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1.
Luxury Tourism and Regional Economic Development in Mexico 总被引:1,自引:0,他引:1
This article argues that little attention has been paid to the territorial and socioeconomic impact of consumer–service globalization on Third World countries. It specifically examines the economic role of tourism in Mexico and its limited effect on the country's regional development. Despite governmental support in order to enhance economic growth, currency receipts, and employment, tourism contributes less than 5 percent to the gross domestic product, and the majority of tourism–related jobs are precarious and low–skilled. The promotion of luxury resorts in coastal areas has led to highly concentrated and fast–growing enclaves of mainly foreign investment. However, this strategy has failed to stimulate productive links between tourist centers and their hinterlands and has led to large–scale urbanization characterized by a considerable lack of basic services for the resident population. 相似文献
2.
Studia Geophysica et Geodaetica - 相似文献
3.
Michael F. Rosenmeier David A. Hodell Mark Brenner Jason H. Curtis Jonathan B. Martin Flavio S. Anselmetti Daniel Ariztegui Thomas P. Guilderson 《Journal of Paleolimnology》2002,27(1):117-131
Stratigraphic shifts in the oxygen isotopic (18O) and trace element (Mg and Sr) composition of biogenic carbonate from tropical lake sediment cores are often interpreted as a proxy record of the changing relation between evaporation and precipitation (E/P). Holocene 18O and Mg and Sr records from Lakes Salpetén and Petén Itzá, Guatemala were apparently affected by drainage basin vegetation changes that influenced watershed hydrology, thereby confounding paleoclimatic interpretations. Oxygen isotope values and trace element concentrations in the two lowland lakes were greatest between ~ 9000 and 6800 14C-yr BP, suggesting relatively high E/P, but pollen data indicate moist conditions and extensive forest cover in the early Holocene. The discrepancy between pollen- and geochemically-inferred climate conditions may be reconciled if the high early Holocene 18O and trace element values were controlled principally by low surface runoff and groundwater flow to the lake, rather than high E/P. Dense forest cover in the early Holocene would have increased evapotranspiration and soil moisture storage, thereby reducing delivery of meteoric water to the lakes. Carbonate 18O and Mg and Sr decreased between 7200 and 3500 14C-yr BP in Lake Salpetén and between 6800 and 5000 14C-yr BP in Lake Petén Itzá. This decline coincided with palynologically documented forest loss that may have led to increased surface and groundwater flow to the lakes. In Lake Salpetén, minimum 18O values (i.e., high lake levels) occurred between 3500 and 1800 14C-yr BP. Relatively high lake levels were confirmed by 14C-dated aquatic gastropods from subaerial soil profiles ~ 1.0–7.5 m above present lake stage. High lake levels were a consequence of lower E/P and/or greater surface runoff and groundwater inflow caused by human-induced deforestation. 相似文献
4.
Melanie A. Riedinger Miriam Steinitz-Kannan William M. Last Mark Brenner 《Journal of Paleolimnology》2002,27(1):1-7
Lithostratigrahic and mineralogic analyses of sediments from hypersaline Bainbridge Crater Lake, Galápagos Islands, provide evidence of past El Niño frequency and intensity. Laminated sediments indicate that at least 435 moderate to very strong El Niño events have occurred since 6100 14C yr BP (7130 cal yr BP), and that frequency and intensity of events increased at about 3000 14C yr BP (3100 cal yr BP). El Niño activity was present between 6100 and 4000 14C yr BP (4600 cal yr BP) but infrequent. The Bainbridge record indicates that there has been considerable millennial-scale variability in El Niño since the mid-Holocene. 相似文献
5.
P.T. Crisp S. Brenner M.I. Venkatesan E. Ruth I.R. Kaplan 《Geochimica et cosmochimica acta》1979,43(11):1791-1801
Particulate matter was collected during September–October, 1977, in particle traps suspended 30–60 m above the floor of San Nicolas, Santa Barbara, Santa Monica and San Pedro Basins, off the coast of southern California. The trap particulates were analyzed for C15–C35 hydrocarbons using gas chromatography (GC) and GC-mass spectrometry. Kerogens and humic acids were characterized by H/C, N/C, δ13C, δ15N and δ34S ratios, and by electron-spin resonance. Hydrocarbons arising from fresh and weathered petroleum, marine autochthonous and terrestrial sources were identified. The rates of petroleum deposition during the collection period followed the order: San Nicolas Basin < Santa Barbara Basin ~ Santa Monica Basin < San Pedro Basin, with the largest amount of weathered petroleum being deposited in San Pedro Basin. The rates of petroleum deposition are correlated more strongly with human activities such as shipping, and the discharge of municipal and industrial wastes, than with natural submarine oil seepage. Analyses of kerogens and humic acids indicate that the majority of the organic matter in the trap particulates is of marine origin. The water column overlying Santa Barbara Basin appears to have the highest marine productivity of the four basins studied. 相似文献
6.
In studies of iron silicate liquids under reducing conditions at 1 atm pressure, iron losses from the melt can be minimized by suspending the liquid as a drop from a short segment of fine Pt wire. For a basaltic composition at 1275°C and oxygen fugacities appropriate to terrestrial magmas, iron losses from the melt are less than 0.5 wt.% of the amount present for run times less than about 20 hr. 相似文献
7.
We inferred the Holocene paleoclimate history of the northeastern Yucatan Peninsula, Mexico, by studying stratigraphic variations in stable isotopes (δ 18O and δ 13C) and lithologic properties (organic matter and carbonate content) in sediment cores taken in 6.3 and 16.2 m of water from Lake Punta Laguna. We present a simple model to explain the lithologic and isotopic variations, and discuss the inferred paleoclimate history in terms of its relation to ancient Maya cultural development. We find evidence for lower lake level and drier climate at about the same time as each major discontinuity in Maya cultural history: Preclassic Abandonment (150–250 A.D.), Maya Hiatus (534 to 593 A.D.), Terminal Classic Collapse (750–1050 A.D.), and Postclassic Abandonment (mid-fifteenth century). Although these broad temporal correlations suggest climate played a role in Maya cultural evolution, chronological uncertainties preclude a detailed analysis of climate changes and archaeologically documented cultural transformations. 相似文献
8.
9.
Jennifer L. Mays Mark Brenner Jason H. Curtis Kathryn V. Curtis David A. Hodell Alex Correa-Metrio Jaime Escobar Andrea L. Dutton Andrew R. Zimmerman Thomas P. Guilderson 《Journal of Paleolimnology》2017,57(4):307-319
Sediment core PI-6 from Lake Petén Itzá, Guatemala, possesses an ~85-ka record of climate and environmental change from lowland Central America. Variations in sediment lithology suggest large and abrupt changes in precipitation during the last glacial and deglacial periods, and into the early Holocene. We measured stable carbon isotope ratios of total organic carbon and long-chain n-alkanes from the core, the latter representing a largely allochthonous (terrestrial) source of organic matter, to reveal past shifts in the relative proportion of C3–C4 terrestrial biomass. We sought to test whether stable carbon isotope results were consistent with other paleoclimate proxies measured in the PI-6 core, and if extraction and isotope analysis of n-alkanes is warranted. The largest δ13C variations are associated with Heinrich Events. Carbon isotope values in sediments deposited during the last glacial maximum indicate moderate precipitation with little fluctuation. The deglacial was a period of pronounced climate variability, e.g. a relatively warm and moist Bølling–Allerød, but a cool and dry Younger Dryas. Arid periods of the deglacial were inferred from samples with high δ13C values in total organic carbon, which reflect times of greater proportions of C4 plants. These inferences are supported by stable isotope measurements on ostracod shells and relative abundance of grass pollen from the same depths in core PI-6. Similar trends in carbon stable isotopes measured on bulk organic carbon and n-alkanes suggest that carbon isotope measures on bulk organic carbon in sediments from this lake are sufficient to infer past climate-driven shifts in local vegetation. 相似文献
10.
We consider an immiscible incompressible two-phase flow in a porous medium composed of two different rocks so that the capillary pressure field is discontinuous at the interface between the rocks. This leads us to apply a concept of multivalued phase pressures and a notion of weak solution for the flow which have been introduced in Cancès and Pierre (SIAM J Math Anal 44(2):966–992, 2012). We discretize the problem by means of a numerical algorithm which reduces to a standard finite volume scheme in each rock and prove the convergence of the approximate solution to a weak solution of the two-phase flow problem. The numerical experiments show in particular that this scheme permits to reproduce the oil-trapping phenomenon. 相似文献