Sierra Minera Research Articles

Trace metal level variation under strong wind conditions and sediment resuspension in the waters of a coastal lagoon highly impacted by mining activities

The levels of metals in the waters of the Mar Menor lagoon are higher in the southern than in the northern zone both in the dissolved (As: 1.78 μg L-1 north vs 1.86 μg L-1 south; Cd: 0.020 μg L-1 vs 0.055 μg L-1; Pb: 0. 686 μg L-1 vs 2.714 μg L-1; Zn: 3.06 μg L-1 vs 10.2 μg L-1) as in the particulate fraction (As: 13.6 μg g-1 north vs 27.3 μg g-1 south; Cd: 0.510 μg g-1 vs 2.11 μg g-1; Pb: 146 μg g-1 vs 575 μg g-1; Zn: 266 μg g-1 vs 729 μg g-1). This difference is associated to the influence of historical and recent inputs from the Sierra Minera Cartagena -La Unión located south of the lagoon. Strong winds cause sediment resuspension in this shallow lagoon, increasing metal levels in the dissolved (twofold) and especially in the particulate fraction (threefold) because the resuspended sediments are rich in metals. Distribution among dissolved and particulate fraction is determined by the chemistry of each element and salinity. This increase causes the levels to reach limits very close to those established by the Water Framework Directive, especially in the case of lead, whose annual average level of 1.23 μg L-1 is very close to the 1.3 μg L-1 established in the Directive. Therefore, slight change in environmental variables could make Pb levels to exceed legal limits. Future work should focus on investigating how unique environmental events, enhanced by global change, affect metal cycles in highly anthropised coastal areas.

Differential response of Oryza sativa L. and Phragmites australis L. plants in trace elements contaminated soils under flooded and unflooded conditions.

Drastic changes in the water regime of trace elements (TEs) contaminated soils under semiarid conditions, from completely dry to flooding situations, may alter the solubility of the contaminants and, therefore, their potential mobility and availability to plants. Certain macrophyte species have shown a promising suitability for their use in the phytoremediation of TEs contaminated soils under fluctuating flooded-unflooded conditions, as a consequence of their high resistance and tolerance to contamination. Similarly, different water conditions occur during rice (Oryza sativa) cultivation, a species often used as a model plant for TEs toxicity studies. The aim of this work was to study the tolerance and oxidative response to TEs of common reed (Phragmites australis) and rice grown in contaminated mining soils, when exposed to different water saturation conditions. Both species (common reed and rice) were cultivated in three different contaminated soils from the Sierra Minera of La Unión-Cartagena (SE-Spain) under contrasting water saturation conditions (flooded and unflooded) in a pot experiment. Soil EC and elevated metal (mainly Cd and Zn) soluble concentrations conditioned the survival of the plants. Whereas, As accumulation in the aerial part of both species influenced the most oxidative stress homeostasis. Common reed showed to be a good candidate for its use in the phytostabilization of TEs contaminated soils under both flooded and unflooded conditions.

Do Old Mining Areas Represent an Environmental Problem and Health Risk? A Critical Discussion through a Particular Case

A bibliographic review was carried out to establish the state of knowledge of a mining area with several centuries of exploitation and currently abandoned. The selected case study, the Sierra Minera de Cartagena-La Union (Spain), has a long history of mining activity, ending in 1990. The area is rich in metallic sulphide (lead, zinc and iron), with underground mines and quarries. The zone is very close to important populations and affects protected sites of special ecological value. It is also adjacent to areas dedicated to agriculture and important centres of tourist interest. It is a territory that meets the requirements to be classified as a critical area, as it is in a state of unstable physical and geochemical equilibrium, giving rise to possible risks to human health and ecosystems. A literature review was carried out according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) methodology criteria, consulting a large number of related publications. The results obtained using the Source-Pathway-Receptor model make it possible to identify the main impacts caused by the contamination sources, the main routes of contamination, as well as the transfer to the biota and the influence on adjacent agricultural soils. In this study, lead, cadmium, zinc, arsenic, copper and manganese were considered as potential toxic elements (PTEs), and data were obtained on concentrations in soil, water and air as well as in fauna and flora. Finally, once the receptors and the associated risks to the ecosystem and human health were identified, a conceptual model of the contamination was drawn up to consider a management proposal to tackle the problems associated with this area, which would also be applicable to critical mining zones.

Flamenco, trovo y cante de las minas

El mundo del trovo de la Sierra Minera de Cartagena-La Unión está íntimamente ligado al devenir de los cantes de las minas: se considera, de hecho, una de las fuentes nutricias del repertorio de letras del cante minero. En este artículo se traen a colación algunas de las más conocidas, así como otras creadas por troveros en su rol como poetas. Se recuerdan también algunas de las melodías de malagueña utilizadas en las veladas troveras, así como ciertos estilos flamencos ligados a nombres de troveros míticos como “Pedro el Morato” o “el Pajarito”. The world of the “trovo” (sudden popular poetry) of the Sierra Minera de Cartagena-La Unión (Murcia-Spain) is intimately linked to the evolution of the “cantes de las minas” (mining song): it is considered, in fact, one of the nutritional sources of the repertoire of lyrics of the “cante minero” (mining folk singing). In this article some of the best known are brought up, as well as others created by “troveros” (poets who improvise their verses) in their role as poets. Some of the malagueña's melodies used in “veladas troveras” (poetic contests) are also remembered, as well as certain flamenco styles linked to the names of mythical names such as “Pedro el Morato” or “El Pajarito”.

Arsenic zoning in a coastal area of the Mediterranean Sea as a base for management and recovery of areas contaminated by old mining activities

The mining activity that has taken place in the mining district of the Sierra Minera of Cartagena-La Unión in the SE Spain has caused a great dispersion of potentially dangerous elements (As, Cd, Cu, Pb, Zn), which requires zoning of the affected area as the basis for correct management. These elements include the arsenic (As) which is considered a carcinogen, mutagen and teratogen and it causes the public health problems. The arsenic content of the soil was chosen for a survey in which both total values and those obtained in different mobilisation trials have been taken into account. The results show that there is spatial variability in the contents of As (5000–15 mgkg−1) depending on the distance to the emitting sources of contamination. Based on these data, a classification is made into four categories of action: maximum, medium, minimum and no priority, coinciding with classes IV, III, II and I, respectively. Slope areas covered in mining tailings in the Sierra Minera, Technosols and Leptosols, as well as the channels of the temporary watercourses, with their high contents in arsenic and heavy metals, constitute the priority areas for the management of soil recovery programmes. These are areas that act as pathways from the primary sources of contamination to coastal zones of the Mar Menor lagoon and the Mediterranean Sea.

The role of Cymodocea nodosa on the dynamics of trace elements in different marine environmental compartments at the Mar Menor Lagoon (Spain)

During mining activities historically developed at Sierra Minera (Cartagena-La Unión, Spain), high amounts of trace elements were discharged to the Mar Menor coastal lagoon mainly through El Beal Wadi. The objective of this study is to establish the role played by the Cymodocea nodosa in the coastal marine dynamics of trace elements at the mouth of the wadi. To this end, the content of nine trace elements (As, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) in different marine environmental compartments (i.e. marine and coastal sediments, C. nodosa tissues collected from live seagrass and C. nodosa beach cast litter) at two different locations were determined by inductively coupled plasma atomic emission spectrometry. The results showed that the seagrass C. nodosa could mobilise part of the elements present in marine sediments and water, thereby causing their re-accumulation in the coastal sediments through the C. nodosa beach cast litter.

Arsenic(V) adsorption-desorption in agricultural and mine soils: Effects of organic matter addition and phosphate competition

High total and bioavailable concentrations of As in soils represent a potential risk for groundwater contamination and entry in the food chain. The use of organic amendments in the remediation of As-contaminated soils has been found to produce distinct effects on the solubility of As in the soil. Therefore, knowledge about As adsorption-desorption processes that govern its solubility in soil is of relevance in order to predict the behaviour of this element during these processes. In this paper, the objective was to determine As adsorption and desorption in four different soils, with and without compost addition, and also in competition with phosphate, through the determination of sorption isotherms. Batch experiments were carried out using three soils affected differently by previous mining activity of the Sierra Minera of La Unión-Cartagena (SE Spain) and an agricultural soil from Segovia province (central Spain). Adsorption was higher in the mining soils (and highest in the acidic one) than in the agricultural soils, although the latter were not affected negatively by organic matter or phosphate competition for sorption sites. The results show that As adsorption in most soils, both with and without compost, fitted better a multimolecular layer model (Freundlich), whereas As adsorption in competition with P fitted a monolayer model (Langmuir). Moreover, the use of compost and phosphate reduced the adsorption of As in the mining soils, while in the agricultural soils compost increased their low adsorption capacity. Therefore, the use of compost can be a good option to favour As immobilisation in soils of low adsorption, but knowledge of the soil composition will be crucial to predict the effects of organic amendments on As solubility in soils and its associated environmental risk.

Tolerancia y acumulación de metales pesados y As en diferentes especies de Cistus L.

In this study the tolerance of five species of Cistus on the presence of heavy metals in two polluted soils of the Sierra Minera de La Union were analysed. The results indicated that the soil 1 provoked a high toxicity in Cistus species due to its high content of heavy metals and salinity. The soil 2 contained lower concentrations of total metal that soil 1 and an acidic pH and therefore, the mineral elements were more soluble and available in the soil. The results indicated that Cistus plants could be used for the recovery of contaminated soils since these plants accumulated high concentrations of metals. However, due to their slow growth, it is necessary to design new strategies which allow their use in phytostabilization processes.

Response of Piptatherum miliaceum to co-culture with a legume species for the phytostabilisation of trace elements contaminated soils

Purpose The presence of high concentrations of trace elements (TEs) in mine soils like those in the Sierra Minera of La Union-Cartagena (SE Spain) limits the development of a vegetation cover on such sites, and pollution dispersion by water and wind erosion represents a serious risk for the surrounding ecosystems. The aim of this study was to evaluate different phytostabilisation procedures based on the co-culture of a legume (Bituminaria bituminosa) and a high-biomass (Piptatherum miliaceum) species for this type of soils.

Impact of acid mine drainages on surficial waters of an abandoned mining site.

Weathering of sulphide minerals produces a great variety of efflorescences of soluble sulphate salts. These minerals play an important role for environmental pollution, since they can be either a sink or a source for acidity and trace elements. This paper aims to characterise surface waters affected by mining activities in the Sierra Minera of Cartagena-La Union (SE, Spain). Water samples were analysed for trace metals (Zn, Cd, Pb, Cu, As and Fe), major ions (Na(+), K(+), Ca(2+) and Mg(2+)) and anions (F(-), Cl(-), NO3 (-), CO3 (2-), SO4 (2-)) concentrations and were submitted to an "evaporation-precipitation" experiment that consisted in identifying the salts resulting from the evaporation of the water aliquots sampled onsite. Mineralogy of the salts was studied using X-ray diffraction and compared with the results of calculations using VISUAL MINTEQ. The study area is heavily polluted as a result of historical mining and processing activities that has produced large amount of wastes characterised by a high trace elements content, acidic pH and containing minerals resulting from the supergene alteration of the raw materials. The mineralogical study of the efflorescences obtained from waters shows that magnesium, zinc, iron and aluminium sulphates predominate in the acid mine drainage precipitates. Minerals of the hexahydrite group have been quantified together with minerals of the rozenite group, alunogen and other phases such as coquimbite and copiapite. Calcium sulphates correspond exclusively to gypsum. In a semiarid climate, such as that of the study area, these minerals contribute to understand the response of the system to episodic rainfall events. MINTEQ model could be used for the analysis of waters affected by mining activities but simulation of evaporation gives more realistic results considering that MINTEQ does not consider soluble hydrated salts.

Geochemical characterisation of surface waters, topsoils and efflorescences in a historic metal-mining area in Spain

Mining activities generate large amounts of wastes that may contain potentially toxic elements (PTE), which, if released into the environment, may cause air, water and soil pollution long after mining operations have ceased. This paper describes the environmental relevance of efflorescences, topsoils and surface waters from the abandoned mine of Sierra Minera of Cartagena-La Union, SE Spain. The exposure of the population to arsenic and the associated risk were also assessed. A total of 10 topsoils and surface waters and 11 efflorescences affected at varying degrees by mining activities were studied. The total potentially toxic element content (As, Cd, Cu, Fe, Pb and Zn) was determined in all samples. In addition, the mineralogical composition of solid samples was determined by X-ray diffraction and some efflorescences were also analysed using a scanning electron microscopy-energy dispersive X-ray spectrometer. Finally, an arsenic-intake risk assessment was carried out, both as regards carcinogenic and non-carcinogenic effects and considering the total and the bioaccesible As content. The study area is heavily polluted as a result of historical mining and processing activities, during which time great amounts of wastes were produced, characterised by a high PTE content, acidic pH and minerals resulting from supergene alteration. The supergene mineralogical assemblages include soluble metal salts, mainly sulphates, iron hydroxysulphates and iron oxyhydroxides, all of which form ochreous precipitates. Topsoil samples showed risk values and hazard quotients higher than the reference levels, particularly for children. In the efflorescences, these values were lower but still unacceptable. The efflorescences are of significance for monitoring purposes because they are involved in cycles of retention release of hydrogen ions, sulphate and potentially toxic elements. In addition, in a semi-arid climate, such as the study area, these minerals contribute to our understanding of the response of the system to episodic rainfall events. In general, it was observed that the arsenic in collected samples represent a potential risk for human health through ingestion.

An assessment of the influence of sulfidic mine wastes on rainwater quality in a semiarid climate (SE Spain)

This study assessed the influence of the Sierra Minera de Cartagena – La Unión mining wastes on the surrounding areas, due to the sediment transport in the atmosphere. Monitoring of 15 weather stations located in the Campo de Cartagena land (SE Spain) was performed in the period December, 2004–March, 2008. A total of 920 rainfall water samples were collected and analyzed in this study. The network of weather stations covered a wide range of soil use and human activities (industrial, urban, agricultural, and mining sites). The physicochemical characterization involved determination of pH, EC, major ions, and the metals of interest in the soluble fraction of rainwater. Precipitations had an alkaline pH (7.0–7.9) and, compared to World Health Organization guidelines for drinking-water quality, samples were characterized by low EC (76–930 μS/cm), Ni (0.1–8 μg/L), Cu (3–88 μg/L), As (0.04–2 μg/L), Na+ (3–16 mg/L), K+ (0.41–30 mg/L), Ca2+ (6–51 mg/L), Mg2+ (up to 5 mg/L), Cl– (4–23 mg/L), NO3– (1–30 mg/L), and SO42− (4–35 mg/L) values. In certain locations, Zn, Cd, and Pb exceeded the guideline limits. A downward trend of H+, Zn, Cd, and Pb concentrations in total depositions was observed while the distance to the area affected by mining activities increased in the first 20 km. Rainwater quality was found to be just subtly affected by the metal-sulfide abandoned minesites, but without presenting a current threat to neither public health nor natural ecosystem. Nevertheless, greater attention should be paid in the future projections of climate change, where a significant increase in aridity may favor the atmospheric transport of pollutant particles.

Isotope geochemistry of waters affected by mining activities in Sierra Minera and Portman Bay (SE, Spain)

The objective of this work was to evaluate processes affecting waters from Portman Bay by way of stable isotopic analysis, particularly H and O stable isotopes from water and S and O from dissolved sulfates. In addition, surface waters from Sierra Minera were examined for the purpose of determining if these waters are affected by similar processes. The results obtained indicate that Portman Bay waters are meteoric, and marine infiltration only takes place in the deepest layers near the shore or if water remains stagnated in sediments with low permeability. The main source of sulfate was the oxidation of sulfides, resulting in the liberation of acid, sulfate and metals. In order to assess the mechanism responsible for sulfide oxidation, the stoichiometric isotope balance model and the general isotope balance model were tested, suggesting that the oxidation via Fe3+ was predominant in the surface, and controlled by Acidithiobacillus ferrooxidans, while at depth, sulfate reduction occurred.

Application of a plant bioassay for the evaluation of ecotoxicological risks of heavy metals in sediments affected by mining activities

PurposeThe objective of this work was to evaluate the effectiveness of a plant bioassay (Phytotoxkit®) for screening ecotoxicological risks in sediments affected by mining activities.Materials and methodsA total of 42 sediment samples affected by mining activities were studied, including 39 sediment samples from the Sierra Minera, Spain, an area affected by old extraction procedures, and three sediments from an area affected by opencast mining. These three samples were then mixed with limestone filler at 10, 20 and 30 %, providing nine stabilised samples. The total and soluble metal(loid) content (As, Cd, Cu, Fe, Pb and Zn) was determined in all samples, and the Phytotoxkit® bioassay was applied to determine the ecotoxicological effect of this procedure.Results and discussionThe stabilised material had a neutral pH and low soluble metal(loid) concentration, similar to that of samples in which a natural attenuation process had taken place because of mixing with surrounding carbonate-rich materials. An ecotoxicological survey identified the low toxicity levels of the stabilised samples.ConclusionsThe applied bioassay is a good tool for screening metal(loid) contamination in areas affected by mining activities, since it provides information on both natural and simulated attenuation processes. The mixing of sediments with limestone filler could be applied to the remediation of zones affected by mining activities, because the toxicological effect on the tested organisms in the stabilised sediments was reduced significantly and the metal(loid) content was diminished.

The electrical resistivity tomography method in the detection of shallow mining cavities. A case study on the Victoria Cave, Cartagena (SE Spain)

Former mining areas which have been under intensive mining activity raise some geotechnical concerns. The main concerns that can arise are, for example, foundation problems on buildings placed on these mining areas, and the damage to roads resulting in potholes. These are due to the collapse of the mining cavities from natural alteration processes during the course of time. In order to check its reliability, the electrical resistivity tomography (ERT) method was tried out on a selected area of La Sierra Minera, where the location and orientation of the main caves are well known. This technique was chosen because the climate of the study area is semi-arid and the cave space is occupied by air, so the electrical resistivity contrast between the cave itself and the host rock could be expected to be high. The geophysical results have shown a close correlation with the position of known caves but further have highlighted the position of new cavities previously unknown before employing the ERT method. The discovery has been corroborated by speleologists' inspection of the area. The ERT method has therefore proved to be very effective and suitable in providing sufficient subsurface information on shallow cavities.

Distribution and bioaccumulation of arsenic and antimony in Dittrichia viscosa growing in mining-affected semiarid soils in southeast Spain

Arsenic and antimony, metalloids that cause environmental and human health problems, display similar characteristics in the environment. In this work, the bioaccumulation of As and Sb in Dittrichia viscosa (L) Greuter from soils polluted by mining activities located in Sierra Minera, (SE Spain) were investigated. The aim of this study was to ascertain whether this plant species that spontaneously colonizes these contaminated soils can be used for revegetation purposes.Hydride generation-atomic fluorescence analysis showed that the total Sb content in soils was lower than that of As. Soils had a larger range of water extractable As than of water extractable Sb concentrations, and in all soils the water extractable As concentration exceeded that of Sb. In plants, the As concentrations in leaves and roots were far higher than those of Sb. D. viscosa can be considered a suitable plant for phytoremediation and revegetation since it transfers arsenic and antimony from the soil to the root but does not translocate them in large quantities to the aerial parts, which are those eaten by animals.

The use of a halophytic plant species and organic amendments for the remediation of a trace elements-contaminated soil under semi-arid conditions

The halophytic shrub Atriplex halimus L. was used in a field phytoremediation experiment in a semi-arid area highly contaminated by trace elements (As, Cd, Cu, Mn, Pb and Zn) within the Sierra Minera of La Unión-Cartagena (SE Spain). The effects of compost and pig slurry on soil conditions and plant growth were determined. The amendments (particularly compost) only slightly affected trace element concentrations in soil pore water or their availability to the plants, increased soil nutrient and organic matter levels and favoured the development of a sustainable soil microbial biomass (effects that were enhanced by the presence of A. halimus) as well as, especially for slurry, increasing A. halimus biomass and ground cover. With regard to the minimisation of trace elements concentrations in the above-ground plant parts, the effectiveness of both amendments was greatest 12–16 months after their incorporation. The findings demonstrate the potential of A. halimus, particularly in combination with an organic amendment, for the challenging task of the phytostabilisation of contaminated soils in (semi-)arid areas and suggest the need for an ecotoxicological evaluation of the remediated soils. However, the ability of A. halimus to accumulate Zn and Cd in the shoot may limit its use to moderately-contaminated sites.

Trace elements contamination in an abandoned mining site in a semiarid zone

The distribution of trace elements throughout mining areas is an important issue because abandoned tailings can be a major source of environmental pollution. The aim of this study was to identify the trace element content, hydric dispersion ways and its reception areas in selected zones of the abandoned mining district of Sierra Minera Cartagena-La Unión. The results obtained allowed to establish points affected by primary, secondary and tertiary contamination, according to their proximity to contamination sources, as a function of its chemical and mineralogical composition. Applied GIS methodology allowed visualisation and confirmation of established conceptual model.

Blood lead levels and δ-ALAD inhibition in nestlings of Eurasian Eagle Owl (Bubo bubo) to assess lead exposure associated to an abandoned mining area

In order to biomonitor lead contamination in Southeastern Spain, 218 blood samples from 28 to 30-day old Eurasian Eagle Owl chicks (Bubo bubo) born between 2003 and 2007 were analysed. In general, mean lead levels showed that chicks were exposed to background concentrations. However, mean levels in chicks born in an ancient and abandoned mining site ("Sierra Minera Cartagena-La Union") or in their surroundings (Geometric mean (GM) = 5.83 μg/dl, range 0.49-25.61 μg/dl), an area highly polluted by lead and other metals, were significantly higher (p < 0.001) than the rest of the population (GM = 1.66 μg/dl, range = Non detected-18.37 μg/dl). Because δ-ALAD activity is considered the best biomarker for lead exposure and effect in birds, the activity of this enzyme was also evaluated and correlated with lead levels in blood. In this study, low levels of blood lead inhibited δ-ALAD, even when lead concentrations were lower than the limits described by other authors in raptors. Adverse effects caused by this inhibition may occur when blood lead levels were above 15 μg/dl, although only eight chicks presented these concentrations in their blood. Sampling site also influenced enzymatic activity, since it decreased about 60% in the polluted area in relation to the rest. For all these reasons, further research regarding risk assessment for lead exposure in Eagle Owls nesting in the polluted area is advisable. Our results suggest that the Eurasian Eagle Owl can be considered a suitable sentinel animal for monitoring lead contamination and δ-ALAD activity can be used as a sensitive biomarker for lead exposure and effect in this species.

Electrical Resistivity Imaging Revealed the Spatial Properties of Mine Tailing Ponds in the Sierra Minera of Southeast Spain

Mine tailing ponds are environmental hazards because of high susceptibility to leaching and erosion by water and wind. Vegetation establishment is an effective technique to reclaim tailing ponds but requires knowledge of the spatial relationship between the structural composition and physical and chemical properties of soils. In this study we have demonstrated the use of electrical resistivity imaging (ERI), combined with soil chemical analyses, to determine the structural and chemical composition of mine tailing ponds to assess efficient measures of environmental protection. We used a Syscal R1 resistivity meter to generate two-and three-dimensional (2-D∕3-D) ERI images from El Lirio and Brunita mine tailing ponds. Soil samples were collected at [Formula: see text] intervals to a depth of [Formula: see text], and were analyzed for pH, electrical conductivity and cadmium (Cd), copper (Cu), lead (Pb) and zinc (Zn) contents. Results show that materials in the ponds can be classified into three categories: fine tailings—low ER [Formula: see text], coarse waste rock—intermediate ER [Formula: see text], and bedrock—high ER [Formula: see text]. Our interpretation of the 2-D∕3-D ERI images with respect to the historical depositions of materials in the ponds show that at El Lirio, decant water outlet was initially at the center and advanced to the east of the tailing pond as the mining activities progressed. At Brunita, the intermediate ER values on the west side of the pond marked the deposition of coarse waste rock materials released during a pond breakage in 1972. The ERI helped us image the spatial distribution of tailings and its qualitative spatial correlation with chemical properties (i.e., pH, EC, metals content). Low ER values are related to high amounts of Zn, Pb, Cu and Cd. These qualitative relationships underlie the usefulness of the combined geophysical and soil chemical approaches to improve our understanding of the properties of mine tailing ponds in the Sierra Minera (and other parts of the world).