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Lower Messinian stromatolites of the Calcare di Base Formation at Sutera in Sicily record periods of low sea-level, strong evaporation and elevated salinity, thought to be associated with the onset of the Messinian Salinity Crisis. Overlying aragonitic limestones were precipitated in normal to slightly evaporative conditions, occasionally influenced by an influx of meteoric water. Evidence of bacterial involvement in carbonate formation is recorded in three dolomite-rich stromatolite beds in the lower portion of the section that contain low domes with irregular crinkly millimetre-scale lamination and small fenestrae. The dominant microfabrics are: (i) peloidal and clotted dolomicrite with calcite-filled fenestrae; (ii) dolomicrite with bacterium-like filaments and pores partially filled by calcite or black amorphous matter; and (iii) micrite in which fenestrae alternate with dark thin wispy micrite. The filaments resemble Beggiatoa-like sulphur bacteria. Under scanning electron microscopy, the filaments consist of spherical aggregates of dolomite, interpreted to result from calcification of bacterial microcolonies. The dolomite crystals are commonly arranged as rounded grains that appear to be incorporated or absorbed into developing crystal faces. Biofilm-like remains occur in voids between the filaments. The dolomite consistently shows negative d13C values (down to -11.3‰) and very positive d18O (mean value 7.9‰) that suggest formation as primary precipitate with a substantial contribution of organic CO2. Very negative d13C values (down to -31.6‰) of early diagenetic calcite associated with the dolomite suggest contribution of CO2 originating by anaerobic methane oxidation. The shale-normalized rare earth element patterns of Sutera stromatolites show features similar to those in present-day microbial mats with enrichment in light rare earth elements, and M-type tetrad effects (enrichment around Pr coupled to a decline around Nd and a peak around Sm and Eu). Taken together, the petrography and geochemistry of the Sutera stromatolites provide diverse and compelling evidence for microbial influence on carbonate precipitation.

The relatively high influx of unregulated industrial and domestic effluents has progressively degraded the Palermo coastal environment in NW Sicily. To evaluate the poorly known effects of these inputs on the Palermo Gulf, three sediment box-cores were collected along a transect perpendicular to the coast, in front of the Oreto river mouth, in water depths of 20—750 m. The samples, dated by 210Pb and 137Cs, were analysed for concentration of major/trace elements, total polycyclic aromatic hydrocarbon (PAH), total organic carbon (TOC) and for organic carbon and nitrogen isotopic compositions. Total organic carbon concentrations show relatively high values (0.4—2.9%), with a decreasing seawards trend. An increasing contamination over the last 80 years was revealed by trace metal (notably Pb, Hg, As, and Cr) and PAH concentration patterns. These concentrations appear to be potentially hazardous, grossly exceeding national and international regulatory guidelines. In the central sector of the Palermo Gulf, changes in the Corg/Ntot ratios and δ13Corg values suggest that a eutrophication process, rather than direct land runoff, is currently developing.

The Augusta area (SE Sicily) is one of the most industrialized and contaminated coastal environments in the Mediterranean region, having a relatively high influx of unregulated industrial effluents. Valuable sets of geochemical data (major elements and trace metals), obtained from box-core sediments collected along a transect from the Sicilian coastal zone seawards of Augusta and dated via 210Pb and 137Cs, indicated increased metal contamination (notably Hg) since ca 1940-1950, related to the industrial development of the area. Metal enrichment is considerable in the coastal sediments, being significantly in excess (for Hg and Pb) of background values estimated for the Strait of Sicily. Moreover, investigations of benthic foraminifera assemblages showed a reduction in foraminiferal abundance, increasing percentages of tests with various morphological deformities, and dominance of opportunistic species in more recent sediments. These findings can be correlated to the strong anthropogenic impact. The results obtained support the idea that the pollutant impact is not only confined to the coastal area, but has also affected the open sea environment. At offshore core sites, repeated abrupt Hg enrichments are roughly concurrent with positive Gd anomalies and significant increases of TOC with substantial proportions of land-derived organic material, indicating that the region experienced changes in natural sediment source/composition induced by repeated discharge of contaminated dredged materials from polluted coastal areas. Consistent with the geochemistry of recent turbidites, these anomalous sedimentary inputs have induced changes in the sediment redox environment, shown by distinct Mn peaks and negative Ce anomalies.

Concentrations of major, minor and trace elements were determined in soil profiles and soil solutions from the island of Pantelleria, Sicily Channel, to evaluate the weathering extent of soils evolved on trachytic and pantelleritic rocks and the aqueous transport of elements by their soil solutions. The chemical index of alteration (CIA) indicates a low-to-moderate degree of weathering; consistently, the mineralogical and geochemical imprints of the parent rocks are generally preserved. The chemical weathering appears to be incongruent, owing to primary minerals and glass dissolving to a variable degree while secondary minerals have formed. Based on the calculated saturation state of primary and secondary minerals with respect to the soil solutions and on mineralogical observations, olivine and pyroxene are unstable and dissolving whereas magnetite and hematite are stable. The main weathering products are amorphous phases, such as ferrihydrite, amorphous aluminium hydroxide and silica. Clay mineral formation appears to be incipient and mainly limited to kaolinite and smectite, although for some soil profiles a hydrothermal origin is suggested for these minerals. Chemical characteristics of soil solutions and elemental mobility are controlled by the element source and water-rock interaction.

The volcanic island of Pantelleria produces a naturally sweet wine Moscato di Pantelleria DOC obtained from the «Moscato d'Alessandria» (or «Zibibbo»), a grape favoured by hot climate. Geochemical and mineralogical investigations performed on soil profiles devoloped on rocks representative of the major outcropping lithologies (pantellerite, trachyte and alkalic basalt) show that the soils have preserved the parent material imprint. Consistently, values of the chemical index of alteration (CIA) indicate a low to moderate weathering degree for the rocks exposed in the Pantelleria area and consequently a low to moderate soil evolution. Soil-solution chemical analyses highlight that macro- and micronutrient elements are present in forms potentially available to plants. Although the grape ripening capacity is controlled by various factors (climate, pedologic substratum, exposure, morphology), different degrees of weathering, as measured by CIA values, appear to correspond to different grape ripening times. Less weathered soils contain noncrystalline phases, mainly Fe and Al hydroxides, which make them more sensitive to drying effects; these soils are generally related to early sites. In more weathered soils, the presence of clay minerals contributes to increased available water content and, in turn, to conditions of enhanced specific heat, which can delay the grape ripening.