Direct Conversion of Food Waste into 3D Porous Carbon Traps for Selective Adsorption of Cationic Dyes

Conversion of waste biomass into valuable functional materials accomplishes the concept of circular economy in the development of sustainable waste management, and also recovery of such resources possibly reduces the requirement of feedstocks. In this scenario, the development of methodologies toward the direct conversion of the raw biomass into solid adsorbent materials without the use of any templates is highly desirable, but exceptionally challenging due to the complexity of the process. Here the direct synthesis of 3D porous carbon traps by a simple, cost-effective, and template-free process starting from a kitchen-based recipe and fermented food waste is described. Precisely, a robust carbon trap is formed with a spongy structure and highly interconnected hierarchical pores after the pyrolysis of a rice-based foam in the air. The developed materials float on water and interact efficiently with cationic dyes at static conditions. Importantly, such performance of the 3D carbon traps is not affected in the presence of anionic dyes, indicating the excellent selectivity towards the adsorption of cationic dyes. The adsorbent can be easily recovered and reused for up to 3 cycles without releasing any byproducts, thus, without causing hazardous risk of any secondary pollution to the environment.     

Identifying rift zones on volcanoes: an example from La Réunion island,Indian Ocean

We describe a methodology for identifying complex rift zones on recent or active volcanoes, where structures hidden by recent deposits and logistical conditions might prevent carrying out detailed fieldwork. La Réunion island was chosen as a test-site. We used georeferenced topographic maps, aerial photos and digital terrain models to perform a statistical analysis of several morphometric parameters of pyroclastic cones. This provides a great deal of geometric information that can help in distinguishing the localisation and orientation of buried magma-feeding fractures, which constitute the surface expression of rift zones. It also allowed the construction of a complete GIS database of the pyroclastic cones. La Réunion is a perfect example where past and active volcanic rift zones are mostly expressed by clusters of monogenic centres. The data has been validated in the field and compared and integrated with the distribution and geometry of dyke swarms. Results show the presence of several main and secondary rift segments of different ages, locations and orientations, whose origin is discussed considering regional tectonics, local geomorphology, and volcano deformation.     

Fluid Geochemistry as Indicator of Tectonically-Related,Deep Water Circulations in the Sardinian Rift-Campidano Graben (Italy): New Insights from Environmental Isotopes

The EC funded Geochemical Seismic Zonation program (EEC GSZ Project 1996–1998) chose Sardinia as a low-seismicity site, in which the relationships between fluid geochemistry and seismo-tectonics had to be investigated and results compared with outcomes from other selected high-seismicity sites. A first article, examining the role of fault segmentation and seismic quiescence on the geochemical composition of groundwaters and gases, has already been presented (Angelone et al. 2005). This article deals with environmental isotopes which, together with selected hydrochemical data, give hints on tectonically-related fluid circulations. Four water-dominated hydrothermal systems were considered, all located along regional fault systems and discharging groundwaters belonging to the Na–HCO₃ and Na–Cl facies. In the considered systems, groundwater circulation takes place, principally, in the Palaeozoic Crystalline Basement (PCB), with the exception of the Logudoro system, where hydrological circuits develop in the Mesozoic Carbonate Platform (MCP). The high CO₂ contents, the non-attainment of fluid-rock equilibrium and the large lithological variability prevent the construction of a unique hydrogeological–geochemical conceptual model. In this case, stable isotopes provide a useful tool to describe the origin of fluids and their subterranean movements. Stable isotopes of water, integrated with hydrochemical data, indicate that fluids are derived from three main end members. The dominant component is a relatively recent local meteoric water; the second one is marine water; and the third one is a fossil freshwater, depleted in heavy isotopes with respect to modern rains. The latter end member entered the aquifer system in the past, when climatic conditions were greatly different from today. At least two circulation systems can be recognised, namely a shallow cold system and a deep hydrothermal system, as well as two distinct hydrological processes: (1) gravity-controlled descent of cold water towards greater depths and (2) convection linked to a thermal gradient, causing deep fluids to rise up from the hydrothermal reservoir towards the surface. The highly variable δ¹³C_TDIC values suggest the presence of two distinct CO₂ sources, namely, a biogenic one and a thermogenic one. The relation between the isotopic compositions of CO₂ and He indicates an increased mantle signature in uprising CO₂-rich fluids.     

A hydraulic invariance‐based methodology for the implementation of storm‐water release restrictions in urban land use master plans

A hydraulic invariance (HI)‐based methodology was developed as a tool to support implementation of storm flow control measures into land use master plans (LUMPs) for urban catchments. The methodology is based on the use of simple hydrologic analysis to compare predevelopment and postdevelopment catchment flow release scenarios. Differently from previous literature examples, for which the parcel scale is usually considered for the analysis, HI was pursued assuming the LUMP areas of transformation as the basic units for assigning storm water control measures in the form of flow release restrictions. The methodology was applied to a case study catchment in the southern part of the City of Catania (Italy), for which the LUMP re‐design has been recently proposed. Simulations were run based on the use of the EPA‐Storm Water Management Model and allowed deriving flow release restrictions in order to achieve HI at the subcatchment level for design events of different return period.     

Vegetation turnover in a braided river: frequency and effectiveness of floods of different magnitude

This work addresses the temporal dynamics of riparian vegetation in large braided rivers, exploring the relationship between vegetation erosion and flood magnitude. In particular, it investigates the existence of a threshold discharge, or a range of discharges, above which erosion of vegetated patches within the channel occurs. The research was conducted on a 14 km long reach of the Tagliamento River, a braided river in north‐eastern Italy. Ten sets of aerial photographs were used to investigate vegetation dynamics in the period 1954–2011. By using different geographic information system (GIS) procedures, three aspects of geomorphic‐vegetation dynamics and interactions were addressed: (i) long‐term (1954–2011) channel evolution and vegetation dynamics; (ii) the relationship between vegetation erosion/establishment and flow regime; (iii) vegetation turnover, in the period 1986–2011. Results show that vegetation turnover is remarkably rapid in the study reach with 50% of in‐channel vegetation persisting for less than 5–6 years and only 10% of vegetation persisting for more than 18–19 years. The analysis shows that significant vegetation erosion is determined by relatively frequent floods, i.e. floods with a recurrence interval of c. 1–2.5 years, although some differences exist between sub‐reaches with different densities of vegetation cover. These findings suggest that the erosion of riparian vegetation in braided rivers may not be controlled solely by very large floods, as is the case for lower energy gravel‐bed rivers. Besides flow regime, other factors seem to play a significant role for in‐channel vegetation cover over long time spans. In particular, erosion of marginal vegetation, which supplies large wood elements to the channel, increased notably over the study period and was an important factor for in‐channel vegetation trends. Copyright © 2014 John Wiley & Sons, Ltd.     

First study of fault trench stratigraphy at Mt. Etna volcano, Southern Italy: understanding Holocene surface faulting along the Moscarello fault

Paleoseismology, the study of past earthquakes based on their geological record in the stratigraphy and landscape, is a successful newly developing field of research. The application of fault trench studies in volcanic environments is one of the youngest branches of paleoseismology. In this paper, we present the results of the first exploratory trenches excavated at Mt. Etna in Sicily, the largest European volcano. Modern surface faulting at Etna is a very well known feature, which poses significant hazard to the local community, both in terms of ground displacement of essential lifelines and ground shacking from frequent damaging earthquakes. However, while the geomorphology and the seismicity of the active fault in the Etna region consistently show very high rates of tectonic activity, the Holocene cumulative throw and slip-rates, along with the nature (coseismic vs. creeping fault slip), dimension and timing of the displacement events, are still poorly constrained. For this purpose, we selected as a sample area the Moscarello fault, one of the most outstanding segment of the Timpe system of active normal faults in the volcano’s lower eastern flank. Displaced landforms and volcanic units at the Fondo Macchia basin, in the central sector of this fault, indicate some hundreds of meters of vertical offset in the last ca. 80 kyr, with a long-term slip-rate substantially higher than 1.5–2.0 mm/yr. According to the historical sources and instrumental observations, the Moscarello fault ruptured four times in the last 150 years during shallow (H < 5 km) and moderate magnitude (M < 4.8) earthquakes. These events were associated with severe damage in a narrow epicentral area (macroseismic intensities up to the IX–X grade of the MSK scale) and extensive surface faulting (end-to-end rupture length up to 6 km, vertical offsets up to 90 cm). This clearly indicates very high modern rates of deformation along this fault. We conducted trench investigations at the Fondo Macchia site, in a point where eyewitnesses observed ca. 20 cm of coseismic vertical displacement after the April 21, 1971, M_s=3.7, earthquake. The excavated sections provided direct stratigraphic evidence for a vertical slip-rate of 1.4–2.7 mm/yr in the last ca. 6 kyr. This should be regarded as a minimum slip-rate for the central section of the fault. We explored a single scarp at a single site, while we know from recent historical observations that several parallel scarps may rupture coseismically at Fondo Macchia. Thus, the relevant deformation rate documented for the modern period might be likely extended back in the past to a time-span of some thousands of years at least. As expected, for such a volcanic environment, the activity rates of the Moscarello fault are also significantly higher than for the Apennines normal faults, typically showing slip-rates lower than 1 mm/yr. The agriculturally reworked trench hangingwall stratigraphy did not allow to recognize individual displacement events. Nevertheless, the sedimentary structures observed in the trench footwall strongly suggest that, as for the last 150–200 years of detailed historical record, fault behavior at Fondo Macchia is governed by coseismic surface displacement rather than fault creep. This research confirms that paleoseismology techniques can be effectively applied also in active volcanic environments, typically characterized by rheology and, consequently, seismicity and fault dynamics very different from those of other tectonic environments in which paleoseismology has been firstly developed and is today extensively applied.     

Predictive Power Evaluation of a Physically Based Model for Shallow Landslides in the Area of Oltrepò Pavese,Northern Italy

The use of real-time landslide early warning systems is attracting the attention of the scientific community, since it allows to assess “where” and “when” a shallow rainfall-induced landslide might occur by coupling rainfall amounts, hydrological models and slope-stability analysis. The paper deals with the main results of a back analysis, which refers to the application of a physically based stability model [Shallow Landslides Instability Prediction (SLIP)] on regional scale. The analysis concerns the occurrence of some recent rainfall-induced shallow landslides in the municipal territory of Broni, in the area of Oltrepò Pavese (Northern Italy). The study area is a hilly region 2.4 km² wide, where more than 40 % of the territory has slopes steeper than 15° and altitudes are between 90 and 250 m a.s.l. As regards the geologic setting, clayey-silty shallow colluvial deposits, with a maximum thickness of about 3 m, overlap a bedrock made of clayey shales, calcareous flysch and marls. The SLIP model is based on the limit equilibrium method applied to an infinite slope and on the Mohr–Coulomb strength criterion for the soil. By assuming that the main hydro-geotechnical process that leads to failure is the saturation of parts of the soil, the model allows to take into account the condition of partial saturation of the soil. The safety factor (F _S ) of a slope is also function of previous rainfalls. After the implementation of the model at territory scale, the input data have been introduced through a geographic information systems platform. In the current paper we mainly intend to evaluate the performance of SLIP at catchment scale, by comparison to (1) observed landslide events and (2) another well-established physically based model (TRIGRS). Further, we want to assess the suitability of the model as early warning tool. The results produced by the model are analyzed both in terms of safety factor maps, corresponding to some particular rainfall events, and in terms of the time-varying percentage of unstable areas over a 2-year span period. The paper shows the comparison between observed landslide localizations and model predictions. A quantitative comparison between the SLIP model and TRIGRS is presented, only for the most important event that occurred during the analyzed period. Overall, the results of the stability analyses based on observed rainfalls show the capability of the SLIP model to predict, in real-time and on a wide area, the occurrence of the analyzed phenomena.     

Historical behaviour of Dome C and Talos Dome (East Antarctica) as investigated by snow accumulation and ice velocity measurements

Ice divide–dome behaviour is used for ice sheet mass balance studies and interpretation of ice core records. In order to characterize the historical behaviour (last 400 yr) of Dome C and Talos Dome (East Antarctica), ice velocities have been measured since 1996 using a GPS system, and the palaeo-spatial variability of snow accumulation has been surveyed using snow radar and firn cores. The snow accumulation distribution of both domes indicates distributions of accumulation that are non-symmetrical in relation to dome morphology. Changes in spatial distributions have been observed over the last few centuries, with a decrease in snow accumulation gradient along the wind direction at Talos Dome and a counter-clockwise rotation of accumulation distribution in the northern part of Dome C. Observations at Dome C reveal a significant increase in accumulation since the 1950s, which could correlate to altered snow accumulation patterns due to changes in snowfall trajectory. Snow accumulation mechanisms are different at the two domes: a wind-driven snow accumulation process operates at Talos Dome, whereas snowfall trajectory direction is the main factor at Dome C. Repeated GPS measurements made at Talos Dome have highlighted changes in ice velocity, with a deceleration in the NE portion, acceleration in the SW portion and migration of dome summit, which are apparently correlated with changes in accumulation distribution. The observed behaviour in accumulation and velocity indicates that even the most remote areas of East Antarctica have changed from a decadal to secular scale.