Annamaria Lima

Multifractal IDW interpolation and fractal filtering method in environmental studies: an application on regional stream sediments of (Italy), Campania region

In recent years environmental geochemical mapping has assumed an increasing relevance and separation of background values to evaluate pollution is, probably, even more critical than the separation between background and anomalies in mineral prospecting studies. The recognition of background values assumes particular relevance as a function of national environmental legislation, which fixes intervention limits for some elements, such as the harmful ones (e.g. As, Cd, Hg, Pb). In this paper a recently developed multifractal IDW interpolation method and a fractal filtering technique are applied to separate natural background and anthropogenic values for the compilation of environmental geochemical mapping from stream sediment samples of Campania region (Italy), where no mineralization occurs. To discuss the application of these recently developed techniques the elements Pb and U were selected because they show two completely different situations, the high Pb values being mostly of anthropogenic origin and high U values being mostly of geogenic origin. The new fractal filtering method works well in both extreme situations.

Background and baseline concentration values of elements harmful to human health in the volcanic soils of the metropolitan and provincial areas of Napoli (Italy)

In this paper, we discuss baseline geochemical maps of elements harmful to human health compiled using concentration data of 982 volcanic soil samples from the metropolitan and provincial areas of Napoli (1171 km2). Each sample was digested in aqua regia and analysed by ICP-MS and ICP-ES. For the compilation of baseline geochemical maps, we apply a recently developed multifractal IDW interpolation method and spectral analysis (S-A) using a new geochemistry-dedicated GIS (GeoDAS). The geochemical baseline in an area of heavy anthropogenic impact, such as the Neapolitan territory, includes the geogenic natural content (background) and the anthropogenic contribution in the soils. The definition and distinction of background (geogenic) values, as opposed to baseline values, are very important in environmental studies because legislation typically fixes the intervention limits for both organic and inorganic substances in soils as a function of local background values. Maps obtained by the S-A method show high baseline values for some metallic elements (Pb, Zn, Sb, Hg, Cd, Cr, Cu) which denote a clear anthropogenic contribution, due to the long period of constant human activities in the study area. These maps also show a high geogenic contribution most probably derived from hydrothermal fluids because the study area is located between two active volcanic fields (Mt. Somma–Vesuvius and Campi Flegrei), where geothermal fluids have been used for spas since Roman times. The maps obtained using the S-A method, implemented in GeoDAS, reflect both the geogenic and anthropogenic contribution, so they must be considered as baseline maps. In order to obtain background values, to be used as reference values for the environmental Italian Law 471/1999, we have applied the concentration–area fractal method (C-A) to classify the pixel values of baseline maps. R-mode factor analysis helped in interpreting data controlled by anthropogenic sources as opposed to those controlled by geogenic sources.

Heavy metal pollution and Pb isotopes in urban soils of Napoli, Italy

Lead isotope analysis is an increasingly widespread tool in the study of environmental pollution as Pb isotope compositions do not change during industrial and environmental processes, and always reflect their source origin. In this study we present the results of R-mode factor analysis for associations between chemical elements in Neapolitan soils, combined with the distribution of Pb concentrations and Pb isotope compositions in order to differentiate natural from anthropogenic metal sources. Results show Neapolitan urban soils to be significantly enriched in Pb, Hg, Zn, Sb, and to a lesser extent in Cu, Cd, Cr and Ni. Lead isotope measurements form a trend suggesting mixing between two end-member compositions, one of clear natural origin (geogenic) and another related to human activities (anthropogenic). Lead isotope investigations demonstrate that road traffic is one of the main sources of metal pollution.

Palladium and platinum concentration in soils from the Napoli metropolitan area, Italy: possible effects of catalytic exhausts

Soils from the Napoli metropolitan area (Italy) were evaluated for Pt and Pd concentrations. One hundred and ninety-five (195) samples were collected from residual soils and non-residual soils from flower-beds in a 120 km(2) area on a 0.5 km grid in the downtown-urbanized area and on 1 km grid in suburban zones. The soils <100 mesh size fraction (150 microm) was analyzed for Pt, Pd and 37 other elements by ICP-ES and ICP-MS after aqua regia digestion. Pt and Pd contents range between <2 and 52 microg/kg and between <10 and 110 microg/kg, respectively. A large number of samples from the metropolitan area were characterized by anomalous values for Pt (>6 microg/kg) and Pd (>17 microg/kg). Non-residual soils from flower-beds are located mainly in the urbanized downtown areas subject to heavy traffic and have higher Pt and Pd contents than residual soils from suburban areas. Geochemical maps show a strong correlation between roads with major traffic flow and high Pt and Pd concentrations. In addition, data from most of the downtown flower-beds fall within the three-way catalytic converters (TWC) field identified by [Ely JC, et al. Environ Sci Technol; 35:3816-3822]. This suggests that emissions of abraded fragments from vehicle exhausts may be the source of the high values and geographic distributions of Pd and especially Pt in urban soils of Napoli. Catalytic converters (Pt/Pd/Rh) have been mandatory for gasoline-powered vehicles in Europe since 1993. Italy permitted the use of non-catalytic motor until January, 2002. This is responsible for the high values for both Pt and Pd in the non-residual soils of the urban areas of Napoli.

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

Abstract 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 ( ±CO 2 ) 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 87 Sr/ 86 Sr study of leachate (carbonate) and the leached cores shows that for most samples (except San Vito 3) the carbonate deposition has been from slightly 87 Sr-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 87 Sr/ 86 Sr 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.

Quantitative model for magma degassing and ground deformation (bradyseism) at Campi Flegrei, Italy: Implications for future eruptions

Campi Flegrei (Phlegrean Fields) is an active volcanic center near Naples, Italy. Numerous eruptions have occurred here during the Quaternary, and repeated episodes of slow vertical ground movement (bradyseism) have been documented since Roman times. Here, we present a quantitative model that relates deformation episodes to magma degassing and fracturing at the brittle-ductile transition in a magmatic-hydrothermal environment. The model is consistent with fi eld and laboratory observations and predicts that uplift between 1982 and 1984 was associated with crystallization of ~0.83 km 3 of H 2 O-saturated magma at 6 km depth. During crystallization, ~6.2 ◊ 10 10 kg of H 2 O and 7.5 ◊ 10 8 kg of CO 2 exsolved from the magma and generated ~7 ◊ 10 15 J of mechanical (PΔV) energy to drive the observed uplift. For comparison, ~10 17 J of thermal energy was released during the 18 May 1980 lateral blast at Mount St. Helens.

Fluid inclusion evidence for magmatic silicate/saline/CO2 immiscibility and geochemistry of alkaline xenoliths from Ventotene Island, Italy

Abstract Fluid and melt inclusions and geochemical features of alkali syenite, mafic, and ultramafic cumulate xenoliths in the last ignimbritic event (volcanism up to 300 ky.b.P.) at the island of Ventotene in the Pontine archipelago (Gaeta Gulf) were investigated to establish the genesis and evolution of the fluids trapped in the inclusions. Ranges in lead isotopic compositions of the xenoliths as a group are narrow: 206Pb/204Pb:18.778–18.864; 207Pb/204Pb:15.641–15.701; 208Pb/204Pb:38.858–39.090; the values overlap among the groups, implying that the xenoliths are closely related. The xenoliths straddle the best-fit line describing the regional NW-SE variation of values for uranogenic Pb in volcanic rocks from the Roman alkaline province. The similarity between the xenoliths and volcanic rocks permits the interpretation that the xenoliths are representative of the source region of the volcanic rocks, residues after partial melting of the source region or fractional crystallization of the volcanic rocks, or even that the xenoliths represent assimilants obtained during the evolution of the magmas that produced the volcanic rocks. Xenoliths belonging to the ultramafic-mafic cumulate group contain only silicate melt inclusions ± vapor bubble ± droplets of an opaque phase and rarely some CO2 trapped in silicate melt inclusions. Xenoliths in the alkali syenite group have three types of fluid inclusions: (1) single phase vapor and silicate melt inclusions; (2) two-phase silicate melt + salt, silicate melt + CO2 (V), aqueous (L + V), and silicate melt + vapor inclusions, and (3) three-phase and multiphase inclusions: CO2 (L) + CO2 (V) + H2O; silicate melt + saline melt + H2O ± birefringent or opaque trapped minerals; H2O + salt + silicate glass ± birefringent trapped minerals. During heating experiments, melting of salt occurs at temperatures from 565 to 815°C, depending on the water content of the inclusions. Homogenization of the vapor bubble occurs from 850–1160°C, and complete melting of the silicate glass at about 950°C. The highly variable proportions of the individual phases in the silicate melt + salt + H2O inclusions and the coexistence of silicate melt + CO2 inclusions indicates immiscibility during the crystallization of the magma. Primary and secondary CO2 inclusions in the alkali syenite suite indicate lower densities (from 0.10 to 0.22 g/cm3) than those resulting from primary CO2 inclusions in the gabbroic suite (from 0.34 to 0.42 g/cm3). The P-T trajectory of the probable fluid evolution path shows that the crystallization of gabbro occurred between ∼1 and 1.4 kbars, whereas alkali syenite crystallized between ∼200 and 400 bars. The secondary H2O inclusions in alkali syenite were trapped in the later stages of the hydrothermal process and at much lower temperatures (130–290°C), but at pressures relatively close to those of alkali syenite crystallization. The almost isobaric conditions during the final stage of the fluid evolution path are explained by the very shallow emplacement of the alkali syenite intrusive body.

Interpolation methods for geochemical maps : a comparative study using arsenic data from European stream waters

A geochemical map of As in water from the FOREGS Geochemical Atlas of Europe, performed using the Alkemia interpolation method based on moving weighted median (MWM), and a comparable map prepared by kriging are compared with an As map prepared with a new multifractal inverse distance weighted (MIDW) interpolation method using GeoDas™ software. The colour scale classification of the MIDW interpolated map of As is based on the concentration–area (C-A) fractal method which allows images to be subdivided into components representing specific features on the ground related, for example, to geology. Conventional techniques, such as MWM and kriging, are shown to smooth out the local variability of the geochemical data. The problem is most serious in maps prepared by kriging which erroneously show large areas of Europe to have high levels of As in water. On the other hand, MIDW creates a geochemical map in which information about the local data structure is retained. This is essential in distinguishing anomalies from background values. The information provided by background and anomaly maps, using the MIDW and fractal filtering methods, are shown to give more reliable upper limits of background values.

Bioavailability and soil-to-plant transfer factors as indicators of potentially toxic element contamination in agricultural soils

Soil pollution in agricultural lands poses a serious threat to food safety, and suggests the need for consolidated methods providing advisory indications for soil management and crop production. In this work, the three-step extraction procedure developed by the EU Measurement and Testing Programme and two soil-to-plant transfer factors (relative to total and bioavailable concentration of elements in soil) were applied on polluted agricultural soils from southern Italy to obtain information on the retention mechanisms of metals in soils and on their level of translocation to edible vegetables. The study was carried out in the Sarno river plain of Campania, an area affected by severe environmental degradation potentially impacting the health of those consuming locally produced vegetables. Soil samples were collected in 36 locations along the two main rivers flowing into the plain. In 11 sites, lettuce plants were collected at the normal stage of consumption. According to Italian environmental law governing residential soils, and on the basis of soil background reference values for the study area, we found diffuse pollution by Be, Sn and Tl, of geogenic origin, Cr and Cu from anthropogenic sources such as tanneries and intensive agriculture, and more limited pollution by Pb, Zn and V. It was found that metals polluting soils as a result of human activities were mainly associated to residual, oxidizable and reducible phases, relatively immobile and only potentially bioavailable to plants. By contrast, the essential elements Zn and Cu showed a tendency to become more readily mobile and bioavailable as their total content in soil increased and were more easily transported to the edible parts of lettuce than other pollutants. According to our results, current soil pollution in the studied area does not affect the proportion of metals taken up by lettuce plants and there is a limited health risk incurred.

A model for the evolution of the Mt. Somma-Vesuvius magmatic system based on fluid and melt inclusion investigations

Abstract In this paper, we present compositional data of reheated silicate melt inclusions (MI) from cumulate nodules and from one skarn xenolith trapped by olivine and clinopyroxene crystals. All MIs were analyzed by electron microprobe, while some were selected to be analyzed by secondary ion mass spectrometry (SIMS). Based on petrography and mineral compositions, clinopyroxene in the studied nodules can be divided into three types: cumulus pyroxene; postumulus pyroxene and fassaitic pyroxene present in the skarn nodule. The coherent trends displayed by the compositions of cumulus and post-cumulus clinopyroxene suggest that they formed at variable stages of fractionation of a single magmatic system. MIs in nodules display large compositional variations. Their compositions are not consistent with an olivine-clinopyroxene co-crystallization, which is a well-established feature of Vesuvius volcanism. Olivine and clinopyroxene from the nodules may have crystallized from the pre-79 AD Vesuvius magmas. Alternatively, variations in MI compositions may results from post-entrapment reequilibration with their hosts during residence within the magmatic system prior to eruption. The compositions of MIs in clinopyroxene from the skarn nodule are characterized by anomalously low TiO 2 and P 2 O 5 contents and high Na 2 O/K 2 O values. FI and MI, in conjunction with data available from previous research, suggest that Mt. Somma-Vesuvius plumbing system is made up of small magma chambers at depths greater than 3.5 km and that possibly a larger chamber exists at or below 12 km. The entire system likely resembles a complex feeding column which is dominated by multiple mush zone environments (small magma chambers), and thus includes a variety of local crystallization environments characterized by contrasting cooling rates and P-T conditions.