The proportion of MTC DNA positive samples was higher in the bovine tuberculosis-infected than in presumed negative area (0.32 and 0.18, respectively). Detection varied with the type of environmental sample and was more frequent in sediment from dams and less frequent in water also from dams (0.22 and 0.05, respectively). The proportion of MTC-positive samples was significantly higher in spring (p<0.001), but MTC DNA concentration per sample was higher in autumn and lower in summer. The average MTC DNA concentration in positive samples was 0.82 MPN/g (CI95 0.70–0.98 MPN/g). We were further able to amplify a DNA sequence specific of Mycobacterium bovis/caprae in 4 environmental samples from the bTB-infected area.

Bromine enrichment in marsh sediments as a marker of environmental changes driven by Grand Solar Minima and anthropogenic activity (Caminha, NW of Portugal)

A sediment core collected in Caminha tidal marsh, NW Portugal, was used to assess bromine (Br) signal over the last ca. 1,700 years. The Br temporal variability reflects its close relationship with soil/sediment organic matter (OM) and also alterations in Br biogeochemical recycling in marsh environment. The highest Br enrichment in sediments was found during the Maunder Solar Minimum, a major solar event characterized by lower irradiance (TSI) and temperature, increased cloudiness and albedo. The obtained results suggest that those climate-induced changes weakened the natural mechanisms that promote Br biochemical transformations, driven by both living plants metabolism and plant litter degradation, with the ensuing generation of volatile methyl bromide (CH3Br). It seems that the prevailing climate conditions during the Maunder favoured the retention of more Br in marsh ecosystem, ultimately decreasing the biogenic Br emissions to the atmosphere. During the 20th century, the Br pattern in sediments appears to mirror likewise anthropogenic sources. The significant correlation (p<0.05) between Br/OM ratios and Pb contents in sediments after 1934 suggests a common source. This is most probably related with the rise, massive consumption and prohibition of leaded gasoline, where ethylene dibromide was added as lead scavenger to antiknock mixtures. More regionally, the concerted use of flame retardants on forest fire management, covering the 1980s through mid-1990s in the north of Portugal and Galicia, could be responsible for the observed increase of sediment Br (relatively to Pb) pool of this tidal marsh. Although man-made brominated compounds are being phased-out since the inception of the 1992 Montreal Protocol, the Caminha tidal marsh sedimentary record showed that Br levels only started to decline after 2002.

Metal Uptake by Native Plants and Revegetation Potential of Mining Sulfide-Rich Waste-Dumps

Waste dumps resulting from metal exploitation create serious environmental damage, providing soil and water degradation over long distances. Phytostabilization can be used to remediate these mining sites. The present study aims to evaluate the behavior of selected plant species (Erica arborea, Ulex europaeus, Agrostis delicatula, and Cytisus multiflorus) that grow spontaneously in three sulfide-rich waste-dumps (Lapa Grande, Cerdeirinha, and Penedono, Portugal). These sites represent different geological, climatic and floristic settings. The results indicate distinctive levels and types of metal contamination: Penedono presents highest sulfate and metal contents, especially As, with low levels of Fe. In contrast, at Lapa Grande and Cerdeirinha Fe, Mn, and Zn are the dominant metals. In accordance, each waste dump develops a typical plant community, providing a specific vegetation inventory. At Penedono, Agrostis delicatula accumulates As, Pb, Cu, Mn, and Zn, showing higher bioaccumulation factors (BF) for Mn (32.1) and As (24.4). At Cerdeirinha, Ulex europaeus has the highest BF for Pb (984), while at Lapa Grande, Erica arborea presents high BF for Mn (9.8) and Pb (8.1). Regarding TF, low values were obtained for most of the metals, especially As (TF < 1). Therefore, the results obtained from representative plant species suggest appropriate behavior for phytostabilization measures.

Geochemistry and mineralogy of ochre-precipitates formed as waste products of passive mine water treatment

ABSTRACT Passive systems with constructed wetlands are designed to simulate natural attenuation processes in order to treat mine water in a long-term and cost-effective manner. In this way, they are especially appropriate to treat mine water discharging from abandoned mines. This paper presents geochemical and mineralogical data obtained from a recently constructed passive system in the Jales abandoned mine, north Portugal. It shows the role of fresh ochre-precipitates, formed as waste products from the neutralization process, in the retention of trace elements. Chemical analysis of these waste products revealed strong enrichment factors for metals and arsenic, relative to the water from which they precipitate. The mineralogical study shows that ochre-precipitates are poorly ordered iron-rich material, such as ferrihydrites, that occur as small spherical aggregates (<0.1 μm in diameter). Heating experiments on these precipitates gave rise to hematite and to a crystalline arsenate. This provides evidence for the scavenging of arsenic by means of a precursor arsenic-rich amorphous compound. The results reveal that ochre-precipitates are wastes of environmental concern, which should be taken into account when considering the possibilities for reuse or disposal.

Occurrence of calcareous foraminifera and calcite- carbonate equilibrium conditions - a case study in Minho/Coura estuary (Northern Portugal)

The Minho/Coura estuary, northern Portugal, has been studied for the influence of hydrochemical and geochemical parameters on living (Rose Bengal stained) foraminiferal assemblages. Our previous works showed a prevalence of agglutinated species in the inner estuary and tidal marsh and significant abundance of calcareous species only in the estuary mouth. The new results clarify syndepositional aspects of the calcareous species related to calcite dissolution, such as thin tests that frequently lack the carbonate layer and show typical destruction features. Sites from the estuary mouth, tidal marsh and river were sampled, under Spring and Autumn conditions, in order to describe physical-chemical features and to allow the geochemical modelling of the solution in which calcification occurs. In particular, the chemical equilibrium regarding calcite was evaluated from the saturation index (SI). Such modelling suggests strongly undersaturated conditions at the majority of the sampling sites, in both sampling periods. The water quality data revealed strong spatial and temporal variability, mainly in the tidal marsh environment, and also the existence of a stressed medium regarding calcite saturation state. The observed geochemical trends provide a plausible explanation for (1) the scarcity and distribution of living calcareous foraminifera in the Minho/Coura estuary and (2) the destruction features observed in the carbonate tests.

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。