A Biogeochemical analysis of Mediterranean ecosystems and the response to nitrogen deposition: an insight on the carbon and nitrogen cycle in Mediterranean Ecosystems

The carbon (C) and nitrogen (N) cycles have been drastically altered by humans as result of the increasing demand for energy, raw material and food. Combustion of fossil fuels and increasing industrial activities are linked with the emission of carbon dioxide (CO2), which is largely responsible for the rise in atmospheric CO2 concentration during the past 50 years. At the same time, there has also been an increase in the concentration of oxidized (NOX) and reduced (NH3) nitrogenous compounds in the atmosphere, largely attributable to vehicular traffic and agricultural practice. In dry and hot conditions of the Mediterranean, the interaction of reactive N with plants and soils didn’t receive much attention. The thesis strongly contributes to fill this knowledge gap with research on the belowground part of the cycles. The work has been part of NitroMed, exciting new network of N deposition experiments in the Mediterranean. More specifically this PhD dissertation bring an insights to the role of N emission in Mediterranean basin through a review of existing literature (ch2), an improved understanding on the role of biocrusts in dryland ecosystem functioning (ch3), an in-depth understanding on how increased N deposition can first stimulate and in the longer term (or at higher deposition rates) break organic matter mineralisation in soils (ch4) and an elegant proposal of mechanistic understanding on N deposition effects on soil biological activity and C mineralization (ch5)

An experimental study of the grain-scale processes of peridotite melting : implications for major and trace element distribution during equilibrium and disequilibrium melting

Author Posting. © Springer, 2008. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Contributions to Mineralogy and Petrology 156 (2008): 87-102, doi:10.1007/s00410-007-0275-8.The grain-scale processes of peridotite melting were examined at 1340°C and 1.5 GPa using reaction couples formed by juxtaposing pre-synthesized clinopyroxenite against pre-synthesized orthopyroxenite or harzburgite in graphite and platinum-lined molybdenum capsules. Reaction between the clinopyroxene and orthopyroxene-rich aggregates produces a melt-enriched, orthopyroxene-free, olivine + clinopyroxene reactive boundary layer. Major and trace element abundance in clinopyroxene vary systematically across the reactive boundary layer with compositional trends similar to the published clinopyroxene core-to-rim compositional variations in the bulk lherzolite partial melting studies conducted at similar P– T conditions. The growth of the reactive boundary layer takes place at the expense of the orthopyroxenite or harzburgite and is consistent with grain-scale processes that involve dissolution, precipitation, reprecipitation, and diffusive exchange between the interstitial melt and surrounding crystals. An important consequence of dissolution–reprecipitation during crystal melt interaction is the dramatic decrease in diffusive reequilibration time between coexisting minerals and melt. This effect is especially important for high charged, slow diffusing cations during peridotite melting and melt-rock reaction. Apparent clinopyroxenemelt partition coefficients for REE, Sr, Y, Ti, and Zr, measured from reprecipitated clinopyroxene and coexisting melt in the reactive boundary layer, approach their equilibrium values reported in the literature. Disequilibrium melting models based on volume diffusion in solid limited mechanism are likely to significantly underestimate the rates at which major and trace elements in residual minerals reequilibrate with their surrounding melt.This work was supported by NSF grants EAR-0208141 and EAR-0510606 to Yan Liang

Using biochar for environmental recovery and boosting the yield of valuable non-food crops: the case of hemp in a soil contaminated by potentially toxic elements (PTEs)

Hemp (Cannabis sativa L.) is known to tolerate high concentrations of soil contaminants which however can limit its biomass yield. On the other hand, organic-based amendments such as biochar can immobilize soil contaminants and assist hemp growth in soils contaminated by potentially toxic elements (PTEs), allowing for environmental recovery and income generation, e.g. due to green energy production from plant biomass. The aim of this study was therefore to evaluate the suitability of a softwood-derived biochar to enhance hemp growth and promote the assisted phytoremediation of a PTE-contaminated soil (i.e., Sb 2175 mg kg-1; Zn 3149 mg kg-1; Pb 403 mg kg-1; and Cd 12 mg kg-1). Adding 3% (w/w) biochar to soil favoured the reduction of soluble and exchangeable PTEs, decreased soil dehydrogenase activity (by ~2.08-fold), and increased alkaline phosphomonoesterase and urease activities, basal respiration and soil microbial carbon (by ~1.18-, 1.22-, 1.22-, and 1.66-fold, respectively). Biochar increased the abundance of selected soil culturable microorganisms, while amplicon sequencing analysis showed a positive biochar impact on α-diversity and the induction of structural changes on soil bacterial community structure. Biochar did not affect root growth of hemp but significantly increased its aboveground biomass by ~1.67-fold for shoots, and by ~2-fold for both seed number and weight. Biochar increased the PTEs phytostabilisation potential of hemp with respect to Cd, Pb and Zn, and also stimulated hemp phytoextracting capacity with respect to Sb. Overall, the results showed that biochar can boost hemp yield and its phytoremediation effectiveness in soils contaminated by PTEs providing valuable biomass that can generate profit in economic, environmental and sustainability terms

Nitrogen deposition effects on soil properties, microbial abundance, and litter decomposition across three shrublands ecosystems from the Mediterranean Basin

Atmospheric nitrogen (N) inputs in the Mediterranean Basin are projected to increase due to fossil fuel combustion, fertilizer use, and the exacerbation of agricultural production processes. Although increasing N deposition is recognized as a major threat to ecosystem functioning, little is known about how local environmental conditions modulate ecosystem function response to N addition, particularly in the context of Mediterranean-Basin ecosystems. Here, we assess how N addition affects important ecosystem properties associated with litter decomposition, soil physical-chemical properties, soil extracellular enzymatic activity and microbial abundance across three long-term N addition experimental sites in the Mediterranean Basin. Sites were located in El Regajal (Madrid, Spain), Capo Caccia (Alghero, Italy), and Arrábida (Lisbon, Portugal) and are all representative of Mediterranean shrublands. No common pattern for litter decomposition process or other studied variables emerged among the control plots of the studied sites. Nitrogen supply only affected soil pH, a major driver of decomposition, in two out of three experimental sites. Moreover, when we explored the role of N addition and soil pH in controlling litter decay, we found that the effects of these factors were site-dependent. Our results point out to local ecosystem features modulating N addition effects in controlling litter decomposition rates in Mediterranean ecosystems, suggesting that the responses of soil functioning to N deposition are sitedependent. These findings provide further knowledge to understand contrasting ecosystem responses to N additions based on a single field experiments

Ecological impacts of atmospheric pollution and interactions with climate change in terrestrial ecosystems of the Mediterranean Basin:Current research and future directions

Mediterranean Basin ecosystems, their unique biodiversity, and the key services they provide are currently at risk due to air pollution and climate change, yet only a limited number of isolated and geographically-restricted studies have addressed this topic, often with contrasting results. Particularities of air pollution in this region include high O3 levels due to high air temperatures and solar radiation, the stability of air masses, and dominance of dry over wet nitrogen deposition. Moreover, the unique abiotic and biotic factors (e.g., climate, vegetation type, relevance of Saharan dust inputs) modulating the response of Mediterranean ecosystems at various spatiotemporal scales make it difficult to understand, and thus predict, the consequences of human activities that cause air pollution in the Mediterranean Basin. Therefore, there is an urgent need to implement coordinated research and experimental platforms along with wider environmental monitoring networks in the region. In particular, a robust deposition monitoring network in conjunction with modelling estimates is crucial, possibly including a set of common biomonitors (ideally cryptogams, an important component of the Mediterranean vegetation), to help refine pollutant deposition maps. Additionally, increased attention must be paid to functional diversity measures in future air pollution and climate change studies to establish the necessary link between biodiversity and the provision of ecosystem services in Mediterranean ecosystems. Through a coordinated effort, the Mediterranean scientific community can fill the above-mentioned gaps and reach a greater understanding of the mechanisms underlying the combined effects of air pollution and climate change in the Mediterranean Basin

The potential evolution of the supply of credit to the productive chain: A focus on Italy and the Regional Sardinian economy

The analysis performed in this chapter aims to define the dynamics of the demand for and supply of credit for the regional Sardinian economy, compared to other Italian regions, during the period from 2002 to 2013. Typical methodologies for the analysis of financial series (velocity and momentum indicators), as well as the methodologies for spatial analysis (principal component analysis, cluster analysis and specialisation indexes), have been employed for this purpose. Based on a sample of macro- and micro-data – the latter being related to 19,000 firms – our analysis highlights the existence of some high-performing industry segments, such as Lodging, Food and Food Services (LFFS). Overall, our results show undeniable criticalities with regard to the allocative efficiency of banks. For the most recent years of the sample, banks severely shrank the credit supply towards the most dynamic sectors, exhibiting instead an increasing credit specialisation towards weaker performing sectors, which are characterised by high rates of impaired loans

Draghi a Rimini. Note e letture al contorno sull'Europa, il Villaggio Globale e il buon samaritano

Questo volumetto racconta del realismo un po’ kantiano di Mario Draghi e della caleidoscopica parabola dell’altro, il buon samaritano, come ce lo racconta Papa Francesco, nel passaggio tra il prima e il dopo pandemia (before the pandemic, b.p., e after pandemic, a.p., nello swahili del villaggio globale, suggerito dal Times). Il discorso secco e nitido di Draghi a Rimini viene riportato, con note e letture d’accompagno, alla moda dei vecchi sussidiari; il cuore oltre l’ostacolo - quello dello spettro per l’Europa dello schiaffo all’altro da sé - gettato dall’ex Presidente della BCE viene coniugato utilizzando frasi estratte, come fior da fiore, dalla lettera/enciclica “Fratelli tutti”. I destinatari sono i giovani d’età o di spirito. I primi con l’ansia di Icaro, i secondi con la perseveranza di Sisifo