Iron is essential for all living things, especially marine organisms, due to its low availability in the marine environment. Iron regulation is key in all vertebrates and is controlled by hepcidin–ferroportin. To improve the knowledge of iron homeostasis in fish, an iron overload was induced in gilthead seabream (Sparus aurata), which was chosen as a study species because of its high interest in Mediterranean aquaculture. The amount of iron in different tissues was measured to determine its biodistribution and/or bioaccumulation. Since the liver is directly involved in iron metabolism, the morphological changes induced in this organ as a consequence of the iron increase were studied. The bactericidal activity of fish skin mucus was also determined, observing that it decreased in fish with high iron levels compared to control fish. In addition, to better understand iron regulation, the gene expression of hepcidin, ferroportin, transferrin, and ferritin was evaluated in the head kidney (the main hematopoietic organ in this species) and in the liver. Special interest was taken in the study of the multiple copies of the hamp2 gene present in the gilthead seabream genome. Bioinformatic analysis of the protein sequences derived from these hepcidin genes allowed us to determine the presence of one type I hepcidin and 12 type II hepcidins, all of them with antimicrobial potential. This number of mature hepcidin sequences found in gilthead seabream is the highest within Eupercaria described to date. All the results obtained indicate that the modulation of iron in seabream seems to be much more complicated than in other vertebrates, probably due to the possible involvement of the different hepcidins as mediators between iron metabolism and host immune response.

<p>In order to predict the future behaviour of technosols designed for the remediation of sites contaminated with mining waste, a pilot experiment was carried out in containers under an enclosed building.</p> <p>One-metre cubic polyvinyl chloride (PVC) containers were used and filled with soil of the different types that are abundant on the site. Four soil types were selected with different textures (sandy to silty-clay), different mineralogy and different PTE content. Soil mixtures were also prepared with limestone filler at different proportions (30, 40 and 50 %).</p> <p>These containers were subjected to a humidity and drying process, simulating the rainfall conditions that the site receives as an average annual value, in 10 successive cycles, maintaining the experience for 4 years. The drains obtained were analysed and their corresponding crystallised phases were obtained and characterised by XRD and electron microscopy. The metals determined were Fe, Cd, Cu, Pb, As and Zn.</p> <p>This experiment allows us to differentiate the behaviour of the selected soils with respect to humidity, since the untreated soils with a clayey loam texture are AMD producers, with very low pH and a high mobilisation of metals. In contrast, sandy textured soils and soils containing 30 % or more limestone filler have a pH close to 7 and small metal contents close to the limit of quantification.</p> <p>Efflorescences are more abundant in those leachates rich in Zn and Fe, being copiapite, hexahydrite, bianchite and gypsum the main soluble phases associated with these leachates.  Finally, the percolates with a higher salt load correspond to the third percolation carried out approximately nine months after the start of the experiment.</p> <p> </p>

<p>The use of phytostabilizing plants in remediation projects of areas affected by mining activities is one of the valid strategies for recovering the ecosystem.  It is often used to obtain biodiversity with the aim of restoring the environment, but the possible risk represented by the ingestion of the plants by the fauna and the consequent passage of As to the trophic chain is forgotten.</p><p>The aim of this study is to evaluate the environmental risk posed by arsenic when revegetation occurs in an area with high levels of this element. To this end, the transfer of arsenic in different plant species that grow spontaneously in an abandoned mining area (Sierra Minera de Cartagena) is analysed, as well as the contribution of these plants to the intake of mammals in the area. In order to make a comparison with the risk analysis applied to human intake, the wild boar is selected since this mammal has a digestive physiology very similar to that of humans. For this purpose, a gastric solution is prepared according to the standard operating procedure (SOP) developed by the Solubility/ Bioavailability Research Consortium (SBRC). Two phases, namely, stomach (AsA) and intestinal (AsN), are considered.</p><p>In this way, it is possible to discriminate between plant species with high, non-bioaccessible contents in the aerial part and plant species with the opposite.</p><p>For this study, 21 plant species that grow naturally in the soils of the Sierra Minera and their corresponding rhizospheres were collected.</p><p>The physical-chemical properties were obtained using the usual procedures. To determine the arsenic content, the soil samples and plant materials were digested in a microwave system and the arsenic concentration was determined using atomic fluorescence spectrometry with an automated continuous flow hydride generation system. Soils are classified into three groups: Low (group 1) (7-35 mg/kg), medium (group 2) (35-327 mg/kg) and high (group 3) (> 327 mg/kg), according to their As content. The descriptive statistical analysis of the population of plants studied shows that the range of As in the roots were from 0.31 to 150 mg/kg, while the concentrations in the leaves were lower (0.21 to 83.4 mg/kg). The possible risk of As entering the food chain through plant species is evaluated. The route of exposure considered is the oral ingestion, calculating the contribution of the plant to the daily dose based on the concentration of arsenic (total and bioaccessible) in the leaves of the analyzed plants</p><p>In general, the bioaccessible fraction by intake is low, although it is higher in the areas most influenced by primary and secondary pollution sources. The availability of bioaccessible As in the leaves of the plants is highly influenced by the mineralogical composition of the soils on which it grows.</p>

<p>Abandoned mining areas are a clear example of the failure of the different administrations to solve the environmental problems they pose, due to the lack of unified legislation and management and the activity of geological processes. It is therefore important to have a clear vision of the environmental problems that occur and the possible actions to solve them.</p><p>The Sierra Minera (Cartagena, SE Spain) presents situations of risk of soil contamination that coincide with those areas with the highest content of soluble and/or bioavailable PTEs (potentially toxic elements) for the health of people and ecosystems, especially in those sites of concentration of polluting sources (flotation mud pools and heterogeneous dumps), with a very fine texture. These areas present numerous points with an urgent need for risk management due to the possible mobilization in different environmental conditions of arsenic and heavy metals, with a control of both soluble and particulate dispersion. Special interest presents arsenic mobilisation in an acidic environment together with reducing situations and the presence of organic matter (waterlogged marshes).</p><p>The recovery technologies to be applied in the Sierra Minera require a great diversity of techniques, depending on the uses of the land. In the contamination foci it is necessary to carry out actions with containment, stabilisation and solidification technologies in situ. Phytoremediation techniques, given the high content of PTEs present, may not all be appropriate in the different situations. Phytoextraction should only be applied in areas with low concentrations of PTEs, and by plants that do not transfer to their aerial part, to avoid the risk of ingestion by animals. Phytostabilisation will be important in combined techniques, in order to ensure that contaminants are not transferred to the environment, and by non-accumulating plants in the aerial part. Wetlands can be a complementary solution to the projects developed at the heading of wadis, providing a double purpose, natural attenuation of contamination and lamination of turbulence and floods.</p><p>A generic overview is given of the most important regeneration approaches from a geochemical point of view, without going into structural solutions, selecting those technologies that are most suitable to the environment in which they are located, trying to imitate natural attenuation processes and using eco-efficient and sustainable materials.</p>

<p>Arsenic is a Potentially Toxic Element (PTE), which is present in the soils/sediments of abandoned mining areas, such as the Sierra Minera de Cartagena La-Unión and the mining site of Mazarron (SE Spain) and its areas of influence. In order to assess the risk to human health and the ecosystem, it is necessary to know the nature of the materials that contain this PTE, their alterability and their speciation.</p><p>On the one hand, there is a geogenic relationship between this element and materials rich in phyllosilicates and Fe minerals. These minerals can constitute primary mineralisation such as sulphide veins (pyrite, arsenopyrite, etc.) or secondary mineralisation such as haematite, goethite, siderite, jarosite, etc., and can even be found as a mineral phase forming various arsenates. Another very important aspect is the climatology of the area, which coincides with a semi-arid Mediterranean climate with infrequent but very heavy rainfall.</p><p>The As concentration range in the studied areas is very wide (5000 -70 mg.Kg-<sup>1</sup>), with an average value of 150 mg.Kg<sup>-1</sup>, being As (V) the predominant species. Only soils located in wetland areas with permanent waterlogging can show significant concentrations of As(III). </p><p>The As content in surface waters, such as runoff water, is low, only reaching significant values (>2 mg.L<sup>-1</sup>) when these waters are acid mine drainage and have pH values <2, coinciding in these cases with the presence of reduced As forms.</p><p>Particulate As is associated both with Fe oxides and hydroxides, through surface adsorption processes on Fe(OH)<sub>3</sub> particles, and with carbonates, through precipitation reactions as calcium arsenate. These reactions are evident in some places such as wadis that transport particulate and dissolved materials from areas affected by mining, and mainly take place both in the riverbed and in flooding areas when rainfall events occur.</p><p>For an appropriate understanding of the main processes involved, a detailed scheme is given. It should be noted that the dynamics of this PTE is of a particular interest in the zones studied due to the proximity of urban sites.</p><p> </p>