Yam Cultivation on the East Coast of New Caledonia: adaptation of agriculture to social and economic changes     

Catherine Gaillard  Harley I. Manner 《The Australian geographer》2010,41(4):485-505

Agriculture represents less than 2 per cent of the GDP of New Caledonia where the economy (and wage-earning activities) is dominated by the service sector and the nickel industry. However, family farming remains strong, especially for the Indigenous Melanesian tribes of the east coast of New Caledonia. Yams (Dioscorea spp.) are still one of the pillars of traditional Kanak society despite the social and economic changes that followed colonisation by France. This study of Kanak yam cultivation on the north-eastern coast of New Caledonia underscores the fact that yam cultivation systems have greatly changed since the 1950s, when they were last described. In addition to customary gift exchanges and subsistence consumption, yams are increasingly being grown for market sales. Five cropping systems, three yam production systems, and three Kanak social activity systems are described and their linkages to each other are explained. There are three levels of Kanak market participation: none, transitional, and fully engaged, and the extent of market participation and associated technical choices defines farmers’ levels of cultural activity and the nature and characteristics of yam cultivation.  相似文献   

Stabilization of Fe/Cu nanoparticles by starch and efficiency of arsenic adsorption from aqueous solutions     

Yassaman Babaee  Catherine N. Mulligan  Md. Saifur Rahaman 《Environmental Earth Sciences》2017,76(19):650

Due to the severity of arsenic contamination of soil and water resources around the world, finding new adsorbents for arsenic removal from the water is of high importance. The present study investigates the possible use and effectiveness of starch-stabilized Fe/Cu nanoparticles for adsorption of arsenic from aqueous solutions. First, Fe/Cu nanoparticles at various starch concentrations of 0, 0.02, 0.04 and 0.06 wt% were synthesized and characterized by X-ray diffraction, transmission electron microscopy and zeta potential/particle size analyzer. Then 0.04 wt% stabilized Fe/Cu nanoparticles were tested for the sorption of As(III) and As(V) from synthetic arsenic-contaminated water. To have an understanding about the arsenic adsorption mechanism of nanoparticles, X-ray photoelectron spectroscopy (XPS) was performed before and after adsorption. The results showed that starch provides nanoparticles with a neutral surface and stabilization of nanoparticles is possible with 0.04 wt% or higher concentrations of starch. For 0.04 wt% starch-stabilized Fe/Cu nanoparticles, the adsorption isotherms fit well within the Langmuir equation, with maximum sorption capacities of 90.1 mg/g for As(III) and 126.58 mg/g for As(V) at a pH of 7.0 from the aqueous arsenic solutions. Examining the XPS spectra of nanoparticles before and after adsorption showed that arsenic adsorption by this nanoparticle can be due to the formation of inner-sphere arsenic complexes on the particle surface, and the surface oxygen-containing functional groups involved in adsorption. The high sorption capacity suggests the potential for applying starch-stabilized Fe/Cu nanoparticles to the contaminated waters for removal of arsenic.  相似文献   

Observations of Centaur 8405 Asbolus: Searching for Water Ice     

Jennifer Romon-MartinMaria A. Barucci  Catherine de BerghAlain Doressoundiram  Nuno Peixinho  François Poulet 《Icarus》2002,160(1):59-65

Near-infrared spectra of Centaur 8405 Asbolus have been obtained, covering the whole rotational period. Complementary photometry and visible spectroscopy have also been performed. The aim of this project was to confirm or refute the water ice detection on one side of Asbolus reported by Kern et al. (2000 Astrophys. J.542, L155-L159). We found no absorption feature at any rotational phase of Asbolus. Our study is the first in-depth investigation of a centaur over a complete rotational period. Our results seem also to indicate that a change in the slope from 0.8 to 1.0 μm may occur in Asbolus spectrum.  相似文献   

The magnesiowüstite: iron equilibrium and its implications for the activity-composition relations of (Mg,Fe)<Subscript>2</Subscript>SiO<Subscript>4</Subscript> olivine solid solutions     

Hugh?St. C.?O'NeillEmail author  Mark?I.?Pownceby  Catherine?A.?McCammon 《Contributions to Mineralogy and Petrology》2003,146(3):308-325

The chemical potential of oxygen (µO₂) in equilibrium with magnesiowüstite solid solution (Mg, Fe)O and metallic Fe has been determined by gas-mixing experiments at 1,473 K supplemented by solid-cell EMF experiments at lower temperatures. The results give:where IW refers to the Fe-"FeO" equilibrium. The previous work of Srecec et al. (1987) and Wiser and Wood (1991) agree well with this equation, as does that of Hahn and Muan (1962) when their reported compositions are corrected to a new calibration curve for lattice parameter vs. composition. The amount of Fe³⁺ in the magnesiowüstite solid solution in equilibrium with Fe metal was determined by Mössbauer spectroscopy on selected samples. These data were combined with literature data from gravimetric studies and fitted to a semi-empirical equation:These results were then used to reassess the activity-composition relations in (Mg, Fe)₂SiO₄ olivine solid solutions at 1,400 K, from the partitioning of Mg and Fe²⁺ between olivine and magnesiowüstite in equilibrium with metallic Fe experimentally determined by Wiser and Wood (1991). The olivine solid solution is constrained to be nearly symmetric with , with a probable uncertainty of less than ±0.5 kJ/mol (one standard deviation). The results also provide a useful constraint on the free energy of formation of Mg₂SiO₄.Editorial responsibility: B. Collins  相似文献   

The porosity and permeability of chondritic meteorites and interplanetary dust particles     

Catherine M. CORRIGAN  Michael E. ZOLENSKY  Jason DAHL  Michael LONG  Joseph WEIR  Clyde SAPP  Patti Jo BURKETT 《Meteoritics & planetary science》1997,32(4):509-515

Abstract— We have investigated the porosity of a large number of chondritic interplanetary dust particles (IDPs) and meteorites by three techniques: standard liquid/gas flow techniques, a new, noninvasive ultrasonic technique, and image processing of backscattered images. The latter technique is obviously best-suited to sub-kilogram sized samples. We have also measured the gas and liquid permeabilities of some chondrites by two techniques: standard liquid/gas flow techniques, and a new, nondestructive pressure release technique. We find that chondritic IDPs have a somewhat bimodal porosity distribution. Peaks are present at 0 and 4% porosity; a tail then extends to 53%. Type 1–3 chondrite matrix porosities range up to 30%, with a peak at 2%. The bulk porosities for type 1–3 chondrites have the same approximate range as exhibited by the matrix, which indicates that other components of the bulk meteorites (including chondrules and aggregates) have the same average porosity as the matrix. These results reveal that the porosities of primitive materials at scales ranging from nanogram to kilogram are similar, which implies that similar accretion dynamics operated through 12 orders of size magnitude. Permeabilities of the investigated chondrites vary by several orders of magnitude, and there appears to be no simple dependence of permeability with degree of aqueous alteration, chondrite type or porosity.  相似文献   

Observation of sections of oceanic crust and mantle cropping out on the southern wall of Kane FZ (N. Atlantic)     

Jean-Marie Auzende  Mathilde Cannat  Pascal Gente  Jean-Pierre Henriet  Thierry Juteau  Jeffrey Karson  Yves Lagabrielle  Catherine Mével  Maurice Tivey 《地学学报》1994,6(2):143-148

The objective of the 20 Nautile dives of the recent Kanaut cruise was to study the southern wall of the Kane Fracture Zone from its eastern intersection with the Mid-Atlantic Ridge (MAR) to 5 Myr in age. The geological mapping shows four successive massifs, wrench faulted and slightly tilted. The transform-facing walls of these massifs exhibit outcrops of fresh and serpentinized peridotites, gabbros and basalts. The entire crustal exposure is cataclased and metamorphosed to greenschist facies.  相似文献   

Biological and Temporal Variations of Trace Element Concentrations in the Moss Species Scleropodium purum (Hedw.) Limpr.     

Sebastien Leblond  Sandrine Gombert  Jean Louis Colin  Remi Losno  Catherine Rausch De Traubenberg 《Journal of Atmospheric Chemistry》2004,49(1-3):95-110

Over a period of one year, the moss Scleropodium purum was sampled every two weeks in a French rural area to determine the levels of Li, Na, Al, Si, P, Ca, V, Mn, Fe, Zn, Ba, Hg, and Pb. The element distribution in the moss shoot was studied throughout the year. An apical bioconcentration was discovered for Na, P, Ca, Mn, and Zn, whereas higher levels were found in the basal fraction for Li, Al, Si, V, Fe, Ba, Hg, and Pb. A significant variation of element concentrations was observed during the sampling period. In the apical part Li, Al, Si, V, Fe, Ba, and Hg show maximum levels in the summer and minimum in the autumn. The same pattern was found with Ca and Mn in the whole plant, whereas Na showed opposite fluctuations.  相似文献   

Spatial survey of trace metal contaminants in the sediments of the Elizabeth River, Virginia   总被引：5，自引：0，他引：5  

Conrad CF  Chisholm-Brause CJ 《Marine pollution bulletin》2004,49(4):319-324

The Elizabeth River is a sub-estuary of the James River, the most southern tributary of the Chesapeake Bay. It is a highly industrialized area, and has been designated a "toxic hot spot" due to the heavy loads of contaminant metals and organic compounds in its bed sediments. Fifty surface sediment samples were taken along the channels and shoals of the Mainstem and the Southern Branch portions of the river. The samples were analyzed for trace metals (Cd, Cr, Cu, Pb and Zn), Fe and particle properties (% sand, % silt, % clay and specific surface area) to discern the spatial distribution of contaminant metals in this system. Enrichment factors were calculated to assess the overall level of contamination relative to other surrounding waterways as well as historic contamination levels within the river itself. The highest levels of metals were found to be in close proximity to industrial sources of contamination. The overall level of contamination was 3-10 times higher than baseline levels within the river, and 2-3 times higher than contaminant levels in other area waters.  相似文献   

A menagerie of graphite morphologies in the Acapulco meteorite with diverse carbon and nitrogen isotopic signatures: Implications for the evolution history of acapulcoite meteorites     

Ahmed El Goresy  Ernst Zinner  Catherine Caillet 《Geochimica et cosmochimica acta》2005,69(18):4535-4556

Morphologies, petrographic settings and carbon and nitrogen isotopic compositions of graphites in the Acapulco meteorite, the latter determined by secondary ionization mass spectrometry, are reported. Seven different graphite morphologies were recognized, the majority of which occur enclosed exclusively in kamacite. Individual graphite grains also rarely occur in the silicate matrix. Kamacite rims surrounding taenite cores of metal grains are separated from the Ni-rich metal cores by graphite veneers. These graphite veneers impeded or prevented Ni-Fe interdiffusion during cooling. In addition, matrix FeNi metal contains considerable amounts of phosphorous (≈ 700 ppm) and silicon (≈ 300 ppm) (Pack et al., 2005 in preparation) thus indicating that results of laboratory cooling experiments in the Fe-Ni binary system are inapplicable to Acapulco metals. Graphites of different morphologies display a range of carbon and nitrogen isotopic compositions, indicating a diversity of source regions before accretion in the Acapulco parent body. The isotopic compositions point to at least three isotopic reservoirs from which the graphites originated: (1) A reservoir with heavy carbon, represented by graphite in silicates (δ¹³C = 14.3 ± 2.4 ‰ and δ¹⁵N = −103.4 ± 10.9 ‰), (2) A reservoir with isotopically light carbon and nitrogen, characteristic for the metals. Its C- and N-isotopic compositions are probably preserved in the graphite exsolutions that are isotopically light in carbon and lightest in nitrogen (δ¹³C = −17 to −23 ‰ δ¹⁵N = −141 to −159 ‰). (3) A reservoir with an assumed isotopic composition (δ¹³C ∼ −5 ‰; δ¹⁵N ∼ −50 ‰). A detailed three-dimensional tomography in reflected light microscopy of the decorations of metal-troilite spherules in the cores of orthopyroxenes and olivines and metal-troilite veins was conducted to clarify their origin. Metal and troilite veins are present only near the fusion crust. Hence, these veins are not pristine to Acapulco parent body but resulted during passage of Acapulco in Earth’s atmosphere. A thorough search for symplectite-type silicate-troilite liquid quench textures was conducted to determine the extent of closed-system partial silicate melting in Acapulco.Metal-troilite spherules in orthopyroxenes and olivines are not randomly distributed but decorate ferromagnesian silicate restite cores, indicating that the metal-spherule decoration around restite silicates took place in a silicate partial melt. Graphite inclusions in these spherules have C- and N- isotopic compositions (δ¹³C = −2.9 ± 2.5 ‰ and δ¹⁵N = −101.2 ± 32 ‰) close to the average values of graphite in metals and in the silicate matrix, thus strongly suggesting that they originated from a mixture of graphite inclusions in metals and silicate matrix graphite during a closed system crystallization process subsequent to silicate-metal-sulfide partial melting. Troilite-orthopyroxene quench symplectite textures in orthopyroxene rims are clear evidence that silicate-sulfide partial melting took place in Acapulco. Due to petrographic heterogeneity on a centimeter scale, bulk REE abundances of individual samples or of individual minerals provide only limited information and the REE abundances alone are not entirely adequate to unravel the formational processes that prevailed in the acapulcoite-lodranite parent body. The present investigations demonstrate the complexity of the evolutionary stages of acapulcoites from accretion to parent body processes.  相似文献   

Carbonate Assimilation at Merapi Volcano, Java, Indonesia: Insights from Crystal Isotope Stratigraphy   总被引：2，自引：0，他引：2  

Chadwick  Jane P.; Troll  Valentin R.; Ginibre  Catherine; Morgan  Daniel; Gertisser  Ralf; Waight  Tod E.; Davidson  Jon P. 《Journal of Petrology》2007,48(9):1793-1812

Recent basaltic andesite lavas from Merapi volcano contain abundant,complexly zoned, plagioclase phenocrysts, analysed here fortheir petrographic textures, major element composition and Srisotope composition. Anorthite (An) content in individual crystalscan vary by as much as 55 mol% (An_40–95) across internalresorption surfaces with a negative correlation between highAn mol% (>70), MgO wt% and FeO wt%. In situ Sr isotope analysesof zoned plagioclase phenocrysts show that the ⁸⁷Sr/⁸⁶Sr ratiosof individual zones range from 0·70568 to 0·70627.The upper end of this range is notably more radiogenic thanthe host basaltic andesite whole-rocks (< 0·70574).Crystal zones with the highest An content have the highest ⁸⁷Sr/⁸⁶Srvalues, requiring a source or melt with elevated radiogenicSr, rich in Ca and with lower Mg and Fe. Recent Merapi eruptiverocks contain abundant xenoliths, including metamorphosed volcanoclasticsediment and carbonate country rock (calc-silicate skarns) analysedhere for petrographic textures, mineralogy, major element compositionand Sr isotope composition. The xenoliths contain extremelycalcic plagioclase (up to An₁₀₀) and have whole-rock ⁸⁷Sr/⁸⁶Srratios of 0·70584 to 0·70786. The presence ofthese xenoliths and their mineralogy and geochemistry, coupledwith the ⁸⁷Sr/⁸⁶Sr ratios observed in different zones of individualphenocrysts, indicate that magma–crust interaction atMerapi is potentially more significant than previously thought,as numerous crystal cores in the phenocrysts appear to be inheritedfrom a metamorphosed sedimentary crustal source. This has potentiallysignificant consequences for geochemical mass-balance calculations,volatile saturation and flux and eruptive behaviour at Merapiand similar island arc volcanic systems elsewhere. KEY WORDS: assimilation; isotopes; Merapi; xenolith; calc-silicate  相似文献