Phosphorus (P) is an essential element for biomass growth and is a major component of fertilizers applied to crops. Excessive application of P to agricultural soils may lead to P-leaching and increasing concentrations of this element in aqueous system. This may cause the degradation of water quality through eutrophication processes. Arsenic on the other hand is a very toxic element that may be present at high concentrations in soil and aqueous environments due to weathering processes or to anthropogenic sources as mining and agricultural activities.To design adequate remediation techniques for the mitigation of phosphorus (P) and arsenic (As) pollution it is key to understand the geochemical processes and the environmental drivers controlling their availability. In soil systems, the mobility of P and As is controlled by their interaction with soil minerals. Among these minerals, iron and aluminum oxyhydroxides are known to form especially strong surface complexes with both components, limiting its availability to the environment. On the other hand, the presence of soil organic matter may compete with these pollutants for the mineral surface sites, increasing the contamination risk in the soil system.In the present work, we have studied at laboratory scale the As and P adsorption process on iron mineral surfaces under variable conditions. This includes changes of pH, redox conditions, presence of major ions (i.e. calcium, sulfate) or other trace elements (i.e. chromate, copper), and the presence of natural organic matter (i.e. humic substances or simple organic acids). Also, surface complexation models were applied in order to simulate and predict the behavior of such systems. The obtained results reveal that the presence of organic matter or other anionic species are important factors capable of increasing the mobility of P and As contaminants, whereas changing the redox potential or the carbon content in the organo-mineral aggregates has little effect.The information obtained, allowed to design remediation solutions that could be applied at field scale. The soil characteristics and the biogeochemical processes can be improved by the application of amendments based on circular economy aspects, i.e. compost, biochar, Technosols. We have studied the effectiveness of the superficial application of these materials to immobilize both P and As, varying the main environmental drivers affecting to the sorption or desorption processes.

Echinacea purpurea is traditionally used in the treatment of inflammatory diseases. Therefore, we investigated the anti-inflammatory capacity of E. purpurea dichloromethanolic (DE) and ethanolic extracts obtained from flowers and roots (R). To identify the class of compounds responsible for the strongest bioactivity, the extracts were fractionated into phenol/carboxylic acid (F1) and alkylamide fraction (F2). The chemical fingerprint of bioactive compounds in the fractions was evaluated by LC-HRMS. E. purpurea extracts and fractions significantly reduced pro-inflammatory cytokines (interleukin 6 and/or tumor necrosis factor) and reactive oxygen and nitrogen species (ROS/RNS) production by lipopolysaccharide-stimulated primary human monocyte-derived macrophages. Dichloromethanolic extract obtained from roots (DE-R) demonstrated the strongest anti-inflammatory activity. Moreover, fractions exhibited greater anti-inflammatory activity than whole extract. Indeed, alkylamides must be the main compounds responsible for the anti-inflammatory activity of extracts; thus, the fractions presenting high content of these compounds presented greater bioactivity. It was demonstrated that alkylamides exert their anti-inflammatory activity through the downregulation of the phosphorylation of p38, ERK 1/2, STAT 3, and/or NF-κB signaling pathways, and/or downregulation of cyclooxygenase 2 expression. E. purpurea extracts and fractions, mainly DE-R-F2, are promising and powerful plant-based anti-inflammatory formulations that can be further used as a basis for the treatment of inflammatory diseases.

Aeolian deposition in coastal system can modify pedogenic processes or provide parent material for new pedogenesis cycles. In Galicia region (NW Spain), as in other regions of the world, the pedogenic processes associated with aeolian deposits under coastal conditions are little know. These processes are also conditioned by the development time from the formation of the sedimentary deposits, which in the case of the Galician coast is highly variable. The main objective was to identify the effect of aeolian deposits on coastal soils, through the characterization and classification of several soil profiles, and the identification of the main pedogenic process that contributed to their formation or modification. The studied soils presented one and two pedogenic cycles as well as in each one different level of pedogenic evolution. The soils with one pedogenic cycle were Endoleptic Umbrisol (Loamic, Hyperdystric, Hyperhumic, Pachic) from Xuxurantes and Haplic Umbrisol (Arenic, Humic, Pachic) from Cabo Vilano. The soils with two cycles were found in Muxia (Aeolic Calcaric Arenosol (Ochric-Novic) over Haplic Phaeozems (Endoloamic)) and Cementerio de los Ingleses (Albic Umbric Podzol (Pantoarenic)). This last type of soil constituted one more step in the evolution of aeolian deposits (first cycle of pedogenesis in the Muxia profile). Thus, changes in the pedogenesis processes and mechanisms were conditioned by the presence of a superficial aeolian deposition as well as the proximity to the coast and determine a chronosequence of the processes in the aeolian sediments.

The São Domingos mine is within the Iberian Pyrite Belt, a mining district with large concentrations of polymetallic massive sulfide deposits. Mine waste heaps are considered extreme environments, since they contain high total concentrations of potentially hazardous elements (PHE), which contribute to inhibiting the development of most plants. Autochthonous plant species, such as Cistus salviifolius L., are able to grow naturally in this degraded environment, and may contribute to minimizing the negative chemical impacts and improving the landscape quality. However, the environmental rehabilitation processes associated with the development of these plants (phytostabilization) are very slow, so the use of materials/wastes to improve some physicochemical properties of the matrix is necessary in order to speed up the process. This work studied the effectiveness of the phytostabilization with C. salviifolius of gossan mine wastes from the mine of São Domingos amended with organic and inorganic wastes in order to construct Technosols. The mine wastes have an acid pH (≈3.5), high total concentrations of PHE and low concentrations of organic C and available nutrients. The best vegetative development occurred without visible signs of toxicity in the Technosols containing a mixture of agriculture residues. These treatments allowed the improvement of the soil-plant system providing a better plant cover and improved several chemical properties of mine wastes, helping to speed up the environmental rehabilitation.

Inflammatory diseases are the focus of several clinical studies, due to limitations and serious side effects of available therapies. Plant-based drugs (e.g., salicylic acid, morphine) have become landmarks in the pharmaceutical field. Therefore, we investigated the immunomodulatory effects of flowers, leaves, and roots from Echinacea purpurea. Ethanolic (EE) and dichloromethanolic extracts (DE) were obtained using the Accelerated Solvent Extractor and aqueous extracts (AE) were prepared under stirring. Their chemical fingerprint was evaluated by liquid chromatography–high resolution mass spectrometry (LC-HRMS). The pro- and anti-inflammatory effects, as well as the reduction in intracellular reactive oxygen and nitrogen species (ROS/RNS), of the different extracts were evaluated using non-stimulated and lipopolysaccharide-stimulated macrophages. Interestingly, AE were able to stimulate macrophages to produce pro-inflammatory cytokines (tumor necrosis factor -TNF-α, interleukin -IL-1β, and IL-6), and to generate ROS/RNS. Conversely, under an inflammatory scenario, all extracts reduced the amount of pro-inflammatory mediators. DE, alkylamides-enriched extracts, showed the strongest anti-inflammatory activity. Moreover, E. purpurea extracts demonstrated generally a more robust anti-inflammatory activity than clinically used anti-inflammatory drugs (dexamethasone, diclofenac, salicylic acid, and celecoxib). Therefore, E. purpurea extracts may be used to develop new effective therapeutic formulations for disorders in which the immune system is either overactive or impaired.

Soil and water characteristics and biogeochemical processes can be improved by the application of an integrated technology based on circular economy: designed Technosol. The evaluation of the effectiveness of the superficial application of a designed Technosol, with andic and eutrophic properties, on the rehabilitation of sulfide tailings of a uranium mine (Fé mining area, Spain) was the aim of this study. After 20 months of the Technosol application, the tailing rehabilitation status (Rehabilitated tailing) was compared to a non-rehabilitated tailing (Tailing). To assess the rehabilitation of these systems, several properties were analyzed: chemical characteristics of the materials and their leachates, soil enzymatic activities (dehydrogenase, β-glucosidase, acid phosphatase and urease), basal respiration and several plant endpoints from direct and indirect bioassays and pot experiment using Lolium perennse L. and Trifolium pratense L.. Potentially toxic concentrations of Co, Mn and Ni were identified in both available fraction and leachates, pointing out the serious environmental risk posed by the tailing. The improvement of overall physicochemical properties in the rehabilitated tailing materials (e.g., decrease of the hazardous element concentrations in leachates and available fraction, and improvement of the fertility and structure) allowed a quick plant cover with pasture species and provided a suitable habitat for active microbial community (evaluated by increasing dehydrogenase activity and basal respiration). This improvement in the rehabilitated tailing contributed to a significant decrease in the ecotoxicological risk and the spread of hazardous elements. The field application of this specific Technosol was a promising and lasting solution for rehabilitation of this type of tailings.

Acid mine drainage represents an extreme environment with high concentrations of potentially toxic elements and low pH values. These aquatic habitats are characterised by harsh conditions for biota, being dominated by acidophilic organisms. The study site, São Domingos mine, located in one of the largest metallogenetic provinces in the world, the Iberian Pyrite Belt, was closed without preventive measures. To identify the algae species and understand the relationships with abiotic parameters of the ecosystem, water and biological material were collected and analysed. Digital terrain models were obtained with an unmanned aerial vehicle for geomorphological and hydrologic characterisation of the mine degraded landscape. The results show two types of algal colours that seem to represent different degrees of photosynthetic activity. Optical and scanning electron microscopy revealed 14 taxa at the genus level, divided into eight classes. The genus Mougeotia is the most abundant multicellular algae. With respect to unicellular algae, diatoms are ubiquitous and abundant. Abiotic analyses expose typical features of acid mine drainage and support an inverse relationship between chemical contamination and biological diversity. Factorial correspondence analysis indicates three groups of attributes and samples by their relationship with specific toxic elements. This analysis also suggests a close association between Spirogyra and Pb, together composing a structurally simple ecosystem. The highest contamination in the river system is related to the hydrologic patterns obtained from photogrammetric products, such as the digital surface model and flow map accumulation, indicating the input of leachates from the section having the finest sulfide-rich wastes. Information about the algae community and their association with flow patterns of toxic elements is a relevant tool from a biomonitoring perspective.

Some autochthones plant species with aromatic and medicinal properties are able to naturally colonize contaminated soils from mining areas from Iberian Pyrite Belt contributing to their rehabilitation. A study was carried out in order to characterize and valorise an autochthones species, which has adequate ecophysiological behaviours for phytostabilization of mining areas, as new sources of bioactive substances. The main aims of this study were to: i) characterise the phytochemical profile of the bioextracts from shoots of L. pedunculata growing in soils from São Domingos mining area and a control area; and ii) evaluate the influence of potentially hazardous elements (PHEs) accumulated in the shoots on the quality of the bioextracts. Composite samples of soils, developed on mine wastes and/or host rocks, as well as C Lavandula pedunculata shoots were collected in São Domingos mine (Iberian pyrite Belt, SE of Portugal) and in a reference area with non-contaminated soils and the same climatic conditions. Classical characterisation of soils and total concentrations of potentially hazardous elements in soils and plant shoots were determined. The bioextracts from Lavandula pedunculata shoots were obtained by an accelerated solvent extractor, and the compounds were analysed by GC-MS. Extracts were extracted with hexane and major components were quantified. The total concentrations of some potentially hazardous elements (e.g. As, Cu, Pb and Zn) were higher in soils from São Domingos than in reference area. However, soils from São Domingos are considered as contaminated with As, Cu, Pb and Sb for agriculture and residential/parkland uses. Concentrations of the PHEs (excepted Cr and Mn) in the shoots collected in São Domingos mine were higher than in the non-contaminated area In the L. pedunculata extracts, obtained in the single extraction with hexane, were identified 34 compounds accounting between 79 and 89 % of the total identified compounds. Camphor was the major component in all extracts but Fenchone, eucalyptol, verbenone, bornyl acetate, borneol and linalool oxide cis also showed considerable amounts. All these compounds present economic interest. Some variation was obtained in the qualitative composition of the L. pedunculata extracts but, in general, it was not clear the differentiation between populations and, consequently, soil contamination level and concentrations of the potentially hazardous elements in shoots. Environmental rehabilitation of mining areas from Iberian Pyrite Belt with this species can provide economic valorisation by the exploration of this plant-based product for fragrance and pharmaceutical industries. Acknowledgment: This research was supported by Portuguese funds, through Fundação para a Ciência e Tecnologia within the scope of the project UID/AGR/04129/202, and Xunta de Galicia (GRC2014/003).

The uranium mineralization from Fé mining area (Spain) contains sulfides, resulting mine wastes generators of acid mine drainage rich in potentially hazardous elements (PHE). The improvement of the physicochemical characteristics and biogeochemical processes of sulfide mine tailings as well as their socioeconomic valorisation can be achieved by the application of a green technology based on circular economy: Technosol. The efficiency of the application of a superficial layer of a designed Technosol with specific properties to the rehabilitation of the sulfide tailings from Fé mining area was tested. Also, the risk assessment of the land recovery by this technology to pasture was evaluated through a microcosm experiment. After 20 months of the Technosol application in the field, composite samples of Technosol, recovered tailing (bottom of the Technosol) and tailings without recuperation (control tailing) were collected. These samples were used for microcosm assay and characterized for pH, electric conductivity, fertility, PHEs concentration in total fraction and available fraction extracted with rhizosphere-based method. The substrate effect on development of Lollium perenne and Trifolium pratense (visual signs of phytotoxity, percentage of plant cover and dry shoots biomass) and multielemental composition in their of shoots was evaluated in microcosm assay under greenhouse conditions. Mine wastes from control tailing had pH ≈4 and high total concentrations of several PHEs (g/kg; Al: 46.2; As, Co and Pb: 0.02-0.03; Cu: 0.04; Fe: 63.2 Mn: 1.3; Ni and Zn: 0.1-0.2). Potentially toxic concentrations of Co, Mn and Ni were identified in the available fraction pointing out the serious environmental risk posed by the control tailing. These chemical characteristics together lack of structure iin mine wastes from control tailing contributed to total inhibition of Trifolium germination and a significant diminution of Lollium growth. Both species growing in Technosol and recovered tailing produced significant plant cover and quite similar amounts of shoot biomass. The improvement of the overall physicochemical properties in the recovered tailing materials (e.g. the decrease of the hazardous element concentrations in available fraction, and the improvement of the fertility and structure) allowed a quick and secure plant cover with pasture species. The results evidenced the efficiency of the designed Technosol in the sulfide mine tailing rehabilitation and potential land recovery to pastures. The authors thank ENUSA for technical cooperation and providing the study area and soil samples.

Soil organic carbon (SOC) stocks and their geographical distribution in peninsular Spain were estimated from a georeferenced database consisting of 12,724 surface samples (0-30 cm) and 3607 subsurface samples (30-50 cm), covering different climate, land use, elevation, parent material, soil type and soil pH. SOC density showed a high heterogeneity, with the lowest values in arid regions, where the average in topsoil ranged between 20 and 60 t C ha(-1), under woody crops and forest respectively. Carbon stocks gradually increases as precipitation increases, and its variability is also dependent of other factors, fundamentally the presence/ab- sence of active lime or active Al. In semi-arid zones, calcaric soils (pH approximate to 8.3) have higher contents of SOC than neutral to weakly acidic soils from siliceous materials. However, in humid regions, calcareous materials have undergo total or partial decarbonatation in the upper layer (pH < 4.0-7.5) and SOC stocks are markedly lower than in other materials. In forest soils it seems that a steady state (around 100-120 t C ha(-1)) (0-30 cm) has been reached in a wide range of precipitation, between 900 and 1700 mm; most of this carbon (about 80%) is labile-C. Soils from granitic rocks are acidic (pH 4.5-5.5) (Al buffering) and the mean SOC stock in the indicated precipitation range is between 170 and 200 t ha(-1) (it is estimated that approximately 60% is stabilized as metal-C or mineral-C complexes). The highest values (190-240 t ha(-1)) are recorded in acidic soils derived from mafic rocks, which in these regions usually develop andic properties (around 73% is involved in stable metal-C or mineral C complexes). Finally, the SOC stored in neutral soils from serpentinized ultramafic rocks (without excess Ca or Al) is similar to that of the decarbonated soils derived from calcareous materials. In all regions, forest soils are a much more important SOC sink than live forest biomass (2-4 times higher in the upper 30 cm and 3-6 times greater in the upper 50 cm). Random Forest regression was used as modeling tool and digital mapping. Mean annual precipitation was estimated to be the most important predictor variable, followed by land use, lithology/soil type and soil pH. Model performance was calibrated by the internal RF validation and through cross-validation, and the results were similar. In topsoil, the mean error, root mean square error and R-2 were - 0.007% C, 1.48% C and 0.61, respectively. In the subsurface layer these indices were - 0.020, 1.07 and 0.37, respectively. SOC stock for peninsular Spain was estimated at 3.33 Pg in the upper (0-30 cm) layer, and 0.85 Pg in the subsurface (30-50 cm) layer. Total SOC stock for 0-50 cm was 4.19 Pg, with a 95% confidence interval ranging between 3.33 and 5.03 Pg.

Mining activity leads to several environmental impacts. After the closure, the realization of a holistic evaluation of the main ecosystem components and their environmental risks is essential in order to define and manage a sustainable rehabilitation program specific to the current environmental situation. The objective of this work was to evaluate the chemical quality of the soils and runoff waters of the uranium mine, Fe mine (Saelices el Chico, Spain), in order to establish a diagnosis of the existing environmental problems and potential recovery actions to apply. Soils located within the mining area and natural soils from adjacent areas were sampled, classified according to the World Reference Base and analysed for their physico-chemical properties. Moreover, runoff water samples were collected for chemical and thermodynamic evaluation as well as, in the dry period, salt efflorescences from surface materials for chemical and mineralogical analysis. The natural soils (classified as Lithic, Haplic and Skeletic Leptosols, Leptic and Haplic Cambisols, Plinthic Acrisols, and Haplic and Gleyic Fluvisols) have low fertility (evaluated by concentration of nutrients and organic matter) and a strong erosive tendency which, together with the climatic conditions of the area, lead to a poor vegetation cover development. These soils are very incipient and are only located in areas where there is a permanent vegetation cover. Most of the mine soils are developed on different mixtures of host rock and sulfide-rich wastes, being classified as Sulfidic or Salic Spolic Technosols, depending on their specific properties and/or conditions. These mixtures of materials diminish the negative effect of the mine wastes, since the total concentrations of potentially toxic elements are similar (except for Pb) between mine and natural soils. However, these mine soils present a high environmental risk due to the generation of leachates with hyper-acid (pH approximate to 2.8), hyper-oxidant (Eh approximate to 759 mV) and hyper-conductor (EC approximate to 12.8 dS m(-1)) characteristics and with potentially high toxic elements (e.g. Al, Fe and Mn) and sulfates (22.9-33.9 g L-1). In the dry period, the ascension of the soil solution rich in elements contributes to the formation of evaporitic salts on the materials which were mainly identified as Al and Mg sulfates (epsomite and halotrichite). These solid phases are only temporary sinks of sulfate and metals, since they are re-dissolved with rain, releasing the elements to the environment. Moreover, the low fertility and cation exchange capacity, high acidity, stoniness and salinity of the mine soils limit the natural colonization and vegetative development. Considering the environmental risk and characteristics/conditions of the mine soils, the recovery process of the Fe mine should focus, mainly, on the sulfide oxidation minimization and fertility improvement in order to promote the establishment of a biodiverse plant cover as well as pedogenetic and biogeochemical processes.

The most fundamental processes determining the properties of a soil involve the exchange of protons and electrons at a specific time over its evolutionary trend. This justifies the use of the Eh-pH diagram (known as Pourbaix diagram) as a framework for defining soil biogeochemical trends, as proposed by Chesworth. Both geogenic and biogenic material undergo modifications (i.e., mineral weathering and breakdown of organic molecules, respectively) with (i) predominance of hydrolytic and/or redox reactions, and (ii) decrease in size and reactivity. Oxidation of organic matter generates a flux of electrons that tend to be neutralized by the oxidants present in the system, and a flux of protons that contribute to the acidification of the weathering system and associated pedogenesis. In turn, through mineral weathering, alkalinity is released and soil pH is buffered. Based on the amount of rainfall and drainage conditions under which a soil evolves, the weathering of most parent materials can follow different evolutionary pathways: (i) the acid trend, (ii) the alkaline trend, and (iii) the reduced trend, with (iv) circum-neutral soils being those that are either at incipient stages of development under an acidifying trend or in poorly leached environments. Mineral transformation (i.e., formation of vermiculite from mica) and neoformation (i.e., through allitization, mono-siallitization or bi-siallitization) are common is most soils, with trends in mineral neoformation being influenced by solution Si/Al ratio, pH, activity of alkaline earth and alkali metal ions, and residence time of the soil solution. The balance between cations released and protons produced controls the CEC and soil reaction, which in turn, (i) establishes the biogeochemical trend that the soil evolves toward, and (ii) controls the thermodynamic stability of primary minerals and the composition of neoformed minerals. Under very specific conditions in the acid, reduced, and alkaline evolutionary pathways, there is no mineral neoformation (the E horizons of Podzols, Planosols, and solodized Solods, respectively) because all minerals are unstable, favoring the dissolution of Al and Si, and hindering the neoformation of silicates. In this paper, based on the framework provided by Chesworth, we use the Pourbaix diagram to describe the genesis and biogeochemical conditions of the different Reference Soil Groups of the World Reference Base for Soil Resources.

espanolLa actividad minera contribuye a diferentes impactos ambientales. Tras el cierre es esencial una evaluacion holistica del estado de los principales componentes del ecosistema y de sus riesgos medioambientales, a modo de establecer y gestionar un programa de rehabilitacion sostenible y especifico a la situacion ambiental existente. El objetivo de este trabajo fue evaluar la calidad quimica de los suelos y aguas de escorrentia de la mina de uranio, mina Fe (Saelices el Chico, Espana), con el fin de obtener un diagnostico de la problematica ambiental existente y de las potenciales intervenciones de recuperacion a aplicar. Los suelos localizados dentro del area minera y los suelos naturales de la zona adyacente fueron muestreados, analizados fisicoquimicamente y clasificados segun la World Reference Base. Ademas, fueron recogidas muestras de aguas de escorrentia de las escombreras, para evaluacion quimica y termodinamica, asi como, en el periodo seco, eflorescencias de sales de la superficie de los materiales para analisis quimica y mineralogica. Los suelos naturales (clasificados como Leptosoles liticos, haplicos y esqueletales, Cambisoles lepticos y haplicos, Acrisoles plinticos y Fluvisoles haplicos y gleicos) presentan baja fertilidad (evaluada por la concentracion de nutrientes y materia organica) y una fuerte tendencia erosiva lo que, junto con las condiciones climaticas de la zona, conllevan a un escaso desarrollo de la cobertura vegetal. Asimismo, estos suelos solo se mantienen, de forma muy incipiente, en las areas donde existe una cobertura vegetal permanente. La mayoria de los suelos de mina estan desarrollados sobre diferentes mezclas de material de partida y residuos de mina ricos en sulfuros, clasificandose como Tecnosoles espolicos, sulfuricos o salicos, dependiendo de sus propiedades y/o condiciones especificas. Estas mezclas de materiales disminuyen el efecto negativo de los materiales de escombrera, ya que las concentraciones totales de los elementos potencialmente toxicos son similares (excepto para el Pb) a las determinadas en los suelos naturales. Sin embargo, estos suelos tienen elevado riesgo ambiental debido a la generacion de drenajes hiperacidos (pH ≈ 2,8), hiperoxidantes (Eh ≈ 759 mV), hiperconductoras (CE ≈ 12,8 dS m-1) con altos contenidos en elementos potencialmente toxicos (ej. Al, Fe y Mn) y sulfatos (22,9-33,9 g L-1). En el periodo seco, la ascension por capilaridad de este drenaje contribuye a la formacion de sales evaporiticas sobre los materiales las cuales fueron identificadas, principalmente, como sulfatos de Al y Mg (epsomita y halotricita). Estas fases solidas son unicamente sumideros temporales de sulfato y metales, pues se redisuelven con las lluvias liberando nuevamente los elementos al medio. Ademas, la baja fertilidad y capacidad de cambio, acidez, pedregosidad y salinidad de los suelos de mina limitan la colonizacion natural y el desarrollo vegetativo. Teniendo en cuenta el riego ambiental y las caracteristicas/condicionantes de los suelos de mina, el proceso de recuperacion de la mina Fe debe enfocarse, principalmente, en la minimizacion de la oxidacion de los sulfuros y mejora de la fertilidad para, consecuentemente, promover el establecimiento de una cobertura vegetal biodiversa y los procesos de edafogenesis y biogeoquimicos. EnglishMining activity leads to several environmental impacts. After the closure, the realization of a holistic evaluation of the main ecosystem components and their environmental risks is essential in order to define and manage a sustainable rehabilitation program specific to the current environmental situation. The objective of this work was to evaluate the chemical quality of the soils and runoff waters of the uranium mine, Fe mine (Saelices el Chico, Spain), in order to establish a diagnosis of the existing environmental problems and potential recovery actions to apply. Soils located within the mining area and natural soils from adjacent areas were sampled, classified according to the World Reference Base and analysed for their physico-chemical properties. Moreover, runoff water samples were collected for chemical and thermodynamic evaluation as well as, in the dry period, salt efflorescences from surface materials for chemical and mineralogical analysis. The natural soils (classified as Lithic, Haplic and Skeletic Leptosols, Leptic and Haplic Cambisols, Plinthic Acrisols, and Haplic and Gleyic Fluvisols) have low fertility (evaluated by concentration of nutrients and organic matter) and a strong erosive tendency which, together with the climatic conditions of the area, lead to a poor vegetation cover development. These soils are very incipient and are only located in areas where there is a permanent vegetation cover. Most of the mine soils are developed on different mixtures of host rock and sulfide-rich wastes, being classified as Sulfidic or Salic Spolic Technosols, depending on their specific properties and/or conditions. These mixtures of materials diminish the negative effect of the mine wastes, since the total concentrations of potentially toxic elements are similar (except for Pb) between mine and natural soils. However, these mine soils present a high environmental risk due to the generation of leachates with hyper-acid (pH ≈ 2.8), hyper-oxidant (Eh ≈ 759 mV) and hyper-conductor (EC ≈ 12.8 dS m-1) characteristics and with potentially high toxic elements (e.g. Al, Fe and Mn) and sulfates (22.9-33.9 g L-1). In the dry period, the ascension of the soil solution rich in elements contributes to the formation of evaporitic salts on the materials which were mainly identified as Al and Mg sulfates (epsomite and halotrichite). These solid phases are only temporary sinks of sulfate and metals, since they are re-dissolved with rain, releasing the elements to the environment. Moreover, the low fertility and cation exchange capacity, high acidity, stoniness and salinity of the mine soils limit the natural colonization and vegetative development. Considering the environmental risk and characteristics/conditions of the mine soils, the recovery process of the Fe mine should focus, mainly, on the sulfide oxidation minimization and fertility improvement in order to promote the establishment of a biodiverse plant cover as well as pedogenetic and biogeochemical processes.

Mining activity leads to several environmental impacts. After the closure, the realization of a holistic evaluation of the main ecosystem components and their environmental risks is essential in order to define and manage a sustainable rehabilitation program specific to the current environmental situation. The objective of this work was to evaluate the chemical quality of the soils and runoff waters of the uranium mine, Fe mine (Saelices el Chico, Spain), in order to establish a diagnosis of the existing environmental problems and potential recovery actions to apply. Soils located within the mining area and natural soils from adjacent areas were sampled, classified according to the World Reference Base and analysed for their physico-chemical properties. Moreover, runoff water samples were collected for chemical and thermodynamic evaluation as well as, in the dry period, salt efflorescences from surface materials for chemical and mineralogical analysis. The natural soils (classified as Lithic, Haplic and Skeletic Leptosols, Leptic and Haplic Cambisols, Plinthic Acrisols, and Haplic and Gleyic Fluvisols) have low fertility (evaluated by concentration of nutrients and organic matter) and a strong erosive tendency which, together with the climatic conditions of the area, lead to a poor vegetation cover development. These soils are very incipient and are only located in areas where there is a permanent vegetation cover. Most of the mine soils are developed on different mixtures of host rock and sulfide-rich wastes, being classified as Sulfidic or Salic Spolic Technosols, depending on their specific properties and/or conditions. These mixtures of materials diminish the negative effect of the mine wastes, since the total concentrations of potentially toxic elements are similar (except for Pb) between mine and natural soils. However, these mine soils present a high environmental risk due to the generation of leachates with hyper-acid (pH ≈ 2.8), hyper-oxidant (Eh ≈ 759 mV) and hyper-conductor (EC ≈ 12.8 dS m-1) characteristics and with potentially high toxic elements (e.g. Al, Fe and Mn) and sulfates (22.9-33.9 g L-1). In the dry period, the ascension of the soil solution rich in elements contributes to the formation of evaporitic salts on the materials which were mainly identified as Al and Mg sulfates (epsomite and halotrichite). These solid phases are only temporary sinks of sulfate and metals, since they are re-dissolved with rain, releasing the elements to the environment. Moreover, the low fertility and cation exchange capacity, high acidity, stoniness and salinity of the mine soils limit the natural colonization and vegetative development. Considering the environmental risk and characteristics/conditions of the mine soils, the recovery process of the Fe mine should focus, mainly, on the sulfide oxidation minimization and fertility improvement in order to promote the establishment of a biodiverse plant cover as well as pedogenetic and biogeochemical processes.

In order to restore the plant cover, improve ecosystem services and decrease the environmental risk of two mine wastes (gossan and sulfide-rich wastes), an integrated biotechnology was tested at long-term and greenhouse conditions. This integrated biotechnology involves the natural isolation of sulfide-rich wastes through an alkaline barrier, covered by designed Technosols (both of them derived from mining and agro-industrial wastes) and a plant cover with Lavandula pedunculata and Cistus ladanifer. Technosols allowed significant germination (L. pendunculata: 16-18%; C. ladanifer: 5-11%) and biomass production of both species (g FW/pot; Roots: 16.3-30.9, Shoots: 41.2-76.4 depending on species and Technosol). In the control was reached the lowest germination (<3%) and seedlings died after 40 days, so the improvement of the chemical characteristics of the surface layer, i.e. the implementation of the designed Technosols, is essential to ensure good vegetative development. No visual symptoms of nutritional deficiency and phytotoxicity neither element concentrations above hazardous levels for domestic animals intake were observed in those plants species. The alkaline barrier's components stabilise the sulfide-rich wastes by decreasing the oxidation and capillary rise of acid solutions that are rich in metals/metalloids. The limestone gravel showed, in some places, a thin layer of salts from alunite-jarosite group and metal-oxyhydroxides. As an outcome, the biotechnology was efficient and sustainable allowing the combined rehabilitation of both mine wastes at long-term.

Pyrolysis of waste materials to produce biochar is an excellent and suitable alternative supporting a circular bio-based economy. One of the properties attributed to biochar is the capacity for sorbing organic contaminants, which is determined by its composition and physicochemical characteristics. In this study, the capacity of waste-derived biochar to retain volatile fuel organic compounds (benzene, toluene, ethylbenzene and xylene (BTEX) and fuel oxygenates (FO)) from artificially contaminated water was assessed using batch-based sorption experiments. Additionally, the sorption isotherms were established. The results showed significant differences between BTEX and FO sorption on biochar, being the most hydrophobic and non-polar contaminants those showing the highest retention. Furthermore, the sorption process reflected a multilayer behaviour and a relatively high sorption capacity of the biochar materials. Langmuir and Freundlich models were adequate to describe the experimental results and to detect general differences in the sorption behaviour of volatile fuel organic compounds. It was also observed that the feedstock material and biochar pyrolysis conditions had a significant influence in the sorption process. The highest sorption capacity was found in biochars produced at high temperature (> 400 °C) and thus rich in aromatic C, such as eucalyptus and corn cob biochars. Overall, waste-derived biochar offers a viable alternative to be used in the remediation of volatile fuel organic compounds from water due to its high sorption capacity.

We have investigated the effect of supercritical drying (SD) on the porosity and the BET-N-2 specific surface area (SSA) of five allophane-rich and three non-allophanic topsoils. The contribution of organic matter (OM) and short-range ordered (SRO) constituents to the nanoscale porosity (< 100 nm size) and SSA was also evaluated following chemical treatments to oxidise OM and then remove the SRO phase. The average pore volume and SSA of the soils, measured after SD, are greater than the values obtained after air drying. For soils that are rich in SRO constituents, oxidation of OM leads to an increase in SSA. This observation is attributed to the unblocking of pore necks previously covered by OM, while the subsequent removal of SRO constituents causes a sharp decrease in SSA. The SRO constituents containing oxalate-extractable Al, are the major contributors to the SSA of the in-organic fraction. Besides confirming that SD can help preserve the nanoscale porosity of allophane-rich soils, the results highlight the contribution of SRO constituents to the SSA of soils and their ability to accumulate OM.

Eutrophication of soils and waters is one of the main problems that threaten the conservation of species and habitats. Recent studies show that P can also substantially affect the loss of biodiversity. In contrast to N, which can be removed by leaching, P remains over time because it is adsorbed to soil colloids. A study to evaluate the common cattail (Typha latifolia) ability to extract phosphorous from a eutrophic Technosol (ET), highly enriched with P, and from an oligotrophic natural soil (NS) was performed. In the soils the total content of nutrients (P, Ca, Mg, K, N) Fe, Al, C, amorphous oxyhydroxides of Al/Fe, bioavailability P and geochemical forms of P was performed. The results showed a significantly high concentration of the TP and bioavailability P in ET than NS. In line with a high concentration of P in ET, a very high concentration of P was extracted by the plants in ET. These results showed that cattail responds positively to very high concentrations of P in the soil and, therefore, must be considered as a very efficient species to reduce soil eutrophication.

La eutrofización de suelos y aguas es uno de los principales problemas que amenazan la conservación de especies y hábitats. Estudios recientes muestran que el P también puede afectar sustancialmente a la pérdida de biodiversidad. En contraste con el N, que puede eliminarse por lixiviación, el P es adsorbido por el suelo pudiendo permanecer a lo largo del tiempo. Se realizó un estudio para evaluar la capacidad de la Typha latifolia para extraer el P del suelo. Para ello se consideró un Technosol eutrófico (ET), altamente enriquecido con P y un suelo natural oligotrófico (NS). En los suelos se analizó el contenido total de Fe, Al, C orgánico, oxihidróxidos amorfos de Al/Fe, formas geoquímicas de P. Los resultados muestran una concentración significativamente más elevada de P total y biodisponible en ET. En consonancia con una alta concentración de P en ET, la población de Thypha mostró también una concentración significativa superior de P comparando con las que crecieron en el NS. Estos resultados muestran que la totora responde positivamente a concentraciones muy elevadas de P en el medio y, por lo tanto, debe ser considerada como una especie muy eficiente para reducir la eutrofización del suelo.

Phosphorus is an essential element that at high concentrations generates eutrophication of aquatic systems. In this study, we used batch and continuous tests to evaluate the efficiency of a Technosol to retain the phosphorus present (as phosphate) in aqueous samples.