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201.
This article introduces and evaluates the implications for global environmental change of the rising power and authority of big brand companies as global environmental governors. Contributing to the private governance literature and, in particular, addressing the gap in this research with respect to the political implications of individual firm ‘buyer power’, the article provides evidence and analysis of how big brand sustainability is altering the power relations within global supply chains, and the governance prospects and limits of this trend. The authors argue that recent brand company efforts through their global supply chains, while still a long way off from their goals, are achieving environmental gains in product design and production. Yet, these advances are also fundamentally limited. Total environmental impacts of consumption are increasing as brand companies leverage corporate sustainability for competitive advantage, business growth, and increased sales. Big brand sustainability, while important, will not on its own resolve the problems of global environmental change. In conclusion, the article highlights the importance of a co-regulatory governance approach that includes stronger state regulations, sustained advocacy, more responsible individual consumerism, and tougher international legal constraints to go beyond the business gains from big brand sustainability to achieve more transformational, ‘absolute’ global environmental progress. 相似文献
202.
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204.
José F. Molina Jane H. Scarrow Pilar G. Montero Fernando Bea 《Contributions to Mineralogy and Petrology》2009,158(1):69-98
Central Iberian Variscan granite batholiths and anatectic complexes are punctuated by coeval stocks of hydrous, high-K calc-alkaline,
ultrabasic to intermediate rock series. Despite their overall calc-alkaline affinity, the mafic–ultramafic members contain
high-Ti amphibole oikocrysts rimmed by lower-Ti amphibole ± cummingtonite and high-Ti amphibole replacing early phlogopite.
To understand the factors controlling the saturation of high-Ti amphibole in the parental magmas, clinopyroxene-melt, phlogopite-melt
and amphibole-melt relationships are reviewed. This analysis reveals that for melts with intermediate compositions, the affinity
of TiO2 for amphibole rises in alkalic magmas. Accordingly, mildly alkalic trachytoid to subalkaline medium- to high-K andesite and
dacite compositions are estimated for interstitial high-Ti amphibole-saturated melts. Amphibole Ce/Pb ratios reveal a mantle–crust
hybrid nature for interstitial melts with subalkaline trachytoid compositions. The hydrous character of the Variscan basic
magmas favoured an overall magmatic evolutionary trend with a low rate of variation of Na2O with respect to silica during amphibole crystallization.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
205.
George A. Desborough Heather A. Lowers Jane M. Hammarstrom Reinhard W. Leinz 《Geochimica et cosmochimica acta》2010,74(3):1041-108
This paper presents a detailed study of the mineralogical, microscopic, thermal, and spectral characteristics of jarosite and natrojarosite minerals. Systematic mineralogic and chemical examination of a suite of 32 natural stoichiometric jarosite and natrojarosite samples from diverse supergene and hydrothermal environments indicates that there is only limited solid solution between Na and K at low temperatures, which suggests the presence of a solvus in the jarosite-natrojarosite system at temperatures below about 140 °C. The samples examined in this study consist of either end members or coexisting end-member pairs of jarosite and natrojarosite. Quantitative electron-probe microanalysis data for several natural hydrothermal samples show only end-member compositions for individual grains or zones, and no detectable alkali-site deficiencies, which indicates that there is no hydronium substitution within the analytical uncertainty of the method. In addition, there is no evidence of Fe deficiencies in the natural hydrothermal samples. Hydronium-bearing jarosite was detected in only one relatively young supergene sample suggesting that terrestrial hydronium-bearing jarosites generally are unstable over geologic timescales.Unit-cell parameters of the 20 natural stoichiometric jarosites and 12 natural stoichiometric natrojarosites examined in this study have distinct and narrow ranges in the a- and c-cell dimensions. There is no overlap of these parameters at the 1σ level for the two end-member compositions. Several hydrothermal samples consist of fine-scale (2-10 μm) intimate intergrowths of jarosite and natrojarosite, which could have resulted from solid-state diffusion segregation or growth zoning due to variations in the Na/K activity ratio of hydrothermal solutions. 相似文献
206.
The Effects of Varying Salinity on Ammonium Exchange in Estuarine Sediments of the Parker River,Massachusetts 总被引:1,自引:0,他引:1
Nathaniel B. Weston Anne E. Giblin Gary T. Banta Charles S. Hopkinson Jane Tucker 《Estuaries and Coasts》2010,33(4):985-1003
We examined the effects of seasonal salinity changes on sediment ammonium (NH4
+) adsorption and exchange across the sediment–water interface in the Parker River Estuary, by means of seasonal field sampling,
laboratory adsorption experiments, and modeling. The fraction of dissolved NH4
+ relative to adsorbed NH4
+ in oligohaline sediments rose significantly with increased pore water salinity over the season. Laboratory experiments demonstrated
that small (∼3) increases in salinity from freshwater conditions had the greatest effect on NH4
+ adsorption by reducing the exchangeable pool from 69% to 14% of the total NH4
+ in the upper estuary sediments that experience large (0–20) seasonal salinity shifts. NH4
+ dynamics did not appear to be significantly affected by salinity in sediments of the lower estuary where salinities under
10 were not measured. We further assessed the importance of salinity-mediated desorption by constructing a simple mechanistic
numerical model for pore water chloride and NH4
+ diffusion for sediments of the upper estuary. The model predicted pore water salinity and NH4
+ profiles that fit measured profiles very well and described a seasonal pattern of NH4
+ flux from the sediment that was significantly affected by salinity. The model demonstrated that changes in salinity on several
timescales (tidally, seasonally, and annually) can significantly alter the magnitude and timing of NH4
+ release from the sediments. Salinity-mediated desorption and fluxes of NH4
+ from sediments in the upper estuary can be of similar magnitude to rates of organic nitrogen mineralization and may therefore
be important in supporting estuarine productivity when watershed inputs of N are low. 相似文献
207.
We isolate the contribution of warming, other large-scale changes and soil moisture decline and feedbacks in driving future projected changes in daily precipitation across Europe. Our confidence in each of these mechanisms differs, so this analysis then allows us to determine an overall confidence (or reliability) in the projected changes. In winter, increases in extreme precipitation over Europe as a whole are judged to be reliable, dominated by increased atmospheric moisture with warming. At scales less than about 2,000 km changing circulation patterns could enhance or offset this increase. Additionally, over the Scandinavian mountains warming-induced circulation changes do offset the effect of increased moisture and the overall change is unreliable. In summer, increases in extreme precipitation over northern Scandinavia and decreases over the Mediterranean are reliable in the absence of considerable circulation change. Over central Europe, an increase in the proportion of summer rainfall falling as extreme events is reliable. 相似文献
208.
Jane Southworth Graeme S. Cumming Matt Marsik Michael W. Binford 《The Professional geographer》2006,58(4):406-420
Anthropogenic, ecological, and land‐surface processes interact in landscapes at multiple spatial and temporal scales to create characteristic patterns. The relationships between temporally and spatially varying processes and patterns are poorly understood because of the lack of spatiotemporal observations of real landscapes over significant stretches of time. We report a new method for observing joint spatiotemporal landscape variation over large areas by analyzing multitemporal Landsat data. We calculate the spatiotemporal variation of the Normalized Difference Vegetation Index (NDVI) in the area covered by one Landsat scene footprint in north central Florida, over spatial windows of 104–108 m2 and time steps of two to sixteen years. The correlations, slopes, and intercepts of spatial versus temporal regressions in the real landscape all differ significantly from results obtained using a null model of a randomized landscape. Spatial variances calculated within windows of 105–107 m2 had the strongest relationships with temporal variances (regressions with both larger and smaller windows had lower coefficients of determination), and the relationships were stronger with longer time steps. Slopes and y‐intercepts increased with window size and decreased with increased time step. The spatial and temporal scales at which NDVI signals are most strongly related may be the characteristic scales of the processes that most strongly determine landscape patterns. For example, the important time and space windows correspond with areas and timing of fires and tree plantation harvests. Observations of landscape dynamics will be most effective if conducted at the characteristic scales of the processes, and our approach may provide a tool for determining those scales. 相似文献
209.
Jane K. Hart 《地球表面变化过程与地形》2006,31(1):65-80
The Athabasca Glacier, resting on a rigid bed, provides an excellent example of subglacial ice and till erosion. The presence of a thin mobile till layer is shown by the presence of flutes, saturated till layer, push moraines and ploughed boulders. Cross‐cutting striations, v‐shaped striations and reversed stoss‐and‐lee clasts are indicative of clasts rotating within this layer. As the till moves it erodes the bedrock and clasts within it. A combination of erosion by ice and till produces stoss‐and‐lee‐clasts and generates striations on flutes and embedded clasts, as well as eroding the bedrock into a continuum of smoothed, rounded and streamlined forms. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
210.
Laurent Bourgouin Hans-Bernd Mühlhaus Alina Jane Hale Antonin Arsac 《Acta Geotechnica》2006,1(4):225-236
The level set method has been implemented in a computational volcanology context. New techniques are presented to solve the advection equation and the reinitialisation equation. These techniques are based upon an algorithm developed in the finite difference context, but are modified to take advantage of the robustness of the finite element method. The resulting algorithm is tested on a well documented Rayleigh–Taylor instability benchmark [19], and on an axisymmetric problem where the analytical solution is known. Finally, the algorithm is applied to a basic study of lava dome growth. 相似文献