A pedological case study of volcanoclastically impacted landscapes: The Vesuvian Avellino air-fall deposits, Southern Italy

Volcanic sediments are involved in both stratigraphic architecture and pedological environment of the impacted surfaces. Volcanic deposits are widespread in the southern Italian region of Campania, generating extensive tephrostratigraphic and pedological studies. Nevertheless, the pedogenetic effects of the distribution of volcanic sediments have not been fully investigated. The implications of tephra burial and composition on pedogenetic processes have been studied by comparing soil profiles in two different locations influenced by the pumice fall-deposit from the Vesuvian Avellino eruption (about 3360 years BP): Mt. Somma volcano and Mt. Arciano. The latter forms part of the carbonate Campanian Apennines, where the carbonate rock has been excluded from the main pedogenetic processes, due to emplacement of pyroclastic products. Among the described soils on Mt. Somma, the analyzed soil profile was extracted from an earlier work (see the text for the pertinent citation). For the investigation, soil morphological, mineralogical, chemical and lithological properties were determined. On Mt. Somma, the pedogenesis from the Avellino pumices was prevented by their rapid and massive burial by other volcanic sediments. In the absence of overlying materials on Mt. Arciano, the Avellino pumices provided a homogeneously developed soil with well-expressed andic soil properties. In this environment, the pumice substratum was also enriched in the glassy fraction as an effect of selection caused by the pyroclastics during the air-fall distribution. The results indicated the distance directly and indirectly influencing the pedogenesis, due to its implications on both the potential burial processes and the lateral variation in the pedogenetic substratum. (C) 2016 Published by Elsevier B.V

Landfill and natural soils on the Somma-Vesuvius volcanic complex, Italy: Differences and similarities in soil morphology and properties

The aims of this investigation were to study the modifications induced by a landfill activity on native soil morphology and properties, and to highlight the critical environmental issues related to this activity in a volcanic environment. We studied the soils from a solid waste disposal activity on Somma-Vesuvius volcanic complex. The disposal site was in operation for about 50 yr, and was recently dismantled. Adjacent natural soils were also selected and investigated. The natural soils were derived from superimposition of pyroclastics deposited by the volcanoes Somma-Vesuvius and Phlegrean Fields. In these soils, andic soil properties were mainly detected in the subsoils, while vitrandic characteristics distinguished the upper soils. Little or no pedogenetic development characterized the human-influenced soils that consisted of chaotic masses of Vesuvian earthy materials and sparse or interbedded garbic material. The earthy materials had physical and chemical characteristics similar to those of the natural upper soil horizons, lacked andic soil properties, and had a sand mineralogy similar to that of natural upper soils. Environmental concerns came out of the presence of garbage in coarse textured and weakly developed soil materials overlaying the permeable aquifer characterizing the studied area. The studied human-influenced soils were arranged using U.S. soil taxonomy into the Vitrandic subgroup of Xerorthents, that also identified the natural soils. This class was inadequate for interpreting the soil morphology and properties of soils from the solid waste disposal site, and the related environmental issues. Therefore, the suitability of adopting Garb-classes is discussed. Copyright © 2005 by Lippincott Williams & Wilkins, Inc

Fluxes of N2O and CH4 from soils of savannas and seasonally-dry ecosystems

Aim: Savannas and seasonally-dry ecosystems cover a significant part of the world's land surface. If undisturbed, these ecosystems might be expected to show a net uptake of methane (CH4) and a limited emission of nitrous oxide (N2O). Land management has the potential to change dramatically the characteristics and gas exchange of ecosystems. The present work investigates the contribution of warm climate seasonally-dry ecosystems to the atmospheric concentration of nitrous oxide and methane, and analyses the impact of land-use change on N2O and CH4 fluxes from the ecosystems in question. Location: Flux data reviewed here were collected from the literature; they come from savannas and seasonally-dry ecosystems in warm climatic regions, including South America, India, Australasia and Mediterranean areas. Methods: Data on gas fluxes were collected from the literature. Two factors were considered as determinants of the variation in gas fluxes: land management and season. Land management was grouped into: (1) control, (2) 'burned only' and (3) managed ecosystems. The season was categorized as dry or wet. In order to avoid the possibility that the influence of soil properties on gas fluxes might confound any differences caused by land management, sites were grouped in homogeneous clusters on the basis of soil properties, using multivariate analyses. Inter- and intra-cluster analysis of gas fluxes were performed, taking into account the effects of season, land management and main vegetation types. Results: Soils were often acid and nutrient-poor, with low water retention. N2O emissions were generally very low (median flux 0.32 mg N2O m-2 day-1), and no significant differences were observed between woodland savannas and managed savannas. The highest fluxes (up to 12.9 mg N2O m-2 day-1) were those on relatively fertile soils with high air-filled porosity and water retention. The effect of season on N2O production was evident only when sites were separated in homogeneous groups on the basis of soil properties. CH4 fluxes varied over a wide range (-22.9 to 3.15 mg CH4 m-2 day-1, where the negative sign denotes removal of gas from the atmosphere), with an annual average daily flux of -0.48 ± 0.96 (SD) mg CH4 m-2 day-1 in undisturbed (control) sites. Land-use change dramatically reduced this CH4 sink. Managed sites were weak sinks of CH4 in the dry season and became sources of CH4 in the wet season. This was particularly evident for pastures. Burning alone did not reduce soil net CH4 oxidation, but decreased N2O production. Main conclusions: Despite the low potential for N2O production, both in natural and managed conditions, tropical seasonally-dry ecosystems represent a significant source of N2O (4.4 Tg N2O year-1) on a global scale, as a consequence of the large area they occupy. The same environments represent a potential CH 4 sink of 5.17 Tg CH4 year-1. However, assuming that c. 30% of the tropical land is converted to different uses, the sink would be reduced to 3.2 Tg CH4 year-1. The limited information on fluxes from Mediterranean ecosystems does not allow a meaningful scaling up. © 2006 Blackwell Publishing Ltd

Relationships between pedogenetic features and clay mineralogy in Entisols from two alluvial plains of southern Italy

The relationships between the southern Italy pedoclimatic environment features, the soil properties, and the composition of the soil clay fraction were investigated. Representative Entisols from either Volturno River (pedon V37) or Sibari (pedon S90) River alluvial plains were collected. Both soils exhibited vertic features, indicating the presence of swelling clay minerals. However, the X-ray diffraction (XRD) analysis provided evidence for difference in the mineralogical composition of the clay fractions. The comparison among the XRD patterns of V37 samples ascertained occurrence of smectite. Differently, chlorite minerals with expansible component were identified by comparing XRD patterns for S90 samples. In both cases, "open' illite and kaolinite were also recognized. -from Author

Vertic soils in alluvion-reclaimed areas, Volturno River Plain, Italy

Reclamation activities in alluvial depressions in Volturno River Plain resulted in the occurrence of soils with vertic characteristics and properties. We studied the genesis and properties of soils in alluvial areas known to be reclaimed by the alluvion system about 100 yr ago, and compared these soils with natural, adjacent alluvial soils. Soils in the reclaimed areas were characterized by cracks, slickensides, and high clay contents. Soils were satisfactorily classified within the existing Vertisol order of U. S. soil taxonomy. Soils with similar vertic morphology and properties also occurred in nonreclaimed adjacent alluvial areas, where they were associated with coarser textured Entisols. Since no important morphological evidence for the reclamation activity was identified in the soils in the reclaimed areas, the anthropogenic origin of such soils only emerged from historical records. The introduction of relational properties such as historical records is currently suggested to interpret and classify soils of various proposed taxonomic classes at different categorical levels. Therefore we discuss some critical aspects of the use of the historical records for classifying the soils in the reclaimed areas into genetic and technical soil categories that are currently being defined by the International Committee on Anthropogenic Soils (ICOMANTH)