Changes In Mineral Composition Research Articles

Sodium hypochlorite oxidation reduces soil organic matter concentrations without affecting inorganic soil constituents

SummaryOxidative treatment can isolate a stable organic matter pool in soils for process studies of organic matter stabilization. Wet oxidation methods using hydrogen peroxide are widely used for that purpose, but are said to modify poorly crystalline soil constituents. We investigated the effect of a modified NaOCl oxidation (pH 8) on the mineral composition of 12 subsoils (4.9–38.2 g organic C kg−1) containing varying amounts of poorly crystalline mineral phases, i.e. 1.1–20.5 g oxalate‐extractable Fe kg−1, and of different phyllosilicate mineralogy. Post‐oxidative changes in mineral composition were estimated by (i) the determination of elements released into the NaOCl solution, (ii) the difference in dithionite‐ and oxalate‐extractable Si, Al and Fe, and (iii) the specific surface areas (SSAs) of the soils. The NaOCl procedure reduced the organic C concentrations by 12–72%. The amounts of elements released into the NaOCl extracts were small (≤ 0.14 g kg−1 for Si, ≤ 0.13 g kg−1 for Al, and ≤ 0.03 g kg−1 for Fe). The SSA data and the amounts of dithionite‐ and oxalate‐extractable elements suggest that the NaOCl oxidation at pH 8 does not attack pedogenic oxides and hydroxides and only slightly dissolves Al from the poorly crystalline minerals. Therefore, we recommend NaOCl oxidation at pH 8 for the purpose of isolating a stable organic matter pool in soils for process studies of organic matter stabilization.

The mineral composition and microscopic changes in thoracic buttons of Chinese Yellow steer with age

Tips of sacral, lumbar and thoracic vertebrae were sampled from 67 Chinese Yellow steer carcasses to determine relationships of the mineral composition in tips of vertebrae to the ossification degree as well as the dental age. Thoracic buttons were taken from another 11 Chinese Yellow steer carcasses to study their microscopic changes with age. Percentages of ash, calcium and phosphorus in thoracic buttons, on a fresh weight basis, increased with increasing ossification degree ( R 2 = 0.9815, 0.9743, 0.9817, respectively) and dental age ( R 2 = 0.9496, 0.9455, 0.9209, respectively), but those in tips of lumbar and sacral vertebrae varied little ( P > 0.05). Based on the same levels of ash percent in thoracic buttons, a corresponding relationship between the ossification degree and the dental age was observed: thoracic buttons did not ossify when the dental age was under 24 months; and 10%, 30%, and 40% of thoracic buttons ossified at the dentition-based age of 36, 50, and 60 months. Observations by scanning electron microscopy indicated that cartilages of Chinese Yellow steer thoracic buttons began to ossify at approximately 24 months and ossified completely at 84 months. The present study could be useful to improve the accuracy of age estimation for Chinese Yellow steers in the Chinese beef grading system.

Spatial changes of soil solution and mineral composition in the rhizosphere of Norway‐spruce seedlings colonized by Piloderma croceum

AbstractEctomycorrhizae (ECM) or the root‐fungal association in forest ecosystems provide a unique soil microenvironment where soil properties and processes differ from the bulk soil. In this study, we would like to better understand the role of ECM systems in mineral weathering and its implications to soil formation and nutrient cycling in forest ecosystems. Specifically, we would like to document the spatial variations in the composition of soil solution and mineralogy of the rhizosphere as influenced by the ECM of Norway spruce + Piloderma croceum. Two‐month‐old seedlings of Norway spruce (control and colonized by P. croceum) were cultivated in special rhizotrons designed to allow spatial collection of soil solution. We used A and C horizons of a Dystric Cambisol collected from Höglwald forest near Munich. Micro suction cups (5 mm x 1mm) were installed in colonized and control rhizotrons, and soil solution was collected from September to November 2000. Our results show that the concentrations of NH$_4^+$, Ca2+, and Mg2+ in the soil solution were lower in <1.0 cm than in >3.0 cm distance from the roots of Norway spruce, due to the possible range of influence of Piloderma mycelium reaching about 2–3 cm from the surface of the mycorrhizal root. In the rhizotron with soil from the A horizon, a higher phosphorus content in Piloderma‐colonized seedlings was observed. X‐ray diffraction data indicate that chlorite and possibly mica are being transformed to 2:1‐expanding clay minerals (probably smectite) within <1.0 cm distance from roots. The spatial variations in soil solution composition and mineral transformation are likely to be due to Piloderma colonization and concentrated mycelial growth within <1.0 cm distance from the roots. This is also evident in more intricate growth of mycelia on surfaces of micaceous minerals as compared to quartz. We assume that Piloderma modifies soil solution and mineralogy through acquisition of essential elements for its own survival and/or for the uptake by plant roots. However, the presence of spontaneous infection with wildtype ECM in the control plots may have altered the influence of Piloderma and must be taken into consideration when interpreting our results.

アールスメロン（Ｃｕｃｕｍｉｓ ｍｅｌｏ Ｌ．）の葉内無機成分に及ぼす着果の影響

We examined changes of mineral composition in leaves of muskmelon (Cucumis melo L.) after removal of fruits at various intervals. Total chlorophyll in first leaf on bearing branch was increased in 30-day and 45-day fruit-removal. In 60-day fruit-removal, it decreased rapidly from 15 days, and reached the lowest level at the time of harvesting. Phosphorus in leaves on bearing branch increased rapidly from 30 days in 45-day and 60-day. Potassium in leaves of main stem were lower in fruiting than in non-fruiting, and there were lower in the treatments with the fruit for longer periods. In first leaf on bearing branch, potassium in leaves of the main stem increased gradually up to 60 days. In fruiting, it increased slightly, but in 60-day, it decreased rapidly from 30 days, and reached about 1/3 of that of non-fruiting 60 days. In all treatments, calcium in first leaf on bearing branch increased rapidly up to 30 days, and then slightly decreased. The decrease rate was highest in 60-day. Magnesium in leaves on bearing branch increased up to 60 days. These results indicated that mineral composition varied with stage of fruiting and position of leaves. Potassium moved into fruits, and most strongly affected first leaf on bearing branch closest to fruits, suggesting development of etiolation. In further studies, it is necessary to examine relationship between mineral composition and quality of the fruit, and to improve quality of the fruit.

Contrasting styles of fluid-rock interaction within the West Fissure Zone in northern Chile

Abstract Geochemical data from three profiles crossing the West Fissure Zone in northern Chile were used to describe the chemical effects of fluids on faulting processes. The results document considerable differences of fluid-rock interactions between the profiles (A–C). Within the area of profile A and C fluid activities have neither led to intensive exchange reactions between fluids and rocks nor to notable changes in whole rock and mineral composition of fault rocks relative to their undeformed host rock. Investigations of stable isotopes (δ 13 C, δ 18 O) and fluid inclusions indicate infiltration of predominantly descending (meteoric) fluids and only subordinate involvement of ascending hydrothermal fluids. In the case of profile B, fluid-enhanced weakening mechanisms are dominant. Dissolution transfer has led to the formation of an alteration zone up to 400 m wide. Along profile B we have no indications for warm fluids derived from a deep source. Rather, a number of lines of evidence (e.g. δ 18 O and δD) show that fault rock alteration took place due to the infiltration of low temperature meteoric water. For this profile, all geochemical data indicate an open fluid system. Moreover, the chemical variations across the West Fissure Zone agree well with the structural variability observed at this traverse. The application of a variety of geochemical analyses of fault rocks shows the heterogeneity of large-scale continental fault zones.

白亜紀花こう岩類の風化にともなう化学組成およびＳｒ・Ｎｄ同位体比組成の変化

We analyzed the changes of mineral, chemical and isotopic compositions of weathered Cretaceous granitic rocks from the Gozu Granite in the Gozu mountain, Niigata Prefecture, Kise Granodiorite in the Ina mountain, Nagano Prefecture, and Aji Granite in the Aji Peninsula, Kagawa Prefecture. The analyzed samples are fresh and weathered rocks and “masa” (sand originated from weathered granitic rocks) collected from the same outcrops for each granite. The change of mineral compositions of weathered granitic rocks is mainly characterized by the appearance of hematite and the increase of alteration degree of mafic minerals. Chemical composition of weathered granitic rocks is characterized by the depletion of major and trace elements. In particular, CaO and Na2O, which are partitioned mostly into plagioclase, and S are reduced extremely. Fe2O3/FeO ratios increase extremely with increasing weathering degree. Variations of total Fe and Cr contents dyring weathering are little. Rb/Sr ratios increase and Sr isotopic ratios change in progress of weathering. Nd isotopic compositions are almost maintained during weathering. The variation of Sr isotopic composition is generally caused by dissolution of minerals and isotope exchenge.

The influence of fluoride exposure on dentin mineralization using an in vitro organ culture model.

This study aimed to characterize fluoride-induced alterations in dentin mineralization within a dentin-pulp organ culture system. Tooth sections derived from male Wistar rat incisors were cultured in Trowel-type culture for 14 days, in the presence of 0 mM, 1 mM, 3 mM and 6 mM sodium fluoride. Tooth sections were processed and analyzed for uptake of fluoride, its subsequent effect on dentin mineralization by tetracycline hydrochloride incorporation and mineral composition, expressed as calcium/phosphorous (Ca/P) ratios. Tetracycline hydrochloride incorporation was demonstrated to decrease with increased fluoride exposure, accompanied by significant increases in both Ca/P ratios and fluoride incorporation. These findings provide further evidence that the established alterations in dentin formation during fluorosis are a consequence of disruption to the mineralization process, and provide a model system with which to investigate further the potential role the extracellular matrix plays in inducing the apparent changes in mineral composition.

An electron microscopy study of deformation microstructures in granitic mylonites from southwestern Sweden, with special emphasis on the micas

The lithology, age, geological setting, structural and metamorphic history of the granitic mylonites from the Mylonite Zone (MZ) in southwestern Sweden have been studied extensively. The deformation history, growth of microstructures, intensity of deformation, changes in mineral compositions, and pressure-temperature conditions of deformation have, however, not been addressed. In this study, powder X-ray diffraction, optical microscopy, electron microprobe analysis and transmission electron microscopy of micas, chlorite, and plagioclase are combined to understand the physical and textural changes experienced by the rocks during mylonitization. It is shown that the occurrence of foliated micas in shear bands, recrystallization of quartz and biotite, and undulatory extinction in quartz grains were not uniform throughout the samples studied. Occurrence of dislocations and low-angle grain boundaries confirm that deformation occurred largely by glide dislocations. The low-angle grain boundaries observed are formed by the re-arrangement of these dislocations during grain size reduction processes. The micas show a high degree of spatial stacking order, but spatial stacking disorder in micas and chlorites has also been found. Ordered stacking faults are formed during low strain while disordered stacking faults are formed under high strain conditions. Occurrence of both ordered and disordered stacking faults indicates that the intensity of deformation was not uniform through the entire MZ. Moreover, the chemical composition of plagioclase shows that the exsolution lamellae observed with optical and electron microscopy are due to Ca-subsolidus reactions during low temperature deformation. Several substitution reactions occurring in the micas indicate that deformation took place between 0.3 and 0.4 GPa, at a temperature higher than 500degreesC. (Less)

The K–Ar and Rb–Sr Isotopic Systems in Rocks from the Jurassic Terrigenous Complex of the Greater Caucasus

The behavior of K–Ar and Rb–Sr isotopic systems in clayey rocks from the Jurassic terrigenouis complex of the Greater Caucasus sampled along the Terek River is discussed. It is shown that the rocks experienced intense postdiagenetic alterations accompanied by substantial changes in mineral composition and K–Ar and Rb–Sr isotopic systems. Lateral stress is the leading factor responsible for secondary mineral and geochemical transformations of rocks in cleavage zones. Rejuvenation of the radiological age of rocks, relative to their stratigraphic age, is 100 Ma and more. The age estimate of approximately 50 Ma obtained for samples from the southern limb of the anticlinorium reflects the Paleocene–Eocene phase of tectonic activity manifested in both the Caucasus and other areas of the Mediterranean foldbelt.

Relations between progressive deformation and fluid-rock interaction during shear-zone growth in a basement-cored thrust sheet, Sevier orogenic belt, Utah

Variations in microtextures, strain, whole-rock chemistry, mineralogy, fluid inclusion characteristics, and fracture network properties record complex interactions between deformation and fluid-rock processes during progressive growth of a shear zone within crystalline basement rocks. This shear zone formed at a depth of about 15 kilometers, T ≈ 350°C, and at elevated fluid pressures. The shear zone (SZ) has a 10 meter thick core of highly deformed phyllonite, and is bounded by a 3 to 8 meter thick transition zone (TZ) of variably fractured chloritic gneiss, which grades outward into relatively undeformed granitic gneiss. Granitic gneiss consists mostly of coarser-grained feldspar and quartz; chloritic gneiss consists of varying amounts of quartz, feldspar, and fine-grained micaceous matrix produced by a mixture of cataclastic, plastic, and alteration processes; and phyllonite consists mostly of very fine-grained quartz-mica-rich matrix produced by pervasive plastic deformation and alteration processes. Estimated strain ratios are 10:1 within the SZ. Whole-rock chemical compositions record significant depletion of Ca and Na, and enrichment of Mg and H2O during progressive alteration of granitic gneiss into phyllonite. Similar average contents of Al, Ti, and Fe, as well as Si, indicate that alteration was about isovolumetric at outcrop scale, although variations between individual samples record up to ±20 percent local volume change. Alteration produced significant changes in mineral abundances and compositions, with conversion of feldspar to muscovite, mafic minerals to Mg-rich chlorite, and dissolution/precipitation of quartz. Fluid inclusion characteristics and mineral compositions indicate that SZ fluids were moderately saline, and became depleted in Mg during alteration. Changes in mineralogy and fluid composition record large influxes of reactive fluids, with geochemical fluid-rock ratios on the order of 102 to 103. Variably deformed, cross-cutting veins, fractures, and microcracks record repeated episodes of cataclasis, fluid influx, and sealing along complex networks. Fluid flow appears to have been concentrated within the SZ along grain-scale and vein networks, with a component of outward flow into the TZ along fracture and microcrack networks. Estimated average fluid fluxes are on the order of 10−7 to 10−10 m/s in the SZ, and 10−9 to 10−12 m/s in the TZ, consistent with average permeabilities of 10−14 to 10−17 m2 in the SZ and 10−16 to 10−19 m2 in the TZ for moderate fluid pressure gradients. These average permeabilities are consistent with observed grain-scale and fracture network properties for a range of sealing and fluid pressure histories. Permeabilities may have been transiently greater during episodes of very high fluid pressure, but decreased as fluid pressure gradients equilibrated and fractures sealed. Strain softening in the SZ was likely produced by reaction softening, grain size reduction, and hydrolytic weakening of quartz. A model of shear zone growth involves: (1) initial fracturing of relatively strong, coarser-grained, quartz-feldspar-rich rock; (2) episodic influx of reactive fluids during periods of fracturing and high fluid pressure, with intervening periods of sealing and reduced fluid pressure; (3) progressive alteration of feldspar and mafic minerals to micas and recrystallization of quartz to form relatively weak, fine-grained matrix; and (4) concentrated deformation and focused fluid flow in a growing SZ core.

Petrology of rocks formed by interaction of mafic magmas and high-grade metamorphic rocks at Suya Taco area, northern Sierra de Comechingones, Argentina

Interaction between mafic magmas and crustal metamorphic rocks at mid-crustal levels causes modification of mafic magma composition by assimilation or reaction with crustal materials. This petrologic process is studied at the Suya Taco Complex where a suite of mafic magmas interacted with metamorphic rocks at 6.6±1 kbar. The Suya Taco Complex consists of close-spaced bodies of biotite-bearing gabbronorites. These magmas intruded into a supracrustal sequence consisting of amphibolite– to granulite–facies gneisses and migmatites. The peak-metamorphic mineral assemblage Bt+Qtz+Pl(An 30)+Grt+Kfs±Crd±Sil of supracrustal rocks crystallised before igneous mafic magmatism. Interaction between mafic magmas and metamorphic rocks produces two major hybrid lithologies: diorites made up of Opx+Bt+Pl (An 38–50)+Ilm±Cpx±Qtz; and garnet- and orthopyroxene-bearing rocks characterised by the coexistence of Bt+Pl (An 30–45)+Grt+Opx+Qtz+Ilm±Spl±Kfs. The latter lithology may locally appear as a quartz-absent and high-aluminous mineral assemblage. The two hybrid rocks occur interlayered at the contact zone between igneous mafic rocks and high-grade gneisses. Individual layers range from centimeter to meter scales; moreover, dioritic and orthopyroxene- and garnet-bearing layers present a spectrum of mineral assemblages and mineral chemistry that spread among those that appear in igneous mafic and metamorphic rocks. The work shows that the changes of mineral assemblages and variations of mineral chemistry in the hybrid diorites and orthopyroxene- and garnet-bearing rocks are the result of interaction processes between mafic magmas and regional metamorphic rocks. Field relationships, petrographic features, mineral compositional changes and qualitative analyses of phase relations suggest that rocks formed by interaction between mafic magmas and metamorphic rocks results from: (1) assimilation of metamorphic rocks by mafic magmas at variable degrees and (2) ion diffusion among mineral assemblages of contrasting composition. The implication of these processes is that Ca is transferred from mafic magmas to metamorphic rocks, which forces the breakdown of garnet and quartz, and induces the crystallisation of plagioclase and orthopyroxene in the resulting hybrid rocks.

Effect of extreme acid and alkali treatment on soil variable charge

This study concentrates on the effects of strong acid or alkaline treatments on subsequent titration curves of soil solid phase. Changes of soil mineral composition and organic matter content were estimated as a background. Samples of upper horizons of three brown, two chernozemic, one pseudopodzolic and three yellow-red soils were treated with hydrochloric acid or sodium hydroxide of concentrations ranging from 0.001 to 1 mol dm −3. Sodium homoionic forms of the original and the treated soils were back titrated to estimate variable charge vs. pH dependencies and surface acidity. The total amount of variable charge decreased after acid and alkali treatments of low concentrations and increased at elevated concentrations. The latter phenomenon was particularly evident for alkali-treated clay-rich soils. In general, surface acidity weakened in acidic treatments and for clay-poor soils in alkaline treatments. The alkali treatment produced stronger surface acidity in clay-rich soils. In yellow-red soils, surface groups of apparent surface dissociation constants around 10 −4.5 were well distinguished. Amount of these groups decreased after acid treatment and sharply increased during alkali treatment. Marked increase of weakly acidic surface groups occurred after acid treatments. Long-term influence of pH on variable charge properties in natural soils can be similar to laboratory treatments, as evidenced by weaker surface acidity in soils of lower pH.

Mineral deficiency and the use of the FETAX bioassay to study environmental teratogens

The Frog Embryo Teratogenesis Assay: Xenopus (FETAX) bioassay has been employed extensively to screen compounds for teratogenic activity. Recent laboratory studies have indicated that low potassium concentrations retard Xenopus laevis development. The effects of varying concentrations of minerals on Xenopus laevis embryo length and development were examined to determine the utility of the FETAX bioassay in the study of environmental teratogens. Water samples collected from 18 wetlands in Minnesota and North Dakota correlated with low mineral levels, causing delayed embryonic development in the FETAX bioassay. When the concentration of sodium or potassium was <5 ppm, Xenopus laevis development was delayed. As a result, it was difficult to assess teratogenic activity after 96 h of incubation. Furthermore, the length of the embryos-an indication of development-paralleled changes in mineral composition. Comparisons between different wetlands based on changes in one specific mineral were not possible due to a synergism between various minerals. If the concentration of sodium and/or potassium was <5 ppm but > or =2 ppm, extension of the FETAX bioassay to 120 h allowed organogenesis to proceed through stage 46, as required for scoring in accordance with ASTM guidelines for the FETAX bioassay. In those cases in which the concentration of sodium and/or potassium were <2 ppm, the embryos could not develop to stage 46 within 120 h and the FETAX bioassay was not suitable for detecting teratogenic activity. Published in 2002 by John Wiley & Sons, Ltd.

The oscillatory intergrowth of feldspars in titanian andradite, Little Dromedary, NSW, Australia

Veins bearing titanian andradite were found in a metasomatically altered clinopyroxenite cumulate of an alkali magmatic suite (Little Dromedary, NSW, Australia). The titanian andradite is up to 2.5 cm in size, mainly subhedral and displays a large concentric, oscillatory intergrowth with layers consisting of plagioclase and alkali feldspar. Detailed field work and petrography showed that there is a gradual change in paragenesis from the cumulitic clinopyroxenite with interstitial plagioclase to an apatite- and scapolite-bearing plagioclase-titanian andradite-pyroxene rock, which hosts the titanian andradite veins. Clinopyroxene composition changes from a magmatic Ti-bearing subsilicic ferrian aluminian diopside to a metamorphic Ti-free, Al-poor diopside. Plagioclase changes composition from oligoclase (Ab 81 An 14 Or 5 ) in the pyroxenite to bytownite (Ab 14 An 86 ) in the garnet-pyroxene rock and to oligoclase (Ab 76 An 21 Or 3 ) in the vein. Orthoclase occurs exclusively in the vein and contains 12% albite component. The titanian andradite-bearing veins and the change in paragenesis, bulk rock and mineral composition provide evidence for the reaction of a late magmatic, oxidizing hydrothermal fluid with the magmatic pyroxenite. The temperature of alteration is constrained by the composition of the coexisting plagioclase and alkali feldspar in titanian andradites to ∼ 420 °C. Crystallization of the titanian andradite indicates that Ti was transported on a metre scale from the magmatic clinopyroxene to the vein by a fluid. Ti solubility may have been enhanced by ligands such as F - , Cl - , PO 4 3- , SO 4 2- and CO 3 2- , which are all present in the fluid as documented by their incorporation in metamorphic apatite, scapolite, and carbonate coexisting with titanian andradite. KCl and NaCl salt inclusions in feldspar within the titanian andradite were found with transmission electron microscopy (TEM) and indicate that the fluid was partly supersaturated in these components. The alternating intergrowth of titanian andradite and feldspars mirrors an oscillating evolution of the fluid. TEM images of the garnet-feldspar interface suggest that garnet has been partly dissolved prior to or during feldspar precipitation, supporting the hypothesis of significantly changing fluid composition during vein formation. The concentric intergrowth is interpreted as the result of both the changing chemistry of the fluid and the different growth behaviour of garnet and feldspar.

Some effects of weathering on joints in granitic rocks

Standard engineering weathering classifications, most of which are based on weathered granite, typically describe the appearance and condition of the weathered material (e.g. whether or not it is friable), the condition of individual minerals (e.g. degree of pitting and micro-cracking and changes in mineral composition), and the degree of staining on joint surfaces or the distance that staining extends into rock from the joints. These classifications do not address changes in frequency, length, and appearance of joints in the rock mass as weathering progresses. This account of work on vertical or steeply dipping joints in granitic rocks shows that not only are there statistically significant differences in mean joint spacings and mean trace lengths with increased weathering, but that the physical appearances of joints also changes as weathering progresses. Mean joint spacing is wide in fresh rock, becomes closer in moderately weathered rock, and then becomes progressively wider from moderately weathered rock through highly and completely weathered rock. Mean joint lengths follow a similar but inverse pattern. Mean trace lengths become shorter from fresh to slightly weathered rock, lengthen in moderately weathered rock, then progressively become shorter from moderately weathered rock through highly and completely weathered rock. Furthermore, joint appearance changes with increased weathering. Joints in fresh rock are sharp-edged and typically straight. The edges begin to round in moderately weathered rock, and in highly weathered rock, joint traces become sinuous and discontinuous around mineral grains. In completely weathered rock, the only visible joints are filled with minerals or marked with iron staining. It is proposed that this evolution in joint pattern and appearance results from increased cracking along grain boundaries and thermal expansion of individual mineral grains, and within-grain micro-cracking as weathering proceeds. These factors allow individual mineral grains to “move” into the spaces between joint surfaces, thus obscuring individual joints and making them appear shorter. These apparent changes in joint properties could lead to incorrect rock mass classification and thus, to inappropriate engineering design and costly errors during construction.

Silicon deprivation and arginine and cystine supplementation affect bone collagen and bone and plasma trace mineral concentrations in rats

AbstractBecause arginine has been established as an essential amino acid for collagen formation, and several bone‐remodeling proteins are rich in cysteine, we performed a study to ascertain whether supplemental arginine (Arg) and cystine (Cys) would affect bone collagen and mineral composition changes in animals deprived of silicon (Si). Male weanling Sprague‐Dawley rats were randomly assigned to treatment groups of 12 in a 2 × 2 factorially arranged experiment. The rats were fed for 9 weeks a basal casein–ground corn–corn oil diet containing per g 2 μg Si, 1.7 mg Cys, 4.7 mg methionine, and 7.8 mg Arg. The independent treatment variables, per g fresh diet, were supplemental Si (as sodium metasilicate) at 0 and 35 μg and Cys or Arg at 0 and 12 mg. Silicon deprivation decreased the concentration of hydroxyproline in femur and potassium in vertebra. An interaction between Si and amino acid supplementation affected hematocrit, liver iron concentration, and bone copper and manganese concentrations. In animals deprived of Si, Cys supplementation compared to Arg supplementation depressed hematocrit, liver iron concentration, and tibia and vertebral copper concentrations and increased tibia and vertebral manganese concentrations. On the other hand, in animals fed adequate Si, supplemental Cys compared to supplemental Arg increased hematocrit, liver iron concentration, and tibia and vertebral copper concentrations and decreased tibia and vertebral manganese concentrations. Dietary Si also influenced the effect of Cys on mineral composition of the vertebra. The calcium and phosphorus concentrations in the vertebra were markedly increased by supplemental Cys compared to supplemental Arg when dietary Si was inadequate but had no effect on these concentrations when dietary Si was adequate. These findings indicate that silicon is needed for collagen formation, that high dietary Cys enhances changes induced by Si deprivation in trabecular‐rich bone, and that Si nutriture has more impact on trabecular‐rich bone than in cortical‐rich bone. J. Trace Elem. Exp. Med. 15:113–122, 2002. Published 2002 Wiley‐Liss, Inc.

Mineral composition changes recorded in the sediments from a 284-m-long drill-well in central part of the Kathmandu Basin, Nepal

The mineralogical study on the sub-surface obtained from drill-well JW-3, in the central part of the Kathmandu Basin was first performed by means of X-ray diffraction (XRD). The minerals detected in the sediments are quartz, feldspar, mica, smectite, chlorite, kaolinite, gypsum and calcite. The former three minerals are main constituent of the sediments and their relative proportion is over 70%. In general, the relative proportion of quartz is congruous with that of feldspar but is reverse proportion to that of mica. The clayey phyllosilicate minerals, such as smectite, chlorite and kaolinite are next dominant minerals in the sediments, and the relative proportion of these minerals shows a similar variation pattern to each other. Gypsum and calcite occur sporadically and their ratio is less than a few percentages, except in some horizons where they exceed 5%.&#x0D; Variation curves of relative amounts of the minerals are mainly divided into two zones, based on the variation patterns of the minerals. In Zone I below115 m depth, the variation curves of minerals show gradual cyclic patterns with low amplitude except gypsum and calcite. On the other hand, the variations of mineral contents in Zone II above 115 m depth are larger than those in the Zone I. Particularly, the variation curves of quartz, feldspar and mica show repetition of shorter cycles at 4-7 m intervals which are overlapping a longer cycle at 30 m intervals. The change in variation pattern across 115 m depth of the drill-well is similar to that of frequency of each pollen in the same sediments, which depicts the climatic variations in the Kathmandu Basin (Fujii and Sakai 2002). Hence, the mineralogical variation must reflect not only the changes of depositional environments in the Kathmandu Basin but also the climatic variations there. Similar difference of variation pattern of mineral composition in the Zone I and Zone II are also reported from the pollen analysis of the same slimes. This difference seems to be related to global climatic changes.

Clay mineral composition and palaeoclimatic interpretation of the Pleistocene deposits of Ukraine

The Pleistocene deposits on the plains regions of Ukraine are subaerial and subaqueous formations of diverse types. Loesses and fossil soils represent 16 climatic stages (8 warm and 8 cold) of the Pleistocene and environmental changes are reflected in their clay mineral composition. Clay fractions (<0.001 mm) of all 16 stages from 34 key sites and boreholes in different regions were analysed mineralogically. In the loesses and palaeosols the main clay minerals are of the smectite group (montmorillonite, nontronite, beidellite), hydromicas, mixed layer hydromica-montmorillonite minerals, kaolinite and halloysite. Chlorite, goethite, calcite, gypsum, and quartz are also present. There are differences in the amounts of the main minerals in palaeosols and loess horizons of different ages. Regional differences in the clay mineral composition of two Middle Pleistocene stages — the Zavadovka and Dnieper — were studied. Changes in mineral composition at 12 key Pleistocene sites in different regions indicate temporal (rhythmic) and spatial (regional) changes that reflect the palaeoclimatic conditions.

Diurnal Changes in Mineral Composition of Xylem Sap and Bleeding Rate at Harvest Stage in Pepper and Melon Cultivated by Drip Irrigation under Desert Condition in Baja California, Mexico.

メキシコ合衆国バハ・カリフォルニア州のゲレロ・ネグロで, 日本政府とメキシコ政府の共同事業として, メキシコ沙漠地域農業開発プロジェクト(以下, プロジェクト)が実施された.プロジェクトの目的は, 沙漠地域で野菜と果樹を点滴灌漑栽培するための技術を開発し, 移転することであった.プロジェクトの圃場の土壌と, そこで用いられる灌漑水は, いずれもpHと塩類濃度が高いという問題を持っているため, 作物の耐塩性に関する問題は重要な課題である.そこで本研究では, 耐塩性の問題を研究していくための基礎的なデータを得るために, 根から吸収されて茎葉部へ転流される様々なイオンについて検討した.すなわち, プロジェクトで重要な作物であるトウガラシとメロンについて, 成熟期の出液中に含まれているイオンの分析を行なうとともに, 出液速度を測定した.露地栽培したトウガラシでは出液中のイオン濃度に昼夜で差があったが, 出液速度も昼頃にピークを持つ山型の日変化パターンを示した.一方, 畝立マルチ栽培のメロンでは, イオン濃度も出液速度も昼夜に関係なくほぼ同じレベルであった.そこで, 出液速度を考慮して検討したところ, 耐塩性に関係しているナトリウムイオンの濃度は出液速度が大きいと低く, 出液速度が小さいと高いことが明らかとなった.なお, 土壌のイオン濃度も場所によって異なっていたため, バックグラウンドとして土壌成分を基準にした比較も行なった.以上のように, 出液成分に着目したアプローチによって, 作物の耐塩性を研究するために基礎的データが得られるが, 出液速度や土壌条件を考慮して解析する必要があることが明らかとなった.

Case studies on the use of temperature-dependent susceptibility for the characterisation of magneto-mineralogical changes during metamorphism

Based on three case studies we show that low-, and high-temperature measurements of magnetic susceptibility (κ(T)-curves) in combination with other mineralogical and rock magnetic methods constitute a sensitive tool for the identification of magnetic minerals. In this study, changes in mineral composition and grain texture, related to various metamorphic processes, are shown for minerals from the titanomagnetite and ilmenite-hematite series. If magnetite is associated with titanomagnetite, the shape of the κ(T)-curve at low temperature is significantly different from that of pure magnetite and pure titanomagnetite and we suspect that susceptibility measurements, especially low temperature, are sensitive to magnetic textures and superimposing effects due to different magnetic phases.