Assessment of the Maltese environmental matrix to define the future monitoring strategy

Chapter 16As a member of the EU and of the international community, Malta has important obligations to report on the state of the environment and the effectiveness of policy measures addressing particular concerns, such as pollution (Regional Environmental Center, 2008). Failure to collect reliable and up-to-date environmental data would make Malta exposed to various environmental pressures due to poorly informed policy decisions, which could eventually also lead to economic implications (European Commission, 2014a). Under this context Malta is in the process of implementing the EU legislative framework regarding the environmental themes of air, water, radiation and soil. Prior to the implementation of the project “Development of environmental monitoring strategy and environmental monitoring baseline surveys”, air and water data from the Maltese environmental network were already available, though data coverage presented some lacunas, whereas radiation and soil network system was not in place, hence minimum baseline data was available. Therefore, the long term monitoring strategic proposal discussed in this article has been designed as a primary tool to improve the state of the environment as well as to be in compliance with the EU Directives related with nature conservation.peer-reviewe

Emergent realities for social wellbeing : environmental, spatial and social pathways

This article summarises the results of an evaluation performed to the air monitoring network of Malta in 2012 where the following elements were evaluated in comparison with national and European legal requirements: the classification of zones and agglomerations in the island, the number, type and location of fixed monitoring stations, the data reporting and the reference methods used for the analysis of parameters.peer-reviewe

Geological surface reconstruction from 3D point clouds

The numerical simulation of phenomena such as subsurface fluid flow or rock deformations are based on geological models, where volumes are typically defined through stratigraphic surfaces and faults, which constitute the geometric constraints, and then discretized into blocks to which relevant petrophysical or stress-strain properties are assigned. This paper illustrates the process by which it is possible to reconstruct the triangulation of 3D geological surfaces assigned as point clouds. These geological surfaces can then be used in codes dedicated to volume discretization to generate models of underground rocks. The method comprises the following: - Characterization of the best fitting plane and identification of the concave hull of the point cloud which is projected on it - Triangulation of the point cloud on the plane, constrained to the Planar Straight Line Graph constituted by the concave hull The algorithm, implemented in C ++ , depends exclusively on two parameters (nDig, maxCut) which allow one to easily evaluate the optimal refinement level of the hull on a case by case basis

Power requirements for complete suspension and aeration in an unbaffled bioslurry reactor

Remediation of contaminated soils is spreading as a matter of crucial importance nowadays. Bioremediation via bioslurry reactors of sites polluted by recalcitrant pollutants has been proved to be a valuable option, although optimization is needed to reduce process costs. Free-surface unbaffled stirred tanks (with central air vortex) have been recently proposed as a promising alternative to the more common systems provided with baffles. In a bioslurry reactor solid-liquid interfacial area, oxygen supply, solid loading per reactor unit volume should be maximized, and, at the same time, operation costs have to be kept low. In this regard, the minimum impeller speeds for complete suspension Njs (suspension of all solid particles) and aeration Nca (air vortex ingested by the turbine and dispersed as bubbles in the system) represents a reasonable compromise between process yield and power requirements. To this purpose, a flat bottomed unbaffled tank with diameter T=0.19 m was investigated. The tank was filled with water up to a height H=T. It was stirred by a radial sixbladed Rushton turbines (RT) with diameter D=T/3 and H=T/3. Mono-dispersed particles with diameter dp=250-300μm and density p≈2500 kg/m3 were employed. Solid loadings B% ranging from 2.5% (weight of solid/weight of liquid) up to the very high 160% w/w were tested. The visual Zwietering criterion along with the aid of a digital camera was employed to evaluate Njs values. An acoustic criterion was adopted to assess Nca. A static frictionless granite turntable was employed to measure the impeller torque at Njs and Nca and to assess the relevant specific power requirements js and ca. Results show that the dependence of Njs and Nca on B% is much lower at low solids loading (B30%). The relevant specific powers per unit mass of solids (i.e. js and ca) were found to exhibit a minimum, at B≈20% for js and B≈60% for ca. On overall, data collected suggest that operating a radially stirred unbaffled bioslurry reactor loaded with a concentration B≈30% could be the best compromise to minimize the costs for achieving complete suspension and aeration conditions

Analytical Instrumental Techniques to Study Archaeological Wood Degradation

Historically, a very large variety of everyday artifacts were made of wood, which makes them representative of their historical period or social context and valuable for archaeologists and historians. In order to preserve degraded wood and to develop and apply suitable conservation treatments, chemical and physical characterization of archaeological wood is needed. This review provides the reader with a survey on state-of-the-art of instrumental analytical tools available to understand the morphology and the chemical composition of archaeological wood. The focus is on microscopic and spectroscopic techniques such as scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Raman, nuclear magnetic resonance (NMR) and analytical techniques based on pyrolysis, such as direct exposure-mass spectrometry (DE-MS), pyrolysis-mass spectrometry (Py-MS), pyrolysis-gas chromtography-mass spectrometry (Py-GC/MS), with emphasis on their respective potentialities and limitations. The advantages of techniques based on synchrotron radiation are also discussed. In addition, the applicability of each examined technique is illustrated and discussed through specific examples from the literature

Analytical Pyrolysis and Mass Spectrometry to Characterise Lignin in Archaeological Wood

This review describes the capability of analytical pyrolysis-based techniques to provide data on lignin composition and on the chemical alteration undergone by lignin in archaeological wooden objects. Applications of Direct Exposure Mass Spectrometry (DE-MS), Evolved Gas Analysis Mass Spectrometry (EGA-MS), and single and double-shot Pyrolysis-Gas Chromatography/Mass Spectrometry (Py-GC/MS) in archaeological lignin characterisation are described. With comparison to cellulose and hemicelluloses, lignin is generally less prone to most degradation processes affecting archaeological artefacts in burial environments, especially waterlogged ones, which are the most favourable for wood preservation. Nevertheless, lignin also undergoes significant chemical changes. As wood from waterlogged environments is mainly composed of lignin, knowledge of its chemical structure and degradation pathways is fundamental for choosing preventive conservation conditions and for optimising consolidation methods and materials, which directly interact with the residual lignin. Analytical pyrolysis coupled with mass spectrometry, used in several complementary operational modes, can gather information regarding the chemical modifications and the state of preservation of lignin, especially concerning oxidation and depolymerisation phenomena. Several applications to the analysis of wood from archaeological artefacts affected by different conservation problems are presented to showcase the potential of analytical pyrolysis in various scenarios that can be encountered when investigating archaeological waterlogged wood

Oxygen Transfer Performances of Unbaffled Bio-Reactors with Various Aspect Ratios

Cultivation of microorganisms, plants or animal cells requires liquid agitation in order to ensure oxygen and nutrient transfer and to maintain cell suspension. Many studies on animal cell damage due to mechanical agitation and sparging aeration have shown that mechanical damage of freely suspended animal cells is in most cases associated with bursting bubbles at the air–liquid interface (Barrett et al., 2010). Gas bubbles are usually generated by direct air sparging aimed at supplying oxygen to the culture medium. Mechanical agitation may also introduce gas bubbles in the culture medium via vortexing entrainment from the free surface. In this work oxygen transfer performance of an unbaffled stirred bioreactor, with various aspect ratios, is presented in view of its use as a biochemical reactor for animal cell growth. In practice oxygen mass transfer occurs through the (more or less deep) free surface vortex which takes place when agitation is started in unbaffled vessels. If this vortex is not allowed to reach impeller blades, bubble formation and subsequent bursting at the free-surface is avoided. Experimental results show that this kind of bioreactor can provide sufficient oxygen mass transfer for animal cell growth, so resulting in a viable alternative to the more common sparged reactors. The mass transfer performance observed with the different aspect ratio configurations is also presented and discussed

Subsidence and safety analysis

Regolamentazione e Best Practice

Oak wood degradation processes induced by the burial environment in the archaeological site of Biskupin (Poland)

The open-air Archaeological Museum in Biskupin (Poland) preserves and shows to the public a prehistoric settlement of Lusatian culture dating back to Early Iron Age (eighth century BC). The monitoring of the environment and dynamics of the wood degradation in the burial conditions at the site is fundamental for the in situ preservation of archaeological wooden materials. A monitoring program thus started in 2003 at the Biskupin site, using contemporary sound oak wood that was placed in two wet burial environments, characterised by different conditions. A multi-analytical protocol was exploited to obtain information on the structural, physical and chemical conditions of the buried wood. The study involved the application of gravimetric and wet chemical analysis, and instrumental techniques, including infrared spectroscopy (FTIR) and analytical pyrolysis (Py–GC/MS) to evaluate alterations in the buried oak wood over a 10-year period. The results showed that, during the burial period in both monitoring stations, there was only limited chemical transformation of the polysaccharide component, mostly involving hemicelluloses. The differences observed might be due to the natural compositional variability and inhomogeneity of oak wood. The final condition of the wood was very similar in the two burial environments. It is therefore suggested that the wet burial conditions in the Biskupin site represent a safe conservation environment for the in situ preservation of the wood remains, at least those presenting a good initial preservation state. This supports the conservation strategy adopted in the Biskupin Museum site

Thermolytic reverse electrodialysis heat engine: model development, integration and performance analysis

Salinity gradient heat engines represent an innovative and promising way to convert low-grade heat into electricity by employing salinity gradient technology in a closed-loop configuration. Among the aqueous solutions which can be used as working fluid, ammonium bicarbonate-water solutions appear very promising due to their capability to decompose at low temperature. In this work, an experimentally validated model for a reverse electrodialysis heat engine fed with ammonium bicarbonate-water solutions was developed. The model consists of two validated sub-models purposely integrated, one for the reverse electrodialysis unit and the other for the stripping/absorption regeneration unit. The impact of using current commercial membranes and future enhanced membranes on the efficiency of the system was evaluated, along with the effect of operating and design parameters through sensitivity analyses. Results indicated that exergy efficiency up to 8.5% may be obtained by considering enhanced future membranes and multi-column regeneration units