B. De Vivo

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.

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.

Urban geochemical mapping in the Campania region (Italy)

This work reviews the results of research conducted in the last five years on urban soils of the Campania region, southern Italy. Approximately 2000 topsoil samples were collected and analysed for 40 elements, among which are included the potentially harmful elements (PHE). The two most relevant objectives achieved were the determination of background levels for each element, using concentration–area (C–A) and separation–anomaly (S-A) algorithms, and the production of an extensive cartography, published in a series of geochemical atlases. The latter show that high PHE concentrations, exceeding many times the local natural backgrounds (especially Pb, Hg, Sb, Zn), are found in the most densely populated areas, often affected by heavy vehicular traffic and industrial activities. Many soil samples exceed the limits set for PHE by the Italian Ministry of the Environment in law DM 471/99 for residential land use. The geochemical maps can prove to be very useful both for scientists and professionals working towards the restoration of contaminated areas, as well as serving to refine the Italian environmental legislation to be more effective in local situations.

Potential environmental hazard in the mining district of southern Iglesiente (SW Sardinia, Italy)

A stream sediment survey carried out in southern Iglesiente, southwestern Sardinia, comprised 249 samples which were analysed for 35 elements. The data from 83 samples derived from a previous survey by Ente Minerario Sardo were also used. Maps showing element distribution were created using the GIS program Arc View 3.1. For the compilation of potential risk maps, the regional distribution of the elements has been reclassified using as thresholds the Italian intervention criteria for residential=recreational and commercial=industrial land use. The main concentrations of heavy elements mainly follow the carbonate lithologies, hosting most of the ore deposits of Mississippi Valley and Sedimentary Exhalative types. Fairly high contents of Pb, Zn, Cd, and As are reflected in the stream sediments sampled along the carbonate ridges bordering the mining district along the Iglesias syncline. Treatment plants, tailings and dumps are also located in this area. Another area with high metal values is the swampy river mouth of Rio Sa Masa, near Gonnesa, draining not only the main mining sites of the Iglesias syncline, but also the small industrial areas around the town of Iglesias and a few villages. Potential risk maps have been compiled for four elements: Zn, Pb, Cd and As. Among those, the state of geochemical pollution is very serious for Cd, Pb, and Zn, which are the main elements contained in the stratabound orebodies, but less so for As. If even only partly transferred to the soils, the concentration in these elements should limit any further development in this area, unless remediation is carried out.

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.

Anthropogenic vs. natural pollution: an environmental study of an industrial site under remediation (Naples, Italy)

Heavy metal concentrations and Pb isotopic composition were determined in the soils, slags, scums and landfill materials from a shut down industrial (brownfield) site. This was the second largest integrated steelworks in Italy, and is now under remediation by a Government project. It is located in the outskirts of Napoli on the Bagnoli–Fuorigrotta plain (BFP), which is part of the Campi Flegrei (CF) volcanic caldera, where many spas and geothermal springs occur. The purpose of this work is to distinguish the natural (geogenic) component, originated by hydrothermal activity, from anthropogenic contamination owing to industrial activity. ‘In-situ sediments’ (soils), slags, scums and landfill materials from 20 drill-cores were selected from a network of 197 drills carried out on a 100 × 100 m grid, covering the entire brownfield site. In general, heavy metal enrichments in the upper 3 m of the cores strongly suggest mixing between natural (geogenic) and anthropogenic components. Pb isotopic data are suggestive of three potential end members, and confirm the existence of a strong natural component in addition to contamination from anthropogenic activities. The slags, scums and landfill materials have been proved, through mineralogy and leachate experiments, to be geochemically stable; this shows that metal pollutants are not bio-available and, hence, do not pose a risk to future developments on this site. The natural contribution of hydrothermal fluids to soil pollution, in addition to the non-bio-availability of metal pollutants from industrial materials, indicate that heavy metal remediation of soils in this area would be of little use. Continuous discharge from mineralized hydrothermal solutions would cancel out any remediation effort.

Melt-mineral-fluid interactions in ultramafic nodules from alkaline lavas of Mount Etna (Sicily, Italy): Melt and fluid inclusion evidence

Abstract Clinopyroxene phenocrysts and ultramafic nodules in the “Ancient Alkaline Lavas” of Mount Etna contain melt and fluid inclusions which represent immiscible trapping of basaltic melt and CO2. Inclusions consist of glass + vapor (CO2) hosted by clinopyroxene with kaersutite, magnetite, spinel and apatite daughter minerals (type I), and liquid (CO2) + vapor (CO2) + glass secondary inclusions (type II) with highly variable fluid/glass ratios. Electron-microprobe investigations on type I melt inclusions indicate a glass of trachitic composition, with extremely high chlorine contents (0.5–1 wt.%), which we believe evolved from an initial melt composition of an alkali-basalt. Homogenization temperatures (Th) (n=128) of type II CO2 + glass inclusions display a bimodal fluid density distribution, with high-density (0.61–0.75 g/cm3) CO2 fluids in the nodules, and low-density (0.23–0.61 g/cm3) CO2 fluids in the phenocrysts. A two-step degassing process is proposed with high-density immiscible CO2 fluids, formed at pressures of about 4.3 kbar. The density distribution suggests interaction events between nodules, ascending lavas, and fluid phases, with a peak around 3.5 kbar. A second generation of lower-density CO2 is recorded around 2.8 kbar, most likely prior to eruption.

Baseline geochemical mapping of Sardinia (Italy)

A total of about 20,000 stream sediment samples from about 13,000 km2 were collected in Sardinia and analysed for eleven elements (Ag, Co, Cr, Cu, F, Hg, Mn, Mo, Ni, Pb, Sb and Zn) by Ente Minerario Sardo (EMS), aimed at mineral exploration. We have reutilized 16,890 samples (covering an area of 7987 km2) of the above data to compile geochemical baseline maps for all single elements as well as maps showing the regional variability of factor scores resulting from R-mode factor analysis. This type of maps has a particular relevance to environmental issues, especially in a region such as Sardinia which has been mined since pre-Roman times.

The rare earth element distribution over Europe: geogenic and anthropogenic sources

The distribution of rare earth elements (REE) in Europe has been investigated using new geochemical data prepared by the Forum of European Geological Surveys (FOREGS), to estimate baseline values and to identify anomalous levels attributable to anthropogenic sources. Interpolated maps showing REE distributions in subsoils were generated using ArcView™ and classified with the new concentration–area (CA) fractal method available in the software GeoDAS™; they identify three broad ranges for baseline REE levels that are related to regional geological/geomorphological features. A combination of REE spider diagrams and interpolated maps showing REE distributions in floodplain and stream sediments was used to investigate anthropogenic sources of REE in Europe. It is concluded that the large-scale distribution patterns of REE over Europe are entirely attributable to geology. No evidence has been found of REE contamination from likely anthropogenic sources such as the electronics or nuclear industry. Three component colour maps of REE ratios (Gd/Lu, Eu/Eu* and La/Y) were used to identify the major plates of the Variscan orogeny and Variscan granites caught up in Alpine nappes in Italy.