Luigi Marini

Bio: Luigi Marini is an academic researcher from University of Genoa. The author has contributed to research in topics: Geothermal gradient & Dissolution. The author has an hindex of 33, co-authored 99 publications receiving 4280 citations.

CO2 Degassing and Energy Release at Solfatara Volcano, Campi Flegrei, Italy

Abstract: In the present period of quiescence, the Solfatara volcano, 1 km far from Pozzuoli, releases 1500 t d−1 of hydrothermal CO2 through soil diffuse degassing from a relatively small area (0.5 km2). This amount of gas is comparable to that released by crater plume emissions of many active volcanoes. On the basis of the CO2/H2O ratio measured in high-temperature fumaroles inside the degassing area, we computed a total thermal energy flux of 1.19×1013 J d−1 (138 MW). Most of this energy is lost by shallow steam condensation and transferred to the atmosphere through the hot soil of the degassing area. The thermal energy released by diffuse degassing at Solfatara is by far the main way of energy release from the whole Campi Flegrei caldera. It is 1 order of magnitude higher than the conductive heat flux through the entire caldera, and, during the last 20 years, it was several times higher than the energy associated with seismic crises and ground deformation events. It is possible that changes in the energy flux from a magma body seated underneath Solfatara and/or argillification processes at relatively shallow depths determine pressurization events in the hydrothermal system and consequently ground deformation and shallow seismic swarms, as recorded during the recent episodes of volcanic unrest centered at Pozzuoli.

Natural hexavalent chromium in groundwaters interacting with ophiolitic rocks

Abstract: Thirty of the 58 groundwaters sampled in September-October 2000 in the study area (La Spezia Province, Italy) have Mg-HCO3 to Ca-HCO3 composition, undetectable Cr(III) contents, and virtually equal concentrations of total dissolved Cr and Cr(VI). Therefore, dissolved Cr is present in toto as Cr(VI), with concentrations of 5-73 ppb. These values are above the maximum permissible level for drinking waters (5 ppb). Local ophiolites, especially serpentinites and ultramafites, are Cr-rich and represent a Cr source for groundwaters. How- ever, since Cr is present as Cr(III) in rock-forming minerals, its release to the aqueous solution requires oxidation of Cr(III) to Cr(VI). This can be per- formed by different electron acceptors, including Mn oxides, H2O2, gaseous O2, and perhaps Fe(III) oxyhydroxides. Based on this evidence and due to the absence of anthropogenic Cr sources, the com- paratively high Cr(VI) concentrations measured in the waters of the study area are attributed to natural pollution.

Heavy metals in soils : trace metals and metalloids in soils and their bioavailability

Abstract: Preface.- Contributors.- List of Abbreviations.- Section 1: Basic Principles: Introduction.-Sources of Heavy Metals and Metalloids in Soils.- Chemistry of Heavy Metals and Metalloids in Soils.- Methods for the Determination of Heavy Metals and Metalloids in Soils.- Effects of Heavy Metals and Metalloids on Soil Organisms.- Soil-Plant Relationships of Heavy Metals and Metalloids.- Heavy Metals and Metalloids as Micronutrients for Plants and Animals.-Critical Loads of Heavy Metals for Soils.- Section 2: Key Heavy Metals And Metalloids: Arsenic.- Cadmium.- Chromium and Nickel.- Cobalt and Manganese.- Copper.-Lead.- Mercury.- Selenium.- Zinc.- Section 3: Other Heavy Metals And Metalloids Of Potential Environmental Significance: Antimony.- Barium.- Gold.- Molybdenum.- Silver.- Thallium.- Tin.- Tungsten.- Uranium.- Vanadium.- Glossary of Specialized Terms.- Index.

In situ carbonation of peridotite for CO2 storage

Abstract: The rate of natural carbonation of tectonically exposed mantle peridotite during weathering and low-temperature alteration can be enhanced to develop a significant sink for atmospheric CO2. Natural carbonation of peridotite in the Samail ophiolite, an uplifted slice of oceanic crust and upper mantle in the Sultanate of Oman, is surprisingly rapid. Carbonate veins in mantle peridotite in Oman have an average 14C age of ≈26,000 years, and are not 30–95 million years old as previously believed. These data and reconnaissance mapping show that ≈104 to 105 tons per year of atmospheric CO2 are converted to solid carbonate minerals via peridotite weathering in Oman. Peridotite carbonation can be accelerated via drilling, hydraulic fracture, input of purified CO2 at elevated pressure, and, in particular, increased temperature at depth. After an initial heating step, CO2 pumped at 25 or 30 °C can be heated by exothermic carbonation reactions that sustain high temperature and rapid reaction rates at depth with little expenditure of energy. In situ carbonation of peridotite could consume >1 billion tons of CO2 per year in Oman alone, affording a low-cost, safe, and permanent method to capture and store atmospheric CO2.

Noble gases and volatile recycling at subduction zones

Abstract: Volatiles are lost from the Earth’s mantle to the atmosphere, hydrosphere and crust through a combination of subaerial and submarine volcanic and magmatic activity. These volatiles can be primordial in origin, trapped in the mantle since planetary accretion, produced in situ, or they may be recycled—re-injected into the mantle via material originally at the surface through the subduction process. Quantifying the absolute and relative contributions of these various volatile sources bears fundamental information on a number of issues in the Earth Sciences ranging from the evolution of the atmosphere and hydrosphere to the nature and scale of chemical heterogeneity in the Earth’s mantle. Noble gases have a pivotal role to play in addressing the volatile mass balance between the Earth’s interior and exterior reservoirs. The primordial isotope 3He provides an unambiguous measure of the juvenile volatile flux from the mantle (Craig et al. 1975). As such, it provides a means to calibrate other volatiles of geological and geochemical interest. A prime example is the CO2 flux at mid-ocean ridges (MOR): by combining estimates of the 3He flux at MOR with measurements of the CO2/3He ratio in oceanic basalts, Marty and Jambon (1987) derived an estimate of the CO2 flux from the (upper) mantle. The approach of using ratios (involving noble gas isotopes) has also been extended to island arcs. Marty et al. (1989) found significantly higher CO2/3He ratios in arc-related geothermal fluids than observed at mid-ocean ridges, consistent with addition of slab-derived CO2 to the mantle wedge. Sano and Williams (1996) scaled the CO2 flux to 3He, showing that the output of CO2 at subduction zones was comparable in magnitude to that at spreading ridges. Therefore, for CO2 at least, subduction zones also …