Enargite by XPS

X-ray photoelectron spectroscopy was used for characterizing the enargite surface. Freshly cleaved samples were analyzed at liquid nitrogen temperature. Enargite is a copper arsenic sulfide of formula Cu3AsS4; it is used as a minor ore of copper. Enargite is a potential source of arsenic and may create environmental problems through the release of toxic elements upon oxidatio

Mercury Dispersion through Streams Draining The Mt. Amiata District, Southern Tuscany, Italy

Abstract The Mt. Amiata area hosts the 3 rd largest Hg district in the world, overlapping with a present-day geothermal system that is exploited for energy production. Mining activity ceased in 1980; remediation of mining areas was only partial, and is still under way. A significant transport of mercury is documented in the streams draining the district. By far the largest output occurs to the southeast in the Paglia River catchment; this river is tributary of Tiber River, the largest river of central Italy. A much smaller transport occurs to the north, in the Orcia-Ombrone catchment. Most transport is in particulate form; mercury is temporarily stored in stream and overbank sediments, and can be significantly mobilized and redistributed by extreme events such as flash floods. Transfer to the biosphere and food chain is not negligible, as some fish in Paglia and Tiber Rivers show Hg contents that may be harmful for human consumption. The overall output from the Monte Amiata district represents a significant contribution to the Mediterranean Sea budget of this metal

Impatto ambientale dell'attività mineraria in Sardegna: studi mineralogici e geochimici

Sardinia is characterized by a large variety of geologic and hydrologic environments, and by a rich wealth of mineral resources, that fueled a millennial history of mining activity. Therefore, it provides an excellent ground for studies of the environmental impact of mining activity. In this communication, we summarize the results of our studies, specifically concerning the deposits of Baccu Locci (polymetallic�Pb,As), Furtei (epithermal Au), Monteponi (Pb-Zn-Ag), and Montevecchio (Pb-Zn-Ag). In abandoned mining districts (Baccu Locci, Monteponi, and Montevecchio), because of a poor management of environmental issues, we observe significant heavy metal contamination. On the other hand, in the active Furtei mine the first four years of exploitation did not cause remarkable changes with respect to pre-mining baseline conditions

Natural attenuation can lead to environmental resilience in mine environment

Four streams flowing in the Iglesiente and Arburese mine districts (SW Sardinia, Italy), exploited for zinc (Zn) and lead (Pb) extraction from sulphides and secondary non-sulphide mineralization (calamine ores), have been studied combining investigations from the macroscale (hydrologic tracer techniques) to the microscale (X-ray powder diffraction, scanning electron microscopy, X-ray absorption spectroscopy). In the investigated area, concerns arise from release of metals to water during weathering of ore minerals and mine-waste. Specifically, Zn is observed at extremely high concentrations (10s of mg/L or more) in waters in some of the investigated catchments. The results from synoptic sampling campaigns showed marked differences of Zn loads, from 6.3 kg/day (Rio San Giorgio) to 2000 kg/day (Rio Irvi). Moreover, natural attenuation of metals was found to occur i) through precipitation of Fe compounds (Fe oxy/hydroxides and “green rust”), ii) by means of the authigenic formation of metal sulphides promoted by microbial sulphate reduction, iii) by metal intake in roots and stems of plants (Phragmites australis and Juncus acutus) and by immobilization in the rhizosphere, and iv) by cyanobacterial biomineralization processes that lead to formation of Zn-rich phases (hydrozincite and amorphous Zn-silicate). The biologically mediated natural processes that lead to significant abatement and/or reduction of metal loads, are the response of environmental systems to perturbations caused from mine activities, and can be considered part of the resilience of the system itself. The aim of this study is to understand the effect of these processes on the evolution of the studied systems towards more stable and, likely, resilient conditions, e.g. by limiting metal mobility and favouring the improvement of the overall quality of water. The understanding of how ecosystems adapt and respond to contamination, and which chemical and physical factors control these natural biogeochemical barriers, can help to plan effective remediation actions

Assessment of origin and fate of contaminants along mining-affected Rio Montevecchio (SW Sardinia, Italy): A hydrologic-tracer and environmental mineralogy study

Hydrologic tracer techniques were applied to Rio Montevecchio (SW Sardinia, Italy), a stream affected by mine drainage, allowing the calculation of discharge and contaminant loads. Discharge along the stream showed a constant increase throughout the 2.7 km-long study reach, up to 13.6 l/s at the last synoptic point. Calculated loads of mine-related constituents were large, reaching values of 1780 kg/day for, 340 kg/day for Zn, 47 kg/day for Fe, and 50 kg/day for Mn. The difference of the cumulative instream metal loads between the first and the last synoptic sampling points indicated gains of 421 kg/day for Zn, 2080 kg/day for, 56 kg/day for Mn, and 50 kg/day for Fe. The source areas critical for contaminants loading were almost all concentrated in the first 800 meters of the stream, with the exception of Pb, whose loading occurs evenly along the whole study reach. Precipitation of secondary minerals along the streambed was responsible for a very high attenuation of Al and Fe loads (66% and 77%) and affected also and Zn loads, though less effectively. Rio Montevecchio has the second highest metal load among the rivers investigated with tracer techniques in SW Sardinia. In comparison with Rio Irvi, which has one order of magnitude higher metal loads, natural attenuation processes limit the loads in Rio Montevecchio. Results are useful to clarify the hydrogeochemical paths involved in the release and attenuation of pollutants, improving our understanding of stream responses to contamination and aiding development of site-specific remediation actions