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Managing sustainable farmed landscape through 'alternative' food networks: a case study from Italy 总被引：1，自引：0，他引：1
LEWIS HOLLOWAY ROSIE COX† LAURA VENN‡ MOYA KNEAFSEY‡ ELIZABETH DOWLER§ HELENA TUOMAINEN§ 《The Geographical journal》2006,172(3):219-229
This paper focuses on a case study of an 'alternative' food network based in the Abruzzo National Park, Italy, to explore how ideas of sustainable farmland management can be expressed through broader understandings of developing networks of care concerned with local economies and societies, high-quality specialist food products, particular 'traditional' farming practices and livestock breeds, as well as the ecology of a farmed landscape. The scheme allows customers, internationally as well as in Italy, to 'adopt' a milking sheep on a large mountain farm. In return, adopters are sent food products from the farm. The adoption scheme is inter-twined with an agri-tourism project which provides accommodation, runs a restaurant and engages in educational activities. The scheme is the result of the individual initiative of its founder, and is associated with a strongly expressed ethical position concerning the value of sustaining valued local rural landscapes and lifestyles, and the importance of 'reconnecting' urban dwellers with rural areas, farming and 'quality' food production. Yet the localness of the scheme is sustained through wider national and international networks: volunteer and paid workers are drawn from several European countries, funding has been acquired from the EU LEADER programme, and internet and transport technologies are essential in connecting with and supplying an international customer base. The broader economy of care instanced in this case study draws attention to a need to develop strategies for sustainable farmland management constructed around wider programmes of social, economic and cultural, as well as environmental, concern. 相似文献
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KELEMEN PETER. B.; JOYCE DAVID. B.; WEBSTER JAMES. D.; HOLLOWAY JOHN. R. 《Journal of Petrology》1990,31(1):99-134
We present results of experiments on mixtures of olivine tholeiiteand mantle harzburgite, at 5 kb and 1050–1150?C, underconditions of controlled hydrogen fugacity. The basalt end-memberwas Kilauea 1921 olivine tholeiite+3 wt.% H2O, and the harzburgiteend-member was a mixture of olivine and orthopyroxene mineralseparates made from a mantle-derived lherzolite xenolith. Theexperiments on mixtures of basalt and harzburgite difl not reachequilibrium in runs ranging from 12 to 200 h duration. Relativelylarge concentration gradients persisted in both liquid and solidphases in mixed samples, whereas ‘control’ samplescontaining only basalt were reasonably homogeneous and wereprobably close to equilibrium. Compositions of solid phases produced, measured by electronmicroprobe, show a regular increase in Mg/(Mg+Fe) with increasingproportion of harzburgite at constant temperature, but olivineand clinopyroxene in mixed samples were not in Fe-Mg exchangeequilibrium. Modes measured for each sample show that the fractionof liquid relative to the amount of basalt in the sample wasconstant at constant temperature, and independent of bulk composition:reaction between 1921 basalt and harzburgite does not changethe mass of liquid in the system. Average experimental liquidcompositions for each sample were obtained by mass balance.Using Kds defined by the ‘control’ sample for eachtemperature, and mass balance constraints, phase assemblages(solid- and liquid-phase compositions and proportions) werecalculated for all mixtures. Whether samples included harzburgite or not, all average experimentalliquid compositions, and all predicted liquid compositions,for samples run at 1050?C, are high-alumina basalts by the definitionof Kuno (1960). By the criteria of Irvine & Baragar (1971),all but two average experimental liquid compositions in basalt-harzburgitemixtures, and all predicted liquid compositions in basalt-harzburgitemixtures, are calc-alkaline basalts and basaltic andesites,whereas liquids in samples containing only basalt are tholeiiticbasalts. Combined crystallization and reaction with harzburgitein the upper mantle will produce calc-alkaline derivative liquidsfrom an olivine tholeiite liquid under conditions of temperature,pressure, water and oxygen fugacity, and initial bulk compositionwhich would produce a tholeiitic liquid line of descent by crystallizationin a closed system.
*Present address: Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543Present address: Grant Institute of Geology, University of Edinburgh, West Mains Road, Edinburgh EH9 3JW, UK 相似文献
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Melting Relations of Basalt with Equilibrium Water Pressure Less Than Total Pressure 总被引：14，自引：7，他引：14
Equilibrium H2O pressure (PeH2O) was fixed at values less thantotal pressure (PT) in melting experiments on mixtures of 1921Kilauea tholeiite, H2O, and CO2 (58.5 mole per cent H2O, 41.5mole per cent CO2), buffered by Ni+NiO. New determinations ofthe beginning of melting of mixtures of 1921 Kilauea tholeiiteand H2O buffered by quartz+fayalite+magnetite were made at 2and 3 kb. Microprobe analyses of coexisting glass, clinopyroxene,?olivine, ?amphibole were determined for several runs. Decreasing H2O fugacity (fH2O) to about six-tenths the fugacityof pure H2O (f?II2O) raises the solidus and the upper stabilitylimit of plagioclase. Plagioclase and clinopyroxene coexistin equilibrium with liquid-a feature not observed in the pureH2O system. Amphibole is stable to about 970 ?C at 2 kb, 1025?C at 5 kb and 1060 ?C at 8 kb. The Al (VI)+Ti contents of theamphibole increase with P, yielding kaersutite at 1050 ?C and8 kb. Calculated modes for the condensed phases reveal large differencesin the amount of glass (liquid) present and large differencesin liquid composition below and above the breakdown temperatureof amphibole at 5 and 8 kb. Liquids coexisting with amphibole,clinopyroxene, olivine, and magnetite are dacitic near the solidusand silica-rich andesites around 1000 ?C at 5 and 8 kb. Theresults of this study substantiate the model for the generationof the calc-alkaline suite by partial melting of H2O-rich basalts. 相似文献
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An Experimental Study of Water and Carbon Dioxide Solubilities in Mid-Ocean Ridge Basaltic Liquids. Part I: Calibration and Solubility Models 总被引：14，自引：7，他引：7
DIXON JACQUELINE EABY; STOLPER EDWARD M.; HOLLOWAY JOHN R. 《Journal of Petrology》1995,36(6):1607-1631
Experiments were conducted to determine the solubilities ofH2O and CO2 and the nature of their mixing behavior in basalticliquid at pressures and temperature relevant to seqfloor eruption.Mid-ocean ridge basaltic (MORB) liquid was equilibrated at 1200°Cwith pure H2O at pressures of 176–717 bar and H2O—CO2vapor at pressures up to 980 bar. Concentrations and speciationof H2O and CO2 dissolved in the quenched glasses were measuredusing IR spectroscopy. Molar absorptivities for the 4500 cm–1band of hydroxyl groups and the 5200 and 1630 cm–1 bandsof molecular water are 0•67±0•03, 0•62±0•07,and 25±3 l/mol-cm, respectively. These and previouslydetermined molar absorptivities for a range of silicate meltcompositions correlate positively and linearly with the concentrationof tetrahedral cations (Si+Al). The speciation of water in glass quenched from vapor-saturatedbasaltic melt is similar to that determined by Silver &Stolper (Journal of Petrology 30, 667–709, 1989) in albiticglass and can be fitted by their regular ternary solution modelusing the coefficients for albitic glasses. Concentrations ofmolecular water measured in the quenched basaltic glasses areproportional to f H2O in all samples regardless of the compositionof the vapor, demonstrating that the activity of molecular waterin basaltic melts follows Henry's law at these pressures. Abest fit to our data and existing higher-pressure water solubilitydata (Khitarov et al., Geochemistry 5, 479–492, 1959;Hamilton et al., Journal of Petrology 5, 21–39, 1964),assuming Henrian behavior for molecular water and that the dependenceof molecular water content on total water content can be describedby the regular solution model, gives estimates for the Vo, mH2Oof 12±1 cm3/mol and for the 1-bar water solubility of0•11 wt%. Concentrations of CO2 dissolved as carbonate in the melt forpure CO2-saturated and mixed H2O-CO2-saturated experiments area simple function of fCO2 These results suggest Henrian behaviorfor the activity of carbonate in basaltic melt and do not supportthe widely held view that water significantly enhances the solutionof carbon dioxide in basaltic melts. Using a Vo, mr of 23 cm3/mol(Pan et al., Geochimica et Cosmochimica Acta 55, 1587–1595,1991), the solubility of carbonate in the melt at 1 bar and1200°C is 0•5 p.p.m. Our revised determination of CO2solubility is 20% higher than that reported by Stolper &Holloway (Earth and Planetary Science Letters 87, 397–408,1988). KEY WORDS: mid-ocean ridge basalts; water and carbon dioxide solubility; experimental petrology 相似文献
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J. T. HOLLOWAY 《New Zealand geographer》1964,20(1):1-9
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Carbon Distribution in the Stiliwater Complex and Evolution of Vapor During Crystallization of Stillwater and Bushveld Magmas 总被引：1，自引：0，他引：1
MATHEZ E. A.; DIETRICH V. J.; HOLLOWAY J. R.; BOUDREAU A. E. 《Journal of Petrology》1989,30(1):153-173
The occurrence and distribution of carbon in the StillwaterComplex have been investigated. In mineralized troctolite andassociated rocks of olivine-bearing zone I (OB I), carbon ispresent as graphitic material and calcite. The assemblage forsterite-antigorite-calcite-graphiteand the petro graphic relations indicate equilibration of thecarbon-rich phases during serpentinization. Typical OB I troctolitecontains 500–1100 ppm wt. carbon, 40–70% of whichis in calcite, whereas troctolite from higher stratigraphicpositions generally contains <400 ppm carbon. Due to themetamorphism, it is not possible to deduce the extent to whichenrichment of carbon in the ore zone is inherited from magmaticprocesses. In contrast, there is good evidence for magmaticgraphite in parts of the Bushveld Complex. The C-O-H-Cl system has been investigated for conditions ofStillwater and Bushveld crystalliz ation. In alkali-poor fluidsover a wide range of igneous and metamorphic conditions, theimportant chlorine species are HCl and CH3Cl The addition ofchlorine to a C-O-H fluid in equilibrium with graphite leadsto a quantitative increase in HCl+CH3Cl and corresponding decreasein H2O contents, and, when Cl/H exceeds 1, to a CO2+CO-richfluid with little H2O Similarly, in more reduced fluids, CH4contents are depressed by the formation of CH3Cl. From consideration of volatile solubilities and abundances inmafic magmas and the nature of the C-O-H-Cl system, it is hypothesizedthat the first fluid to exsolve from Bushveld and Stillwaterintercumulus melt was composed of a mixture of CO2 CO, and HClwith minor amounts of sulfur species and H2O A model is developedfor the evolution of such a fluid with cooling. The model assumesthat graphite began to precipitate from the fluid at supersolidustemperature and that the system cooled down a T-fo2 path parallelto and >2 log units below that of the Ni-NiO oxygen buffer.Upon the appearance of graphite, the fluid evolved to a morehydrogen-rich composition by graphite precipitation and lossof oxygen to the surrounding silicate-oxide assemblage. Coolingof fluid to 25?C below the first appearance of graphite resultedin reduction in the fluid mass by >70%, thus concentratingchlorine, sulfur and other residual species in the intercumulusfluid and melt. The model explains the presence of chlor-apatiteand the enrichment of graphite in the Bushveld Critical Zoneand predicts that chlor-apatite-bearing Stillwater rocks weresimilarly enriched in graphite during crystallization. 相似文献
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