<p>Understanding the chemical and physical properties of molecules and materials at a fundamental level often requires quantum-mechanical models for these substance's electronic structure. This type of many body quantum mechanics calculation is computationally demanding, hindering its application to substances with more than a few hundreds atoms. The supreme goal of many researches in quantum chemistry-and the topic of this dissertation-is to develop more efficient computational algorithms for electronic structure calculations. In particular, this dissertation develops two new numerical integration techniques for computing molecular and atomic properties within conventional Kohn-Sham-Density Functional Theory (KS-DFT) of molecular electronic structure. </p> <p>The first of these grid-based techniques is based on the transformed sparse grid construction. In this construction, a sparse grid is generated in the unit cube and then mapped to real space according to the pro-molecular density using the conditional distribution transformation. The transformed sparse grid was implemented in program deMon2k, where it is used as the numerical integrator for the exchange-correlation energy and potential in the KS-DFT procedure. We tested our grid by computing ground state energies, equilibrium geometries, and atomization energies. The accuracy on these test calculations shows that our grid is more efficient than some previous integration methods: our grids use fewer points to obtain the same accuracy. The transformed sparse grids were also tested for integrating, interpolating and differentiating in different dimensions (n = 1, 2, 3, 6).</p> <p> The second technique is a grid-based method for computing atomic properties within QTAIM. It was also implemented in deMon2k. The performance of the method was tested by computing QTAIM atomic energies, charges, dipole moments, and quadrupole moments. For medium accuracy, our method is the fastest one we know of.</p> / Thesis / Doctor of Philosophy (PhD)

INTRODUCTION: The compatibility of EndoSequence BC Sealer (BC Sealer; Brasseler USA, Savannah, GA) for warm vertical compaction has been questioned due to changing physical properties under higher temperature. The aim was to evaluate the effect of heating on the physical properties (flowability and radiopacity) of a new calcium-based root canal sealer (EndoSequence BC Sealer HiFlow [HiFlow]) in comparison with EndoSequence BC Sealer. METHODS: The flow, and radiopacity of the 2 sealers were measured according to ISO 6786/2012 at different temperatures. Forty real printed plastic teeth (incisor) were used to evaluate the flowability of the two Standard EndoSequence BC Sealer and HiFlow EndoSequence BC Sealer into the lateral and apical accessory canals. These evaluation was done with two obturation techniques including single cone and warm vertical condensation. RESULT: The mean flowability was ranging from 22.25 mm to 9.52 mm. The results indicate that there is a statistical difference between the flowability of the two calcium silicate based sealers under all three different temperatures (37˚C, 100˚C and 150˚C). Radiopacity was measured at two different temperatures including 21˚C and 100˚C. The mean gray value ranged from 213.55 to 202.25. Results showed that HiFlow is more radiopaque and there is a statistically significant difference at both temperatures. The results of single cone and warm vertical obturation techniques show that there is no significant difference between the flowability of the two calcium silicate based sealers into the lateral and apical accessory canals at 21°C and there is a significant difference at higher temperatures. CONCLUSIONS: HiFlow BC sealer had higher flow and was more radiopaque, especially at high temperatures, which are generated by the commonly used warm vertical compaction technique.

No description available.

Applications of fertilizers derived from non-renewable resources, along with improved land management practices have contributed greatly increased crop yields in the past 70 years. Biofertilizers and organic amendments, provide alternative sources of nutrients for increased plant yields and resistance against abiotic stress. The objective of this work was to evaluate the effectiveness of various biofertilizers and an organic amendment on improve plant health and/or crop yield. The first study focused on the organic amendment, glucoheptonate and found that applications of 800-1600 kg/ha can increase available water capacity in fine textured soils by up to 3%. The second study evaluated the effectiveness of dual-inoculating biofertilizers Mung beans (Vigna radiata (L.) Wilczek) with two, bradyrhizobium spp. and arbuscular mycorrhizal fungi. Dual inoculation significantly increased grain yield (+33%) compared to a synthetic N fertilizer application but did not significantly increase grain yield compared to the control (+22%). Dual inoculation may increase grain yields of mung beans compared to synthetic fertilizer regime but does not show evidence of improving N fixation. The final study was a greenhouse experiment focused on evaluating some mung bean cultivars to determine their susceptibility to salt stress while also evaluating the effect of inoculation in combating saline soils. Germination was significantly decreased at 6 dS/m in all cultivars by about 36% when compared to the control treatment (0 dS/m). Seed yields, pods per plant and seeds per plant, increased as salt concentration increased. No factors recorded where affected by inoculation. Overall, our research suggests that the use of biofertilizers and organic amendments can improve crop health, but other management and environmental considerations need to be accounted for when reporting effectiveness of such alternative soil amendments / Doctor of Philosophy / Applications of fertilizers derived from non-renewable resources, along with improved land management practices have contributed greatly to increased crop yields in the past 70 years. Biofertilizers and organic amendments, provide alternative sources of nutrients for increased plant yields and resistance against abiotic stress. The objective of this work was to evaluate the effectiveness of an organic amendment and various biofertilizers to improve plant health and/or crop yield. The first study focused on the organic amendment, glucoheptonate and found that applications of 800-1600 kg/ha can increase available water capacity in fine textured soils by up to 3%. The second study evaluated the effectiveness of dual-inoculating Mung beans (Vigna radiata (L.)Wilczek) with two biofertilizers, bradyrhizobium spp. and arbuscular mycorrhizal fungi. Dual inoculation significantly increased grain yield (+33%) compared to a synthetic N fertilizer application but did not significantly increase grain yield compared to the control (+22%). Dual inoculation may increase grain yields of mung bean compared to synthetic fertilizer regime but does not show evidence of improving N fixation. The final study was a greenhouse experiment focused on evaluating mung bean cultivars (4) to determine their susceptibility to salt stress while also evaluating the effect of inoculation in combating the effect of saline soils. Germination was significantly decreased by about 36% at a salinity of 6 dS/m across all cultivars compared to the control at 0 dS/m. Seed yields, pods per plant and seeds per plant, increased as salt concentration increased for some cultivars. No factors recorded were observed to be affected by inoculation. Overall, our research suggests that the use of biofertilizers and organic amendments can improve crop health, but other management and environmental considerations need to be accounted for when reporting effectiveness of such alternative soil amendments.

The amount of CCA treated wood being removed from spent residential decks is increasing at a tremendous rate. While most spent CCA treated wood is being disposed in landfills, further useful and environmentally beneficial alternatives have to be met. This research estimated the percentage of recoverable lumber from spent CCA decks that can be recycled into other usable products. Six residential decks were removed from service, by either demolition or deconstruction procedures. It was found that 86% of the CCA treated wood from the residential decks could be recovered as reusable CCA treated lumber. It was also found that deconstruction of a residential deck, rather than demolition, was not a factor in the volume of CCA treated wood recovered. Chemical and mechanical properties of the removed CCA treated wood were also analyzed. The chemical retention of the deck material proved that most of the spent CCA treated wood could be used in above ground applications. The stiffness of spent CCA treated wood from residential decks was approximately equal to that of recently treated CCA wood. The strength properties were slightly lower than recently treated CCA wood probably due mainly to physical and climatic degradation. Products were then produced that could be successfully utilized by recycling centers or community and government organizations. Products manufactured included, pallets, picnic tables, outdoor furniture, residential decks, and landscaping components. Waste management, recycling, and government organizations were interviewed to determine what markets and barriers exist for recycled CCA treated products. Most landfill and recycling facilities do not currently sort or recycle CCA treated wood, citing the main reason as a lack of a viable market. Potential users were interested in the material but citied they did not know where to locate the material. A communication barrier exists between the waste management industry, recyclers, and users; which is preventing the successful recycling of CCA treated wood from spent residential decks. / Master of Science

Tesis por compendio / [ES] El pre-tratamiento de los residuos de la agroindustria es una de las etapas más complejas del proceso de conversión de biomasa en bioetanol. Esta etapa consiste basicamente en aplicar tratamientos físicos o químicos a la biomasa con el objetivo de conseguir la hidrolización parcial de los carbohidratos y que ésos se vuelvan más acesibles para la posterior actuación de enzimas y microrganismos. En este sentido, el uso de ultrasonidos de alta intensidad se ha mostrado como una tecnología con un potencial interesante para, en combinación con métodos convencionales, intensificar los procesos de transporte de materia y energía. En el presente estudio se caracterizaron algunos residuos agroindustriales, concretamente el bagazo de yuca, cáscaras de cacahuetes y residuos de alcachofa, como ejemplos de materias potenciales para la producción de bioetanol después del pre-tratamiento ácido, con y sin la aplicación de ultrasonidos. Así, se caracterizaron los diferentes sistemas biomasa/soluciones ácidas de acuerdo con sus propiedades termofísicas (densidad, calor específico, difusividad térmica y conductividad térmica) y comportamiento reológico. Además, se caracterizó el campo acústico generado en cada uno de los diferentes sistemas mediante un método calorimétrico y se establecieron relaciones entre las medidas acústicas y las propiedades termofísicas y reológicas. Posteriormente, se determinaron las cinéticas de liberación de azúcares reductores y totales y los cambios estructurales producidos en las suspensiones consideradas durante los pretratamientos en disoluciones ácidas, realizados con agitación convencional o asistidos por ultrasonidos. Los resultados obtenidos indicaron que las suspensiones con alta concentración de ácido y alto contenido de sólidos presentaron una menor capacidad de transferencia de calor, debido a los valores más altos de calor específico, difusividad térmica, conductividad térmica. Estas mismas suspensiones presentaron también valores más altos de densidad y viscosidad, lo que indica una mayor resistencia al flujo. Esto se atribuye, no solo a la alta viscosidad, sino también a la aparición de un comportamiento reológico no-Newtoniano, como se observó a partir del ajuste del modelo de Herschel-Bulkley. Así, en suspensiones de cáscaras de cachuetes o de bagazo de yuca con concentraciones de sólidos de 8% y 6%, respectivamente, se observó una tensión residual considerable y un comportamiento pseudoplástico. La temperatura también presentó un efecto significativo en las propiedades termofísicas. Aunque el efecto fue menos intenso, el incremento de temperatura facilitó la transferencia de calor y de cantidad de movimiento. Al aumentar las concentraciones de sólidos y ácido en las suspensiones, también se observó una reducción de la intensidad acústica generada durante la sonicación. Lo mismo pasó al realizar las mediciones de temperatura en puntos más lejanos de la punta de la sonda, indicando la atenuación de la energía acústica en el seno de las suspensiones. La eficiencia de conversión de energía eléctrica en energía acústica se incrementó por el aumento de la potencia nominal y/o la redución en la concentración de sólidos y ácido, mientras, el factor de atenuación de la intensidad acústica se mostró constante en 0.021 cm-1 en todas las condiciones estudiadas. Los datos de intensidad acústica se relacionaron bien con las propiedades físicas previamente determinadas presentado elevados coeficientes de correlación. Así, a una misma potencia nominal, la intensidad acústica aumentó en suspensiones con baja densidad y viscosidad. Por otra parte, se observaron mayores intensidades en suspensiones con mayor calor específico, difusividad térmica y conductividad térmica. La aplicación de ultrasonidos resultó más eficiente para acelerar el proceso de disolución de azúcares en medio acuoso que al proceso de agitación conve / [CA] El pretractament dels residus de l'agroindústria és una de les etapes més complexes del procés de conversió de biomassa a bioetanol. Aquesta etapa consisteix bàsicament en aplicar tractaments físics o químics a la biomassa per a conseguir que els carbohidrats siguin parcialment hidrolisats i siguen més accessibles per a la posterior actuació d'enzims i microorganismes. En aquest sentit, l'ús d'ultrasons d'alta intensitat s'ha mostrat com una tecnologia amb un potencial interessant per a, en combinació amb mètodes convencionals, intensificar els processos de transport de matèria i energia. En el present estudi, es van caracteritzar residus agroindustrials com el bagàs de iuca, corfes de cacauets i residus de carxofa com a matèries potencials per a la producció de bioetanol després del pretractament àcid, amb i sense l'aplicació d'ultrasons. Així, es van caracteritzar els diferents sistemes biomassa/solucions àcides d'acord amb les seves propietats termofísiques (densitat, calor específica, difusivitat tèrmica i conductivitat tèrmica) i comportament reològic. A més, es va caracteritzar el camp acústic generat en cada un dels diferents sistemes mitjançant un mètode calorimètric i es van establir relacions entre les mesures acústiques i les propietats termofísiques i reològiques. Posteriorment, es van determinar les cinètiques d'alliberament de sucres reductors i totals i els canvis estructurals produïts en les suspensions considerades durant els pretractaments en dissolucions àcides realitzats amb agitació convencional o assistits per ultrasons. Els resultats obtinguts van indicar que les suspensions amb alta concentració d'àcid i alt contingut de sòlids van presentar una menor capacitat de transferència de calor, donada per valors més alts per calor específica, difusivitat tèrmica, conductivitat tèrmica. Les mateixes suspensions van presentar valors més alts de densitat i viscositat, el que indica una major resistència al flux. Això es pot atribuir, no només a l'alta viscositat, però també a l'aparició de un comportament reològic no-newtonià, com es va observar a partir de l'ajust del model de Herschel-Bulkley. Aixi, en suspensions de corfes de cacauets o bagàs de yuca amb concentracions de sòlids de 8% i 6%, respectivament, es va observar una tensió residual considerable i un comportament pseudoplàstic. La temperatura també va presentar un efecte significatiu en les propietats termofísiques. Encara que l'efecte sigui menys intens, l'increment de temperatura va facilitar la transferència de calor i de quantitat de moviment. En augmentar les concentracions de sòlids i àcid, també es va observar una reducció de la intensitat acústica generada en les suspensions durant la sonicació. El mateix es va passar al realitzar els mesuraments en punts més llunyans de la sonda, indicant l'atenuació d'energia acústica. L'eficiència de conversió d'energia elèctrica en energia acústica va poder ser millorada per l'augment de la potència nominal i/o redución en la concentració de sòlids i àcid, mentre el factor d'atenuació de la intensitat acústica es va mostrar constant en 0.021 cm-1 en les condicions estudiades. Les dades d'intensitat acústica es van relacionar bé amb les propietats físiques prèviament determinades amb alts coeficients de correlació. A una mateixa potència nominal, la intensitat acústica es va augmentar en suspensions amb baixa densitat i viscositat. D'altra banda, es van observar majors intensitats en suspensions amb més calor específica, difusivitat tèrmica i conductivitat tèrmica. L'aplicación d'ultrasons van reultar més eficient per accelerar el procés de dissolució de sucres en medi aquós que el procés d'agitació convencional. A més, els ultrasons van ser eficients per hidrolitzar la biomassa en condicions d'àcid i temperatura més suaus que els utilitzats convencionalment, principalment en el cas de les suspensions més / [EN] The pre-treatment of agroindustrial wastes is one of the most complex steps of their conversion process into bioethanol. This step consists basically of applying physical or chemical treatments in biomass in order to obtain carbohydrates partially hydrolyzed and more accessible for future action of enzymes and microorganisms. In this sense, the use of high-intensity ultrasound has been shown as a technology with an interesting potential, in combination with conventional methods, to enhance the mass and energy transfer processes. In the present study, it was characterized agroindustrial residues such as cassava bagasse, peanut shells and artichoke residues as potential materials for the production of bioethanol after acid pre-treatment with and without the application of ultrasound. Thus, the different biomass/acid solutions systems were characterized according to their thermophysical properties (density, specific heat, thermal diffusivity and thermal conductivity) and rheological behavior. The acoustic fields generated in these different systems during ultrasound application were also characterized by a calorimetric method. Then, the ultrasonic intensity obtained in each case was related to the termophysical and reological properties. Subsequently, the kinetics of reducing and total sugar release and the structural changes produced in the suspensions considered during the pretreatments in acid solutions with conventional agitation or assisted by ultrasound were determined. The results obtained indicated that suspensions with higher acid concentration and higher solids content showed lower heat transfer capacity, given by the higher values for specific heat, thermal diffusivity, thermal conductivity. The same suspensions presented higher values of density and viscosity, which leads to greater resistance to flow. This fact was attributed, not only to the high viscosity, but also to the appearance of non-Newtonian rheological behavior as showed by the fitting of Herschel-Bulkley model. In these cases, the suspensions containing peanut shells or cassava bagasse showed noticeable yield stress and shear-thinning behavior above solids concentration of 8% and 6%, respectively. Temperature also had a significant effect on thermophysical properties. Although the effect was less intense than the other variables, the increase in temperature made easier the heat and momentum transfer. The increase of solids and acid concentration in the suspensions produced a reduction of the acoustic intensity generated during sonication. The same fact was observed when the distance from the probe where measurements were taken increased, indicating the occurrence of attenuation of acoustic energy. The conversion yield of electrical energy into acoustic energy could be improved by increasing the nominal power and/or reducing the concentration of solids and acid, while the attenuation factor of the acoustic intensity remained constant at 0.021 cm-1 for the conditions studied. The acoustic intensity data correlated well with the physical properties previously determined, as showed the high correlation coefficients obtained. At the same acoustic power, the acoustic intensity was increased in suspensions with low density and viscosity. On the other hand, higher acoustic intensities were found for suspensions with higher specific heat, thermal diffusivity and thermal conductivity. The ultrasound application was efficient to accelerate the sugar dissolution process in aqueous medium when compared to the conventional agitation. In addition, the ultrasound was efficient for hydrolyzing the biomass under milder conditions of acid and temperature than those conventionally used, mainly in the case of the diluted suspensions in solids studied. This could be observed both by the reducing and total sugar release experimental data as well as by the fitting of the Naik model. On the other hand, greater effects were observed in the biomass microstructure (cont.) / This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001. This study was also financed by CAPES to develop part of this PhD thesis in Spain under the grant number 88881.132626/2016-01. Thanks to the São Paulo Research Foundation (FAPESP) (Grant number 2017/06518-2) for their financial support to develop this project. / Carregari Polachini, T. (2019). Evaluation of the acid pretreatment of agroindustrial waste assisted by high-intensity ultrasound for further bioethanol production [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/129850 / Compendio

Transparent glasses embedded with ferroelectric/nonlinear optic crystallites have been in increasing demand as these exhibit promising physical properties. These could be fabricated in large sizes and shapes with high optical homogeneity accompanied by high degree of transparency over a wide range of wavelengths of light. Amongst a variety of glasses that are known, borate-based glasses are of particular interest owing to their greater transparency, good chemical and mechanical stability, low materials cost, and useful electrical and dielectric properties. Keeping the potential multifarious applications of transparent glass-microcrystal composites in view, BaO-0.5Na2O-4.5B2O3, BaO-0.5Li2O-4.5B2O3, SrO-0.5Li2O-4.5B2O3, 3BaO-3TiO2-B2O3 and Li2O-3B2O3 glasses and glass-microcrystal composites were fabricated. These glasses on controlled heat treatment at appropriate temperatures yielded BaNaB9O15, BaLiB9O15, SrLiB9O15, Ba3Ti3B2O12 and LiB3O5 crystalline phases, respectively. Further transparent surface crystallized BaO-0.5Na2O-4.5B2O3 glasses were fabricated using ultrasonic treatment and their thermal properties have been investigated in detail using differential scanning calorimetry. It is observed that these glasses were homogeneously crystallizing on the surfaces after Ultrasonic treatment which can be exploited for planner wave-guide applications. Glass forming ability, thermal stability, glass-transition behavior, crystallization kinetics and viscosity of these glasses were studied extensively using various methods and rationalized by invoking various models. The above glasses have been characterized for their dielectric and electrical relaxation properties (as these properties are related to their electro-optic and non-linear optical properties) over 30- 600oC temperature range and frequencies (100 Hz -10 MHz) that are normally of interest in the applications of these materials. Several interesting features such as high ionic conductivity, marginally low dielectric loss and high dielectric constant behavior along with low thermal coefficient of dielectric constant were observed in these glasses and were rationalized using various models. The combination of these dielectric characteristics suggests that these are potential candidates for electrical energy storage device applications.

Τα δείγματα που μελετήθηκαν στην παρούσα διπλωματική εργασία προέρχονται από τη θέση Τούμπα - Ανθοβούνι, στις ΒΔ-Δ-ΝΔ υπώρειες του όρους Βαρνούντα του νομού Φλώρινας. Στην περιοχή αυτή κατασκευάστηκε Αιολικό Πάρκο, όπου πραγματοποιήθηκαν συνολικά τριάντα τέσσερις γεωτρήσεις για την εγκατάσταση ανεμογεννητριών. Η ευρύτερη περιοχή τη Φλώρινας ανήκει γεωλογικά στην Πελαγονική Ζώνη και δομείται γενικά από γνευσίους και ημι-μεταμορφωμένα πετρώματα. Στα πλαίσια αυτής της εργασίας εκτελέστηκαν εργαστηριακές δοκιμές σε δείγματα βραχωδών σχηματισμών. Στο τρίτο κεφάλαιο περιγράφονται αναλυτικά οι δοκιμές που χρησιμοποιήθηκαν. Μετά τη συλλογή τους, τα βραχώδη δείγματα διαμορφώθηκαν σε κυλινδρικό σχήμα, διαμέτρου 53 mm με εργαστηριακή καροταρία. Τα άκρα των δοκιμίων κόπηκαν σε μήκη ανάλογα των προβλεπόμενων εργαστηριακών δοκιμών. Οι βάσεις τους λειάνθηκαν ώστε να είναι κάθετες προς τον μεγάλο άξονα του δοκιμίου. Στο επόμενο κεφάλαιο αναφέρεται η δειγματοληψία των γρανιτών. Η θέση δειγματοληψίας εντοπίζεται στην περιοχή Πισοδερίου, που βρίσκεται στο νομό Φλώρινας. Επίσης, στην ενότητα αυτή περιγράφονται και οι δύο τρόποι διαμόρφωσης των δειγμάτων μετά από τη δειγματοληψία με το δειγματοληπτικό γεωτρύπανο. Στο εργαστήριο εξετάστηκαν τα φυσικά και τα μηχανικά χαρακτηριστικά των γρανιτών. Οι εργαστηριακές αυτές δοκιμές βραχομηχανικής γίνονται για τον προσδιορισμό της πυκνότητας, του λόγου κενών, του πορώδους, και της αντοχής των γρανιτών σε μοναξονική ανεμπόδιστη θλίψη. Στο κεφάλαιο αυτό, τα αποτελέσματα από κάθε εργαστηριακή δοκιμή προβάλλονται σε πίνακες, καθένας από τους πίνακες αυτούς αναφέρεται και σε μία άλλη δοκιμή. Ο αριθμός των δοκίμια που χρησιμοποιήθηκαν για κάθε δοκιμή είναι ο εξής: για τον προσδιορισμός των φυσικών παραμέτρων οκτώ (8) δοκίμια, για τον προσδιορισμός των δυναμικών παραμέτρων έξι (6) δοκίμια και για τον προσδιορισμός των παραμέτρων αντοχής χρειάστηκαν δέκα (10) δοκίμια. Στο έκτο κεφάλαιο συγκεντρώνονται σε ένα πίνακα όλα τα αποτελέσματα από όλες τις δοκιμές που εκτελέστηκαν. Οι δοκιμές αυτές πραγματοποιήθηκαν στους γνεύσιους, γρανίτες και γρανιτογνεύσιους. / The samples that have been studied in the current diplomatic project come from Toumpa-Anthovouni, at the NW-W-SW foot of the mountain Varnouda of county Florina. At these area was built a wind park, where had taken place thirty-four drilling for the installing of the wind turbines. The wider area of Florina geologically belongs to the Pelagonian zone and is generally structured by gneisses semi-transformed stones. Within the project laboratory testing have taken place on samples of rock formations. In the third chapter the testing that were used are described in depth. After their collection, the rock samples were reformed into cylindrical shape, diameter 53mm by laboratory karotaria. The ends of the samples were cut into lengths as the planned laboratory tests. Their bases were planished to be perpendicular to the long axis of the specimen. In the next chapter the sampling of the granites are mentioned. The place of the sampling is located in the area of Pisoderio, which belongs to the county Florina. Also, on that section both two ways of forming the samples after the sampling by sampling rig are described. At the laboratory the natural and mechanical characteristics of the granites were examined. These laboratory tests on rock mechanics have been done for the determination of the density, the ratio of spaces, the porosity and the durability of the granites under uniaxial unconfined compression. In this chapter, the results from each laboratory test are displayed on tables, each one of them mentions a different test. The number of the samples that were used for each test are the following; for the determination of the natural parameters eight (8) samples, for the determination of the dynamic parameters six (6) samples and for the determination of the durability parameters were used ten (10) samples. In the sixth chapter all the results from all the tests that have been executed are gathered in one table. These tests took place in gneiss and granites.

<p>The removal of vegetation and overburden changes the naturalwater purifying processes and thus decreases the groundwaterprotection in gravel pit areas. The sand and gravel depositsusedfor aggregate extraction in Sweden are also often valuablefor extraction of groundwater as a drinking water resource. TheSwedish legislation requires that gravel pits be restored afterthe cessation of extraction, the aim being to reestablishvegetation and to reinstate groundwater purifyingprocesses.</p><p>The objective of this study was to improve our understandingof the processes governing groundwater protection andvegetation establishment so that these could be applied toimproving restoration methods for reestablishing naturalgroundwater protection. The focus was on the importance of soilphysical properties of the topsoil for vegetation establishmentand groundwater recharge.</p><p>Actual field methods for restoration were reviewed.Conflicts between aggregate extraction and groundwaterinterests were common. In many cases the actual restorationcarried out differed from pre-planned specifications in permitdocumentation.</p><p>Commonly available substrates that might be used forrestoration of gravel pits were investigated. The soils weredescribed as regards texture, organic content, porosity, waterretention and hydraulic conductivity. The way in which acombination of the water retention characteristic and theunsaturated conductivity influenced the behaviour of thesoil-plant-atmosphere system was demonstrated using aprocess-orientated simulation model. Plants with well-developedaboveground characteristics and shallow roots in particularexerted the highest requirements on the soil physicalproperties.</p><p><b>Key words:</b>groundwater protection, soil physicalproperties, CoupModel, unsaturated conductivity, waterretention, transpiration, soil evaporation</p>

No description available.