Perceptions of local community members towards foreign aid: A case study of Vava'u,Tonga

Foreign aid has arguably played a significant role in the economic development of the Pacific Island countries. Tonga is deemed to have succeeded in implementing the principles of the Paris Declaration of 2005, especially Ownership, Alignment and Harmonisation, by aid funding channelled through state institutions. Nevertheless, it is still unknown if the aid effect has reached civil society, and how community members perceive aid. This article examines the perceptions of community members towards foreign aid, using the case study of the archipelago of Vava'u, Tonga.     

Arsenic and antimony contamination of waters,stream sediments and soils in the vicinity of abandoned antimony mines in the Western Carpathians,Slovakia

Environmental contamination with As and Sb caused by past mining activities at Sb mines is a significant problem in Slovakia. This study is focused on the environmental effects of the 5 abandoned Sb mines on water, stream sediment and soil since the mines are situated in the close vicinity of residential areas. Samples of mine wastes, various types of waters, stream sediments, soils, and leachates of the mine wastes, stream sediments and selected soils were analyzed for As and Sb to evaluate their geochemical dispersion from the mines. Mine wastes collected at the mine sites contained up to 5166 mg/kg As and 9861 mg/kg Sb. Arsenic in mine wastes was associated mostly with Fe oxides, whereas Sb was present frequently in the form of individual Sb, Sb(Fe) and Fe(Sb) oxides. Waters of different types such as groundwater, surface waters and mine waters, all contained elevated concentrations of As and Sb, reaching up to 2150 μg/L As and 9300 μg/L Sb, and had circum-neutral pH values because of the buffering capacity of abundant Ca- and Mg-carbonates. The concentrations of Sb in several household wells are a cause for concern, exceeding the Sb drinking water limit of 5 μg/L by as much as 25 times. Some attenuation of the As and Sb concentrations in mine and impoundment waters was expected because of the deposition of metalloids onto hydrous ferric oxides built up below adit entrances and impoundment discharges. These HFOs contained >20 wt.% As and 1.5 wt.% Sb. Stream sediments and soils have also been contaminated by As and Sb with the peak concentrations generally found near open adits and mine wastes. In addition to the discharged waters from open adits, the significant source of As and Sb contamination are waste-rock dumps and tailings impoundments. Leachates from mine wastes contained as much as 8400 μg/L As and 4060 μg/L Sb, suggesting that the mine wastes would have a great potential to contaminate the downstream environment. Moreover, the results of water leaching tests showed that Sb was released from the solids more efficiently than As under oxidizing conditions. This might partly explain the predominance of Sb over As in most water samples.     

Experimental study of the K2ZrSi3O9 (wadeite)–K2TiSi3O9 and K2(Zr,Ti)Si3O9–phlogopite systems at 2–3 GPa

Experiments ranging from 2 to 3 GPa and 800 to 1300 °C and at 0.15 GPa and 770 °C were performed to investigate the stability and mutual solubility of the K₂ZrSi₃O₉ (wadeite) and K₂TiSi₃O₉ cyclosilicates under upper mantle conditions. The K₂ZrSi₃O₉–K₂TiSi₃O₉ join exhibits complete miscibility in the P–T interval investigated. With increasing degree of melting the solid solution becomes progressively enriched in Zr, indicating that K₂ZrSi₃O₉ is the more refractory end member. At 2 GPa, in the more complex K₂ZrSi₃O₉–K₂TiSi₃O₉–K₂Mg₆Al₂Si₆O₂₀(OH)₄ system, the presence of phlogopite clearly limits the extent of solid solution of the cyclosilicate to more Zr-rich compositions [Zr/(Zr + Ti) > 0.85], comparable to wadeite found in nature, with TiO₂ partitioning strongly into the coexisting mica and/or liquid. However, at 1200 °C, with increasing pressure from 2 to 3 GPa, the partitioning behaviour of TiO₂ changes in favour of the cyclosilicate, with Zr/(Zr + Ti) of the K₂(Zr,Ti)Si₃O₉ phase decreasing from ∼0.9 to ∼0.6. The variation in the Ti content of the coexisting phlogopite is related to its degree of melting to forsterite and liquid, following the major substitution ^VITi+^VI□=2^VIMg. Received: 26 January 1999 / Accepted: 10 January 2000     

Pure elastic stiffness of sand represented by response envelopes derived from cyclic triaxial tests with local strain measurements

Acta Geotechnica - The elastic stiffness of a fine sand at small to moderate strains ( $$\varepsilon \le 2 \times 10^{-4}$$ ) has been studied based on cyclic triaxial tests on cube-shaped samples...     

Implications of experimental petrology to the evolution of ultrapotassic rocks

The contributions of experimental studies pertinent to ultrapotassic rocks of Groups I (lamproites) and II (kamafugites and related rocks) are discussed in terms of synthetic systems, ultrapotassic rock compositions, experiments on characteristic minerals in these rocks and experiments designed to model mantle metasomatism. These studies indicate that the majority of ultrapotassic magmas are derived by partial melting of a metasomatically enriched mantle source at depths of 100 km or greater, and under fluid conditions represented by the C---O---H system with fluorine that may be reduced or oxidized relative to other compositions. Many lamproitic magmas may be derived from a phlogopite-harzburgite with volatiles that are predominantly H₂O and F₁ whereas kamafugitic type ultrapotassic magmas may be products of partial melts of a more wehrlitic mantle source in which the main volatiles are H₂O, CO₂ and possibly F. Experimental and theoretical considerations of mantle metasomatism suggest that it occurs at of f_O2 in the range of the FMQ buffer. Metasomatism involves low density mantle fluids (melts?) in which H₂O and CO₂ are the important volatiles, buffered by amphibole, phlogopite and carbonates. Results of recent experiments suggest that the reactions causing metasomatism may be decoupled and cyclic and occur at different depths.     

Fluorine-bearing phases in lamproites

Summary The distribution of F between phlogopite, amphibole, apatite, and glass has been determined for 261amproites from Leucite Hills, Wyoming; West Kimberley, Western Australia; Smoky Butte, Montana; Prairie Creek, Arkansas; and Gaussberg, Antarctica. The F contents of these phases are inconsistent in different lamproite localities, with distinct variations, for example, between the Leucite Hills and West Kimberley lamproites. Fluorine commonly occurs in greatest abundance in phlogopite and apatite. Evolved glass in some lamproites may have no detectable F. With increasing evolution of lamproites, F tends to decrease in whole rocks, amphibole and glass. Fluorine also shows a variety of relationships with BaO in phlogopite and apatite. Based on plots of F/(F + OH) in apatite and phlogopite, apatite and amphibole, and phlogopite and amphibole, the distribution of F is variable in different lamproites and hence determination of partition coefficients is not possible. The F distribution patterns are affected by lack of mutual equilibrium between F-bearing phases, possible removal of F in a fluid phase during magma degassing, variations in physical conditions between different phases during crystallization of the magma, and other causes. This study suggests that F preferentially enters solid rather than liquid phases. Hence, on partial melting of a F-rich mantle source, the F entering melts is unlikely to be sufficient to produce high F-bearing lamproites.

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Fluor führende Phasen in Lamproiten

Zusammenfassung Die Verteilung von Fluor zwischen Phlogopit, Amphibol, Apatit und Glas wurde für 26 Lamproite aus den Leucite Hills, Wyoming; West Kimberley, West-Australien, Smokie Butte, Montana; Prairie Creek, Arkansas; und Gaussberg, Antarktis, bestimmt. Der Fluorgehalt dieser Phasen schwankt in verschiedenen Lamproitvorkommen, und besonders Kimberley. Fluor kommt im allgemeinen besonders reichlich in Phlogopit und Apatit vor. Das Glas in manchen Lamproiten führt keine nachweisbaren Fluorgehalte. Mit zunehmender Evolution von Lamproiten tendiert F in den Gesamtgesteins-analysen, wie auch in Amphibol und im Glas abzunehmen. Fluor zeigt auch Beziehungen zu den BaO Gehalten in Phlogopit und Apatit. Auf der Basis von Plots von F/(F + OH) in Apatit und Phlogopit, Apatit und Amphibol, und Phlogopit und Amphibol, läßt sich erkennen, daß die Verteilung von F in verschiedenen Lamproiten variabel ist und daher eine Bestimmung von Verteilungskoefizienten nicht möglich ist. Die F-Verteilungsmuster werden von dem Mangel an gegenseitigem Euqilibrium zwischen F-führenden Phasen, möglichem Wegtransport von F in einer fluiden Phase während MagmaEntgasung, Variationen in den physikalischen Bedingungen zwischen verschiedenen Phasen bei der Kristallisation des Magmas, und durch andere Ursachen beeinflußt. Diese Untersuchung zeigt, daß F vorzugsweise in festen und nicht in flüssigen Phasen untergebracht wird. Daher wird das Fluor, das in Schmelzen bei der teilweisen Rufschmelzung von fluor-reichen Mantelgesteinen untergebracht wird, kaum ausreichen, um fluor-reiche Lamproite zu erzeugen.

     

Patent mantle-metasomatism: Inferences based on experimental studies

K, Na and Ca are the most common elements transported during mantle metasomatism and result in formation of phlogopite (K), amphibole (Na) and clinopyroxene (Ca) by various reactions. This review presents models for this type of metasomatism based on experiments on the pyrolite-K₂CO₃-H₂O, pyrolite-Na₂ CO₃-H₂O systems and on the pyrolite-CaCO₃ system. The addition of K₂CO₃ and Na₂CO₃ lowers the liquidus of pyrolite providing a low temperature, alkali-rich hydrous melt which may ascend and metasomatize overlying mantle regions. Several reactions are proposed for the formation of phlogopite and amphibole (pargasite-edenite) in these systems. The compositions of amphiboles correspond to those found in metasomatized mantle xenoliths. In contrast, Ca-metasomatism is considered to be mainly an anhydrous process in which orthopyroxene and carbonate react to produce clinopyroxene, olivine and CO₂. High pressure liquids in this model system are of carbonatitic composition and this low viscosity melt can ascend converting harzburgite mantle assemblages to olivine-rich wehrlite. Based on an inverse experimental approach, moderately high degrees of partial melting of a model metasomatized alkali clinopyroxenite xenolith yield liquids at 30kb which are very comparable in composition to the lavas enclosing such types of xenoliths. Experimental modelling of mantle metasomatism produces assemblages which are in good agreement with the mineral assemblages and textural relationships found in metasomatized mantle xenoliths from areas such as West Eifel and South-West Uganda.