Gradual Change In Composition Research Articles

Biodiversity of epibenthic community in the inshore waters of southeast coast of India

AbstractThe epifaunal assemblage was evaluated at three different depths (5, 15 and 25 m) in the inshore waters of Pazhayar, Parangipettai and Cuddalore apart from 5 m depth near SIPCOT covering totally 10 stations (11°21′ N to 11°42′ N; 79°46′49″ E to 79°52′34″ E) in the southeast coast of India, Bay of Bengal. The occurrence of as many as 112 species belonging to 6 groups was recorded. Among these, gastropods constituted the largest component (42.85%) with 48 species. Bivalves came next with the percentage contribution of 24.10% with 27 species. Crustaceans and polychaetes contributed with 16.96% (19 species) and 6.25% (7 species), respectively. Others contributed with 9.82% (11 species). The maximum number of species was recorded in Cuddalore transect (65 species) and the minimum in SIPCOT (20 species). The maximum abundance was recorded in SIPCOT (1363 ind./haul) but the diversity was found to be lower here than in the other stations. The bivalve, Scapharca inaequivalvis was abundant only in this station whereas the large sized polychaetes, Epidiopatra hupferiana monroi and Sternaspis scutata were found only in the Pazhayar transect during all the seasons. Multivariate analyses were done to define assemblages. The total number of species estimated by various extrapolators varied from 112 species to 169.73 species. The cluster analysis revealed the gradual change in species composition with increase in depth. In the principal coordinate analysis (PCO) the first two axes explained 49.8% of the total variability in the case of biota and 98.3% of the total variability in the case of environmental variables. The distance based linear model (DISTLM) was used to find out the relationship between the abundance of epifauna and environmental variables. Depth explained about 23.7% of the variability while temperature and pH explained 17.5 and 10.6%, respectively. The best solution suggested all the nine environmental variables to combinedly explain about 92.49% of the total variability

Calcium Oxalate Stone Formation in the Inner Ear as a Result of an Slc26a4 Mutation

Calcium oxalate stone formation occurs under pathological conditions and accounts for more than 80% of all types of kidney stones. In the current study, we show for the first time that calcium oxalate stones are formed in the mouse inner ear of a genetic model for hearing loss and vestibular dysfunction in humans. The vestibular system within the inner ear is dependent on extracellular tiny calcium carbonate minerals for proper function. Thousands of these biominerals, known as otoconia, are associated with the utricle and saccule sensory maculae and are vital for mechanical stimulation of the sensory hair cells. We show that a missense mutation within the Slc26a4 gene abolishes the transport activity of its encoded protein, pendrin. As a consequence, dramatic changes in mineral composition, size, and shape occur within the utricle and saccule in a differential manner. Although abnormal giant carbonate minerals reside in the utricle at all ages, in the saccule, a gradual change in mineral composition leads to a formation of calcium oxalate in adult mice. By combining imaging and spectroscopy tools, we determined the profile of mineral composition and morphology at different time points. We propose a novel mechanism for the accumulation and aggregation of oxalate crystals in the inner ear.

Surface Reactions on Pt during NOx Storage−Reduction Studied by Polarization-Modulation Infrared Reflection−Absorption Spectroscopy

NOx storage−reduction (NSR) cycles on a model catalyst, consisting of Pt particles on a BaO thin film deposited on a polished Al substrate, have been investigated by means of in situ polarization-modulation infrared reflection−absorption spectroscopy (PM-IRRAS). The method affords simultaneous time-resolved detection of bulk Ba species and species in gas-phase and on the Pt surface. The study revealed the special role of atop NO adsorption sites on platinum for NO oxidation leading to efficient NOx storage on the Ba component, and a gradual change in adsorbate composition resulting in a transition from N2O- to NO2-formation reaction on Pt during lean periods.

Hydrothermal sediment alteration at a seafloor vent field: Grimsey Graben, Tjörnes Fracture Zone, north of Iceland

An active seafloor hydrothermal system subjects the background sediments of the Grimsey Graben (Tjörnes Fracture Zone) to alteration that produces dissolution of the primary volcaniclastic matrix and replacement/precipitation of sulfides, sulfates, oxides, oxyhydroxides, carbonates and phyllosilicates. Three types of hydrothermal alteration of the sediment are defined on the basis of the dominant hydrothermal phyllosilicate formed: smectite, kaolinite, chlorite. The most common alteration is near‐total conversion of the volcaniclastic material to smectite (95–116°C). The dominant smectite in the deepest sediments sampled is beidellite, which is replaced by montmorillonite and an intimate mixture of di‐ and tri‐octahedral smectite up core. This gradual vertical change in smectite composition suggests an increase in the Mg supply upward, the result of sediment alteration by the ascending hydrothermal fluids mixing with descending seawater. The vertical sequence kaolinite → kaolinite‐smectite mixed‐layer → smectite from bottom to top of a core, as well as the distinct zonation across the veins (kaolinite in the central zone → kaolinite‐smectite in the rim), suggests hydrothermal transformation of the initially formed smectite to kaolinite through kaolinite‐smectite mixed‐layer (150–160°C). The cause of this transformation might have been an evolution of the fluids toward a slightly acidic pH or a relative increase in the Al concentration. Minor amounts of chamosite fill thin veins in the deepest sections of some cores. The gradual change from background clinochlore to chamosite across the veins suggests that chamosite replaces clinochlore as Fe is made available from hydrothermal dissolution of detrital Fe‐containing minerals. The internal textures, REE distribution patterns and the mode of occurrence of another magnesian phyllosilicate, kerolite, suggest that this mineral is the primary precipitate in the hydrothermal chimneys rather than an alteration product in the sediment. Kerolite precipitated after and grew on anhydrite in the chimneys. Oxygen isotope ratios are interpreted to reflect precipitation of kerolite at temperatures of 302° to 336°C. It accumulated in the hydrothermal mounds following the collapse of the chimneys and subsequent dissolution of anhydrite, thereby forming highly permeable aquifer layers underlying the vent field. Some kerolite was redeposited in the near vent field sediments by turbidity flows. The altered sediments are depleted in Mn, Rb and Sr, and enriched in U, Mo, Pb, Ba, As, Bi, Sb, Ag, Tl and Ga, as a result of leaching and precipitation, respectively. Conservative elements (Ti, Zr, Hf, Sc, Cr, Nb and Sn) are depleted or enriched in the altered sediments because of passive (precipitation or leaching of other phases) rather than active (because of their mobility) processes.

Consequences of the cessation of 3000 years of grazing on dry Mediterranean grassland ground-active beetle assemblages

Due to extensive grazing regimes over a long period of time, the Plain of Crau, the unique steppe of France, is a particularly suitable model to study the role of sheep grazing on beetle (Coleoptera) assemblages and their response to grazing abandonment. After four years of abandonment, beetle assemblages first only undergo a decrease in the abundance of a few species and then a gradual and slight change in species composition. Later, there is a change in the structure of assemblages, which increases with increasing time since abandonment. After 23 years of grazing abandonment, there is no significant loss of species. To cite this article: S. Fadda et al., C. R. Biologies 331 (2008).

The search for reference conditions for stream vegetation in northern Europe

Summary1. The European Water Framework Directive provides a framework for improving the ecological quality of stream ecosystems, with deviation from reference used as a measure of ecological status.2. Here we examine the possibility of using less impacted stream sites from Latvia, Lithuania and Poland to establish a Danish reference network for macrophyte assemblages, and as a guiding image for identification of possible references sites within Denmark. Both approaches were evaluated using historical Danish records.3. Four different macrophyte assemblages were identified for mid‐sized streams in the Central and Eastern Lowland ecoregions. Macrophyte assemblages could not be delineated using physical stream site characteristics; however a gradual change in assemblage composition was attributed to differences in alkalinity and human impact.4. Assemblages of contemporary vegetation in Denmark were quite similar to those found in Polish, Latvian and Lithuanian streams (26–35%). However, more importantly, from species‐based predictions we noted higher similarity, particularly with Latvian and Lithuanian streams, before intensive land use commenced in Denmark (c. 1900). These results show that stream sites from these three countries can be considered in a Danish reference network.5. Two of the four macrophyte assemblages comprised species such as Fontinalis antipyretica, Myriophyllum spicatum, Nuphar lutea, Potamogeton alpinus and P. perfoliatus that have a very scattered occurrence in the contemporary vegetation in Denmark. These groups were closely associated with the predictions from historic records, thereby lending support the conjecture that these assemblages could be part of the guiding image for the identification of potential reference sites within Denmark.

ZrO2-Ni Functionally Graded Joining Interlayers: Microstructure and Properties

Functionally graded materials (FGMs) are multi-component composites with a gradual change in composition and/or structure. ZrO2-Ni FGMs in the form of a bonding interlayer with thicknesses in the range 40–100 μm were capable of joining dense ZrO2 pieces (a) or ZrO2 to Ni specimens (b). The number of composition steps in these FGMs was adjusted according to the end joining parts in order to reduce residual stresses. The small formation of Ni7Zr2 at temperatures of 1200 °C favoured the interfacial contact giving a maximum shear stress of 20MPa for the ZrO2/FGM/ZrO2 joints.

Interface reaction systematics in the Cu/In–48Sn/Cu system bonded by diffusion soldering

An alternative lead-free solder alloy In–48 at%Sn with a melting point of 120 °C and its implementation to bond Cu substrates in a diffusion soldering joining method are presented. According to the EPMA, TEM/EDX and electron diffraction analyses, two different behaviors were observed in the interconnection zone depending on the temperature range: (i) a single layer consisting of η phase below 200 °C; (ii) a Cu-poor region consisting of η phase and a Cu-rich layer formed by a mixture of thin alternate regions of ζ-Cu 10Sn 3 and δ-Cu 7In 3 phases perpendicular to the interconnection plane above 200 °C. The η layer shows two morphologies: large grains and fine grains at the η/In–48Sn (liquid) and at the η/Cu-rich interfaces, respectively. Additionally, the η region shows a gradual change in composition, suggesting a change from the Cu 6Sn 5 to the Cu 2In structures. Thermal stability tests indicate that the thermal resistance of the bonds is about 750 °C.

Fabrication of Functionally Graded SiAlON Ceramics by Tape Casting

Functionally graded SiAlON ceramics (FG‐SiAlONs) were successfully prepared by the tape casting and lamination approach. Non‐aqueous SiAlON slurries with five different α to β‐SiAlON ratios (85α:15β, 70α:30β, 55α:45β, 40α:60β, and 25α:75β) were prepared by a 66 methyl ethyl ketone/34 ethanol (vol%) mixture. Phase and microstructure analyses incorporation with hardness measurements clearly show that the FG‐SiAlONs, prepared by tape casting, exhibit a continuous and gradual change in composition and hardness. Thus, the tape casting approach is a viable method to produce FG‐SiAlONs with a precisely controlled composition, and subsequently properties, as a function of position.

Influence of climate changes on animal communities in space and time: the case of spider assemblages along an alpine glacier foreland

AbstractThe impact of global warming in space and time is described for species assemblages of wandering spiders along the alpine glacier foreland of the Forni Valley (Northern Italy). We tested the effect of environmental variables (e.g. elevation, age of glacier retreat, vegetation cover, debris cover) on species richness and on species composition of spiders. Age of glacier retreat was the only significant variable influencing spider species assemblages in the valley. A spatially structured distribution of species and species assemblages along the chronosequence of glacier retreat was evidenced. The threshold abruptly differentiating two groups of species richness and species composition fell between sites deglaciated 100 and 155 years before the analysis. Latitudinal shifts towards the poles in species ranges at the global scale in response to climatic changes are known, and an altitudinal shift in species range should be expected for spiders at the local scale of the Forni Valley. Such a shift is present in spider species assemblages, although not as an expected gradual change in species richness and composition, but with a threshold effect after one century of glacier retreat. We discuss our results in the light of plausible future scenarios due to global warming, the consequence of further glacier retreats onto spiders, and caveats for monitoring studies.

Glass–ceramic functionally graded materials produced with different methods

Functionally graded materials (FGMs) are innovative composite materials characterized by a gradual spatial change in composition, microstructure and related properties. This work was focused on glass–alumina functionally graded materials, produced via percolation of molten glass into a sintered polycrystalline alumina substrate and via plasma spraying. The glass composition, belonging to the CaO–ZrO 2–SiO 2 system, was purposely designed in order to minimize the difference between the coefficients of thermal expansion of the constituent phases, which may induce thermal residual stresses in service or during fabrication. The ingredient materials as well as the resultant FGMs were carefully characterized. In particular, a great attention was devoted to the microstructural investigation of the penetration profile.

High-Throughput Synthesis and Screening of a Library of Random and Gradient Copoly(2-oxazoline)s

ReceiVed July 8, 2005 Introduction. The living cationic ring opening polymerization (CROP; see Scheme 1) of 2-oxazolines was discovered in 1966.1-3 After this discovery, the resulting biocompatible poly(2-oxazoline)s have been used for a wide variety of applications.4-6 Moreover, amphiphilic structures are easily accessible by the sequential polymerization of a hydrophilic monomer (e.g., 2-methylor 2-ethyl-2-oxazoline) and a hydrophobic monomer (e.g., 2-nonylor 2-phenyl-2oxazoline). Unlike block copoly(2-oxazoline)s, random copoly(2-oxazoline)s have not been extensively investigated so far. The possibility of copolymerizing different 2-oxazolines has been demonstrated by several groups;7-9 however, reactivity ratios have only been determined for copolymerizations involving 2-phenyl-2-oxazoline (PhOx).10 Due to the low reactivity of PhOx, the copolymerizations resulted in blocky structures instead of random or gradient copolymers. Moreover, the properties of copoly(2-oxazoline)s have not been studied in detail. Inspired by this lack of knowledge in the literature, we decided to investigate the synthesis and properties of a library of random copolymers from 2-methyl-2-oxazoline (MeOx), 2-ethyl-2-oxazoline (EtOx), and 2-nonyl-2-oxazoline (NonOx). Such systematical copolymerization studies and corresponding structure-property investigations are reported for the first time. In polymer science, this report is the first example of a high-throughput approach in which kinetic details, library synthesis, and property screening were investigated simultaneously, providing both fundamental and application-directed insights. Results and Discussion. The currently described work was preceded by detailed (automated parallel) kinetic investigation of the homopolymerizations of four monomers (MeOx, EtOx, NonOx, and PhOx) with four initiators at four molecular weights and two temperatures.11 The optimal conditions from this kinetic screening (polymerization with benzyl bromide as initiator at 100 °C in N,N-dimethylacetamide) were applied to synthesize copolymers from combinations of MeOx, EtOx, and NonOx utilizing a Chemspeed ASW2000 synthesis robot.12 For each combination, nine copolymers were synthesized with 0-100 mol % (steps of 12.5 mol %) of the second monomer, resulting in 27 parallel polymerizations. For each of the copolymerizations, the monomer conversion in time was investigated by automated sampling from the polymerization mixtures for GC analysis.13 The measured monomer-to-solvent ratios of the polymerization mixtures before heating (Figure 1) clearly demonstrate the gradual change in monomer composition for the different copolymerization series: With increasing mole fraction of the second monomer, the ratio of the second monomer to solvent increases linearly, and the ratio of the first monomer to solvent decreases linearly. Figure 2 (top row) depicts the resulting kinetic plots in time for the 50 mol % copolymerizations. Similar kinetic plots were obtained for all other copolymerizations (only one of the polymerizations failed during the library synthesis cq. kinetic screening). The linearity of the first-order kinetic plots (ln{[M]0/[M]t}) confirmed a constant concentration of living polymer chains as expected for a living polymerization. Moreover, monomodal GPC traces with narrow molecular weight distributions (PDI < 1.3) were obtained for the endsamples, which is indicative of a living polymerization mechanism, as well. The kinetic plots revealed a slightly faster consumption (higher reactivity) of MeOx, as compared to EtOx and NonOx. To further elucidate the copolymer compositions, the reactivity ratios (r1 ) k11/k12 and r2 ) k22/k21) were determined from the relation between the fraction of monomer A in the monomer feed (f1) and the incorporated fraction of monomer A in the polymer (F1) at both ∼20% and ∼60% monomer conversion (Figure 3.15, bottom row). For living polymerizations, the reactivity ratios should be calculated at higher monomer conversions (20% or higher) since different reactivities during the initiation process are commonly observed.15,16 Also for the polymerization of 2-oxazolines, it is well-known that the polymerization rate during initiation can be different from the final polymerization rate.17 In the first instance, the reactivity ratios were determined using the classical Mayo-Lewis terminal model (MLTM) utilizing nonlinear least-squares fitting of the data in Figure 2, bottom.18 However, the applied MLMT method is strictly only valid for 0% monomer conversion, and therefore, reliable reactivity ratios can only be determined from extrapolation of the data obtained at low monomer conversions up to ∼10%. To accurately determine the * Phone: +31 40 247 5303. Fax: +31 40 247 4186. E-mail: u.s.schubert@tue.nl. Scheme 1. Schematic Representation of the CROP of 2-Oxazolines Initiated with Benzyl Bromide 145 J. Comb. Chem. 2006, 8, 145-148

Morphocoenoclines, character combination, and environmental gradients: a case study using symbiont-bearing benthic foraminifera

Abstract The species-characteristic combination of morphological characters that depend on an environmental gradient can be used to determine the frequency distribution of the species along the gradient. All functional characters of a phylogenetically closely related species group demonstrate overlapping intervals along an environmental gradient. The gradual change in character composition along the gradient is called a morphocoenocline. Based on transfer functions, a morphocoenocline can be used for gradient values estimation (proxies) in the historical or geological past, similar to a coenocline based on species (democoenocline). Transforming the empirical frequency distributions of characters and character states along the gradient to probability distributions enables calculating a probability density function of any subset of characters of the morphocoenocline. Because a species is distinguished by a specific combination of characters that are functionally related to the gradient, the distribution of ...

Equilibrium Modeling of Mixtures of Methanol and Water

An understanding of the species that form in mixtures of alcohol and water is important for their use in liquid chromatography applications. In reverse-phase liquid chromatography the retention of solutes on a chromatography column is influenced by the composition of the mobile phase, and in the case of alcohol and water mobile phases, the amount of free alcohol and water present. Previous and similar modeling studies of methanol (MeOH) and water mixtures by near-infrared (NIR) spectroscopy have found up to four species present including free MeOH and water and MeOH and water complexes formed by hydrogen bonding associations. In this work an equilibrium model has been applied to NIR measurements of MeOH and water mixtures. A high-performance liquid chromatography (HPLC) pump was coupled to an NIR flow cell to produce a gradual change in mixture composition. This resulted in a greater mixture resolution than has been achieved previously by manual mixture preparation. It was determined that five species contributed to the data. An equilibria model consisting of MeOH, H2O, MeOH(H2O) (log K(MeOH)H2O = 0.10+/-0.03), MeOH(H2O)4 (log K(MeOH)4H2O = -2.14+/-0.08), and MeOH(H2O)9 (log K(MeOH)9H2O = -8.6+/-0.1) was successfully fitted to the data. The model supports the results of previous work and highlights the progressive formation of MeOH and water complexes that occur with changing mixture composition. The model also supports that mixtures of MeOH and water are not simple binary mixtures and that this is responsible for observed deviations from expected elution behavior.

Temporal development of vegetation and geomorphology in a man‐made beach‐dune system by natural processes

Twenty‐four yrs of primary succession in a man‐made beach‐dune system at the Baltic coast of Denmark, built of calcareous, marine sand and the dune planted with Ammophila arenaria, was studied by qualitative observations, quantitative records in permanent plots, levelling and soil analysis within a selected area of 0.75 ha. The aim of the study was to discuss whether human initiated and influenced beach and dune dynamics mimick natural beach and dune processes, and to discuss the relationship between succession and zonation. During the study period, which started in 1979, the man‐made dune stabilized rather fast. In the stabilized dune, a sand‐pararendzina with a thin A‐horizon developed. The beach expanded by accretion of less calcareous, marine sand. On the beach new dunes, 3 m high, successively developed. The number of species in the study area increased from 16 to 55, accompanied by species and life form dynamics, characteristic for primary succession on sandy coasts. A gradual change in species composition of the permanent plots, which appeared by a DCA analysis, could by using TWINSPAN be structured into four groups or plant communities, which reflect succession as well as zonation. Two groups represent the vegetation of sandy beaches with annual dicotyledon species, and mobile dunes dominated by rhizomatous geophytes, especially A. arenaria. The two other groups represent stabilized, calcareous dune, dominated by hemicryptophytes, specially Festuca rubra, and less stabilized dune with F. rubra and the invasive alien Rosa rugosa. It was concluded, that the main trends in the geomorphological and vegetational development of the man‐made beach‐dune system is similar to the development in natural dunes. In the future, further accretion and seaward dune formation may be expected, but is it also expected, that larger parts of the area gradually will be covered by low scrubs of R. rugosa.

Characteristics of carbon films prepared by plasma-based ion implantation

A series of carbon films have been prepared by plasma-based ion implantation (PBII) with C on pure Al and Si. Emphasis has been placed on the effect of implanting voltage on the characteristics of these films. The structures of the films were analyzed by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The morphologies were observed by atomic force microscope (AFM). Surface hardness and electrical resistivity were also measured. The results indicate that the characteristics of these films are strongly dependent on the implanting voltage. An implanting voltage threshold value ranging from 3 to 5 kV starts to form a C-substrate transition layer owing to C + ions implanted into the substrate. The transition layer exhibits a gradual change in composition and structure and effectively connects the carbon film and the substrate. Also, an implanting voltage threshold value ranging from 5 to 10 kV starts to form diamond-like carbon (DLC) films. An increasing voltage causes the resultant DLC films to be smoother and more compact. Moreover, Raman spectrum, chemical state of C1s, surface hardness and electrical resistivity all prove an optimum voltage of approximately 30 kV corresponding to the lowest ratio of sp 2/sp 3.

Seawater transport and reaction in upper oceanic basaltic basement: chemical data from continuous monitoring of sealed boreholes in a ridge flank environment

Osmotically pumped fluid samplers were deployed in four deep-sea boreholes that were drilled during Ocean Drilling Program (ODP) Leg 168 on the eastern flank of the Juan de Fuca Ridge. Samplers were recovered from ODP Sites 1024 and 1027 and aliquots were analyzed for a variety of dissolved ions. Results from both of the samplers show a drastic change in the major ion composition within the first 20–40 days after the borehole was sealed at the seafloor followed by a more gradual change in composition. This gradual change ceased after 820 days at Site 1024 but continued throughout the 3-year deployment at Site 1027. We modeled this change in composition to estimate the flux of formation fluid through the open borehole. The rapid early change requires a flow of ∼1500 kg of formation fluid per day. The more gradual later change requires flow rates of 38 kg/day at Site 1024 and 17.5 kg/day at Site 1027. The latter fluxes require a minimum average specific discharge of meters to hundreds of meters per year through the surrounding basaltic matrix. Trace element data show surprisingly little contamination given the presence of steel casing, Li-organic-rich grease at each joint, cement, and drilling muds. Observed changes in trace element concentrations relative to those of bottom seawater provide a measure for the global significance of cool (23°C; ODP Site 1024) ridge flank hydrothermal systems relative to warm (64°C; Baby Bare and ODP Site 1027) hydrothermal systems and illustrate the importance of these cooler systems to global geochemical budgets.

Modulated Structures in Cu-32Ni-3Cr and Cu-46Ni-17Cr Alloys

Spinodal decomposition is characterized by small composition fluctuations over large distances, whereas a classical nucleation process is characterized by large composition variations over small distances. Since the new phases form by a continuous diffusional process with a gradual change in composition across the interface, they must have similar crystal structures to the original solid solution and be initially coherent. The resulting microstructure consists of a uniform dispersion of small, coherent interconnected particles. Experimental observations have shown that spinodal decomposition occurs in metallic, ceramic and glass systems. In this study, the modulated (spinodal) structures in Cu-32Ni-3Cr and Cu-46Ni-17Cr (all at-%) alloys were investigated by means of transmission electron microscopy (TEM) and X-ray diffraction (XRD). It was found that the 3Cr and 17Cr alloys undergo spinodal decomposition when quenched from 950 and 1050 °C, and aged at 300-600 °C and 300-800 °C respectively. Also, lattice parameters and volume fractions are altered at different temperatures due to chemical composition changes.

Modulated Structures in Cu-32Ni-3Cr and Cu-46Ni-17Cr Alloys

Spinodal decomposition is characterized by small composition fluctuations over large distances, whereas a classical nucleation process is characterized by large composition variations over small distances. Since the new phases form by a continuous diffusional process with a gradual change in composition across the interface, they must have similar crystal structures to the original solid solution and be initially coherent. The resulting microstructure consists of a uniform dispersion of small, coherent interconnected particles. Experimental observations have shown that spinodal decomposition occurs in metallic, ceramic and glass systems. In this study, the modulated (spinodal) structures in Cu-32Ni-3Cr and Cu-46Ni-17Cr (all at-%) alloys were investigated by means of transmission electron microscopy (TEM) and X-ray diffraction (XRD). It was found that the 3Cr and 17Cr alloys undergo spinodal decomposition when quenched from 950 and 1050 °C, and aged at 300-600 °C and 300-800 °C respectively. Also, lattice parameters and volume fractions are altered at different temperatures due to chemical composition changes.

Groundwater and surface water contamination in the area of the Hitura nickel mine, Western Finland

Tailings-derived mine drainage water that is neutral in character, has a high electrical conductivity and contains elevated sulphate, chloride and nickel concentrations, has caused deterioration in groundwater and surface water quality in the mining area of Hitura in Western Finland. This deterioration, and thereby the location of the contaminant plume, was recognized in the water chemistry in the form of a gradual change in ion composition from Ca-HCO3-type water towards a Mg-SO4-rich type. It was possible to define the extent of the pollution by using cluster analysis to distinguish between hydrochemically different regimes and performing an electrical sounding survey. The results indicated that contamination is most intense close to the tailings impoundment and is related to an esker complex running across this area. Nevertheless, the water in the eastern and southern parts of the area upgradient of the hydraulic head is uncontaminated and suitable for water supply purposes.