Variation in water use efficiency and δC levels in Eucalyptus grandis clones     

B.W. Olbrich  D. Le Roux  A.G. Poulter  W.J. Bond  W.D. Stock 《Journal of Hydrology》1993,150(2-4):615-633

This study aimed to determine whether the δ¹³C levels in the foliage and twigs of four Eucalyptus grandis clones were related to their water use efficiency (WUE). This relationship has previously been demonstrated in a number of herbaceous species but not in mature trees. The study involved accurate measurements of tree trunk growth and water use over a period of 4 months, with subsequent isotopic analysis of mature foliage from the north and south side of the canopy, and young leaves from the top of the canopy.

The water use efficiencies were found to vary from 5.97 × 10⁻³ to 12.3 × 10⁻³ m³ m⁻³. Significant differences were observed between clonal-mean water use efficiencies averaged over six sampling periods. The average δ¹³C of the mature and young foliage was found to be significantly correlated with WUE. However, the correlation was weak, suggesting that the relationship between δ¹³C and WUE is more complex in trees than suggested in the literature on crop plants. It is suggested that differences between sample trees in carbon allocation and leaf-to-air vapour pressure deficits may account for the poor correlation between δ¹³C and WUE in the four E. grandis clones studied.  相似文献   

RARE EARTH ELEMENT CONCENTRATIONS IN USGS AND CCRMP IGNEOUS ROCK STANDARDS DETERMINED BY HIGH PERFORMANCE ION CHROMATOGRAPHY     

Ronald T. WATKINS  Anton P. le  ROEX 《Geostandards and Geoanalytical Research》1993,17(1):105-111

Eleven rare earth elements (REE) have been determined in ten USGS and two CCRMP igneous rock standards using high performance ion chromatography. Duplicate analyses of two or more separately prepared aliquots of each sample were undertaken; reproducibility was better than 5% for each of the REE. In most cases, the results compare closely with published REE values for those samples for which the REE are well characterised. Where the results for individual elements are in disagreement with published data, the more erratic patterns yielded by the earlier data when plotted on chondrite-normalised REE diagrams suggest that values determined in this study are of greater accuracy.  相似文献   

Propriétés thermodynamiques des solutions (Na,K)ClH₂O entre 400 et 800°C, 1–2 Kb: une revue des équilibres d'échange avec les silicates sodipotassiques     

Marie-Lola Pascal  Jacques Roux 《Geochimica et cosmochimica acta》1982,46(3):331-337

Several independant determinations of the difference in Gibbs free energy of formation (from the elements at 25°, 1 bar) between NaCl⁰ and KCl⁰ in aqueous solutions (molality > 0.5) are derived from equilibrium data between alkali feldspars, feldspathoids (nepheline-kalsilite), micas (muscoviteparagonite) and hydrothermal (Na, K)Cl-H₂O solutions. These results along with other data from the literature are discussed. The relation: $\text{Δ}{}^0\text{?,}\text{KCl}{}^0\text{? Δ}{}^0\text{/tf,}\text{NaCl}{}^0\text{(}\text{J}\text{) = ?16500(± 2500) ? 18(± 4) T(}\text{K}\text{)}$. is proposed from 400 to 800°C and 1 to 2 Kbar.  相似文献   

Geochemistry of Karroo dolerite sills in the Calvinia district,Western Cape Province,South Africa     

Anton P. le Roex  David L. Reid 《Contributions to Mineralogy and Petrology》1978,66(4):351-360

Two Karroo dolerite sills display chemical and mineralogical variation compatible with cumulus enrichment. The Blaauwkrans sill is an olivine tholeiite and contains a central zone slightly enriched in olivine, plagioclase and clinopyroxene. The thicker Hangnest sill is a quartz tholeiite and shows evidence of crystal settling and has a lower zone enriched in cumulus orthopyroxene and plagioclase.The two sills differ quite markedly in their trace element compositions, with the Hangnest magma enriched by a factor of two in LIL elements (Rb, Ba, Nb, Zr, Y) relative to the Blaauwkrans magma. The Hangnest magma contained extremely low Ni contents (3–5 ppm), whereas the Blaauwkrans magma contained higher but more normal Ni (100–110ppm). Such contrasting trace element compositions preclude any simple genetic relationship between the two Karroo magmas but they may be related either through a common parent or are derivatives from separate parental magmas.South African Contribution No. 24 to the International Geodynamics Project  相似文献   

Alkali feldspar liquid equilibrium relationships in peralkaline oversaturated systems and volcanic rocks     

Jacques Roux  Jacques Varet 《Contributions to Mineralogy and Petrology》1975,49(1):67-81

A critical review of both experimental data and natural rock sequences allows a comparison of liquid lines of descent in peralkaline oversaturated systems. Available experimental data have been used to draw the liquidus surfaces and the fractionation curves in various planes including the alkali feldspar join. The thermal valley becomes steeper, the fractionation curves being channeled faster towards the thermal valley with increasing alkali-silica ratio. The slope of the thermal valley varies so that the higher the peralkalinity, the more sodic the most fractionated liquids. Rock series from Easter Island, Gran Canaria, Pantellaria Island, Boina (Afar), Fantale (Ethiopia) and Menengai (Kenya) in which there is good evidence for alkali feldspar fractionation, show that such variations do occur in nature. Factors other than the peralkalinity of the series, such as additional components and changes in the confining pressure are shown to affect the orientation and location of the thermal valley.  相似文献   

Infiltration von Flusswasser in Dünengebieten     

Prof. Dr. J. K. Von Baars  Frau Dr. Ivonne J. le Cosquino de Bussy 《Aquatic Sciences - Research Across Boundaries》1960,22(1):380-395

Ohne Zusammenfassung  相似文献   

Energetics of water dissolution in trachyte glasses and liquids     

Pascal Richet  Guy Hovis  Jacques Roux 《Geochimica et cosmochimica acta》2004,68(24):5151-5158

Enthalpies of dissolution in HF solutions have been measured at 323 K for a series of hydrous trachyte glasses. Enthalpies of mixing between water and molten trachyte have then been calculated from heat capacity data for the same set of samples and available enthalpy for pure water. The moderately negative enthalpies of mixing suggested at 1 bar by the measurements made on glasses almost disappear when trachyte liquids and water are referred to the same temperature, and particularly so when enthalpies of mixing are calculated for a few kbars pressure. As found for albite and phonolite liquids, trachyte melts thus appear to mix nearly ideally as far as enthalpy is concerned. These results imply that the enthalpy of exsolution of water from magmas is very small or negligible under the P-T-X conditions relevant to trachytic volcanism, even for complete degassing of up to 5 wt% H₂O. Furthermore, the viscosity increase associated with exsolution-driven cooling is negligible compared to the decrease caused directly by water exsolution.  相似文献   

Spinel lherzolite xenoliths from the Premier kimberlite (Kaapvaal craton, South Africa): Nature and evolution of the shallow upper mantle beneath the Bushveld complex   总被引：1，自引：0，他引：1  

M. Grgoire  C. Tinguely  D.R. Bell  A.P. le Roex 《Lithos》2005,84(3-4):185-205

Coarse-grained, granular spinel lherzolites xenoliths from the Premier kimberlite show evidence of melt extraction and metasomatic enrichment, documenting a complex history for the shallow mantle beneath the Bushveld complex. Compositions of orthopyroxene, clinopyroxene and spinel indicate equilibration within the spinel–peridotite facies of the upper mantle, at depths from 80 to 100 km and temperatures from 720 to 850 °C. Bulk compositions have lower Mg-number [atomic 100 Mg/(Mg + Fe*)] than previously studied spinel peridotites from Premier, and have higher Mg/Si than low-temperature coarse grained garnet lherzolites, suggesting shallower melting conditions or metasomatic enrichment. Clinopyroxene in one sample is highly LREE-depleted indicating very minor modification of a residue of 20% melt extraction, whereas the calculated REE pattern for a melt in equilibrium with a mildly LREE-depleted sample is similar to MORB or late Archean basalt, possibly related to the Bushveld Complex. Bulk and mineral compositions suggest minimal refertilization by silicate melts in four out of six samples, but REE patterns indicate introduction of a LIL-enriched component that may be related to kimberlite.  相似文献   

Spécificités hydrogéologiques des hautes vallées alpines: Exemple de la Haute-Sarine (Suisse)     

Julien Vaudan  Aurèle Parriaux  Laurent Tacher  Gianni della Valle 《Eclogae Geologicae Helvetiae》2005,98(3):371-383

The alpine valley of the Haute-Sarine is on several accounts representative of the alluvial aquifers of mountain by its very environment and its hydrogeologic characteristics. The investigations and the analysis carried out within the framework of this study enabled us to improve knowledge on the Quaternary filling of the valley and to highlight the preferential supplies of the aquifer by infiltration of the river and precipitations and also by the underground contributions of evaporitic karsts. We also could note the opulence of groundwater resources of the Haute-Sarine both from the qualitative and the quantitative points of view. The knowledge of these typical characteristics of alluvial aquifers of high altitude allowed finally the development of a concept of management and protection of groundwater resources that falls under a sustainable development policy of the groundwater storage in the alpine areas. Manuscrit re?u le 4 février 2003 Révision acceptée le 30 mars 2005  相似文献   

Accumulation rates and predominant atmospheric sources of natural and anthropogenic Hg and Pb on the Faroe Islands     

W. Shotyk  M.E. Goodsite  F. Roos-Barraclough  N. Givelet  G. Le Roux  A.K. Cheburkin  J. Heinemeier  S.A. Norton 《Geochimica et cosmochimica acta》2005,69(1):1-17

A monolith representing 5420 ¹⁴C yr of peat accumulation was collected from a blanket bog at Myrarnar, Faroe Islands. The maximum Hg concentration (498 ng/g at a depth of 4.5 cm) coincides with the maximum concentration of anthropogenic Pb (111 μg/g). Age dating of recent peat accumulation using ²¹⁰Pb (CRS model) shows that the maxima in Hg and Pb concentrations occur at AD 1954 ± 2. These results, combined with the isotopic composition of Pb in that sample (²⁰⁶Pb/²⁰⁷Pb = 1.1720 ± 0.0017), suggest that coal burning was the dominant source of both elements. From the onset of peat accumulation (ca. 4286 BC) until AD 1385, the ratios Hg/Br and Hg/Se were constant (2.2 ± 0.5 × 10^-4 and 8.5 ± 1.8 × 10^-3, respectively). Since then, Hg/Br and Hg/Se values have increased, also reaching their maxima in AD 1954. The age date of the maximum concentrations of anthropogenic Hg and Pb in the Faroe Islands is consistent with a previous study of peat cores from Greenland and Denmark (dated using the atmospheric bomb pulse curve of ¹⁴C), which showed maximum concentrations in AD 1953.The average rate of atmospheric Hg accumulation from 1520 BC to AD 1385 was 1.27 ± 0.38 μg/m²/yr. The Br and Se concentrations and the background Hg/Br and Hg/Se ratios were used to calculate the average rate of natural Hg accumulation for the same period, 1.32 ± 0.36 μg/m²/yr and 1.34 ± 0.29 μg/m²/yr, respectively. These fluxes are similar to the preanthropogenic rates obtained using peat cores from Switzerland, southern Greenland, southern Ontario, Canada, and the northeastern United States. Episodic volcanic emissions and the continual supply of marine aerosols to the Faroe Islands, therefore, have not contributed significantly to the Hg inventory or the Hg accumulation rates, relative to these other areas. The maximum rate of Hg accumulation was 34 μg/m²/yr. The greatest fluxes of anthropogenic Hg accumulation calculated using Br and Se, respectively, were 26 and 31 μg/m²/yr. The rate of atmospheric Hg accumulation in 1998 (16 μg/m²/yr) is comparable to the values recently obtained by atmospheric transport modeling for Denmark, the Faroe Islands, and Greenland.  相似文献