Geology topics

P. Lattanzi

Publications and source records attributed to P. Lattanzi.

8 recordsLinked to original sources

USGS2015

Metallogeny, exploitation and environmental impact of the Mt. Amiata mercury ore district (Southern Tuscany, Italy)

The Mt. Amiata mining district (Southern Tuscany, Italy) is a world class Hg district, with a cumulate production of more than 100,000 tonnes of Hg, mostly occurring between 1870 and 1980. The Hg mineralization at Mt. Amiata is younger than 0.3 Ma, and is directly related to shallow hydrothermal systems similar to present-day geothermal fields of the region. There is likely a continuum of Hg deposition to present day, because Hg emission from geothermal power plants is on-going. In this sense, the Mt. Amiata deposits present some analogies with “hot-spring type” deposits of western USA, although an ore deposit model for the district has not been established. Specifically, the source of Hg remains highly speculative. The mineralizing hydrothermal fluids are of low temperature, and of essentially meteoric origin. Recent results by our research group indicate that, 30 years after mine closure, the environmental effects of Hg contamination related to mining are still recorded by the ecosystem, namely on waterways of the Paglia and Tiber River basins. In particular, the close spatial connection between the town of Abbadia San Salvatore, the Hg mine within its immediate neighborhood, and the drainage catchment of the Paglia River has an influence also on Hg speciation, transported mainly in the particulate form by the river system. The extent of Hg contamination has been identified at least 100 km from Abbadia San Salvatore along the Paglia-Tiber River system. Estimated annual Hg mass loads transported by the Paglia River to the Tiber River were about 11 kg yr −1 . However, there is evidence that flood events may enhance Hg mobilization in the Paglia River basin, increasing Hg concentrations in stream sediment. The high methyl-Hg/Hg ratio in water in this area is an additional factor of great concern due to the potential harmful effects on human and wildlife health. Results of our studies indicate that the Mt. Amiata region is at present a source of Hg of remarkable environmental concern at the local, regional (Tiber River), and Mediterranean scales. Ongoing studies are aimed to a more detailed quantification of the Hg mass load input to the Mediterranean Sea, and to unravel the processes concerning Hg transport and fluid dynamics.

Tuscany↗

USGS2014

Mass loads of dissolved and particulate mercury and other trace elements in the Mt. Amiata mining district, Southern Tuscany (Italy)

Total dissolved and particulate mercury (Hg), arsenic (As), and antimony (Sb) mass loads were estimated in different seasons (March and September 2011 and March 2012) in the Paglia River basin (PRB) (central Italy). The Paglia River drains the Mt. Amiata Hg district, one of the largest Hg-rich regions worldwide. Quantification of Hg, As, and Sb mass loads in this watershed allowed (1) identification of the contamination sources, (2) evaluation of the effects of Hg on the environment, and (3) determination of processes affecting Hg transport. The dominant source of Hg in the Paglia River is runoff from Hg mines in the Mt. Amiata region. The maximum Hg mass load was found to be related to runoff from the inactive Abbadia San Salvatore Mine (ASSM), and up to 30 g day −1 of Hg, dominantly in the particulate form, was transported both in high and low flow conditions in 2011. In addition, enrichment factors (EFs) calculated for suspended particulate matter (SPM) were similar in different seasons indicating that water discharge controls the quantities of Hg transported in the PRB, and considerable Hg was transported in all seasons studied. Overall, as much as 11 kg of Hg are discharged annually in the PRB and this Hg is transported downstream to the Tiber River, and eventually to the Mediterranean Sea. Similar to Hg, maximum mass loads for As and Sb were found in March 2011, when as much as 190 g day −1 each of As and Sb were measured from sites downstream from the ASSM. Therefore, the Paglia River represents a significant source of Hg, Sb, and As to the Mediterranean Sea.

Tuscany↗

USGS2014

Quantifying biomineralization of zinc in the Rio Naracauli (Sardinia, Italy), using a tracer injection and synoptic sampling

Streams draining mined areas throughout the world commonly have high concentrations of Zn. Because Zn is not easily removed from stream water and because it can be toxic to aquatic organisms, its presence is a persistent problem. The discovery of biomineralization of Zn-bearing solids in the mine drainage of Rio Naracauli, in Sardinia, Italy, provides insights into strategies for removing Zn and improving water quality in streams affected by mine drainage. Until now, the transport and attenuation of Zn has not been quantified in this stream setting. A continuous tracer injection experiment was conducted to quantify the biomineralization process and to identify the loading of constituents that causes a change from precipitation of hydrozincite [Zn 5 (CO 3 ) 2 (OH) 6 ] in the upstream reach to precipitation of a Zn-silicate phase downstream. Based on the mass-load calculations derived from the tracer experiment, about 1.2 kg/day of Zn is sequestered in hydrozincite. This biomineralization represents nearly 90% removal of Zn. Other elements such as Pb and Cd also are sequestered, either in the hydrozincite, or in a separate phase that forms simultaneously. In the lower 600 m of the stream, where the Zn-silicate forms, as much as 0.7 kg/day Zn are sequestered in this solid, but additions of Zn to the stream from groundwater discharge lead to an overall increase in load in that portion of the Rio Naracauli.

Sardinia↗

USGS2013

Formation of a low-crystalline Zn-silicate in a stream in SW Sardinia, Italy

n southwestern Sardinia, Italy, the Rio Naracauli drains a catchment that includes several abandoned mines. The drainage from the mines and associated waste rocks has led to extreme concentrations of dissolved Zn, but because of the near-neutral pH, concentrations of other metals remain low. In the reach from approximately 2300 to 3000 m downstream from the headwaters area, an amorphous Zn-silicate precipitates from the water. In this reach, concentrations of both Zn and silica remain nearly constant, but the loads (measured in mass/time) of both increase, suggesting that new Zn and silica are supplied to the stream, likely from emerging groundwater. Zinc isotope signatures of the solid are heavier than the dissolved Zn by about 0.5 permil in 66/64 Zn, suggesting that an extracellular biologically mediated adsorption process may be involved in the formation of the Zn-silicate.

Sardinia↗

USGS2012

Hydrozincite seasonal precipitation at Naracauli (Sardinia – Italy): Hydrochemical factors and morphological features of the biomineralization process

Hydrozincite [Zn 5 (CO 3 ) 2 (OH) 6 ] precipitation from Naracauli waters (SW Sardinia) is, among other things, promoted by a microbial community made up of a filamentous cyanobacterium ( Scytonema sp.) and a microalgae ( Chlorella sp.). Hydrozincite bioprecipitation is responsible for the natural removal of harmful metals, especially Zn, from the stream waters. Thus, hydrozincite could be used to attenuate metal pollution in mining waters. Information on environmental conditions which promote the biomineralization process is fundamental for the development of remediation strategies. This paper aims to investigate the variables controlling the biomineralization process, and seasonal variation of the hydrochemical factors that affect hydrozincite precipitation. Hydrozincite morphology varies depending on the environmental conditions. Specifically, changes were observed between samples collected in late spring and samples collected in summer, and among samples precipitated under different water flow conditions. According to field observations, correlated with speciation and equilibrium calculation, the maximum intensity in hydrozincite precipitation occurs in the late spring during rainy years. In these conditions, the hydraulic regime in the stream reaches stationary conditions, and saturation index values with respect to hydrozincite reach their highest values. Concomitantly, the Zn 2+ / CO 3 2 - "> CO32- molar ratio reaches values close to 1, indicating that kinetic processes have a role on the hydrozincite biomineralization process.

Sardinia↗

USGS2012

Concentration, distribution, and translocation of mercury and methylmercury in mine-waste, sediment, soil, water, and fish collected near the Abbadia San Salvatore mercury mine, Monte Amiata district, Italy

The distribution and translocation of mercury (Hg) was studied in the Paglia River ecosystem, located downstream from the inactive Abbadia San Salvatore mine (ASSM). The ASSM is part of the Monte Amiata Hg district, Southern Tuscany, Italy, which was one of the world’s largest Hg districts. Concentrations of Hg and methyl-Hg were determined in mine-waste calcine (retorted ore), sediment, water, soil, and freshwater fish collected from the ASSM and the downstream Paglia River. Concentrations of Hg in calcine samples ranged from 25 to 1500 μg/g, all of which exceeded the industrial soil contamination level for Hg of 5 μg/g used in Italy. Stream and lake sediment samples collected downstream from the ASSM ranged in Hg concentration from 0.26 to 15 μg/g, of which more than 50% exceeded the probable effect concentration for Hg of 1.06 μg/g, the concentration above which harmful effects are likely to be observed in sediment-dwelling organisms. Stream and lake sediment methyl-Hg concentrations showed a significant correlation with TOC indicating considerable methylation and potential bioavailability of Hg. Stream water contained Hg as high as 1400 ng/L, but only one water sample exceeded the 1000 ng/L drinking water Hg standard used in Italy. Concentrations of Hg were elevated in freshwater fish muscle samples and ranged from 0.16 to 1.2 μg/g (wet weight), averaged 0.84 μg/g, and 96% of these exceeded the 0.3 μg/g (methyl-Hg, wet weight) USEPA fish muscle standard recommended to protect human health. Analysis of fish muscle for methyl-Hg confirmed that > 90% of the Hg in these fish is methyl-Hg. Such highly elevated Hg concentrations in fish indicated active methylation, significant bioavailability, and uptake of Hg by fish in the Paglia River ecosystem. Methyl-Hg is highly toxic and the high Hg concentrations in these fish represent a potential pathway of Hg to the human food chain.

Monte Amiata↗

USGS1989

The campi flegrei (Italy) geothermal system: A fluid inclusion study of the mofete and San Vito fields

A fluid inclusion study of core from the Mofete 1, Mofete 2, Mofete 5, San Vito 1, and San Vito 3 geothermal wells (Campi Flegrei, Campania, Italy) indicates that the hydrothermal minerals were precipitated from aqueous fluids (??CO2) that were moderately saline (3-4 wt.% NaCl equiv.) to hypersaline (> 26 wt.% NaCl equiv.) and at least in part, boiling. Three types of primary fluid inclusions were found in authigenic K-feldspar, quartz, calcite, and epidote: (A) two-phase [liquid (L) + vapor (V)], liquid-rich inclusions with a range of salinity; (B) two-phase (L + V), vaporrich inclusions with low salinity; and (C) three-phase [L + V + crystals (NaCL)], liquid-rich inclusions with hypersalinity. Results of microthermometric and crushing studies are reported for twenty drill core samples taken from the lower portions of the five vertical wells. Data presented for selected core samples reveal a general decrease in porosity and increase in bulk density with increasing depth and temperature. Hydrothermal minerals commonly fill fractures and pore-spaces and define a zonation pattern, similar in all five wells studied, in response to increasing depth (pressure) and temperature. A greenschist facies assemblage, defined by albite + actinolite, gives way to an amphibolite facies, defined by plagioclase (andesine) + hornblende, in the San Vito 1 well at about 380??C. The fluid inclusion salinity values mimic the saline and hypersaline fluids found by drilling. Fluid inclusion V/L homogenization temperatures increase with depth and generally correspond to the extrapolated down-hole temperatures. However, fluid inclusion data for Mofete 5 and mineral assemblage data for San Vito 3, indicate fossil, higher-temperature regimes. A limited 87Sr/86Sr study of leachate (carbonate) and the leached cores shows that for most samples (except San Vito 3) the carbonate deposition has been from slightly 87Sr-enriched fluids and that Sr isotopic exchange has been incomplete. However, San Vito 3 cores show an approach to fluid/rock Sr equilibrium with a fluid similar to modern ocean water in 87Sr/86Sr ratio. The Campi Flegrei volcanic system has evolved undersaturated products, mostly trachyte, and defines a large (??? 12 km) caldera. The hydrothermal system developed in this location can be used as an analog for fossil systems in similar trachytic environments. The potential for ore mineralization is expressed by the recognition, from fluid inclusion and drilling data, of ore-forming environments such as boiling and brine stratification. ?? 1989.

Journal of Volcanology and Geothermal Research↗

USGS1985

Fluid inclusions in minerals from the geothermal fields of Tuscany, Italy

A reconnaissance study on fluid inclusions from the geothermal fields of Tuscany indicates that the hydrothermal minerals were formed by fluids which were, at least in part, boiling. Four types of aqueous inclusions were recognized: (A) two-phase (liquid + vapor) liquid rich, (B) two-phase (vapor + liquid) vapor rich, (C) polyphase hypersaline liquid rich and (D) three phase—H 2 O liquid + CO 2 liquid + CO 2 -rich vapor. Freezing and heating microthermometric determinations are reported for 230 inclusions from samples from six wells. It is suggested that boiling of an originally homogeneous, moderately saline, CO 2 -bearing liquid phase produced a residual hypersaline brine and a CO 2 -rich vapor phase. There are indications of a temperature decrease in the geothermal field of Larderello, especially in its peripheral zones.

Geothermics↗