Simona Vingiani

MIXED-LAYER KAOLINITE-SMECTITE MINERALS IN A RED-BLACK SOIL SEQUENCE FROM BASALT IN SARDINIA (ITALY)

Clay minerals from soils of a red-black soil complex developed from basaltic parent material in Sardinia are formed along a short toposequence (200 m). At the foot of the sequence, a clay-rich, black Vertisol forms, whereas at the summit, the soil is a dark reddish-brown Inceptisol. X-ray diffraction, infrared spectroscopy (FTIR), cation exchange capacity (CEC) and permanent and variable charges analyses were used, and the data show that clay minerals varied according to soil horizon and topographic position of the soil. Clay minerals in the Inceptisol are dominated by kaolinite and mixed-layer kaolinitesmectite (K-S, K:S >0.5), whereas the Vertisol contains smectites and K-S with K:S proportions <0.5. In the Vertisol, the proportion of kaolinitic layers in the K-S increases from the C horizon (K:S ∼0.35–0.40) to the Ap horizon (K:S ∼0.40–0.45). This soil clay-mineral distribution, in relation to topography, is similar to that reported for other (kaolinitic) red-black (smectitic) soil associations in subtropical and tropical areas. The sequence forms by downward drainage on summits and slopes, and buildup of ions in ‘lows’ produces smectites. Fourier transform infrared spectra indicate that two types of smectite are formed in the C horizon of the Vertisol; one is more ferric (Fe-beidellite, nontronite), the other more aluminous. Mineralogical evolution in the soil profile (from C to Ap horizon) shows a decreasing proportion of ferric smectite layers (compared to the more aluminous smectite layers). This would indicate that ferric smectite layers are preferentially transformed (or dissolved) to give kaolinite layers, with Fe precipitating as oxides and/or oxy-hydroxides or retained partly in kaolinite layers. Because the surface properties of clay minerals are related to mineralogy, the CEC (33–41 cmol kg−1) in the brown Inceptisol is ∼50% pH-dependent charge while in the Vertisol up to ∼75% of the CEC (48–61 cmol kg−1) comes from accessible permanent charges.

Landslide processes and Andosols: the case study of the Campania region, Italy

Most catastrophic mudslides in Campania are related to soils developing upon pyroclastic materials covering carbonatic relieves of the Campanian Apennines. The soil observed in the detachment crowns of the investigated fast mudflow consisted of fertile Andosols (generally Hapludands and Udivitrands) that were very sensitive to anthropic or natural changes. This is due to the unique chemical, physical, morphological and hydrological behaviour of these soils, including (i) high water retention near saturation, (ii) high hydraulic conductivity, (iii) high smeariness of most horizons, and (iv) high vertical and lateral variability of the properties of the soil horizons. Aspect is important in determining soil susceptibility to landslide triggering and landslide susceptibility is related to hydrological properties that induce higher water storage especially in northern aspect soils. It is clear that stability of these soils requires conservation, implemented through appropriate forest planning and management. Improved risk management policies are necessary to preserve soil continuity and to decrease the risk both of surface soil erosion and to human lives and infrastructure.

Soil properties, strontium isotopic signatures and multi-element profiles to authenticate the origin of vegetables from small-scale regions: illustration with early potatoes from southern Italy†

We propose a method for the authentication of the origin of vegetables grown under similar weather conditions, in sites less than 10 km distance from the sea and distributed over a rather small scale area (58651 km(2)). We studied how the strontium (Sr) isotopic signature and selected elemental concentrations ([Mn], [Cu], [Zn], [Rb], [Sr] and [Cd]) in early potatoes from three neighbouring administrative regions in the south of Italy were related to the geological substrate (alluvial sediments, volcanic substrates and carbonate rocks) and to selected soil chemical properties influencing the bioavailability of elements in soils (pH, cation exchange capacity and total carbonate content). Through multiple-step multivariate statistics (PLS-DA) we could assign 26 potatoes (including two already commercialised samples) to their respective eight sites of production, corresponding to the first two types of geological substrates. The other 12 potatoes from four sites of production had similar characteristics in terms of the geological substrate (third type) and these soil properties could be grouped together. In this case, more discriminative parameters would be required to allow the differentiation between sites. The validation of our models included external prediction tests with data of potatoes harvested the year before and a study on the robustness of the uncertainties of the measurement results. Annual variations between multi-elemental and Sr isotopic fingerprints were observed in potatoes harvested from soils overlying carbonate rocks, stressing the importance of testing long term variations in authentication studies.

Future Soil Issues

This chapter aims to address future soil issues from a specific viewpoint, namely the need of our country. It starts by analysing both Italy’s physical landscape along with the social and economic structure and its population. From this basis, the chapter focuses on country limitations and potentialities and identifies the most important country-specific contributions by soil science aiming towards the well-being of Italy. We claim that future soil scientist must give major contributions in the followings: (1) spatial planning of the landscape (oriented to urban planning), (2) archaeology and natural heritage, (3) agriculture and forestry combining productivity and environmental protection, (4) hydrogeological risks, (5) integrated landscape management. In order to get these results, the authors anticipate that soil science requires a novel vision, novel approaches and most importantly a novel education combining in-depth specialized knowledge with a very good but broad and basic soil knowledge.

Soil properties and debris flows in Italy: potential relationships

Debris flows are known to be very dangerous hazards that can produce fatalities and severe damages. In the Campania region they involve Andosols with a unique set of morphological, chemical, physical, and hydrological properties that give them high fertility but, at the same time, high fragility as concerns land degradation processes, such as erosion and landslides. Because of the shallow character of some debris flows (e.g. Campania), they can strongly involve and evolve in and over the soil cover. Therefore, a better understanding of the soil properties is crucial in an integrated approach finalized to evaluate the landslide susceptibility of mountain ecosystems. The aim of this work is to investigate the soil (chemical, physical, and hydrological) properties of the detachment areas of eight debris flows occurred in non-volcanic mountain ecosystems (NVME) of Italy in the last 70 years. In this framework, we will mainly focus on the assessment of the soil andic properties, in order to verify if in the studied landscapes the debris flows involve soils characterised by these properties, as it happens in the Campania region.The analyzed events occurred on moderate to high slope gradient (ranging from 25° and 50°) and at different altitudes. Despite the lithological heterogeneity of the bedrock, the analyzed soils show remarkably similar features. Specifically, soils are generally deep and characterized by well developed topsoils, demonstrating that investigated sites were not subjected to intense erosion, which would have been expected considering the slope gradient. Moreover, these soils are markedly chemically and physically fertile, as indicated by the high organic carbon content and the prevalent loamy texture. As concerns the soil type, the preliminary analyses show that the investigated non-volcanic soils have andic and vitric features (except for Ceriana).These findings shed new light on the similarity of the materials involved by debris flows both in volcanic and non-volcanic mountain ecosystems of Italy, suggesting a pedological control on the debris flow hazard.

Monitoring metal pollution in soils using portable-XRF and conventional laboratory-based techniques: Evaluation of the performance and limitations according to metal properties and sources

Large variability in the spatial distribution and content of metals is generally recognised in anthropogenically-polluted soils, hence, a detailed site investigation implying the collection and analysis of a large number of soil samples is often necessary. To this regard, the selection of a rapid, cost-effective and accurate analytical technique to assess the concentration of metals in soil is of paramount importance. The overall objective of this work was to evaluate the possibility of assessing the aqua regia-extractable (AR) content of metals in soil from the multi-element profile of the soil obtained by a portable X-ray fluorescence analyser (pXRF). To this objective, we attempted: (i) to establish, by simple linear regressions, the relations occurring between the metal contents measured by pXRF and AR in laboratory setting on air-dried and 2 mm-sieved soil samples from two case studies (A-agricultural and B-industrial sites); (ii) to define metal-based linear models predicting metal AR contents from pXRF measurements; (iii) to assess the influence of metal properties and sources on relations found between the two analytical methods. Very satisfying correlations (R2 > 0.90) were observed between the AR and pXRF contents of Ca, Cu, Cr, Ni, Pb and Zn in the site A, and of Cd, Cu, Pb and Zn in the site B. For the majority of metals, lower AR than pXRF contents were measured, as result of the AR incomplete dissolution of metal-bearing silicates. This was not observed when metals - of anthropogenic origin - occurred in soil in very high concentrations (i.e., Cr for A and Pb for B). In both sites, the comparison among different regression parameters revealed a strong metal-dependence. Moreover, for most of the metals, the parameters of each metal-regression line significantly differed between the two case studies, indicating site-dependence of regression fits.

Soils of the Aversa plain (southern Italy)

ABSTRACT The Aversa plain is one of the most important agricultural areas of the Campania region, combining the presence of very fertile soils, sites of great archaeological interest and growing residential urbanization. In this paper, the soil map (1:50,000 scale) of the Aversa plain is presented. Three main land systems (coastal, alluvial and foothill plains) characterized by different soil types (Andosols, Phaeozems, Cambisols, Vertisols, Arenosols, Histosols, Luvisols) have been identified. However, Andosols are the most widespread soil type (9768 ha) and, along with part of the Phaeozems and Cambisols, represent the most fertile soils of the Aversa plain (first and second classes of the land capability classification). In order to evaluate recent intense soil sealing, its impact over land capability classes was assessed during the last 60 years. Results show that soil sealing in the Aversa plain affected mainly the most fertile first- and second-class soils.