Luca Fanfani

Arsenic enrichment in waters and sediments of the Rio Loa (Second Region, Chile)

The Second Region of Chile (126,500 km2) is extremely arid, with a dramatic scarcity of water. The only water resource for the population (about 420,000 habitants) and the mining industry (the most important economic activity in the region) is the 440 km long Rio Loa. Moreover, this is highly enriched in As. In order to assess As concentrations and sources, and to evaluate the impact of mining activity on the water quality in the Rio Loa basin, water and sediment samples were taken at strategic points along the river and its major tributaries. The water in the whole basin is quite saline (total dissolved solids up to 11 g/l) and heavily enriched in As (average: 1400 μg/l) and B (average: 21,000 μg/l). These values are up to 300 and 100 times higher than the respective guidelines suggested by the WHO for drinking water. The quality of water is extremely poor along the tributary Salado, mainly fed by the El Tatio geothermal waters that are very rich in As (up to 27,000 μg/l) and other components. Sediments from the Rio Loa and its tributaries have As contents in the range of 26–2000 mg/kg (mean value of 60 samples: 320 mg/kg), and reach 11,000 mg/kg at El Tatio. Sequential extraction analyses show the As to be mainly associated with Fe–Mn oxy-hydroxides and residual phases, but part of the As (about 20%) is readily available being extracted from the exchangeable and carbonate phases. This result is in agreement with the correlation observed between As content in sediments and As concentration in waters in the area. The extreme arid conditions, high evaporation, and the lack of low-As tributaries contribute to maintain high concentrations of As and other components in the Rio Loa water to the mouth. Due to the oxidising conditions, neutral to alkaline pH, high salinity and high As concentrations, adsorption of As-species is not favoured. The main As source in the Rio Loa basin is considered to be natural, i.e. linked to the lithologies in the area. Smelter emissions and mining wastes, as well as the As-rich effluents from the water treatment plants, possibly represent additional sources.

Geochemistry of the high-PCO2 waters in Logudoro, Sardinia, Italy

Abstract A geochemical study of the high-PCO2 waters in Logudoro, northern Sardinia, was carried out starting from regional hydrogeochemical prospecting for geothermal energy, based on the major dissolved components and some minor elements. This preliminary investigation led to the identification of five different lithologies marking the different aquifers. The high-PCO2 waters can be divided into the less saline (TDS

The abandoned Pb-Zn mine of Ingurtosu, Sardinia (Italy)

Abstract The Ingurtosu Pb-Zn mine, situated in the southwestern part of Sardinia, has been in production from the beginning of the last century up to 1968. The orebody consists of galena/sphalerite/barite/siderite veins in Ordovician arenaceous and phyllitic sediments, near the contact with a Hercynian batholith. Abundant tailings were collected in a pond from which they were discharged during the winter months into the sea via the Rio Naracauli stream. Today this area of outstanding scenic beauty, is degraded by tailings and waste rock scattered all along the stream. Material derived from mining activities was studied for grain size, mineralogical and geochemical composition. The Rio Naracauli was sampled over a length of ten kilometers at regular intervals. The results can be summarized as follows: (a) tailings contain a varying, but often quite high, percentage of Pb; lower percentages were found for Zn and Cd; (b) a sharp increase in dissolved Zn, Cd and Pb was observed in the Rio Naracauli where it leached the tailings; and (c) tailings and waste rocks should be recycled or revegetated.

Hydrogeochemical exploration for gold in the Osilo area, Sardinia, Italy

A study to test the use of hydrogeochemical methods for gold prospecting was carried out in the Osilo area, northern Sardinia. The study area, covering about 30 km2 is characterised by Tertiary andesitic rocks. Gold concentrations up to several ppm, associated with abundant pyrite, arsenopyrite, stibnite, tetrahedrite and electrum, and subordinate galena, sphalerite and chalcopyrite, are present in quartz veins associated with a polyphase, incipient and pervasive alteration of the andesitic rocks. Forty-eight water samples (17 streams, 29 springs and 2 boreholes) were analysed for Au and a wide range of major and trace elements, both in solution (< 0.4 μm) and in suspension. Background values for dissolved Au were below the detection limit of the methods used (between 0.3 and 0.5 ng L−1 Au). Gold concentrations in solution up to 3 ng L−1 were found in waters draining the mineralised vein system. The observed dispersion of Au in surface waters was restricted to about 500 m from the auriferous veins. Dissolved Au anomalies do not vary significantly in water samples, taken monthly over a one year period, suggesting that the dispersion of Au is unaffected by seasonal conditions in the Osilo area. For samples where Au was detected both in solution and in suspension, the Au content of the suspended matter was usually lower than that in solution. The best indicators of Au mineralisation, apart from Au itself, both in solution and in suspension, were As and Sb which showed a dispersion clearly related to the known auriferous veins.

GRIDA3—a shared resources manager for environmental data analysis and applications

GRIDA3 (Shared Resources Manager for Environmental Data Analysis and Applications) is a multidisciplinary project designed to deliver an integrated system to forge solutions to some environmental challenges such as the constant increase of polluted sites, the sustainability of natural resources usage and the forecast of extreme meteorological events. The GRIDA3 portal is mainly based on Web 2.0 technologies and EnginFrame framework. The portal, now at an advanced stage of development, provides end-users with intuitive Web-interfaces and tools that simplify job submission to the underneath computing resources. The framework manages the user authentication and authorization, then controls the action and job execution into the grid computing environment, collects the results and transforms them into an useful format on the client side. The GRIDA3 Portal framework will provide a problem-solving platform allowing, through appropriate access policies, the integration and the sharing of skills, resources and tools located at multiple sites across federated domains.

AQUAGRID: an extensible platform for collaborative problem solving in groundwater protection

AQUAGRID is the subsurface hydrology computational service of the Sardinian GRIDA3 infrastructure, designed to deliver complex environmental applications via a user-friendly Web portal. The service aims to provide to water professionals integrated modeling tools to solve water resources management problems and aid decision making for contaminated soil and groundwater. In this paper, the AQUAGRID application concept and enabling technologies are illustrated. At the heart of the service are the computational models to simulate complex and large groundwater flow and contaminant transport problems and geochemical speciation. AQUAGRID is built on top of compute-Grid technologies by means of the EnginFrame Grid framework. Distributed data management is provided by the Storage Resource Broker data-Grid middleware. The resulting environment allows end-users to perform groundwater simulations and to visualize and interact with their results, using graphs, 3D images and annotated maps. The problem solving capability of the platform is demonstrated using the results of two case studies deployed.

A Worldwide Emergency: Arsenic Risk in Water. Case Study of an Abandoned Mine in Italy

Water is an essential resource for the development of human societies. Inadequate availability of good quality water especially in the future will probably cause transboundary and social conflicts. Presently, As contamination in water represents the most relevant risk for many populations in the world, because the diffusion of the contaminant has been facilitated by inappropriate water management, and the effects on the health are serious, though delayed in time. Risk mitigation is expensive and sometimes not completely successful. The case study concerns a small hilly area around an abandoned mine in Sardinia (Italy), and the downstream coastal plain where a subsistence agriculture is developed. Uncontrolled dispersion of wastes from the exploited area and the processing plant, transported downstream, is still affecting (after 40–50 years) the quality of the water in the catchment with concentration of As up to 0.9 mg/l. A study of the As dissolved content in the excavated wells of the plain reveals an irregular spatial distribution with higher values (up to 1 mg/l) in low-lying zones covered by contaminated sediments overflooded from the nearby river. The remediation plan, limited to the hilly area, intends to reduce the supply of contaminant downstream and includes the building of a save dump, where most of the waste-rocks and tailings will be collected, treating the acid waters from the adits on-site, and reclamating in situ small old dumps in the lower part of the catchment.