ABSTRACT
Remediation of heavy metal-contaminated aquifers is a challenging process because they cannot be degraded by microorganisms. Together with the usually limited effectiveness of technologies applied today for treatment of heavy metal contaminated groundwater, this creates a need for new remediation technologies. We therefore developed a new treatment, in which permeable adsorption barriers are established in situ in aquifers by the injection of colloidal iron oxides. These adsorption barriers aim at the immobilization of heavy metals in aquifers groundwater, which was assessed in a large-scale field study in a brownfield site. Colloidal iron oxide (goethite) nanoparticles were used to install an in situ adsorption barrier in a very heterogeneous, contaminated aquifer of a brownfield in Asturias, Spain. The groundwater contained high concentrations of heavy metals with up to 25 mg/L zinc, 1.3 mg/L lead, 40 mg/L copper, 0.1 mg/L nickel and other minor heavy metal pollutants below 1 mg/L. High amounts of zinc (>900 mg/kg), lead (>2000 mg/kg), nickel (>190 mg/kg) were also present in the sediment. Ca. 1500 kg of goethite nanoparticles of 461 ± 266 nm diameter were injected at low pressure (< 0.6 bar) into the aquifer through nine screened injection wells. For each injection well, a radius of influence of at least 2.5 m was achieved within 8 h, creating an in situ barrier of 22 × 3 × 9 m. Despite the extremely high heavy metal contamination and the strong heterogeneity of the aquifer, successful immobilization of contaminants was observed in the tested area. The contaminant concentrations were strongly reduced immediately after the injection and the abatement of the heavy metals continued for a total post-injection monitoring period of 189 days. The iron oxide particles were found to adsorb heavy metals even at pH-values between 4 and 6, where low adsorption would have been expected. The study demonstrated the applicability of iron oxide nanoparticles for installing adsorption barriers for containment of heavy metals in contaminated groundwater under real conditions.
Subject(s)
Environmental Restoration and Remediation , Groundwater , Metals, Heavy , Water Pollutants, Chemical , Adsorption , Magnetic Iron Oxide Nanoparticles , Spain , Water Pollutants, Chemical/analysisABSTRACT
La historiografía ha mostrado extensamente cómo los médicos irlandeses tuvieron un papel de primer nivel en la medicina del siglo XVIII a lo largo de toda la Monarquía Hispánica. Sin embargo, más allá de las prominentes figuras ligadas a los círculos cortesanos y militares -tales como, Higgins, Purcell, Gorman u O'Scanlan-, puede reivindicarse todo un número de doctores irlandeses que desempeñaron su ejercicio en ámbitos público-privados de menor proyección, pero con sólidos posicionamientos profesionales, y en muchos de los casos, vehiculizando las nuevas corrientes ideológicas del continente, adquiridas en la trayectoria de su emigración. Así, Raymond Everard, natural del condado de Waterford (Irlanda), representa muy fielmente el arquetipo de médico irlandés que, tras un paso por las universidades y los círculos pre-ilustrados franceses, recaló en Bilbao como médico municipal, atendiendo a la villa durante casi cuarenta años, e impregnándola de la modernidad técnico-científica del momento a través de su labor médica
Historiography has extensively demonstrated that Irish doctors played a very relevant role in the medicine of the Spanish Monarchy along 18th century. Nevertheless, beyond the prominent figures linked to the court and military circles -such as Higgins, Purcell, Gorman or O'Scanlan-, a significant number of Irish doctors can be claimed, who practised medicine in public-private spheres of less projection. In any case, they were well established professionals, who conveyed the new ideological currents generated in the continent and acquired along their migration pathways. Raymond Everard, born in co. Waterford (Ireland), truly depicts the archetype of the Irish doctor who, after being immersed in the French enlightened circles and universities, settled down in Bilbao as municipal doctor, where he took care of the town for nearly forty years, imbuing it with the existing technical-scientific modernity through his medical work
Subject(s)
Humans , History, 15th Century , History, 16th Century , History of Medicine , IrelandABSTRACT
A microcosm (MS-3) with a multispecies soil system is introduced as an experimental tool for direct toxicity assessment of contaminated soils. The capacity of MS-3 to determine soil ecotoxicity potential was evaluated using samples from three sites contaminated with organic and/or inorganic compounds. Soils were toxic to soil-dwelling organisms (earthworm, plants, and microorganisms) and to aquatic organisms (algae and RTG-2 cell fish). As expected, responses varied substantially among different soils and organisms. The application of this evaluation system provided complementary information to the chemical characterization. For soils containing metals the toxic response was lower than predicted from total metal concentrations. For hydrocarbons, the toxicity response agreed with estimated values. The induction of EROD activity suggested the presence of dioxin-like compounds, which had not been addressed in the chemical characterization. The proposed multispecies system affords the measurement of 11 endpoints covering three soil and three aquatic taxonomic groups, reproduces soil conditions and gradients, and appears as an excellent complementary tool to chemical analysis for characterization of contaminated sites.