Soil contamination evaluation by Enrichment Factor (EF) and Geoaccumulation Index (Igeo)

Heavy metals are natural constituents of soils and their concentration varies depending on parental materials. The soils were formed by. In the last years, the content of heavy metal in soils has increased due to human activities as: distribution of fertilizers, pesticides, industries, waste disposal and air pollution. Due to these activities the life capacity of soils decreased; especially where the natural background is already high because of natural parental material richness in heavy metal. As a matter of fact it is very important to distinguish between the natural background values and anthropogenic inputs, and to understand that the background values change from area to area and with the scale of the area investigated. To evaluate the soil contamination rate different indexes like Enrichment Factor (EF) and geoaccumulation index (Igeo) can be applied. These indexes are used to assess the presence and intensity of anthropogenic contaminant deposition on surface soil

Strontium Isotope as Tracers of Groundwater Contamination

Groundwater flowing under a municipal solid waste landfill has been studied to identify potential contamination phenomenon and to test strontium isotopic composition as a natural tracer of contamination. The study was carried on in June 2014 in central Italy. Five selected boreholes were selected and analysed according to their location related to the site. Samples taken from boreholes placed upward to the site were considered as uncontaminated groundwater. One borehole located downward from the site and with major contaminant values has been considered as potentially contaminated end-member. Sr isotope results show that samples located upward from the site present lower Sr concentration and highest Sr isotopic values, which reflects weathered bedrock, while borehole located downward from the site show lowest Sr values and 87Sr/86Sr ratio, probably due to pollution by landfill leachate. The mixing calculation highlights the possible mixing phenomenon for the other samples located downward from the site

Critical currents and pinning forces in Nd2−xCexCuO4− thin films

Critical current density, Jc, and flux-pinning force density, Fp, have been investigated at different temperatures in electron-doped Nd2−xCexCuO4− thin films for magnetic fields, H, applied parallel to the c axis. The reduced pinning force density fFp /Fp max shows a clear scaling behavior when H is normalized to the irreversibility field H, indicating the presence of the same pinning mechanism in the investigated temperature range. Moreover the maximum of Fp as function of the field at each temperature depends linearly on H. The experimental data, interpreted using a modified Anderson-Kim description of the flux-creep theory, imply a magnetic field dependence of the activation energy UHH− with =0.8. This value indicates that in Nd2−xCexCuO4− a quasi-two-dimensional vortex system is present, intermediate between Bi-based and Y-based hole-doped compounds

Competition between intrinsic and extrinsic effects in the quenching of the superconducting state in FeSeTe thin films

We report the first experimental observation of the quenching of the superconducting state in current-voltage characteristics of an iron-based superconductor, namely, in FeSeTe thin films. Based on available theoretical models, our analysis suggests the presence of an intrinsic flux-flow electronic instability along with non-negligible extrinsic thermal effects. The coexistence and competition of these two mechanisms classify the observed instability as halfway between those of low-temperature and of high-temperature superconductors, where thermal effects are respectively largely negligible or predominant.Comment: 7 pages, 5 figures, fixed typo

Stability mechanisms of high current transport in iron-chalcogenides superconducting films

The improvement in the fabrication techniques of iron-based superconductors have made these materials real competitors of high temperature superconductors and MgB$_2$. In particular, iron-chalcogenides have proved to be the most promising for the realization of high current carrying tapes. But their use on a large scale cannot be achieved without the understanding of the current stability mechanisms in these compounds. Indeed, we have recently observed the presence of flux flow instabilities features in Fe(Se,Te) thin films grown on CaF$_2$. Here we present the results of current-voltage characterizations at different temperatures and applied magnetic fields on Fe(Se,Te) microbridges grown on CaF$_2$. These results will be analyzed from the point of view of the most validated models with the aim to identify the nature of the flux flow instabilities features (i.e., thermal or electronic), in order to give a further advance to the high current carrying capability of iron-chalcogenide superconductors.Comment: 4 pages, 3 figure

First Report of 'Candidatus Phytoplasma phoenicium' on Almond in Southern Italy

In spring 2017, phytoplasma suspected symptoms were reported on 25% of 15-year-old almond plants, cultivars Filippo Ceo and Genco grafted onto GF677, in a commercial orchard (20 ha) located at Grottaglie, Apulia (southeast Italy). Among the symptoms, development of many axillary buds with small and yellowish leaves, and witches' brooms developing from the trunk, were the most frequent, followed by leaf rosetting, proliferation of slender shoots, tree decline, and dieback

Groundwater: a matter of quality and quantity in Limpopo National Park

Groundwater is a matter of quantity and quality, especially where groundwater is the primary source of water for people living in the SADC (Southern African Development Community) region, because it is used, extensively, for multiple purposes, covering a crucial role in supplying water for farming and domestic uses. The large SADC area has limited surface and groundwater resources, because most of the water management areas are severely stressed and many people still do not have access to the accepted minimum supply of water. Increasing water demand, population growth, abstraction of surficial water and climate change are the main drivers on groundwater resources in SADC Region. Water scarcity is becoming a limiting factor for economic development in the basin, as it is in many other basins located in developing countries with arid climates, lagging water infrastructure development, and rapidly increasing populations. The first step for a sound water resources planning is the knowledge of the hydrogeological conceptual model in the area under study. Most rural communities in SADC are served by groundwater resources. Access to these resources is one and important critical factors. The lack of management of groundwater resources is also evident in community water supplies, where in some cases groundwater resources are developed in unsustainable way. The aim of the present study is to design the water resources status quo, defining the hydrological conceptual model assessing the hydrogeochemical properties of groundwater in the Limpopo National Park, one of the jewels in the crown of Mozambique’s protected areas, in order to quantify the water balance and to provide recommendations for a future correct management, focusing future research on this subject