In Situ Use of Mining Substrates for Wetland Construction: Results of a Pilot Experiment.

This paper evaluates an experimental wetland as part of a pilot soil reclamation project in a mining area. The wetland was constructed using materials of mining origin from the area; most reactive materials of acid pH were stabilised using limestone filler. The study selected macrophytes that are tolerant to potentially toxic elements (PTEs) and resistant to salinity, namely Phragmites australis, Juncus effusus, and Iris pseudacorus. These macrophytes were then placed in pots containing substrates composed of different mixtures of topsoil, peat, and mining waste (black or yellow sand). A thorough analysis of the physicochemical and mineralogical characteristics of the materials included studies of PTE mobilisation. This study emphasises the significance of the rhizosphere in directing the transfer of PTEs to the plant and the correlation between the substrate and the development of plant defence mechanisms, such as the formation of Fe-plates. Scanning electron microscopy was used to highlight these aspects and validate the results of the analytical determinations. These wetlands can be proposed as a phytoremediation strategy for areas affected by mining and maritime influence. They are easy to construct and remain stable, providing important ecosystem services such as the natural attenuation of acid mine drainage, support for vegetation development and fauna, and a clean ecosystem.

Long-term sediment records reveal over three thousand years of heavy metal inputs in the Mar Menor coastal lagoon (SE Spain).

The Mar Menor lagoon combined high biological production and environmental quality, making it an important economic engine. However, the pressure of human activities put its ecological integrity at risk, the oldest environmental impact being mining activity recorded since Roman times, about 3500 years ago, reaching its maximum intensity in the 20th century, contributing heavy metals to the lagoon sediments for almost 30 centuries. This work reviews the spatiotemporal evolution of the main heavy metals in this coastal lagoon using data from 272 surface sediment samples obtained during the last 40 years and two deep cores covering the total history of the lagoon (c. 6500 yrs BP), so as their incidence in the lagoon trophic web. The observed patterns in sedimentation, sediment characteristics and heavy metal content respond to the complex interaction, sometimes synergistic and sometimes opposing, between climatic conditions, biological production and human activities, with mining being mainly responsible for Pb, Zn and Cd inputs and port activities for Cu. High Fe/Al, Ti/Al and Zr/Al ratios identify periods of mining activity, while periods of arid climatic conditions and deforestation that increase erosion processes in the drainage basin and silt concentration in the lagoon sediments are determined by high Zr/Rb and, to a lesser extent, Zr/Al and Si/Al ratios. After the cessation of direct discharges into the lagoon in the 1950s, the recent evolution of heavy metals concentration and its spatial redistribution would be determined by hydrographic and biogeochemical processes, solubility of different elements, and coastal works in harbours and on beaches. The bioconcentration factor decreases along the trophic levels of the food web, suggesting that the lagoon ecosystem provides an important service by retaining heavy metals in the sediment, largely preventing their bioavailability, but actions involving resuspension or changes in sediment conditions would pose a risk to organisms.

Uptake of potentially toxic elements by edible plants in experimental mining Technosols: preliminary assessment.

A study was carried out to evaluate the absorption of potentially toxic elements from mining Technosols by three types of vegetable plants (broccoli (Brassica oleracea var. italica), lettuce (Lactuca sativa) and onion (Allium cepa)), the different parts of which are intended for human and farm animal consumption (leaves, roots, edible parts). The preliminary results obtained highlight the importance of the design of the mining Technosols used for agricultural purposes, obtained from soils and sediments of mining origin and amended with residues of high calcium carbonate concentrations (limestone filler and construction and demolition wastes). The experiment was carried out in a greenhouse, and the total metal(loid)s concentration (As, Pb, Cd, Cu, Fe, Mn and Zn) of the soil, rhizosphere, aqueous leachates and plant samples was monitored, the translocation and bioconcentration factors (TF and BCF, respectively) being calculated. The characterization of the soils included a mobilization study in media simulating different environmental conditions that can affect these soils and predicting the differences in behavior of each Technosol. The results obtained showed that the levels of potentially toxic elements present in the cultivated species are within the range of values mentioned in the literature when they were cultivated in soils with calcareous amendments. However, when the plants were grown in contaminated soils, the potentially toxic elements levels varied greatly according to the species, being higher in onions than in lettuce. Experiments with the use of lime filler or construction and demolition wastes for soil remediation result in crops that, in principle, do not present health risks and are similar in development to those grown on non-contaminated soil.

Assessment of risk from lead intake in mining areas: proposal of indicators.

This study discusses an estimate of the risk associated with the intake of soil contaminated by lead, based on the nature of the source, through a detailed study of the parameters that can influence the bioaccessibility of the element from soil intake. Statistical variables that are related to the solubility and bioavailability of lead are used for this purpose. This includes considering the values of pH, electrical conductivity, particle size, mineralogical composition and the bioaccessibility/bioasimilability of lead. Obtaining an algorithm, represented by different probability distributions of the parameters considered, needs a thorough knowledge of the source materials, which may allow estimating/evaluating the intake health risk provided by the concentration of the metal present. The selected materials are from sites affected by mining activities in the Region of Murcia (SE of Spain) and soils in nearby areas, using a total of 186 samples. Soil samples, once screened and homogenized, were parameterized by determining pH, electrical conductivity, granulometry, both total and water-extractable Pb content. Oral bioaccessibility tests were also performed, and a detailed mineralogical analysis by X-ray diffraction was carried out.

Assessment of the risk associated with mining-derived arsenic inputs in a lagoon system.

Southern Mediterranean lagoons are considered among the systems most vulnerable to anthropogenic activities. In its present condition, the Mar Menor lagoon in south-eastern Spain must be considered as degraded as a result of the pressures to which its shoreline is exposed. These include the transport of arsenic from nearby mining areas, linked to soluble or particulate run-off following rainfall events and flooding. This work studies the solubility and bioavailability of arsenic in the soils of watercourses that drain into the Mar Menor, using nine single chemical extractions with different reagents. The values obtained for As, as well as for Fe and Mn, throw light on the interactions of these metals with As and predict future behaviour patterns for different scenarios. The mineral composition is seen to significantly influence the mobility of the studied elements and shows the relation between the soils and materials of mining origin. It has been suggested that the sediments deposited in the in the watercourses or "ramblas" that transport these materials may act as foci of dispersion.

Inorganic arsenic causes apoptosis cell death and immunotoxicity on European sea bass (Dicentrarchus labrax).

Inorganic arsenic (As) is one of the most toxic pollutants in the water. We have studied their effects on the marine teleost European sea bass (Dicentrarchus labrax) at 2 and 10 days of 5 µM of As2O3 (sub-lethal doses) waterborne exposure. Arsenic accumulates in liver and gill tissues. The expression profile of five genes (bax, blc2, casp3, casp8 and casp9) involved in apoptosis cell death confirmed apoptotic effects in liver, slight changes in gill and no effects in skin according with the histopathology findings. Total IgM level and peroxidase activities were increased at 2 and 10 days, respectively. The bactericidal activity was decreased at 2 days after As exposure. A general decrease of cellular immune activities with significant differences in the case of respiratory burst activity was observed after 2 and 10 days of exposure. This work describes for the first time the effects of As exposure on European sea bass.

Head kidney, liver and skin histopathology and gene expression in gilthead seabream (Sparus aurata L.) exposed to highly polluted marine sediments from Portman Bay (Spain).

Biomarkers have become crucial tools in modern environmental assessment as they can help to predict magnitude of pollution. The head-kidney (HK) and liver (hematopoietic and xenobiotic metabolism organs, respectively) are the key organs in all fish toxicological studies, although the skin has received less attention in this respect. The impact of two different types of polluted sediment collected from Portman Bay (Spain) on HK, liver and skin gene expression in gilthead seabream (Sparus aurata L.) exposed for two weeks to the sediments was determined by real time-PCR. The expression levels of different antioxidant enzyme genes [superoxide dismutase (sod) glutathione reductase (gr) and catalase (cat)] and immune-related genes [interleukin -1ß (il-1b), immunoglobulin M (igm), T-Cell receptor (tcr-b), cyclooxygenase-2 (cox-2), colony-stimulating factor 1-receptor (csf-1r) and hepcidin (hep)] was analysed. Expression varied depending on both the organ and gene studied: tcr-b, csf-1r and hep genes were down-regulated in HK, as were gr, tcr-b and il-1b in liver and gr and il-1b in skin, while cox-2 was up-regulated in skin after exposure to both sediments. Concomitantly, histopathological alterations were also studied in HK, liver and skin. While no significant changes were detected in skin cells of fish reared in aquaria with polluted sediments marked changes in the general morphology of HK and liver were observed, accompanied by a substantial degree of cell death and melano-macrophage centre disorganization. The present study suggests that the biomarkers studied in gilthead seabream could be useful for assessing the impact of pollution in coastal environments.

Influence of waterborne arsenic on nutritive and potentially harmful elements in gilthead seabream (Sparus aurata).

Fish are an important source of nutrients in human nutrition. Although arsenic (As) is considered potentially carcinogenic for human being, very little is known about its toxicity in fish biology. To increase our knowledge of the effect of exposure to waterborne As on fish, gilthead seabream (Sparus aurata) were exposed to 5 µM As2O3 and the bioaccumulation of macronutrients (Ca, K, Mg, Na, P), micronutrients (Fe, Mn, Zn) and Potentially Harmful Elements (As, Cd) was determined using spectrometric techniques. All elements were determined in the muscle and liver of non-exposed fish and those exposed to As for 2, 10 or 30 days. The concentrations of K, Na, Mg, Mn and Zn (in muscle) and Fe and Mn (in liver) of control (non-exposed) fish were higher than those determined in exposed fish. Furthermore, neither As nor Cd accumulated in the edible part (muscle) of seabream and were only evident in liver after 30 days of continuous exposure to As, but both concentrations remained below legally established limits.

Importance of the oral arsenic bioaccessibility factor for characterising the risk associated with soil ingestion in a mining-influenced zone.

Arsenic is a carcinogenic metalloid and the risks of accidental ingestion should therefore be borne in mind when assessing areas with high levels of this element. In this work, the concentrations of bioaccessible As in mining-influenced soils, in SE Spain are determined. The risk posed by the accidental ingestion is studied in two soil fractions (<2mm and <250µm), taking into consideration the possible uses of the soils (residential/agricultural) and possible receptors (adults and/or children). The properties and mineralogical composition of 26 soil samples are analysed. The results showed that the use of a conservative approach to calculate the Chemical Daily Intake (CDI) based on the total concentrations of arsenic, may overestimate the risk existing in the zone, leading to problems in the management of contaminated soils. The paper emphasises the importance of considering the amount of bioaccessible As in the <250µm fraction before permitting land near temporary watercourses to be used for residential purposes, as beaches or for agriculture.

Spatial distribution and sources of trace elements in sediments affected by old mining activities.

The distribution of trace elements throughout mining areas is an important issue because abandoned tailings could be a major source of environmental pollution. In order to analyze the spatial variation of trace elements in a zone where mining activities took place and to identify pollution sources in the study area, a three-step study was carried out at a regional, at a local, and a detailed scale. In addition, a conceptual model of trace elements dispersion was established and confirmed by a geographic information system. The results obtained allowed to establish points affected by primary, secondary, and tertiary contamination, according to their proximity to contamination sources and as a function of attenuation processes which could take place in the studied area.

Symbolic use of marine shells and mineral pigments by Iberian Neandertals.

Two sites of the Neandertal-associated Middle Paleolithic of Iberia, dated to as early as approximately 50,000 years ago, yielded perforated and pigment-stained marine shells. At Cueva de los Aviones, three umbo-perforated valves of Acanthocardia and Glycymeris were found alongside lumps of yellow and red colorants, and residues preserved inside a Spondylus shell consist of a red lepidocrocite base mixed with ground, dark red-to-black fragments of hematite and pyrite. A perforated Pecten shell, painted on its external, white side with an orange mix of goethite and hematite, was abandoned after breakage at Cueva Antón, 60 km inland. Comparable early modern human-associated material from Africa and the Near East is widely accepted as evidence for body ornamentation, implying behavioral modernity. The Iberian finds show that European Neandertals were no different from coeval Africans in this regard, countering genetic/cognitive explanations for the emergence of symbolism and strengthening demographic/social ones.

Testing of the region of Murcia soils by near infrared diffuse reflectance spectroscopy and chemometrics.

A partial least squares near infrared (PLS-NIR) method has been developed for the determination of several physicochemical parameters in soils from different locations of the Region of Murcia. The method was based on the proper chemometric treatment of diffuse reflectance spectra of soil samples. Reflectance spectra were scanned from samples stored in glass vials in the NIR region between 800 and 2600 nm, averaging 36 scans per spectrum at a resolution of 8 cm(-1). Models were built using reference data of 39 samples selected from a dendrogram obtained after hierarchical cluster analysis of NIR spectra of soils and prediction parameters were established from a validation set of 109 additional samples of the same area not considered to build the model. Organic matter, CaCO(3), pH, electrical conductivity (EC), together with several trace metals as Cr, Co, Ni, Cu, Zn, As, Se, Cd and Tl, were employed as characteristic parameters of the soils under study, and found results evidenced that PLS-NIR provides a valuable tool for screening purposes providing residual predictive deviations which ranged from 0.9 to 1.5 as a function of the considered parameter.

Comparison of two derivatizing agents for the simultaneous determination of selenite and organoselenium species by gas chromatography and atomic emission detection after preconcentration using solid-phase microextraction.

Two methods for the simultaneous determination of selenite and two organoselenium compounds, dimethylselenide (DMSe) and dimethyldiselenide (DMDSe), are proposed. Both methods involve sample preconcentration by solid-phase microextraction (SPME) and capillary gas chromatography coupled to atomic emission detection (GC-AED). The main difference between the methods is the derivatizing agent used to complex the inorganic species: sodium tetraethylborate and 4,5-dichloro-1,2-phenylenediamine. The parameters affecting the derivatization and preconcentration steps, chromatographic separation as well as detection of the compounds were optimized. Direct immersion (DI) mode and a relatively long extraction time were selected for the method involving the formation of the piazselenol complex, better sensitivity being achieved for the three analytes under study. In this case, detection limits ranged between 3 and 25 ng L(-1), depending on the compound. Headspace mode (HS) and extraction times of 20 min were selected for the method involving tetraalkylborate, and detection limits of between 7.3 and 55 ng L(-1) were obtained. DMSe and Se(IV) were found in several of the water samples analyzed at concentrations of 0.07-1.0 ng mL(-1).