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.