Trivalent chromium conversion coatings formed on Al and Al-Cu alloys has been investigated using high-resolution, analytical electron microscopy, atomic force microscopy, ion beam analysis, glow discharge optical emission spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, electrochemical impedance spectroscopy, potentiodynamic polarization and electrochemical noise analysis. These coatings on the electropolished Al and sputtering-deposed Al consist of a chromium- and zirconium-rich outer layer and a thinner, aluminium-rich inner layer. Zirconium and chromium are presented in chemical states consistent with ZrO2, Cr(OH)3, Cr2(SO4)3, CrF3 and CrO3 or CrO42-. However, negligible amounts of hexavalent chromium species occurred in both coatings formed in de-aerated solution. On AA2024-T351 alloys, the coating above the second phase particles was thicker than that on the matrix due to the increased localized alkalinity. Moreover, the localized corrosion and copper enrichment of the matrix occurred at the coating base. The presence of copper resulted in a thinner coating at the matrix compared with superpure aluminium. An Fe(III)-containing D30 desmutter can effectively remove the protruded particles generated by alkaline etching. Moreover, a thinner oxide film on the D30-treated surface was evidenced to promote the coating initiation on the matrix. Further, the coating comprised the concentrated zirconium oxyfluorides and decreased contents of aluminium and copper. Coated alloys displayed a significantly enhanced corrosion protection, especially the cathoidc inhibition. In terms of coating post-treatments, the water immersion (40 ºC, pH 5) soon after conversion treatment revealed a simple but effective process to improve the fluoride enrichment in coatings and to enhance corrosion protection of freshly-developed coatings. Increasing concentration of solid-solution copper in sputtering-deposited alloys, in a range of 2, 24, 40 and 64 at.%Cu, significantly promotes the coating growth kinetics and an evident and a thicker corrosion layer by substrate dissolution was observed on Al-40 at.%Cu alloys. In addition, the relationship of copper-rich deposits with Cr(VI) transformation was demonstrated by Raman spectroscopy.

The X-band FMR has been employed to investigate the angular variation of resonance Fields of DC sputtered Co-Cr Films with different substrate temperatures. This angular variation has been Fitted with the classical uniaxial anisotropy crystal model and yields the values of 2K₁/M-4πM=-4∼-7 KOe, 4K₂ =-0.8∼0.8 KOe and g-factor = 2.3~2.8. The FMR measurments of the first anisotropy constant are quite different from the counterparts measured with VSM. This discrepancy is interpreted as a result of the formation of two ferromagnetic phases. With this simple model, the substrate temperature dependence of First anisotropy is explained and it is predicted that a lower substrate temperature will improve the Co-Cr Films for their potential application in perpendicular magnetic recording devices. The angular dependence of the FMR linewidth is discussed. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Ph.D. / Spin—density—wave (SDW) effects are investigated in four dilute Cr—Ir alloy single crystals. The Ir concentrations in these crystals were chosen to cover all four magnetic phases existing on the magnetic phase diagram of the Cr—Ir system. Thermal expansion, electrical resistivity, elastic constants and ultrasonic attenuation are studied as functions of temperature and alloy concentration. The elastic constants are also studied as a function of applied hydrostatic pressure. The SDW effects in the Cr—Ir system are compared with those in other Cr alloys. The full temperature—concentration and temperature—pressure magnetic phase diagrams of the Cr—Ir system are determined. Existing theories are used to discuss the observations. The following major observations are made: Magnetoelastic interactions in Cr—Ir alloys are very large, resulting in well defined magnetic anomalies in the elastic constants and thermal expansion at all magnetic phase transition temperatures. Elastic constant measurements as a function of temperature appear to be a very sensitive tool to determine the magnetic phase transition temperatures of the Cr—Ir alloy system. Below TN of Cr—Ir alloys, where TN is the transition temperature from the incommensurate transverse spin—density-wave (TISDW) magnetic phase to the paramagnetic phase, elastic constant and thermal expansion measurements show the existence of hysteresis effects, which are probably due to a redistribution of antiferromagnetic domains. These hysteresis effects are the first evidence of such effects in Cr alloys. Spin fluctuation effects are shown to exist to temperatures well above the Neel temperatures of the Cr—Ir alloys. Analyses of the data for electrical resistivity measurements of Cr—Ir alloys show that the fraction of the electron and hole Fermi surface sheets that nests is roughly the same in the ISDW and CSDW (commensurate spin—density—wave) phases, making the resistivity anomaly near the ISDW—CSDW transition temperature very small or non—existing. Measurements of elastic constants as a function of applied pressure at different constant temperatures are shown to be a very powerful tool for an investigation of the interaction of the SDW with the acoustic phonons in dilute Cr—Ir alloys. It is found that the SDW in Cr—Ir alloys couples mainly with the longitudinal—mode acoustic phonons. Coupling to the shear—mode phonons is relatively small. Empirical correspondence is found between the temperature—concentration and temperature— pressure magnetic phase diagrams of the dilute Cr—Ir alloy system by using a linear scaling between pressure and concentration. Existing thermodynamic models fit the experimental results for the elastic constants and magnetovolume of the Cr—Ir alloys well. The main features of the temperature—concentration and temperature—pressure magnetic phase diagrams of the Cr—Ir alloy system are resonably well predicted by existing microscopic theories.

M.Sc. (Chemistry) / Please refer to full text to view abstract

O objetivo geral do trabalho foi avaliar a distribuição e os efeitos tóxicos dos metais Cr e Cu sobre os ecossistemas aquáticos lênticos, incluindo seus componentes bióticos e abióticos, utilizando-se sistemas com diferentes níveis de complexidade e organização. Os sistemas utilizados na avaliação da toxicidade de Cr e Cu foram: a) testes uniespecíficos com Selenastrum capricornutum (microalga), Daphnia similis e Ceriodaphnia dubia (Cladocera), Chironomus xanthus (Diptera, Chironomidae), Oreochromis niloticus (peixe) e Pistia stratiotes (macrófita); b) experimentos em microcosmos (testes multiespecíficos) com as comunidades naturais da represa do Lobo; c) experimentos em mesocosmos, contando com água, sedimento, plâncton, bentos, peixes e macrófitas naturais da represa do Lobo. Nos testes de toxicidade todas as espécies foram mais sensíveis ao Cu que ao Cr, e a sequência de sensibilidade foi D. similis> C. dubia> S. capricornutum> C. xanthus > P. stratiotes > O. niloticus. Nos experimentos em microcosmos e mesocosmos, as concentrações-teste foram definidas como o valor máximo permitido pela Resolução nº 20/1986 do CONAMA para Cr6+ e Cu2+ para corpos dágua Classe 2 (50 µg.L-1 e 20 µg.L-1, respectivamente). Em todos os experimentos a concentração de clorofila foi reduzida significativamente após a adição dos metais. Os efeitos sobre a densidade e riqueza de espécies das comunidades zooplanctônicas foram mais severos para o Cr que para o Cu; porém Cladocera foi mais sensível ao Cu. Cromo provocou uma maior inibição na produção primária em abril de 2002, enquanto que em novembro/dezembro de 2002 a produção primária sofreu maior decréscimo após a adição de Cu. Ambos os metais estudados apresentaram efeitos significativos sobre um grande número de variáveis da água, como oxigênio dissolvido, amônio, distribuição das formas fosfatadas, clorofila e material em suspensão, sendo os efeitos do Cr mais severos que os do Cu, em relação ao número de variáveis afetadas e ao tempo de restauração do sistema. Os sedimentos não apresentaram alterações após a adição de metais. Foi observada a ocorrência de bioacumulação de Cr e Cu pelo plâncton, bentos, macrófitas e peixes. A toxicidade dos metais estudados foi reduzida após a inclusão de peixes e macrófitas, principalmente para Cu. Apesar das concentrações de Cr e Cu relativamente baixas empregadas, os metais provocaram efeitos nos compartimentos bióticos e abióticos do sistema. Os resultados obtidos no presente trabalho podem ser úteis como subsídio para a avaliação dos valores máximos permitidos pela Resolução nº 20/1986 do CONAMA para os metais estudados. / The general aim of this work was to evaluate the distribution and the toxic effects of the metals Cr and Cu on lenthic aquatic ecosystems, using systems of different complexity and organization levels. The systems used for Cr and Cu toxicity evaluations were: a) single-specific tests with Selenastrum capricornutum (microalgae), Daphnia similis e Ceriodaphnia dubia (Cladocera), Chironomus xanthus (Diptera, Chironomidae), Oreochromis niloticus (fish) and Pistia stratiotes (macrophyte); b) microcosms experiments (multi- specific tests) with the Lobos reservoir natural communities; c) mesocosms experiments, with natural water, sediment, plankton, benthics, fishes and macrophytes from Lobos reservoir. In the toxicity tests, all the species were more sensitive to Cu than to Cr, and the sensitiviness sequence was D. similis> C. dubia> S. capricornutum> C. xanthus > P. stratiotes > O. niloticus. In the microcosms and mesocosms experiments, the test-concentrations were the maximum value allowed by the CONAMA Resolution nº 20/1986 to Cr6+ and Cu2+ to Class 2 water bodies (50 µg.L-1 and 20 µg.L-1, respectively). In all experiments the chlorophyll concentration was significantly reduced after the metal addition. The effects on the Zooplankton density and richness were stronger to Cr than to Cu; however Cladocera was more sensitive to Cu. Chromium caused higher inhibition in primary production in April/ 2002, but in November/ December 2002 the primary production suffered higher inhibition by Cu addition. Both studied metals showed significant effects on several water variables, as dissolved oxygen, ammonium, phosphate forms distribution, chlorophyll and suspended material, being the Cr effects stronger than the Cu effects, in relation to the number of affected variables and the system restoration time. The sediments didnt show alterations after the metal addition. Chromium and Cu bioaccumulation was observed by plankton, benthic invertebrates, macrophytes and fishes. The toxicity of the studied metals was reduced by the fish and macrophyte inclusion, mainly to Cu. Although the concentration of Cr and Cu were low, toxic effects were observed on both biotic and abiotic system compartments. The results obtained in this work may be useful as subsidy to evaluation of the maximum value allowed by the CONAMA Resolution nº 20/1986 to the studied metals.

Teores anômalos de cromo hexavalente vêm sendo detectados na água subterrânea de vários municípios da região noroeste do Estado de São Paulo, sendo que em Urânia foram observadas as maiores concentrações do elemento, afetando as condições do consumo e uso humano. Estudos prévios realizados indicaram que a origem do cromo na água subterrânea é natural e proveniente de minerais com cromo no aqüífero profundo. Este projeto teve como principais objetivos: (1) a caracterização química e mineralógica da fase sólida do aqüífero profundo, realizada em testemunhos de duas sondagens profundas; (2) a caracterização da estratificação das concentrações de cromo na água subterrânea, com base na coleta e análise de amostras de água provenientes de poços de monitoramento instalados em diferentes profundidades do aqüífero; (3) a identificação dos processos hidrogeoquímicos que justificam a passagem do cromo da fase sólida para a água. Para tanto, foram realizadas análises químicas e mineralógicas por WDS, microssonda eletrônica e CTC, diversos métodos de análise química da água subterrânea, utilizados programas como o AquaChem e PHREEQc para trabalhamento do banco de dados e modelagens, além de uma grande variedade de experimentos de laboratório. As análises químicas por WDS e microssonda eletrônica indicaram concentrações de cromo de até 12.600 ppm em cristais de diopsídio, e de 650 ppm em capas de argilomineral. O material sólido apresenta uma capacidade de troca de cátions da ordem de 30 meq/100g, com ordem de abundância dos cátions Ca>>Mg>>K>Na. Na porção profunda do aqüífero, foi observada uma anomalia de sódio adsorvido, influenciando na composição química da água. As características hidroquímicas do aqüífero indicaram a ocorrência de estratificações de águas com diferentes perfis hidroquímicos. As águas são, no geral, do tipo bicarbonatadas cálcicas, porém com uma elevação do conteúdo de sódio na base do aqüífero. O cromo foi identificado na água predominantemente na forma hexavalente, com concentrações que atingiram 0,139 mg/L, acima, portanto do limite de potabilidade (0,05 mg/L). A ocorrência de valores mais elevados de cromo na água parece estar associada a ambientes de elevados pH e Eh, como observado no aqüífero profundo, enquanto que nas zonas rasas, que apresentam valores de pH e Eh neutros, apresentaram baixo conteúdo de cromo. Os principais resultados dos ensaios de laboratório indicaram que há passagem de cromo para água subterrânea, através do ataque aos minerais pesados com pH ácido; os ensaios de batch test realizados apontaram que o material sólido do aqüífero apresenta alguma capacidade de adsorção de Cr6+, chegando a um máximo de 0,12 ppm; o experimento de solubilização indicou a passagem de pequenas concentrações de cromo para a água e que a composição química da água do ensaio é semelhante à água do aqüífero. O modelo mais provável das reações geoquímicas que explicam a passagem do cromo da fase sólida para a água é apresentado a seguir, divido por etapas: (1) o intemperismo dos diopsídios cromíferos deve ser o processo inicial de disponibilização de cromo para a água, resultando na precipitação do cromo como hidróxidos ou sendo adsorvido por hidróxidos de ferro e manganês; (2) ocorrência de uma reação de oxi-redução a partir do cromo trivalente que ocorre nos minerais secundários, disponibilizando o cromo para a água subterrânea, sendo que esta oxidação ocorre a partir da redução de óxidos de manganês presentes como minerais em aqüíferos, liberando Mn2+; (3) O Cr3+ é rapidamente e fortemente imobilizado por adsorção em argilominerais de baixo valor de pHpzc, enquanto que o Cr6+, devido à sua natureza aniônica, é preferencialmente retido em superfícies carregadas positivamente, como os óxidos e hidróxidos de ferro e alumínio (minerais com elevados valores de pHpzc), principalmente em condições hidroquímicas neutras a ácidas; (4) altas concentrações de OH-, de HCO3- e de CO3 2- provavelmente elevam a competição pelos sítios de adsorção de ânions e causam a dessorção dos ânions de Cr6+ para a água do aqüífero. / Anomalous hexavalent chromium contents have been detected in groundwater in many municipalities of the northwestern region of São Paulo state. In the city of Urânia, the highest concentrations of this element have been observed, affecting the conditions for human consumption. Previous studies indicated that the origin of chromium in groundwater is from natural sources and derived from chromium minerals in the deep aquifer. The main objectives of this research are to: (1) characterize chemically and mineralogically the solid phase from the deep aquifer; (2) characterize the stratification of chromium concentrations in groundwater, based on sampling and analysis of groundwater from wells installed in different depths of the aquifer; (3) identify hydrogeochemical processes that justify the passage of chromium from solid phase to groundwater. To achieve these objectives, chemical and mineralogical analysis by WDS, microprobe and CEC were made, diverse chemical analytical methods were used for groundwater, database and modeling were used through AquaChem and PHREEQc programs, besides a great variety of laboratory experiments. Chemical analysis from WDS and microprobe indicated chromium concentrations of up to 12.600 ppm in diopside crystals, and up to 650 ppm in clay mineral coats. The solid material has a Cation Exchange Capacity (CEC) of about 30 meq/100g, with cation abundance order of Ca>>Mg>>K>Na. In the aquifer deep zone, it was observed an adsorbed sodium anomaly, that influences groundwater chemical composition. The aquifer hydrochemical characteristics indicated the occurrence of water stratifications with different hydrochemical profiles. The groundwaters are, in general, calcium bicarbonated, with a elevation of sodium contents in the base of the aquifer. Chromium was identified predominatly in hexavalent state of oxidation, with concentrations of up to 0,139 mg/L, thus above potability standards (0,05 mg/L). The occurrence of higher chromium concentrations in groundwater seems to be related to high pH and Eh environments, whereas shallow zones, that have neutral values of pH and Eh, presented low chromium contents. The main results of laboratory experiments have indicated that there is passage of chromium to groundwater through acid etching in heavy minerals; batch tests have shown that solid phase has some sorption capacity, reaching a maximum of 0,12 ppm; solubilization experiment indicated the passage of low concentrations of chromium to water and that chemical composition from the experiment water is similar to groundwater. The probable model that explain the passage of chromium from solid phase to groundwater is presented hereafter, divided in steps: (1) it is indicated that weathering of chromium diopsides must be the initial process of availability of chromium to water; (2) hexavalent chromium can only occur in groundwater after the occurrence of an oxi-reduction reaction from the trivalent chromium that occurs in minerals. Many authors recognize that this oxidation occurs from the reduction of manganese oxide presented as minerals in the aquifer, releasing Mn2+, that later will be oxidated again; (3) the trivalent chromium is rapidly and strongly immobilized by sorption in clay minerals of low values of pHzpc, whereas the hexavalent chromium, due to its anionic nature, is preferably retained in positively charged surfaces, like iron and aluminium hydroxides (minerals with high values of pHzpc), mainly in neutral to acid hydrochemical conditions; (4) high OH-, HCO3 - and CO3 2- concentrations probably elevate the competition for anion sorption sites and cause the desorption of hexavalent chromium anions to groundwater.

O objetivo geral do trabalho foi avaliar a distribuição e os efeitos tóxicos dos metais Cr e Cu sobre os ecossistemas aquáticos lênticos, incluindo seus componentes bióticos e abióticos, utilizando-se sistemas com diferentes níveis de complexidade e organização. Os sistemas utilizados na avaliação da toxicidade de Cr e Cu foram: a) testes uniespecíficos com Selenastrum capricornutum (microalga), Daphnia similis e Ceriodaphnia dubia (Cladocera), Chironomus xanthus (Diptera, Chironomidae), Oreochromis niloticus (peixe) e Pistia stratiotes (macrófita); b) experimentos em microcosmos (testes multiespecíficos) com as comunidades naturais da represa do Lobo; c) experimentos em mesocosmos, contando com água, sedimento, plâncton, bentos, peixes e macrófitas naturais da represa do Lobo. Nos testes de toxicidade todas as espécies foram mais sensíveis ao Cu que ao Cr, e a sequência de sensibilidade foi D. similis> C. dubia> S. capricornutum> C. xanthus > P. stratiotes > O. niloticus. Nos experimentos em microcosmos e mesocosmos, as concentrações-teste foram definidas como o valor máximo permitido pela Resolução nº 20/1986 do CONAMA para Cr6+ e Cu2+ para corpos dágua Classe 2 (50 µg.L-1 e 20 µg.L-1, respectivamente). Em todos os experimentos a concentração de clorofila foi reduzida significativamente após a adição dos metais. Os efeitos sobre a densidade e riqueza de espécies das comunidades zooplanctônicas foram mais severos para o Cr que para o Cu; porém Cladocera foi mais sensível ao Cu. Cromo provocou uma maior inibição na produção primária em abril de 2002, enquanto que em novembro/dezembro de 2002 a produção primária sofreu maior decréscimo após a adição de Cu. Ambos os metais estudados apresentaram efeitos significativos sobre um grande número de variáveis da água, como oxigênio dissolvido, amônio, distribuição das formas fosfatadas, clorofila e material em suspensão, sendo os efeitos do Cr mais severos que os do Cu, em relação ao número de variáveis afetadas e ao tempo de restauração do sistema. Os sedimentos não apresentaram alterações após a adição de metais. Foi observada a ocorrência de bioacumulação de Cr e Cu pelo plâncton, bentos, macrófitas e peixes. A toxicidade dos metais estudados foi reduzida após a inclusão de peixes e macrófitas, principalmente para Cu. Apesar das concentrações de Cr e Cu relativamente baixas empregadas, os metais provocaram efeitos nos compartimentos bióticos e abióticos do sistema. Os resultados obtidos no presente trabalho podem ser úteis como subsídio para a avaliação dos valores máximos permitidos pela Resolução nº 20/1986 do CONAMA para os metais estudados. / The general aim of this work was to evaluate the distribution and the toxic effects of the metals Cr and Cu on lenthic aquatic ecosystems, using systems of different complexity and organization levels. The systems used for Cr and Cu toxicity evaluations were: a) single-specific tests with Selenastrum capricornutum (microalgae), Daphnia similis e Ceriodaphnia dubia (Cladocera), Chironomus xanthus (Diptera, Chironomidae), Oreochromis niloticus (fish) and Pistia stratiotes (macrophyte); b) microcosms experiments (multi- specific tests) with the Lobos reservoir natural communities; c) mesocosms experiments, with natural water, sediment, plankton, benthics, fishes and macrophytes from Lobos reservoir. In the toxicity tests, all the species were more sensitive to Cu than to Cr, and the sensitiviness sequence was D. similis> C. dubia> S. capricornutum> C. xanthus > P. stratiotes > O. niloticus. In the microcosms and mesocosms experiments, the test-concentrations were the maximum value allowed by the CONAMA Resolution nº 20/1986 to Cr6+ and Cu2+ to Class 2 water bodies (50 µg.L-1 and 20 µg.L-1, respectively). In all experiments the chlorophyll concentration was significantly reduced after the metal addition. The effects on the Zooplankton density and richness were stronger to Cr than to Cu; however Cladocera was more sensitive to Cu. Chromium caused higher inhibition in primary production in April/ 2002, but in November/ December 2002 the primary production suffered higher inhibition by Cu addition. Both studied metals showed significant effects on several water variables, as dissolved oxygen, ammonium, phosphate forms distribution, chlorophyll and suspended material, being the Cr effects stronger than the Cu effects, in relation to the number of affected variables and the system restoration time. The sediments didnt show alterations after the metal addition. Chromium and Cu bioaccumulation was observed by plankton, benthic invertebrates, macrophytes and fishes. The toxicity of the studied metals was reduced by the fish and macrophyte inclusion, mainly to Cu. Although the concentration of Cr and Cu were low, toxic effects were observed on both biotic and abiotic system compartments. The results obtained in this work may be useful as subsidy to evaluation of the maximum value allowed by the CONAMA Resolution nº 20/1986 to the studied metals.

Amid a growing world population and diminishing living space, the discerning and beneficial use of steel plant slag as liming material in agriculture has become a viable option. However, until the potentially detrimental effect on human health and environmental quality of heavy metals contained within the matrixes of slag has been assessed, the use of slag in agriculture cannot be deemed sustainable. This study aims to correlate the mechanisms by which chromium(III) and nickel are sorbed in Eastern Highveld soils to easily classifiable soil constituents. In addition, the influence of an external source of silicon, as would be the case in dissolving slag, on Cr(III) and Ni mobility was investigated. The study consisted of an investigation into the mechanisms by which Cr(III) and Ni are sequestered in soil within a single wetting and drying cycle, as well as over a period of five rewetting and drying cycles. The effect of Si was observed for the latter and a detailed mineralogical study conducted as part of the former. Additionally, the reactivity of and heavy metal (Cr and Ni) release from two commercially available slag samples used as liming material in a highly buffered soil was investigated. Five main conclusions were drawn: (i) whereas Cr(III) is effectively sorbed (even at near water saturated conditions) and precipitation ascribed to bulk-solution saturation, Ni is not sequestered as effectively, and initially precipitates owing to the influence of soil mineralogy; (ii) conclusive evidence could not be gathered for the further immobilisation after sorption of Cr(III) and Ni over a short time period; (iii) both Cr(III) and Ni associate mainly with the amorphous Fe oxide mineral phase; (iv) an external source of Si renders Ni less mobile in soil that does not sequester the element effectively, but more mobile in soil that does tend to sequester the element to some degree; and (v) although neither Cr(III) nor Ni mobility could be explained using field classifiable soil characteristics (soil colour and texture), soil mineralogical and detailed surface charge characterisation did provide explanations for sorption behaviour. Copyright / Dissertation (MSc(Agric))--University of Pretoria, 2009. / Plant Production and Soil Science / unrestricted

The research presented in this paper evaluates the potential impact of municipal solid waste (MSW) landfill leachate quality on the loss of metals from discarded treated wood during disposal. The loss of arsenic (As), chromium (Cr), copper (Cu), and boron (B) from several types of pressure-treated wood (CCA: chromated copper arsenate, ACQ: alkaline copper quaternary, CBA: copper boron azole, and DOT: disodium octaborate tetrahydrate) using leachate collected from 26 MSW landfills in Florida was examined. The toxicity characteristic leaching procedure (TCLP), the synthetic precipitation leaching procedure (SPLP), and California's waste extraction test (WET) were also performed. The results suggested that loss of preservative components was influenced by leachate chemistry. Copper loss from CCA-, ACQ- and CBA-treated wood was similar in magnitude when in contact with landfill leachates compared to synthetic TCLP and SPLP solutions. Ammonia was found as one of the major parameters influencing the leaching of Cu from treated wood when leached with MSW landfill leachates. The results suggest that disposal of ACQ- and CBA-treated wood in substantial quantity in MSW landfills may elevate the Cu concentration in the leachate; this could be of potential concern, especially for a bioreactor MSW landfill in which relatively higher ammonia concentrations in leachate have been reported in recent literature. For the As, Cr and B the concentrations observed with the landfill leachate as the leaching solutions were over a range from some sample showing the concentrations below and some showing above the observed value from corresponding SPLP and TCLP tests. In general the WET test showed the highest concentrations.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18952号 / 工博第3994号 / 新制||工||1615(附属図書館) / 31903 / 京都大学大学院工学研究科合成・生物化学専攻 / (主査)教授 北川 進, 教授 杉野目 道紀, 教授 宮原 稔 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM