GEOCHEMICAL

Author: ANTELO MARTINEZ JUAN.
Year: 2004.
University: SANTIAGO DE COMPOSTELA.
Place of defense: FACULTAD DE QUÍMICA.
Place of preparation: FACULTAD DE QUÍMICA.

Summary: This work includes the synthesis and characterization of a oxihidróxido iron as goetita and coomo study of the adsorption properties of the oxide mineral.En Specifically, we studied the adsorption of anions and the substances húmicas and also conducted a survey of competition between phosphate and substances húmicas.Previamente was necessary to make an extraction and characterization of an acid fúlvico and húmico a land of Galicia, and within the characterization is a study of the balance of protonación of the two substances extracted. The structural analysis of the substances húmicas we provide information about the functional groups that provide this type of sustancias.El study of the balance of protonación took place through a series of evaluations potenciométricas acid and allowed us to get some parameters protonación it is essential to interpret the process of adsorption of such substances. Once sistetizadas the goetitas work was done a characterization that enabled us to see that the samples of work were typically other goetitas recogidad in bibliografía.Entre properties can be studied to highlight the determination of specific surface area and the loading point zero (PZC), as they are two of the fundamental characteristics of any oxide ore. From study of the properties of adsorption of anions on goetita found that this process is dependent on pH, being favored adsorption values of pH bajos.Por other hand was compared adsorvción phosphate and arsenate and it was noted that these anions behave in a similar manner to work at high ionic strength, while a low ionic strength arsenate has a greater affinity for the surface ore. The results obtained by studying the adsorption of substances húmicas show that this process is dependent on the pH and ionic strength of the work being adsorption favored to acidic pH values and ionic strength alta.Además found that the adsorption of acid húmico it is much larger than the acid fúlvico. By studying the processes of competition noted that both the acid fúlvico as húmico reduce acid phosphate adsorption on goetita, sientdo higher this reduction as it increases the concentration of substance húmica.Por other hand it was found that after adsorption of the substance húmica produces a greater reduction in l absorption of phosphate on goetita.Además, the presence of phosphate in the middle also caused a decrease in the adsorption of substances húmidas and in the case of adsorption prior substances húmicas it is confirmed that the phosphate is capable of producing a process desorption delas húmicas substances. Finally it should be noted that all the results on the experimental adsorption goetita reproduce were achieved through a surface complexation model, which also allowed us to see that a complexation constants of anions and húmicas substances.

Author: CADENA ZAMUDIO JOSE LUIS.
Year: 2004.
University: BARCELONA.
Place of defense: FACULTAD DE GEOLOGÍA.
Place of preparation: FACULTAD DE GEOLOGIA.

Summary: Research on a process of hydrolysis of iron (III) in acidic solutions of sulfato-nirato and sulfato-cloruro and a substrate synthesized in situ, consisting of gypsum and their solid solutions. The substrate leaches along the process of synthesis jarositica, products water molecules, ions hidronio, hydroxyl, sulfate and calcium affect the chemical composition, morphology and physical properties of precipitates jarositicos mainly. Concentrations of iron (III) lower 0.2 M Fe2 (80y) 3 in the middle sulfato-nirato generate morfologías of spherical rounded. Concentrations lower 0.1M Fe2 (S04) 3 generates particles morfologías of microtubes, microvarillas and / 0 micro cavities. It has implemented a process of hydrolysis of iron (III) in acidic solutions that can determine the morphology of the particles jarositicas as areas rounded, microtubes ymicrovarillas.

Author: IGLESIAS GONZÁLEZ ANA CRISTINA.
Year: 2005.
University: SANTIAGO DE COMPOSTELA.
Place of defense: FACULTAD DE QUÍMICA.
Place of preparation: FACULTAD DE QUÍMICAS.

Summary: This work includes the study of the adsorption of two organic pesticide paraquat and MCPA on substances húmicas, conducting a study of the effect of the presence of calcium in the interaction of paraquat and húmico acid. Moreover studies were conducted adsorption of both pesticides on a oxihidróxido iron ore, goetita. Finally analyzed the adsorption of paraquat and MCPA on the association of organic matter and mineral fraction, in particular on the association acid húmico and goetita. To conduct this study, was previously required the extraction and characterization of a substance húmicas Galician soil, and within the characterization is a study of the balance of protonación of substances húmicas extra back. The structural analysis of the substances húmicas provided us with information on the functional groups that provide this type of substances. The study of the balance of protonación was conducted through a series of evaluations potencíométricas acid. The application of a model and an electrostatic adsorption isotherm allows us to obtain the parameters of protonación intrinsic, essential to interpret the processes of adsorption of these substances. To make the study of adsorption of organic pesticides on Substances húmicas was necessary to optimize a technique dialysis to separate pesticide free of other components of reaction and to determine the extent of adsorption. From study of the adsorption properties of the pesticide paraquat on cationic substances húmicas found that this process is dependent on the pH and ionic strength, favors adsorption with increasing pH and reduces the concentration of electrolyte. We compared the adsorption of paraquat on the two fractions of substances húmicas observed that the pesticide has a greater affinity for the acid húmico. The application of a model and an electrostatic adsorption isotherm allowed to interpret the behavior of adsorption of paraquat on substances húmicas using parameters protonación previously obtained. From the study of the interaction of paraquat húmico acid in the presence of calcium was found that the adsorption of paraquat decreases in the presence of Ca2 +. So that eliminates the effect of pH observed in the absence of calcium. From the study of the interaction of pesticide anionic MCPA Substances húmicas in different experimental conditions, it is concluded that its adsorption on substances húmicas is little significance. To make the study of adsorption of organic pesticides on goetita, previously it was necessary to synthesize and characterize the surface ore. The characterization of goetita revealed that the sample synthesized showed the typical characteristics of other goetitas collected from the literature. Among the properties studied include the determination of specific surface area and the loading point zero (PZC). From study of the adsorption properties of MCPA on goetita found that the adsorption of this pesticide is favored to pH and ionic strength low. In the case of paraquat on goetita adsorption was observed that the interaction is facilitated with decreasing concentration of electrolyte and pH values high. Comparing the interaction of the two pesticides with goetita in their optimum adsorption is observed adsorption approximately one hundred times greater for the pesticide anion. Applying a model of surface complexation was posibl 8 and determ 51b inar parameters of interaction intrinsic to the process of adsorption on goetita MCPA. The study of the interaction of MCPA and paraquat on goetita coated acid húmico showed that the adsorption of both pesticides. Decreases with respect to interaction on the fractions isolated by presenting affinity. Thus we conclude that interaction with paraquat goetita coated takes place through the substance húmica and in the case of MCPA positions through free surface oxide ore.

Author: PARAMÁ ARJONES MARÍA DEL ROCÍO.
Year: 2005.
University: VIGO.
Place of defense: FACULTAD DE BIOLOGÍA.
Place of preparation: UNVIERSIDAD DE SANTIAGO DE COMPOSTELA.

Summary: La importancia de la heterogeneidad espacial de los recursos del suelo es bien conocida, pero pocos trabajos explican la escala a la que sucede y como puede diferir entre comunidades. The information on the spatial variability of soil resources is scarce in most of the world's ecosystems, and generally restricted to a set of physicochemical properties. The thesis examines the spatial heterogeneity of different variables soil (moisture, crude density, anmonio, nitrate, phosphate and microbial rates among others) on a scale relevant at the level of individual, ie meters to tens of meters and aims to help understand the pattern of spatial variation of soil nutrients and their effect on plants. The study was carried out in natural communities of plants, exploring changes in the spatial structure of soil nutrients in a successional series typical of northwestern peninsular. In addition, changes in the spatial pattern after a disturbance caused by an intense hurricane dummies. The thesis also includes the study of the spatial variability of essential and non-essential nutrients for plants, microbial processes involved in nutrient cycling and finally notes the effect of spatial patterns of ammonium nirato in a population simulated plant, noting the response of individuals depending on the size of root of the same nutrients that present different grain size, ie different size stain.

Author: ROCIO DÍEZ ROS.
Year: 2006.
University: ALICANTE.
Place of defense: FACULTAD DE FILOSOFÍA Y LETRAS.
Place of preparation: INSTITUTO UNIVERSITARIO DE GEOGRAFÍA.

Summary: THE ACCUMULATION OF URBAN WASTE IS ONE OF MAJOR ENVIRONMENTAL PROBLEMS OF OUR CITIES. ATTEMPTING TO MINIMIZE THE PRODUCTION AND IMPROVE MANAGEMENT OF THAT MAKES THEM, IS PUBLIC POLICY MORE SUSTAINABLE, BASED ON SEPARATE COLLECTION, THE CONSTRUCTION OF PLANTS AND APPROPRIATE BUSINESS INFORMATION AND ENVIRONMENTAL EDUCATION. THIS SITUATION THESIS ANALYSIS OF WASTE IN MAJOR URBAN MUNICIPALITIES OF THE PROVINCE OF ALICANTE THROUGH THE ANALYSIS OF THE PROCESS OF IMPLEMENTATION OF THE PLAN OF INTEGRATED WASTE OF VALENCIA AND CHARACTERISTICS OF EACH MUNICIPALITY, ESPECIALLY HIS PEOPLE OR CITY VISITOR AND URBAN WASTE MANAGEMENT., INCIDIENDO IN THE ACTIVITIES OF ENVIRONMENTAL EDUCATION AND DEVELOPMENT OF ITS DEGREE OF INCIDENCIALA THESIS IS STRUCTURED CHAPTERS IN SIX, THE FOUR PRIMEROS-DE CARÁCTE RMÁS INTRODUCTORIO- INTRODUCING THE CONCEPTUAL FRAMEWORK AND METHODOLOGICAL, DISCUSS THE PROBLEM THE ACCUMULATION OF URBAN WASTE, THE ENVIRONMENTAL LEGISLATION IN THE FIELD AND THE IMPORTANCE TO CORRECT THE MANAGEMENT OF THE UK HAVE FOR CURRENT AYUNTAMIENTOS .. THE LAST TWO CHAPTERS DISCUSS THE SITUATION AND TREND IN EACH OF THE MUNICIPALITIES ESTUDIADOS WITH SPECIAL IMPACT ON ENVIRONMENTAL EDUCATION ISSUES.

Author: ACERO SALAZAR PATRICIA.
Year: 2006.
University: POLITÉCNICA DE CATALUÑA.
Place of defense: EDIFICI C1 - AULA 002. CAMPUS NORD. UPC.
Place of preparation: EDIFICI D2 205 Campus NORD.

Summary: Weathering of sulfidic waste resulting from mining activities is a major environmental problem. When exposed to air, these wastes may produce acid waters (pH typically between 2 and 4) with high concentrations of sulfate, iron and other potentially pollutant elements (Acid Mine Drainage; AMD). Sustainable AMD remediation requires a previous knowledge and quantitative evaluation of weathering processes and their complex interactions. This thesis deals with some of the key processes and interactions. The main weathering process generating metal-bearing acid drainage is the dissolution of sulfide minerals. In the first part of this thesis, the dissolution kinetics in acid environment of three sulfide minerals (namely sphalerite; ZnS, chalcopyrite; CuFeS2, and galena; PbS) were studied by long term flow-through experiments. The influence of pH, dissolved oxygen and temperature on the dissolution rates was assessed. The three sulfides exhibited very different dependence on pH. In contrast to pyrite behavior, dissolution rates of sphalerite and chalcopyrite were found to be independent of dissolved oxygen and galena dissolution was only dependent on dissolved oxygen at pH above 2. Dissolution rate laws for these sulfide minerals were also proposed. These laws can be incorporated into reactive transport models, allowing the performance of more realistic calculations and predictions. The dissolution of pyrite and some other sulfides is oxidative and the availability of oxygen is a key factor in the generation of acid waters. Oxygen availability is enhanced in the vadose zone of mine tailings and related polluted soils. Therefore, the second part of this thesis was aimed at studying geochemical and thermohydraulic processes in the vadose zone. With this aim, unsaturated column experiments were carried out. Columns were forced to dry by heating and the evolution with depth of water content, temperature, porewater hydrochemistry and solid phases was examined at different stages of evolution. It was observed that capillary liquid flux transported solutes to the column top, where they precipitated, thereby reducing porosity, permeability and diffusivity and inhibiting evaporation. Water vapour was then forced to move downwards and its condensation caused dilution of porewater concentrations at the columns bottom. Coupled study of flow processes and chemical reactions was proven to be essential to understand and quantify the evolution of vadose tailings. Therefore, a fully coupled multiphase flow and reactive transport model was developed to simulate these coupled processes. Once AMD is generated, its environmental impact also depends on natural attenuation. One of the main attenuation processes in acid environments is the precipitation of Fe(III)-secondary phases, which may act as sinks for trace elements present in the porewater of mine tailings or acid discharges. Schwertmannite (Fe8O8(SO4)2(OH)4) is one of the most ubiquitous Fe(III)-phases in these environments. In the last part of this thesis, the evolution of trace elements during the precipitation and aging of schwertmannite was studied at field and laboratory scale. Schwertmannite precipitation was observed to be responsible for the removal of more than half of the arsenic load from solution, whereas the concentration of divalent trace metals (Zn, Cu, Pb, Cd, Ni and Co) remained almost unchanged. During the earlier stages of aging, schwertmannite transformed into goethite (FeOOH) plus H3O-jarosite ((H3O)Fe3(SO4)2(OH)6) but, subsequently, goethite was the only mineral to form. Some of the trace elements, such as Cu, Pb and As were depleted in solution during the first stage as schwertmannite transformed into goethite plus H3O-jarosite. On the contrary, the transformation of schwertmannite to goethite (with no jarosite) during the second stage r 8 eleased 2a2 Cu and As to the solution.