Dispersion of metals and arsenic from the tailings of an abandoned mine in Sierra of Madrid

The extraction and processing of minerals produce significant environmental impacts that last long after mining operations have ended. Abandoned mines provide obvious sources of contamination by metals and arsenic in surrounding areas. These areas typically support sparse vegetation, so weather events, typical of Mediterranean environments such as heavy rains, can drag metals and metalloids, in a more or less available form for vegetation, as in solution and suspension to accumulate in lower lands. In this study, the area affected by a copper mine, abandoned early last century in the Sierra de Madrid, was sampled. Soil properties such as pH, EC, total OM and texture were analyzed. Furthermore, the BCR (Bureau Community of Reference) fractionation of metals was carried out in order to evaluate the weathering of the starting materials and the selective movement of different fractions along the slope . Metals and arsenic were detected beyond the mine limits, in areas where water flows in a preferential way. Results showed high concentrations and readily extractable Cu and As, which may suggest potential bioavailability for organisms and may create an environmental risk and potential human exposure what results in a health risk for the population

Utilización de nanopartículas de magnetita en la descontaminación de suelos afectados por actividad minera = Use of magnetite nanoparticles for decontamination of soils affected by mine activity

La aplicación de nanoparticulas de Fe a suelos contaminados por metales pesados y metaloides ha sido ampliamente propuesto para su inmovilización en suelos. Basado en el uso de nanopartículas de hierro en aguas y efluentes contaminados por metales pesados y metaloides para luego separar las partículas mediante imanes, se está empezando a ensayar la utilización de esta técnica en suelos. En este estudio se utilizaron 2 suelos de la Comunidad de Madrid, 2 dosis de nanopartículas de magnetita (5 y 10%), 3 niveles de humedad (seco, capacidad de campo y saturación) y 4 periodos de incubación (4, 10, 20 y 40 días). Despues de cada periodo, se secaron las muestras y se separó una fracción atraída por un electroimán. Se determinó Cu y Zn en el suelo restante. Se observo que el imán atraía cantidades relativamentes altas de suelo y que la cantidad de Cu y Zn en el suelo disminuía. Se observó que al incrementar la cantidad de magnetita que se añadía, el nivel de humedad y el tiempo de incubación, tambien aumentaba la redución de metales en suelos por lo que estas 3 variables se puede modificar para optimizar la extracciónde metales en suelos contaminados

Effect of magnetite nanoparticles on heavy metals behavior in contaminated soils

The extraction and processing of minerals produce significant environmental impacts that last long after mining operations have ended. Abandoned mines provide obvious sources of contamination by metals and arsenic in surrounding areas. These areas typically support sparse vegetation, so weather events, typical of Mediterranean environments such as heavy rains, can drag metals and metalloids, in a more or less available form for vegetation, as in solution and suspension to accumulate in lower lands. In this study, the area affected by a copper mine, abandoned early last century in the Sierra de Madrid, was sampled. Soil properties such as pH, EC, total OM and texture were analyzed. Furthermore, the BCR (Bureau Community of Reference) fractionation of metals was carried out in order to evaluate the weathering of the starting materials and the selective movement of different fractions along the slope . Metals and arsenic were detected beyond the mine limits, in areas where water flows in a preferential way. Results showed high concentrations and readily extractable Cu and As, which may suggest potential bioavailability for organisms and may create an environmental risk and potential human exposure what results in a health risk for the population

Phytoextraction of heavy metals from mine soils using hyperaccumulator plants.

Phytoextraction is an environmental-friendly and cost-effective technology that uses metal hyperaccumulator plants to remove heavy metals from soils. The metals are absorbed by the roots, transported and accumulated in the aerial parts of the plants, which can be harvested and eliminated. The aim of this work was to study some hyperaccumulator species that could be useful to decontaminate mine soils and also to investigate the bioavailability and uptake of these metals by plants with the addition of organic amendments. Pot experiments were performed with soil samples collected from two mining areas in the north of Madrid, where there was an intense mining activity more than 50 years ago. Three species (Thlaspi arvense, Brassica juncea and Atriplex halimus) were grown under controlled conditions in pots filled with contaminated soils mixed with 0 Mg, 30 Mg and 60 Mg per hectare of two different organic amendments: a commercial compost made of pine bark, peat and wood fiber and other made of horse and sheep manure and wood fiber. Plants were harvested at the end of their crop cycle and were digested in order to measure metal concentration (Zn, Cu and Cd) in roots and shoots. Highest plant metal concentration was observed in pots treated with pine bark amendment and with pure soil due to an increase in metal bioavailability with decreasing pH. Also in those treatments the total plant biomass was lower, even some plants could not germinate. On the contrary, there was a lower metal concentration in plant tissues of pots with manure because its higher pH whereas plant growth was significantly larger so there was an incresing amount of metals removed from soil by plants. Comparing the three species results indicate a higher total metal uptake in A. halimus than B. juncea and T. arvense. In conclusion, results show that pH affects metal bioavailability and uptake by hyperaccumulator plants. Addition of organic amendments could be a successful technique for stabilization of metals in contaminated soils

Diversidad bacteriana en suelos de zonas contaminadas y no contaminadas de una mina de cobre = Bacterial diversity in soils from contaminated and uncontaminated areas of a copper mine

Para entender la dinámica ecológica del suelo es de primordial importancia realizar un esquema de la distribución filogenética de las distintas bacterias que viven en él. Los análisis moleculares, en especial el metagenómico, puede aportar información detallada sobre la diversidad, estructura y funcionamiento de los microorganismos presentes en un suelo, información que pueden servir como base para su manejo y recuperación. El objetivo de este estudio fue evaluar la diversidad de las comunidades bacterianas en dos zonas de un suelo minero ubicado en la comunidad de Madrid. Los muestreos se realizaron en dos zonas de la mina identificadas como zona 1 (suelo no afectado) y zona 3 (zona de escombrera). Se realizaron análisis metagenómicos de las comunidades bacterianas presentes, con muestras de ambas zonas. Del total de secuencias bacterianas evaluadas, sólo el 1% mostró coincidencias en las bases de datos del Centro Nacional para la Información Biotecnológica (NCBI). Los resultados mostraron que el número de secuencias del dominio Bacteria es mayor en la zona 1 que en la zona 3. Aunque no se encontraron diferencias significativas entre los diferentes filos de bacterias por zona, sí se observaron diferencias en cuanto al número de especies dentro de los diferentes filos y entre las zonas de muestreo

Effects of soluble humic acids on the uptake of heavy metals by Vetiveria zizanioides (L.) Nash in contaminated mining soils

In the past, mining wastes were left wherever they might lie in the surroundings of the mine area. Unfortunately, inactive and abandoned mines continue to pollute our environment, reason why these sites should be restored with minimum impact. Phytoextraction is an environmental-friendly and cost-effective technology less harmful than traditional methods that uses metal hyperaccumulator or at least tolerant plants to extract heavy metals from polluted soils. One disadvantage of hyperaccumulator species is their slow growth rate and low biomass production. Vetiveria zizanioides (L.) Nash, perennial species adapted to Mediterranean climate has a strong root system which can reach up to 3 m deep, is fast growing, and can survive in sites with high metal levels (Chen et al., 2004). Due to the fact that metals in abandoned mine tailings become strongly bonded to soil solids, humic acids used as chelating agents could increase metal bioavailability (Evangelou et al., 2004; Wilde et al., 2005) and thereby promote higher accumulation in the harvestable parts of the plant. The objective of this study was to examine the performance of humic acid assisted phytoextraction using Vetiveria zizanioides (L.) Nash in heavy metals contaminated soils

Use of leonardite humic acids for metals extraction in mine soils

Mine soils usually exhibit high levels of metal contamination. Phytoextraction is an environmental friendly and cost-effective technique for soil remediation, which consists of removal of metals from soil by plant roots and their translocation to aerial parts. Humic substances used as soil amendments could enhance metal mobility and uptake by plants due to formation of soluble complexes. This study aimed to evaluate the effects of a commercial humic acid derived from leonardite added at different rates and pH to a contaminated soil from an abandoned copper mine in Colmenarejo (Madrid, Spain) on metal mobility. The objective was to assess its potential as soil amendment for phytoextraction. Soil samples (10 g) were sequentially extracted 6 times with 20 mL of solution containing humic acid at: 0 (control), 0.25, 1, and 5 g L-1. Solutions were previously adjusted to pH: 4, 6.1 (natural soil pH) and 8. Extracts were analyzed for pH, electrical conductivity, metal concentrations (Cu and Zn) and ratio of absorption at 465 to 665 nm (E4/E6) as an indirect measure of soluble organic matter content. Results showed that addition of higher doses of humic acid increased soluble organic matter content, and therefore extracted a higher concentration of Zn and particularly Cu, due to formation of soluble humic complexes. At higher pH humic acid became more soluble and managed to extract increasing amounts of metals, except in the highest humic acid treatment due to its precipitation or flocculation. The use of this humic acid as soil amendment could promote metal phytoextraction by tolerant plants in contaminated mine soils, but it should be applied at proper pH and other soil conditions to avoid risk of metal leaching to groundwate

Intraoperative radiotherapy electron boost followed by moderate doses of external beam radiotherapy in resected soft-tissue sarcoma of the extremities

To analyze the patterns of failure and the toxicity profile of intraoperative electron beam radiotherapy (IOERT) after resection of soft tissue sarcomas of the extremities (STS). PATIENTS AND METHODS: Forty-five patients with extremity STS were treated with IOERT and moderate-dose postoperative radiotherapy (45-50 Gy). Twenty-six patients were treated for primary disease (PD) and 19 patients for an isolated recurrence (ILR). Tumor size was >5 cm (maximum diameter) in 36 patients (80%), and high-grade histology in PD patients was present in 14 patients (54%). In nine patients, IOERT was used alone, due to previous irradiation or patient refusal. Chemotherapy (neoadjuvant and/or adjuvant) was mainly given to high-grade tumors. RESULTS: Nine patients relapsed in the extremity (20%), and 12 patients in distant sites (28%). Actuarial local control at 5 years was 88% for patients with negative/close margins and 57% for patients presenting positive margins (P=0.04). Five patients (11%) developed neuropathy associated with the treatment. Extremity preservation was achieved in 40 patients (88%). With a median follow-up of 93 months (range: 27-143 months) for the patients at risk, 25 patients remain alive (a 7-year actuarial survival rate of 75% for PD and 47% for ILR; P=0.01). CONCLUSIONS: IOERT combined with moderate doses of external beam irradiation yields high local control and extremity preservation rates in resected extremity STS. Peripheral nerves in the IOERT field are dose-limiting structures requiring a dose compromise in the IOERT component to avoid severe neurological damage