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1.
S.J. Davies S.E. Metcalfe A.B. MacKenzie A.J. Newton G.H. Endfield J.G. Farmer 《Journal of Paleolimnology》2004,31(1):77-98
Lago de Zirahuén (19° 26 N, 101° 44 W) lies within a montane basin in highland Michoacán, Mexico at 2075 m a.s.l. The lake basin has high recreational value and is promoted as a tourist attraction. Four short (<1 m), sediment–water interface cores were used to investigate Late Holocene environmental change. The cores span approximately the last 1000 years, based on 210Pb dating, AMS 14C dating and tephrochronology. Cesium-137, Americium-241 and tephra layers from Volcan Paricutín (AD 1943–1952) and Volcan Jorullo (AD 1759–1774) provide independent age markers. Cores were analysed for diatoms, magnetic susceptibility and heavy metals (iron, lead, manganese, copper and zinc). Drier climate around 1000 years BP is tentatively inferred from the diatom assemblage and is concordant with other regional records. Increased soil erosion between ca. AD 1100 and AD 1550 may be associated with Pre-Hispanic settlement in the basin, but there is no archaeological evidence to support this. A period of catchment stability occurred during the early Colonial Period, ca. AD 1550–1750. The dramatic decline in the indigenous population following the Spanish Conquest in 1521 may have promoted vegetation recovery on the basin slopes. After the mid-18th century, a significant change in diatom species composition is observed along with an increase in soil erosion, as inferred from the magnetic susceptibility profile. Concentrations of copper and lead also increased. These changes are associated with the establishment of a copper smelting industry in the basin and increased Colonial agricultural development. Recently, tourist developments and commercial agriculture have impacted on the basin. The diatom flora has changed dramatically in the last 20 years, apparently in response to the onset of cultural eutrophication. The palaeoenvironmental evidence suggests that the lake is responding rapidly to land use intensification in the basin, which may have implications for future developments. 相似文献
2.
Michael Gentile 《Urban geography》2013,34(10):1455-1464
ABSTRACTDespite the recent planetary turn that has swept through gentrification research, the theoretical barycentre remains pegged to a few strongholds located in the global north-west. Against this background, this essay offers a provincialized account of three gentrification-like trends – tele-urbanization, Schengtrification and colour-splashing – which are currently taking place in Tbilisi, Riga and Kiev. It is proposed that these processes are supported by an underlying logic that is not pinned to these cities’ specific (“post-communist”) contexts, raising questions about the avowedly universal validity of theories of gentrification stemming from the global northwest, and particularly those developed within the more critical scholarly tradition. 相似文献
3.
Limnological responses to warming on the Xizang Plateau,Tibet, over the past 200 years 总被引：1，自引：0，他引：1
Paleolimnological analyses can be used to evaluate limnological responses to changing climate over decadal to centennial timescales,
especially in regions with sparse lake monitoring data. We used a training set with 90 lakes to develop a diatom-based conductivity
transfer function and address climate-driven changes in lakes on the Qinghai-Xizang Plateau, Tibet. This new training set
is an expanded version of a previous model (Yang et al. in J Paleolimnol 30:1–19, 2003) and shows improved performance statistics for the conductivity model. The expanded training set also contains diatom species
not previously identified from the region, such as Stephanodiscus sp. and Cyclotella sp., which are common eutrophic indicator species in other regions, but can also be influenced by water column conductivity.
The new conductivity transfer function was applied to Lakes Nam Co and Chen Co in Tibet. Recent conductivity inferences were
compared with climate data from the Dangxiong weather station and water level records from Yangzhuyong Co, which show increasing
temperature and lower water levels, respectively, since AD 1960. Other studies showed that the water balance for many lakes
on the Qinghai-Xizang Plateau is complex, affected by both evaporation and glacial melting. Our paleolimnological reconstructions,
which include sediment particle size data, indicate that over relatively short timescales glacial meltwater can influence
lake hydrology, but over decadal timescales, increases in evaporation, driven by rising temperatures, dominate. Our findings
suggest that regional warming is lowering water levels at these sites and will continue to do so given predicted future climate
warming. 相似文献
4.
Ramesh Dhussa 《The Professional geographer》2013,65(2):312-313
In this article, we first replicate and then adapt an existing index of social vulnerability to hazard developed for the United States to a non-U.S. context. We construct indexes for Norwegian municipalities, describe the adjustment process, and compare the replicated and adapted assessments. Our results indicate only a moderate correlation between the replicated and adapted vulnerability indexes and for several municipalities the difference between the indexes is considerable. This demonstrates that context matters and that indexes of vulnerability need to be adapted rather than replicated. To facilitate such adaption processes, we identify three types of accommodation: conceptual, technical, and geographic. 相似文献
5.
Heike Jöns 《The Professional geographer》2017,69(4):670-682
This article examines the role of early female academics at the University of Cambridge in the production and dissemination of knowledge between 1926 and 1955. A statistical comparison of women's use of academic leave of absence with that of their male colleagues reveals that, across disciplines, women were less integrated into (inter)national knowledge networks and thus less visible in their epistemic communities than men because women focused their academic leaves more on research, rarely attended conferences, traveled overseas less often than men, and went more frequently to destinations within Europe than the United States as the new economic hegemon. Biographical case studies of these early female academics demonstrate the importance, variously, of their upper middle-class background, academic excellence, and familial and nonfamilial patronage in developing their careers, overcoming multiple hurdles, and producing intellectual contributions of equal quality to that of their male peers. Conceptually, this article calls for the inclusion of academic travelers from disciplines other than geography into feminist histories of geographical knowledge and argues that rather than stereotyping gender differences, greater comparative research on the experiences of female and male academics is needed to understand the mechanisms of gender inequality within the university. 相似文献
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Nicholas L. Balascio Stephen Wickler 《Norsk geografisk tidsskrift. Norwegian journal of geography》2018,72(3):146-160
Integrated archaeological and paleoenvironmental investigations provide long-term perspectives on human–environment interactions. In the North Atlantic region, early human settlements were established in marginal agricultural environments and were susceptible to various environmental stressors. The Lofoten Islands have had an important role in the history of this region, particularly during the Iron Age, when Lofoten developed from pioneering agricultural settlements to a prominent node of power and trade under Viking chieftains. Iron Age developments in Lofoten were concurrent with significant natural environmental changes, including variations in climate and sea level. However, there has not been a comprehensive investigation of their influence on early settlements. The purpose of the study is to review Iron Age cultural developments in Lofoten using published archaeological data and paleoenvironmental records of past climate and sea-level change, and to present specific examples of the intersection of early human development and natural environmental changes. The findings show that climate changes probably influenced agricultural phases and that relative sea-level variations had important impacts on maritime developments. In conclusion, the findings demonstrate that human–environment interactions were significant factors in Lofoten’s history and the authors suggest specific areas for future research. 相似文献
8.
This article presents some of the findings of a multi-indicator investigation of the history of vegetational changes and land degradation in the Lake Baringo basin, Kenya, East Africa, during the Late Holocene. 14C- and 210Pb-dated record of the lithostratigraphy is used to reconstruct the paleoenvironment in the region of the lake. The stratigraphic record from Lake Baringo reveals the presence of two abrupt dry episodes at ca. AD 1650 and AD 1720 in east Africa that led to drying up of the lake. The record also shows evidence of a third period of desiccation at ca. AD 1880, which resulted in lowering of the lake level and is corroborated by oral tradition from the area. This article shows the potential of how the paleoenvironmental record can be combined with the historical record to understand East Africa's paleoenvironment. 相似文献
9.
Sedimentation rates in the Wanggang salt marshes, Jiangsu 总被引：1，自引：0，他引：1
WANGAijun GAOShu JIAJianjun PANShaoming 《地理学报(英文版)》2005,15(2):199-209
1 IntroductionLand-ocean interaction in coastalzone is one of the key m atters of the International G eosphereand Biosphere Program (IG BP). The key problem s of the second phase in the next decadeinclude the m aterial cycle, the system evolution process … 相似文献
10.
《Norsk geografisk tidsskrift. Norwegian journal of geography》2012,66(3-4):193-197
Located at approximately 150 m above the present base level, the caves of Niaux, Lombrives and Sabart are an old drainage system, which worked between the Vicdessos and Ariège Valleys. In these caves, three successive sedimentary units were studied in detail. Each unit consists of two parts: the lower deposit is detrital, of fluvial origin, and testifies to a hydrological working of the conduit system; the upper deposit of each unit is mostly speleothems, corresponding to a draining of the conduits as the palcokarst evolved above base level. This is similar to the present environment of the caves. Only the speleothems from the upper part of each unit were dated by the 230Th/234 U method. The dates, from 27 samples, are in good agreement with Europe and North America data. The data from the middle (250 to 200 ka BP) and upper (90 to 20 ka BP) fluvial sediments correspond to major glacial events, which re-activated the karst system. Two further events resulted in a lack of carbonated sedimentation, the first between 350 and 290 ka BP, the second between 175 and 130 ka BP. Comparing the data from other places, these two events can be related to glacial periods of minor importance in the study area, because of the lack of erosion and of detrital sediments. The oldest detrital sediments are covered by speleothems older than 350 ka BP and, partly, older than 720 ka BP (from paleomagnctic data to be confirmed); from sedimentary data, they may not be related to a glacial event. They are perhaps contemporary with the area's initial cave formation. 相似文献
11.
《Norsk geografisk tidsskrift. Norwegian journal of geography》2012,66(3-4):165-174
The behaviour of the ice-dammed lake, Strupvatnet, Troms County, Norway, is described. Past observations are noted and related to observations in 1959 and to other ice-dammed lakes. Mechanisms for opening and maintaining water flow during a ‘hlaup’ are discussed. It is considered that Liestol's melt widening process operates after initiation by a pressure gradient across the dam. The lake and the internal drainage system of the glacier are thus linked. There is no evidence of lifting of the ice dam at Strupbreen. 相似文献
12.
Dominik Pawłowski Beata Gruszka Hanna Gallas Joanna Petera-Zganiacz 《Journal of Paleolimnology》2013,49(4):679-696
Upper Saalian (Illinoian) glaciolacustrine deposits in central Poland, preserved in a tectonic graben, were exposed in an opencast lignite mine and investigated using sedimentological and micro-paleontological methods. The extraglacial lake sediments provide the first records of late Saalian cladoceran communities in central Europe, recovered from glaciolacustrine deposits. Sedimentation was dominated by a supply of clastics that fluctuated with the seasons, forming rhythmites. In addition to seasonal cyclicity, sedimentary and environmental conditions changed every several years to decades, with periods of increased inflow to the lake delivering sandy material, and periods of almost stagnant water dominated by suspension settling. The sediments contain Cladocera assemblages that indicate the lake was initially deep, oligotrophic, and filled with moderately cold water. Changes in Cladocera community composition and abundance were perhaps responses to climate seasonality. Zones without Cladocera were associated with seasons of higher inflow and sediment supply, and directly or indirectly, with tectonic activity in the graben. Earthquakes, documented by the presence of seismites, caused not only deformation of unconsolidated lake-bottom sediments, but possibly also changes in habitat characteristics. Combined sedimentological and biological data were used to infer the lake’s history and show that deposits of glaciolacustrine lakes can be used as indicators of past ecological and climate changes. 相似文献
13.
Karin Holmgren Jan Risberg Johan Freudendahl Mussa Achimo Anneli Ekblom Joao Mugabe Elin Norstr?m Sandra Sitoe 《Journal of Paleolimnology》2012,48(2):311-322
Stratigraphic variations in diatom composition and phytolith abundance in a sediment core from a small, hydrologically isolated waterbody, Lake Nhauhache, Mozambique, provide evidence of water-level fluctuations over the past ~2,300?years. Ten AMS radiocarbon dates on bulk sediment samples show that the lake came into existence about 2,300?years ago and that it has dried out since then, but only for brief time periods. Changes in the diatom assemblage composition indicate that lake level fluctuated in response to shifting humidity conditions. The changes reflect wetter conditions ca. 300 BC?CAD 800, more variable conditions between AD 800 and 1150, a distinct dry phase within the time span AD 1150?C1700 and a return thereafter to more humid conditions until present. There is general agreement between the Lake Nhauhache record and other records from the Southern Hemisphere summer rainfall region. This suggests that sediments from small interdunal lakes, which are abundant along the coast of southern Africa, provide reliable, regional paleoenvironmental information about an area from which more such data are needed. 相似文献
14.
Paul Knox 《Urban geography》2013,34(8):1107-1110
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In the contemporary American urban renaissance, formerly fringe efforts to produce place, conducted by longtime residents and “urban pioneers” alike, now shape mainstream urbanism. Gardening and bicycling are constitutive of contemporary excitement about the city, representing the reinvigoration of the urban neighborhood following the depredations of suburbanization. This paper draws on research in California cities to offer a sympathetic critique of these leading edges of progressive urbanism, arguing that advocates’ overwhelming focus on the local creates a scalar mismatch between the horizon of political action and the problems they hope to address. Even as supporters of gardening and cycling understand themselves as implicitly allied with struggles for the right to the city, their work to produce local space is often blind to, and even complicit in, racialized dynamics of accumulation and exclusion that organize metropolises. The result is a progressive urbanism largely disconnected from broader left struggles for spatial justice. 相似文献
17.
George W. Wenzel 《Polar research》2009,28(1):89-99
Considerable attention has been devoted to the possible effects of global climate change on the environment of the circumpolar world. With regard to the Inuit, the aboriginal culture of Arctic Canada, research interest has focused principally on the vulnerability of the hunting and harvesting component of the traditional food system, otherwise frequently referred to as the subsistence system, if wild terrestrial and marine resources become less available. Although also concerned with the traditional Inuit food economy, this paper concentrates on the customary institutional mechanisms by which the Inuit distribute and share the products obtained from hunting. After analysing this social economy, a review of the data on recent climate-related range changes of a number of Arctic animal populations is carried out, in terms of how projected environmental changes may affect this other aspect of Inuit subsistence. After tentatively concluding that some species substitution and/or replacement will occur, the final aspect of the paper considers the potential for the possible exclusion of these "replacements" as a result of the political aspect of climate change. 相似文献
18.
Remus Creţan 《Urban geography》2019,40(6):805-825
ABSTRACTRecent scholarship in critical toponymy has raised questions about the impacts on urban residents of selling naming rights and the possibility of contesting the commodification of urban place names. This article examines these issues using Poli Timi?oara, the major football team of Timi?oara, Romania, as a case study. The cash-strapped local authority sold the naming rights for the team to raise revenue. However, when the club’s private owner was unable to finance the team, the local authority reacquired the naming rights of Poli, now under the name Asocia?ia Club Sportiv Poli (a new team with a small fan base). Drawing on the everyday narratives of fans, this article explores how the commodification of a local club name can cause social tensions. This is important for understanding urban residents’ access, or lack thereof, to social capital resources and how this leads to the manifestation of social inequalities which co-determine fans’ reactions and responses to the change in the name of a sports team. The findings suggest that commodifying names can mobilize serious contestations among partisan groups about who owns the name, although such contestations appear to be on uncertain ground because of post-communist urban practices of delayed economic restructuring. 相似文献
19.
In order to study the element contents and distribution of various mosses collected in the Antarctica, we analyzed the heavy elements of 3 species of Polytri-chum in the Fildes Peninsula, P. alpinum, P. juniperinum and P. alpestre, by synchrotron radiation X-ray fluorescence ( SR-XRF). The result shows that the elements, such as K, Ca, Mn, Fe, Cu, Zn and Sr, are nearly the same in Potytrichum. The peak intensity of K is higher than that of Ca, and the peak intensity of Ca is higher than that of Fe in P. alpinum. In P. juniperinum, the peak intensity of K is higher than that of Ca, and the peak intensity of Ca is close to that of Fe. The peak intensity of K is nearly equal to those of Ca and Fe in P. alpestre. Therefore, the habitats of 3 species of Polytrichum are similar in the Fildes Peninsula. By XRF analyzing of different parts of P. alpestre, we found that the peak intensities of relative concentration of elements are obviously different. The peak intensity of K in apical-bud is the highest in orga 相似文献
20.
The mobile telephone is one of the most widely adopted innovations of the late twentieth century. We examine the worldwide diffusion of the cellular telephone during a decade of explosive growth. We evaluate the influences of competition, location, and wealth on global and regional variations in cell phone penetration and address the role that cultural differences play in technology adoption and use. Telephony measures in the analysis vary significantly by competition type and by region, although gross national product per capita explains more than 75 percent of variation in cell phone penetration rates globally and nearly 90 percent in Asia. 相似文献