An updated numerical model of the Larderello–Travale geothermal system, Italy

Larderello–Travale is one of the few geothermal systems in the world that is characterized by a reservoir pressure much lower than hydrostatic. This is a consequence of its natural evolution from an initial liquid-dominated to the current steam-dominated system. Beneath a nearly impermeable cover, the geothermal reservoir consists of carbonate-anhydrite formations and, at greater depth, by metamorphic rocks. The shallow reservoir has temperatures in the range of 220–250 °C, and pressures of about 20 bar at a depth of 1000 m, while the deep metamorphic reservoir has temperatures of 300–350 °C, and pressures of about 70 bar at a depth of 3000 m. The 3D numerical code “TOUGH2” has been used to conduct a regional modeling study to investigate the production mechanism of superheated steam, the interactions between the geothermal field and the surrounding deep aquifers, and the field sustainability. All the available geoscientific data collected in about one century of exploration and exploitation have been used to provide the necessary input parameters for the model, which covers an area (4900 km²) about 10 times wider than the Larderello–Travale geothermal field (400 km²). The numerical model explains the origin of the steam extracted in about one century of exploitation and shows that, at the current level, the production is sustainable at least for the next 100 years.     

意大利2003年9月28日大停电简介

2003年9月日意大利发生全国大停电后,涉及联网的奥地利、法国、意大利、斯洛文尼亚、和瑞士等5国输电系统运行人(TSO)在其输电协调联合会(UCTE)的框架内会面和决定成立由5国专家组成的独立调查委员会,并约请来自比利时、德国、荷兰和西班牙的专家参加,共同对此次事件进行深入调查,对有关的UCTE的运行规则进行评价,并在必要时对运行方面的一些习惯做法的改进和规则的设置提出建议。2003年10月27日调查委员会按调查结果提出了一份中期报告。本刊编辑部特就其部份主要内容进行摘要编译供读者参阅。     

Isotopic and fluid inclusion study of hydrothermal and metamorphic carbonates in the Larderello geothermal field and surrounding areas, Italy

Fluid inclusions have been studied on six calcite veins from the shallow part (480 to 1515 m below ground level) of the Larderello geothermal field and outcropping in peripheral zones of the geothermal area. Oxygen and carbon isotopic analyses have been carried out on these carbonate veins, as well as on the dolostone layers found inside the Paleozoic metamorphic units of the deep part of the field (from 1939 to 3177 m below ground level). Fluid inclusion observations suggest that boiling processes probably occurred during calcite precipitation in most of the veins. The fluids that formed or interacted with the calcite veins below the uppermost reservoir (made up of Mesozoic marine carbonates), and with the calcite hydrothermal veins of Sassa, were characterised by an apparent salinity from 1.3 to 5.3 wt.% NaCl eq. and a homogenisation temperature from 137 to 245°C. The fluid inclusions related to the calcite veins hosted above the uppermost reservoir show a wide range of apparent salinity (from 1.7 to 22.2 wt.% NaCl eq.) and homogenisation temperatures from 224 to 296°C. Apparent salinity/homogenisation temperature covariations of the latter veins are interpreted as being the result of a mixing process between a low-temperature, high-salinity fluid and a higher-temperature, moderate-salinity fluid. The oxygen isotopic compositions of the calcite veins (δ¹⁸O from 10.34 to 11.45‰) located below the Mesozoic carbonates and in the outcrops (δ¹⁸O from 9.42 to 17.07‰) indicate that the vapour in equilibrium with these veins was isotopically similar to the present-day discharge steam. The aqueous fluids in equilibrium with these veins could be meteoric water that interacted with the Mesozoic carbonates of the upper reservoir. The δ¹³C values of the CO₂ produced at Larderello and the constant concentration of this gas over time are, however, indicative of a deep source inside the reservoir that is probably related to the decarbonation reaction within the metamorphic units that form the present-day deep reservoir. Fluid inclusion salinities (up to 22.2 wt.% NaCl eq.) and isotopic results (δ¹⁸O from 13.43 to 21.99‰, δ¹³C between −1.26 and −0.18‰) on the calcite veins hosted above the uppermost reservoir suggest that the water circulating in these veins has strongly interacted with Mesozoic carbonates or Neogene sediments containing evaporite layers. The isotopic values (δ¹⁸O from 14.09 to 19.91‰, δ¹³C from −4.09 to 1.90‰) of dolomite samples present in the Paleozoic metamorphic rocks indicate a reaction with fluid of variable temperatures under different water/rock ratios. The isotopic composition of one sample reveals equilibrium with present-day discharge fluids. This fact aside, the remaining data indicate that the Paleozoic dolomitic layers do not seem to contribute significantly to the production of CO₂.     

Polychlorinated Biphenyls in Sediments from Sicilian Coastal Area (Scoglitti) using Automated Soxhlet,GC-MS,and Principal Component Analysis

A methodology for the PAHs and PCBs congener determination in sediment samples has been revised. We determined the distributions of PAHs and PCBs in the superficial sediments of the Scoglitti (Italy) coastal area to provide data for comparison with other marine systems and to hypothesize the sources. Extraction yield, for PCB, was never less than 60% in most cases, while for PAHs, utilizing perdeuterated surrogate standard (benz[a]anthracene-d₁₂ and anthracene-d₁₀) was never less than 72%. The total concentration of the 16 PAHs investigated, expressed as the sum of concentrations, ∑PAHs, varied from 1–5087 μg/kg of dry matrix, while the ∑ PCBs ranged from detection limit to 36 μg/kg of dry matrix. Linear relationships were found between PAHs concentration and organic matter percentages (R² = 0.60) and water content and organic matter percentages (R² = 0.87). Isomeric ratios were used for discriminating between pyrolitic and petroleum origin. The principal component analysis (PCA) has been conduced to discriminate the different sampling sites in internal or external harbor area.     

意大利遗址公园规划设计探究——以罗马图拉真考古遗址公园为例

遗址公园作为遗址保护、展示教育与考古研究的有效途径，在世界范围内得以广泛推广与发展。意大利在文化遗产保护领域走在世界前列，其完备的法律保护制度、成熟的遗产保护理念和文物保护技术都有一定的借鉴意义。以罗马图拉真遗址公园为例，通过对其历史沿革的梳理，从遗址的空间结构和历史时序性上解读遗址时空特性，探讨其在坚持遗址原真性的基础上，如何从遗址保护理念、规划设计策略和实施技术路径3个层面对遗址进行保护与阐释，旨在解析意大利在遗址公园规划设计中的理念与方法，探讨其对于遗址公园建设实践的价值。     

Tanaro Bridge: Dynamic Tests on a Couple of Spans

The Tanaro Bridge, an 18-span 225-m long bridge on the Tanaro River in northwestern Italy, presented the following elements of interest: (1) the barrel divided into adjacent arches; and (2) transverse tie bars and internal spandrels connecting the three parts of the barrels. Its demolition, in 2003, gave the opportunity of performing dynamic tests on a couple of spans at two stages of demolition: (1) fill removed; and (2) fill and internal spandrels removed. Without the uncertain contribution of the fill, some features of the mechanical response of masonry bridges are discussed and the efficiency of tie bars and internal spandrels is addressed. The data provided can be useful for safety assessment procedures.     

Assessment of dietary intake of polychlorinated biphenyls from a total diet study conducted in Pavia, Northern Italy

The diet is considered to be the main source of body burden of polychlorobiphenyls (PCBs) in the general population. The most cost-effective and reliable way to estimate the dietary intake is based on total diet studies (TDSs). The aim of the present study was to provide a reliable estimate of recent average dietary intakes of PCBs in Northern Italy. Congener-specific analysis of PCBs was undertaken on total diet samples collected at the cafeteria of the University of Pavia. The average daily intake for total PCBs was calculated to be 0.26 µg/person day^-1. The major contributor to PCB intake was accounted for by pooled samples of bread, cereals and potatoes, followed by the protein composite, and fruit and vegetables. Although diverse dietary habits and differences in sampling and analytical procedures make comparison between different studies difficult, the daily intake of PCBs in Northern Italy can be located in the lower part of the range for values reported in the literature.     

Isotope systematics of C-bearing gas compounds in the geothermal fluids of Larderello, Italy

The origin of carbon-bearing compounds (CO₂, CH₄, C₂–C₄ saturated hydrocarbons) and helium in the geothermal fluid of Larderello is investigated by means of the variations in concentration and isotopic composition. The CO₂ (δ¹³C from −1.4 to −7.1‰ versus V-PDB) is mainly of crustal origin. The carbon isotopes of methane (δ¹³C from −20.9 to −31.7‰) and other hydrocarbons indicate a complex thermogenic origin. The temperatures obtained with the CH₄–CO₂ isotope geothermometer are in rough agreement with those observed in deeper geothermal wells. The CH₄/C₂H₆ ratios show a tendency towards partial equilibrium with increasing temperature. He isotopes (R/R_A from 0.5 to 3) indicate that although the major part of helium derives from crustal sources, a significant fraction of mantle helium is also present. Helium contamination by air, deducted from He/Ne ratios, is generally negligible.     

Influence of notch root radius on ductile rupture fracture toughness evaluation with Charpy-V type specimens

The blunt notch fracture toughness of four types of carbon-manganese steel (ASTM A516 grade 70) has been determined by J-integral tests on Charpy-V type samples with different values of notch root radius, ρ. J-ρ plots, determined using specimens with a notch depth to width ratio, a/w, equal to 0.5, have shown the existence of a limiting ρ value (ρ_eff) below which applied J-intergral values at fracture initiation are constant. These ρ_eff values have been seen to depend only on second-phase particle distribution and not on their volume fraction or on the steel ferritic grain size. The procedure for deriving J-integral values at the onset of stable crack growth from J resistance curves in the case of notches has also been discussed. Experiments with Charpy specimens with a/w = 0.2 do not allow the derivation of meaningful J-ρ plots. In all cases, a ductile fracture criterion based on the constancy of the notch tip strain at rupture initiation has been proved when ρ >ρ_eff.     

Ichthyotoxic effects of some anti-pollution products

A study has been carried out on the ichthyotoxicity effects of 14 anti-pollution products used for the dispersion of hydrocarbons in water, on the Carassius auratus. The better tolerated products are Esso Corexit 8666 and 7664; followed by Fina Sol OSR/2 and SC whilst the other products were found to contain higher ichthyotoxicity characteristics.