A deficiência de Zn no solo causa efeitos indesejáveis na produção agrícola, pois a baixa disponibilidade deste micronutriente para as plantas promove a diminuição da atividade enzimática, além da deficiência deste elemento na alimentação, que pode levar ao estado de subnutrição. Tendo em vista a problemática do Zn no sistema solo-planta e suas variações nos compartimentos do solo, é importante a avaliação de sua fitodisponibilidade e as frações do solo que este elemento está associado. O objetivo deste trabalho foi avaliar a fitodisponibilidade e a compartimentalização de Zn no solo, para as culturas de arroz (Oryza sativa L.) e soja (Glycine max L. Merrill) e avaliar o efeito das doses de Zn sobre a nutrição e exportação deste nutriente pela cultura. Utilizou-se como plantas teste as culturas de arroz e soja para avaliar o efeito das doses de Zn sobre a nutrição e translocação deste nutriente até os grãos. Para tanto, uma amostra de um Latossolo Vermelho, textura argilosa da região de Piracicaba (SP) foi utilizada e ZnCl2 (marcado com 65Zn) como fonte. O experimento foi conduzido em casa de vegetação em DIC, com cinco doses de Zn (0, 1, 2, 4 e 8 mg kg-1 de solo), com quatro repetições. O experimento foi conduzido até a formação de grãos e foi realizada determinação de Zn por Espectrômetria de Absorção Atômica após digestão nitroperclórica e contagem do 65Zn nas partes da planta: parte aérea (PA) e panícula (P), para arroz e PA, vagem (V) e grão (G), para soja. Calculou-se a quantidade de Zn proveniente da fonte (Znpf) nas partes das plantas e o aproveitamento do Zn da fonte pelas culturas (Ap). Nas amostras de solo foram realizadas extrações por DTPA (ZnDTPA) e Mehlich-1 (ZnM1) em duas subamostragens (t1 e t2), antes da semeadura e florescimento, respectivamente. O fracionamento de Zn foi realizado em amostras de t2 nas frações: trocável (ZnTroc); ligado a carbonatos (ZnCarb); a matéria orgânica (ZnMO); a óxidos (ZnOxi) e residual (Znres). Adicionalmente, foi realizada análise do teor pseudo-total de Zn (ZnPST). Os dados obtidos foram submetidos à análise de variância pelo teste-F a 95 % de probabilidade, ajuste das variáveis em função das doses por regressões e teste de média e análises de correlações entre as principais variáveis respostas. O Zn acumulado total na planta se ajustou à regressão linear em função do aumento das doses, entretanto ao analisar as partes separadamente, só houve diferença entre as doses para a variável PA em ambas as culturas. O Znpf total nas plantas apresentou incremento com a adição das doses crescentes de Zn ao solo, entretanto, eu aproveitamento foi baixo, 12 e 8,75 % para arroz e soja, respectivamente. As doses de ZnCl2 adicionadas ao solo, aumentaram a concentração de Zn presente nas frações ZnTroc > ZnMO > ZnCarb, em ordem decrescente. O Zn total acumulado nas plantas de arroz e soja apresentam correlações crescentes para os extratores DTPA e M1 nas duas subamostragens (t1 e t2), em função das doses avaliadas. O Zn extraído pelo DTPA ou M1, apresentaram correlação significativa com o Zn extraído nas frações, na ordem decrescente, ZnTroc > ZnCarb > ZnMO / Zn deficiency in soil causes undesirable effects on agricultural production because the low availability of this micronutrient for plants promotes the decrease in enzymatic activity besides the deficiency of this element in food, which can lead to a state of malnutrition. Considering the problem of Zn in soil-plant system and its variations in soil compartments, it is important to evaluate its bioavailability and forms in soil which this element is associated. The objective of this study was to evaluate Zn bioavailability and compartmentalization in the soil, to the rice (Oryza sativa L.) and soybean (Glycine max L. Merrill) crops and evaluate the effect of Zn levels on nutrition and exportation of this nutrient by the crops. As test plant rice and soybeans were used to evaluate the effect of Zn rates on nutrition and the nutrient translocation to the grains. For this purpose, a sample of an Oxisol (FAO), an clay texture from Piracicaba (SP) region, was used and ZnCl2 (labelled with 65Zn) as a source. The experiment was conducted in a greenhouse in CRD, with five rates of Zn (0, 1, 2, 4 and 8 mg kg-1 soil), with four repetition. The experiment was conducted until the formation of grains and Zn analyzis were performed by Atomic Absorption Spectrophotometery after nitricperchloric digestion and 65Zn counting of parts: shoot (PA) and panicle (P) for rice and PA, beans pods (Pd) and grains (G) for soybeans. The amount of Zn derived from the source (Znpf) was calculated in the plant parts and the recovery of the Zn by the crops (Ap). In the soil samples, extractions were performed by DTPA (ZnDTPA) and Mehlich-1 (ZnM1) methods in two sub samples (t1 and t2) prior to seeding and flowering, respectively. The Zn fractionation was performed on samples of t2 in the fractions: exchangeable (ZnTroc); linked to carbonates (ZnCarb); to organic matter (ZnMO); to oxides (ZnOxi) and residual (Znres). Additionally, analysis of the pseudo-total content of Zn (ZnPST) was performed. Data obtained was subjected to analysis of variance by the F-test at 95% probability, adjusting the variables depending on the rates for regression and average test and analysis of correlations between the main variables. The total cumulative Zn in the plant set to the linear regression in terms of increasing rates, however when analyzing the parts separately, just the PA showed differences between doses, for both crops. The total Znpf increased with the increasing rates, however its recoveries were low, approximately 12% for rice and 8.75 % for soybean. The ZnCl2 rates in soil increased the Zn concentration in the fractions: ZnTroc > ZnMO > ZnCarb, in descending order. The total cumulative Zn in the rice and soybean plants are growing correlations for extractors DTPA and M1 for two sub samples (t1 and t2), depending on the rates evaluated. The Zn extracted by DTPA or M1 were significantly correlated with Zn extracted in fractions in descending order: ZnTroc > ZnCarb > ZnMO

Para avaliar o efeito do gadolínio sobre os metabólitos Colina (CO), Creatina (CRE) e N-acetil-aspartato (NAA) foi realizada espectroscopia por ressonância magnética em 25 pacientes com tumores intracranianos antes e após a injeção venosa do meio de contraste. Foram quantificadas e comparadas as relações CO/CRE, CO/NAA e NAA/CRE bem como a largura a meia altura dos picos dos metabólitos CO, CRE e NAA nos espectros pré e pós-contraste. Verificou-se redução das relações CO/CRE e CO/NAA e da largura a meia altura do pico do NAA nos espectros pós-contraste / In order to evaluate the gadolinium effect on the metabolites choline (CHO), creatine (CRE) and N-acetyl-aspartate (NAA) we performed multivoxel spectroscopy in 25 patients with intracranial tumors before and after the injection of the contrast material. The metabolite ratios CHO/CRE, CHO/NAA and NAA/CRE and the peak width at half height of the metabolites were calculated and compared between the pre and post contrast spectra. Measurements showed reduction of the CO/CRE and CO/NAA ratios and of the NAA width after the administration of the contrast material

Para avaliar o efeito do gadolínio sobre os metabólitos Colina (CO), Creatina (CRE) e N-acetil-aspartato (NAA) foi realizada espectroscopia por ressonância magnética em 25 pacientes com tumores intracranianos antes e após a injeção venosa do meio de contraste. Foram quantificadas e comparadas as relações CO/CRE, CO/NAA e NAA/CRE bem como a largura a meia altura dos picos dos metabólitos CO, CRE e NAA nos espectros pré e pós-contraste. Verificou-se redução das relações CO/CRE e CO/NAA e da largura a meia altura do pico do NAA nos espectros pós-contraste / In order to evaluate the gadolinium effect on the metabolites choline (CHO), creatine (CRE) and N-acetyl-aspartate (NAA) we performed multivoxel spectroscopy in 25 patients with intracranial tumors before and after the injection of the contrast material. The metabolite ratios CHO/CRE, CHO/NAA and NAA/CRE and the peak width at half height of the metabolites were calculated and compared between the pre and post contrast spectra. Measurements showed reduction of the CO/CRE and CO/NAA ratios and of the NAA width after the administration of the contrast material

Résumé : En imagerie médicale, il est courant d’associer plusieurs modalités afin de tirer profit des renseignements complémentaires qu’elles fournissent. Par exemple, la tomographie d’émission par positrons (TEP) peut être combinée à l’imagerie par résonance magnétique (IRM) pour obtenir à la fois des renseignements sur les processus biologiques et sur l’anatomie du sujet. Le but de ce projet est d’explorer les synergies entre l’IRM et la TEP dans le cadre d’analyses pharmacocinétiques. Plus spécifiquement, d’exploiter la haute résolution spatiale et les renseignements sur la perfusion et la perméabilité vasculaire fournis par l’IRM dynamique avec agent de contraste afin de mieux évaluer ces mêmes paramètres pour un radiotraceur TEP injecté peu de temps après. L’évaluation précise des paramètres de perfusion du radiotraceur devrait permettre de mieux quantifier le métabolisme et de distinguer l’accumulation spécifique et non spécifique. Les travaux ont porté sur deux radiotraceurs de TEP (18F-fluorodésoxyglucose [FDG] et 18F-fluoroéthyle-tyrosine [FET]) ainsi que sur un agent de contraste d’IRM (acide gadopentétique [Gd DTPA]) dans un modèle de glioblastome chez le rat. Les images ont été acquises séquentiellement, en IRM, puis en TEP, et des prélèvements sanguins ont été effectués afin d’obtenir une fonction d’entrée artérielle (AIF) pour chaque molécule. Par la suite, les images obtenues avec chaque modalité ont été recalées et l’analyse pharmacocinétique a été effectuée par régions d’intérêt (ROI) et par voxel. Pour le FDG, un modèle irréversible à 3 compartiments (2 tissus) a été utilisé conformément à la littérature. Pour la FET, il a été déterminé qu’un modèle irréversible à 2 tissus pouvait être appliqué au cerveau et à la tumeur, alors qu’un modèle réversible à 2 tissus convenait aux muscles. La possibilité d’effectuer une conversion d’AIF (sanguine ou dérivée de l’image) entre le Gd DTPA et la FET, ou vice versa, a aussi été étudiée et s’est avérée faisable dans le cas des AIF sanguines obtenues à partir de l’artère caudale, comme c’est le cas pour le FDG. Finalement, l’analyse pharmacocinétique combinée IRM et TEP a relevé un lien entre la perfusion du Gd-DTPA et du FDG, ou de la FET, pour les muscles, mais elle a démontré des disparités importantes dans la tumeur. Ces résultats soulignent la complexité du microenvironnement tumoral (p. ex. coexistence de divers modes de transport pour une même molécule) et les nombreux défis rencontrées lors de sa caractérisation chez le petit animal. / Abstract : In medical imaging, different modalities are frequently combined in order to obtain complementary information. For example, positron emission tomography (PET) can be associated with magnetic resonance imaging (MRI) to derive both anatomical and biological information. This project explores the synergies between MRI and PET for pharmacokinetic modeling. Specifically, it exploits the high spatial resolution of MRI as well as the information about perfusion and vascular permeability derived from dynamic contrast-enhanced studies to better assess these parameters in a PET radiotracer injected shortly after the MRI examination. This more precise assessment of perfusion is thought to improve metabolism quantification for the radiotracer and to discriminate between its specific and non-specific accumulation. The present work focussed on 2 PET radiotracers, (18F-fluorodeoxyglucose [FDG] and 18F-fluoroethyltyrosine [FET]) as well as a MRI contrast agent (gadopentetic acid [Gd-DTPA]) applied to a rat glioblastoma model. Images were acquired using a sequential MRI-PET protocol and blood was drawn to derive the arterial input function (AIF) for each molecule. PET and MR images were subsequently registered and pharmacokinetic modeling was performed on regions of interest (ROI) or voxel-wise. For FDG, an irreversible 3 compartments (2-tissue) model was used in accordance to the literature. For FET, it was determined that an irreversible 2-tissue model is applicable for the brain and the tumor and a reversible 2-tissue model is preferred for the muscles. AIF (blood or image-derived) conversion between Gd-DTPA and FET, or vice versa, was also considered and proved feasible for the blood AIF derived from the caudal artery, similar to FDG. Finally, combined kinetic modeling for MRI and PET showed a relationship between the perfusion of FDG, or FET, and that of Gd-DTPA in muscle. Important disparities were noted for the tumor. These results illustrate the complexity of the tumor microenvironment (e.g. presence of various transport mechanisms for the same molecule) and the numerous challenges encountered during its characterization in small animals.

Radiofármacos são compostos radioativos que podem ser usados tanto para diagnóstico como para terapia. O radiofármaco 99m-Tc-MIBI é a formação de um complexo contendo o radionúclideo Tecnécium-99m e seis moléculas de Sestamibi, usado principalmente para cintilografias do miocárdio, sendo o procedimento mais realizado dentro da medicina nuclear, por consequência, o radiofármaco mais comercializado. Já o radiofármaco 99m-Tc-DTPA é composto também pelo mesmo radioisótopo e por uma molécula de ácido pentético, a qual tem característica de um quelante com afinidade pelos rins, por isso, é possível fazer avaliação do sistema renal. Como os radiofármacos são considerados medicamentos, estão sujeitos às mesmas normativas, logo o objetivo deste trabalho foi desenvolver metodologia de doseamento destes insumos ativos antes da complexação com o radionuclídeo através da metodologia de Cromatografia Líquida de Alta Eficiência (CLAE). Dois métodos simples e eficientes foram desenvolvidos e validados para o MIBI em produto acabado e para a matéria-prima ácido pentético (DTPA), utilizando-se misturas de solvente orgânico e tampão. Os parâmetros de validação foram avaliados, obtendo resultados satisfatórios. Um teste de estabilidade para o radiofármaco MIBI em solução foi realizado e o resultado indicou uma preservação das características de aproximadamente 60 dias, e quando liofilizado de mais de 12 meses. Sendo assim, os métodos propostos foram considerados adequados para utilização na rotina da indústria farmacêutica. Como perspectivas, novas condições serão testadas para obter método de quantificação para o radiofármaco 99m-Tc-DTPA em produto acabado. / Radiopharmaceuticals are radioactive compounds that can be used for diagnostic and therapeutic purposes. Technetium (99mTc) sestamibi is a radiopharmaceutical including a coordination complex consisting of the radioisotope technetium-99m bound to six Sestamibi ligands, which is mainly used to image the myocardium via scintigraphy. This is the most common nuclear medicine procedure, making Technetium (99mTc) sestamibi the most commercialized radiopharmaceutical. Technetium (99mTC)-DTPA in turn is composed by the same radioisotope plus a molecule of Pentetic Acid, which, by its chelating properties, is used to scan renal system. As radiopharmaceuticals are regarded as drugs, they are subject to the same regulations; therefore, the objective of this study is to develop quantification methodology for these both active pharmaceutical ingredients before their complexation with the radioisotope by employing high-performance liquid chromatography (HPLC) methodology. Two simple, efficient methods were developed and validated for Sestamibi at its final form as well as for DTPA's raw material by using buffer and organic solvent mixtures. The validation parameters were evaluated with satisfactory results. A stability test was carried out for Sestamibi, indicating the preservation of characteristics for nearly 60 days, and for over 12 months when at its freezedryed form. The proposed methods were thus considered adequate for pharmaceutical industries. As perspectives, new conditions shall be tested to obtain a quantification method for Technetium (99mTC)-DTPA at its final form.

It was recently shown that V-doped acid-prepared mesoporous silica (APMS) nanoparticles are active catalysts for the oxidation of the mustard gas analogue 2-chloroethyl ethyl sulfide (CEES) under ambient conditions in the presence of aldehydes, using O2 from air as the oxidation source. However, the vanadium ion leached from the surface when water was present, leading to decreased catalytic activity. Therefore, in this work, the environment around the vanadium is changed, using diethylenetriamine pentaacetic acid (dtpa) as a ligand and anchoring it to the surface of a mesoporous silica nanoparticle, to investigate its effect on vanadium’s ability to perform oxidation reactions. VO(dtpa)-APMS was synthesized by covalently linking the multi-dentate chelator dtpa onto the surface through peptide coupling of one of the acetate groups to aminopropyltriethoxysilane (APTES), condensing the dtpa-APTES molecule onto the mesoporous silica surface, and then exchanging a vanadyl salt into the resulting solid. Physical characterization of the material confirmed that the substrate retained its porosity after modification, and that the vanadium did not leach from the solid, in contrast to samples that did not contain dtpa. Solid-state EPR spectroscopy, combined with ongoing computational modeling, indicated that the vanadium was in a distorted five-coordinate environment. Various vanadium catalysts have been shown to oxidize alkanes, alkenes, alcohols and aromatic compounds. To further understand the catalyst’s ability to perform oxidation reactions, mechanisms of sulfides and alkenes were studied. Two model substrates were chosen for the investigation: CEES and cis-cyclooctene. The catalytic system effectively oxidizes CEES at room temperature in less than 15 minutes and cis-cyclooctene at 47 °C within 3 hours, using a peroxyacid generated in situ as the oxidant source. Kinetic experiments demonstrated that the mechanism of the sulfide reaction changed at higher temperatures, while the alkene reaction did not. In each reaction, a partial negative charge on the peroxyacid during the oxidation process was indicated. The confirmation of radical formation in the mechanism was experimentally shown by the appearance of an induction period when diphenylamine, a radical trap, was introduced into the reaction. VO(dtpa)-APMS performs two catalytic oxidations: the oxidation of propionaldehyde to make the peroxyacid and the oxidation of alkenes or sulfides. In the first reaction, O2 binds to the vanadium complex to form a superoxo eta-1-bound O2 radical. This species leads to the formation of peroxyacid through a radical process. The peroxyacid produced in this manner can then react with a sulfide or an alkene in a process also catalyzed by the VO(dtpa) complex. The peroxyacid coordinates with the vanadium center. Upon coordination, the sulfide or alkene directly reacts with the oxygen of the peroxyacid while the peroxyacid is being deprotonated. A 6-coordinate catalyst intermediate is formed prior to the release of the oxidation product and propionic acid to regenerate the VO(dtpa) complex.

This thesis describes a study of the remobilisation of heavy metals from sediments by three aminopolycarboxylic acids (APCAs). They are nitrilotriacetic acid, ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid. The investigation is introduced by examining the sources, uses and chemistry of these acids. The introduction also includes a discussion of what is known about the inclusion of heavy metals into sediments and their remobilisation from sediments. Typical concentrations of APCAs in natural waters and sediments have been catalogued from the literature. The advantages and disadvantages of various laboratory techniques employed for the remobilisation of heavy metals by APCAs from sediments are assessed, as is the use of such experiments in quantifying the role of APCAs in the remobilisation of heavy metals from sediments. Sediments from three areas were sampled for this study; they were the Alexandra Canal, Captains Flat and Jenolan Caves in New South Wales, Australia. In each area several sites were sampled. For each site there is a brief description of the catchment geology and hydrology. Selected sediment-associated waters in the areas were analysed for their metal concentrations as well as for ultratrace levels of APCAs employing a method developed in the present study. The waters were analysed for the major ions Ca2+, Mg2+, K+, Na+, Cl-, NO3- and SO42-. The sediments from selected sites in each of the areas were dried and fractionated. The dry total and fine sediments were analysed for their metal content and the latter was found to adequately represent the former in this respect. Water samples from the three areas showed different chemistries and exhibited more subtle differences between sites. In general, the Alexandra Canal waters are saline and alkaline and are a mixture of urban runoff and seawater; the Captains Flat waters are acidic and contain high sulfate from acid mine and tailings drainage; the Jenolan Caves waters are neutral and have the features characteristic of waters draining through limestone. The APCA contamination in all water samples when ranked against other global sites is very low. Although the current APCA levels in the waters appear low, it was concluded that they should be closely monitored so that efforts can be made to minimise the risk of APCAs being hazardous environmental contaminants and also that any remobilisation of heavy metals from sediments by APCAs can be controlled. Agitation and column laboratory-scale experiments were carried out in order to obtain an understanding of the remobilisation of metals by contamination levels of APCAs in water, both as the individual APCAs and as a mixture of APCAs. Complimentary experiments were carried out using a molar excess of APCAs calculated from the metal concentrations obtained by acid digestion (assuming 1:1 metal complex formation). Both types of remobilisation experiments were designed to investigate the role that redox potential (Eh) and concentration of APCAs in natural waters have on the remobilisation of heavy metals from the sediments. The agitation experiments were employed to assess metal remobilisation for the situation where the sediments are disturbed while the column experiments explored metal remobilisation for the case where the sediments are left undisturbed in situ. The major conclusions from the agitation experiments that used fine sediment from the Alexandra Canal were that 100 ppm APCA solutions will remobilise metals from the sediments under oxic conditions but only remobilise infinitesimally small amounts of metal under anoxic conditions. The use of fine sediments for the duplicate agitation experiments was found to give adequate duplication of results. A mixture of APCAs in solution acts similarly to the average of the three individual APCA solutions, showing that there are no antagonistic or synergistic effects likely to occur when they are found together in the environment. It was found that the mmoles of the metals remobilised exceeded the mmoles of the APCAs added when 500.0 mL of 100 ppm APCA solution was used on 50.00 g of sediment. This might be due to APCAs remobilising metals from the sediments in ways other than by complexation. Even though an excess of APCAs was available, metal remobilisation was not complete when the experiments were forced to terminate. During the 14 days of the experiment, only one quarter of the metals liberated from the sediment by HNO3 and 30 % H2O2 digestion were remobilised by the APCAs. Therefore an excess of free APCAs remains in solution. Fine sediments from Alexandra Canal, Captains Flat and Jenolan Caves were employed in the oxic agitation experiments using excess APCAs in solution. These experiments resulted in the following major conclusion: when producing an APCA remobilisation signature for trace and ultratrace metals, the geochemistry of the site is of secondary importance to the source of the contaminating metals. This is a feature of the trace and ultratrace metal speciation in the source rather than their concentration in it. From the different levels of calcium present in the three areas it was found that calcium is unlikely to form stable 1:1 APCA complexes at the pH values employed and is unlikely to compete with the heavy metal remobilisation by APCAs. Total sediments from Alexandra Canal and 100 ppm APCA solutions were employed for the column leaching experiments. From mass, pore water volumes and flow measurements it was shown that the ten mini cores taken from the same site were not true replicates. Despite this, when the sediments have settled and the pore waters removed from the cores, the levels of metal being leached stabilise and may represent a clearer picture of the in situ metal leaching from sediment with time. The levels of metal leached from the cores in 14 days suggest that during this period the cores are essentially anoxic, with the oxygen supplied from the oxic leaching solutions used for inorganic and microbial processes in the sediments. Agitation experiments appeared to yield an adequate picture of what would happen if free APCA solution came in contact with fine sediments suspended in the water column. Column leaching experiments employing total sediment were found to be only of limited value in assessing heavy metal remobilisation from undisturbed sediment. These experiments do not give a reliable assessment of the bioavailability of heavy metals and further testing of the acute and chronic toxicity of the sediments is recommended. APCA solutions that have been used in sediment and soil washing under conditions related to those used in the present study may contain an excess of the free APCAs as well as APCA heavy metal complexes and hence may be toxic to biota.

Iron (Fe) and zinc (Zn) deficiencies affect an estimated 3 billion people worldwide and are linked with cognitive and physical impairments, maternal and child mortality rates, and decreased adult work activity. To combat this "hidden" hunger, plant breeders in Mali are working to increase sorghum grain Fe and Zn concentrations. The objective of this study was to investigate soil and mold influences that affect Fe and Zn uptake and accumulation in sorghum grain. In southern Mali, soils from participatory sorghum variety trials and areas of different parent material and proximity to Shea (Vitellaria paradoxa) trees were analyzed for diethylenetriaminepentaacetic acid (DTPA)-extractable Zn and related soil properties, and sorghum grain was analyzed for Zn concentration. An inoculation trial was also performed at College Station, TX to determine if sorghum grain infected by the mold Curvularia lunata significantly increased grain Fe concentrations. DTPA-extractable Zn concentration was highly variable with high concentrations found in soils under Shea tree canopies with high pH and organic carbon and derived from mafic, high Zn-content parent material. However, these high concentrations did not significantly affect grain Zn concentrations in sorghum grown outside of the canopy. Groundnut grown underneath the canopy is likely to be affected and warrants further investigation. In many cases, soil DTPA-extractable Zn concentrations were at deficient levels, thus hampering its correlation to sorghum grain Zn concentration and potentially limiting the expression of genetic Zn biofortification. Knowledge of soil DTPA-extractable Zn concentrations or basic soil properties such as pH, organic carbon, and soil parent material may aid in the location of suitable available Zn fields and overall biofortification efforts. Grain Fe concentration was not significantly related to Curvularia lunata percent recovery or grain mold rating, but instead showed a relatively high variance by panicle, digestion batch, and grain subsample. Additional work is needed to address these sources of Fe variation so as to determine better if mold affects grain Fe concentrations.

This thesis describes a study of the remobilisation of heavy metals from sediments by three aminopolycarboxylic acids (APCAs). They are nitrilotriacetic acid, ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid. The investigation is introduced by examining the sources, uses and chemistry of these acids. The introduction also includes a discussion of what is known about the inclusion of heavy metals into sediments and their remobilisation from sediments. Typical concentrations of APCAs in natural waters and sediments have been catalogued from the literature. The advantages and disadvantages of various laboratory techniques employed for the remobilisation of heavy metals by APCAs from sediments are assessed, as is the use of such experiments in quantifying the role of APCAs in the remobilisation of heavy metals from sediments. Sediments from three areas were sampled for this study; they were the Alexandra Canal, Captains Flat and Jenolan Caves in New South Wales, Australia. In each area several sites were sampled. For each site there is a brief description of the catchment geology and hydrology. Selected sediment-associated waters in the areas were analysed for their metal concentrations as well as for ultratrace levels of APCAs employing a method developed in the present study. The waters were analysed for the major ions Ca2+, Mg2+, K+, Na+, Cl-, NO3- and SO42-. The sediments from selected sites in each of the areas were dried and fractionated. The dry total and fine sediments were analysed for their metal content and the latter was found to adequately represent the former in this respect. Water samples from the three areas showed different chemistries and exhibited more subtle differences between sites. In general, the Alexandra Canal waters are saline and alkaline and are a mixture of urban runoff and seawater; the Captains Flat waters are acidic and contain high sulfate from acid mine and tailings drainage; the Jenolan Caves waters are neutral and have the features characteristic of waters draining through limestone. The APCA contamination in all water samples when ranked against other global sites is very low. Although the current APCA levels in the waters appear low, it was concluded that they should be closely monitored so that efforts can be made to minimise the risk of APCAs being hazardous environmental contaminants and also that any remobilisation of heavy metals from sediments by APCAs can be controlled. Agitation and column laboratory-scale experiments were carried out in order to obtain an understanding of the remobilisation of metals by contamination levels of APCAs in water, both as the individual APCAs and as a mixture of APCAs. Complimentary experiments were carried out using a molar excess of APCAs calculated from the metal concentrations obtained by acid digestion (assuming 1:1 metal complex formation). Both types of remobilisation experiments were designed to investigate the role that redox potential (Eh) and concentration of APCAs in natural waters have on the remobilisation of heavy metals from the sediments. The agitation experiments were employed to assess metal remobilisation for the situation where the sediments are disturbed while the column experiments explored metal remobilisation for the case where the sediments are left undisturbed in situ. The major conclusions from the agitation experiments that used fine sediment from the Alexandra Canal were that 100 ppm APCA solutions will remobilise metals from the sediments under oxic conditions but only remobilise infinitesimally small amounts of metal under anoxic conditions. The use of fine sediments for the duplicate agitation experiments was found to give adequate duplication of results. A mixture of APCAs in solution acts similarly to the average of the three individual APCA solutions, showing that there are no antagonistic or synergistic effects likely to occur when they are found together in the environment. It was found that the mmoles of the metals remobilised exceeded the mmoles of the APCAs added when 500.0 mL of 100 ppm APCA solution was used on 50.00 g of sediment. This might be due to APCAs remobilising metals from the sediments in ways other than by complexation. Even though an excess of APCAs was available, metal remobilisation was not complete when the experiments were forced to terminate. During the 14 days of the experiment, only one quarter of the metals liberated from the sediment by HNO3 and 30 % H2O2 digestion were remobilised by the APCAs. Therefore an excess of free APCAs remains in solution. Fine sediments from Alexandra Canal, Captains Flat and Jenolan Caves were employed in the oxic agitation experiments using excess APCAs in solution. These experiments resulted in the following major conclusion: when producing an APCA remobilisation signature for trace and ultratrace metals, the geochemistry of the site is of secondary importance to the source of the contaminating metals. This is a feature of the trace and ultratrace metal speciation in the source rather than their concentration in it. From the different levels of calcium present in the three areas it was found that calcium is unlikely to form stable 1:1 APCA complexes at the pH values employed and is unlikely to compete with the heavy metal remobilisation by APCAs. Total sediments from Alexandra Canal and 100 ppm APCA solutions were employed for the column leaching experiments. From mass, pore water volumes and flow measurements it was shown that the ten mini cores taken from the same site were not true replicates. Despite this, when the sediments have settled and the pore waters removed from the cores, the levels of metal being leached stabilise and may represent a clearer picture of the in situ metal leaching from sediment with time. The levels of metal leached from the cores in 14 days suggest that during this period the cores are essentially anoxic, with the oxygen supplied from the oxic leaching solutions used for inorganic and microbial processes in the sediments. Agitation experiments appeared to yield an adequate picture of what would happen if free APCA solution came in contact with fine sediments suspended in the water column. Column leaching experiments employing total sediment were found to be only of limited value in assessing heavy metal remobilisation from undisturbed sediment. These experiments do not give a reliable assessment of the bioavailability of heavy metals and further testing of the acute and chronic toxicity of the sediments is recommended. APCA solutions that have been used in sediment and soil washing under conditions related to those used in the present study may contain an excess of the free APCAs as well as APCA heavy metal complexes and hence may be toxic to biota.

Licentiatavhandling (sammanfattning) Linköping : Linköpings universitet, 2009. / Härtill 2 uppsatser.