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1.
Steven Tufts 《Geoforum》2009,40(6):980-990
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2.
现代港口地理学的研究进展及展望   总被引:7,自引:0,他引:7  
基于港口地理研究的时代背景变迁,分析了现代港口地理学的研究进展与研究内容,重点从港口地理的基本研究范畴、港口理论、港口体系、枢纽港、港口与腹地关系、航运网络、航运企业和码头企业等角度深入解析其重点历程与主要论点,对中国港口地理学的研究进展和国际学者的相关论点进行了阐述,然后从研究内容、研究范式、研究重点和研究地区等角度,总结和评价现代港口地理学的研究特征,梳理其发展规律与研究轨迹。同时基于以上研究,从研究范式、研究重点、研究单位等角度,对港口地理学的未来研究趋向进行了深入探讨。通过该研究,系统总结了港口地理学的研究进展,有助于该学科的理论和实证研究。  相似文献   

3.
Chronologies of particle-associated contaminant levels were developed for Jamaica Bay, an embayment of the Atlantic Ocean on southwestern Long Island. A major potential source of contaminants to the system is wastewater discharge, which comprises most of the freshwater input to the bay. Sediment core sections were analyzed for Cs-137, Pu-239, 240, and Be-7 activities which were then used to establish net particle accumulation rates. Samples deposited from the early 1950s through the late 1980s were analyzed for metals and chlorinated hydrocarbon contaminants. Trace metals, including copper, lead, chromium, zinc, and mercury, were elevated to levels several times those of pre-industrial concentrations. These metals decreased by about 50% between the mid 1960s and the late 1980s. Chlorinated hydrocarbon concentrations, including polychlorinated biphenyls, chlordane, and dichlorodiphenyltrichloroethane-derived compounds, decreased by a factor of five to ten between the late 1960s and the late 1980s. Local improvements in wastewater treatment and national efforts to regulate the uses and releases of specific chemicals are the most likely explanation of declines in contaminant levels in these sediments.  相似文献   

4.
Like most sill fjords, Gullmar Fjord on the Swedish west coast, is subject to periods of stagnation. Deep water is usually renewed annually, but since the late 1970s several low-oxygen events have been documented in the deepest part of the fjord. These events occurred during a time when the North Atlantic Oscillation (NAO) was in a highly positive phase. We investigated how the benthic environment, in the deepest part of the fjord, has varied during the 20th century, using benthic foraminifera and an extensive history of instrumental hydrographic data. The foraminifera have undergone one major faunal change and two minor modifications during this time. The major faunal change occurred in the late 1970s to early 1980s, when the common Skagerrak-Kattegat fauna was replaced by one dominated by the opportunistic, low-oxygen-tolerant species,Stainforthia fusiformis. This major faunal change appears to be related to the severe low-oxygen event in 1979–1980. In the latter part of the 1990s the fauna changed again; the concentration ofS. fusiformis was still high, but other low-oxygen-tolerant species also became important. This minor faunal modification occurred in connection with the 2-yr stagnation period between 1996 and 1998 when a low-oxygenevent evolved, the most severe recorded in Gullmar Fjord. Between 1930 and 1980, there was little faunal variation, and a stable fjord environment is indicated. During this time, negative NAO indexes dominated and climate was more continental, with an increase in winds from the northeast and east. In connection with a climate transition indicated by the NAO index switching from positive to negative, a minor faunal change occurred in the late 1920s to early 1930s: the concentration of the Skagerrak-Kattegat fauna increased markedly in the fjord. The fauna characterizing the positive NAO phase between 1900 and the late 1920s is very different from the present positive NAO fauna. The foraminiferal record laid down between approximately 1914 and 2001 indicates that between 1930 and 1980 Gullmar Fjord was a stable fjord environment. During the last 20 yr, it experienced conditions that were more fluctuating and changing. For the most part, changes in the foraminiferal fauna are caused by changes in the deep-water renewal, their extent and frequency, which in turn are caused by climatic oscillations.  相似文献   

5.
The present Mediterranean climate of coastal California is unique in North America and reflects the interaction of several important synoptic controls, principally the North Pacific semipermanent anticyclone, and to a lesser extent the Aleutian low-pressure system and the cool California oceanic current. These synoptic climatic controls, key parts of the global air-sea circulation, were probably operative throughout late Quaternary time as shown by paleoecologic evidence. The thick accumulations of sediments in basins of offshore California indicate that while variable sedimentation regimes reflect changing climatic and oceanographic conditions, the Quaternary climate was probably semiarid as now, even during glacial maxima. Late Quaternary coastal dunes preserve former wind directions and show that prevailing late Quaternary winds were directionally equivalent to modern winds, which are controlled by the North Pacific anticyclone and by interactions between the North Pacific high and the interior basin low. These sand dunes contain buried, datable, carbonate-rich soils. Precipitation then, like the present rainfall regime, was not enough to leach the carbonates from the soils. Charcoal in buried dunes and soils shows that fire was environmentally important throughout the Quaternary, just as it is today. Fossil plants indicate that sclerophyllous vegetation and forest stands of conifers, adapted to a Mediterranean climate, were widely distributed during late Quaternary time. Fossil pollen in the Sierra Nevada indicates the influence of the North Pacific high. The historical precipitation record overlaps a late Holocene tree-ring record permitting extrapolation of the precipitation curve back nearly 600 years. Well-defined wet and dry trends in the precipitation pattern characterized this time span, and provide a possible analog to the earlier Holocene and Pleistocene precipitation regime. The paleoecologic record shows that the late Quaternary climate of coastal California was characterized by regimes similar to those prevailing today. The persistence of a Mediterranean climate in California during the last glaciation contrasts with dramatic climatic changes experienced in glaciated parts of North America. California thus was an Ice Age refugium for animals and cold-sensitive plants.  相似文献   

6.
Water renewal in semi-enclosed coastal areas is crucial for the supply of oxygen and seston and for the removal of organic loadings from finfish or shellfish aquaculture sites. Water renewal depends on hydrodynamic processes and can have a complex spatial distribution due to irregular topographic features. This study describes some physical oceanography observations gathered in the Richibucto estuary, New Brunswick, Canada, and provides an estimate of the spatial distribution of water renewal in the North Arm, a location in the estuary where the largest American oyster (Crassostrea virginica) aquaculture operation in eastern Canada is located. The estuary changes from a well mixed estuary to a partially stratified estuary depending on runoff conditions. Tides are mixed but mainly diurnal due to the nearby presence of the second M2 amphidromic point in the Gulf of St. Lawrence. Tidal amplitudes vary from 0.3 to 0.6 m and show a slight increase some 35 km upstream. Currents in the main channel can reach over 0.60 m s−1 during ebb and 0.3 m s−1 during flood, with a slack water period of approximately 8 h. Low frequency sea level fluctuations have a range of 0.5 m at the mouth and are coherent within the estuary. Hydrodynamic and advection-dispersion models are used to calculate the spatial distribution of the local renewal time (LRT) in the North Arm for high and low freshwater discharge conditions, using the dissolved tracer method. Results show that the LRT varies from less than 5 d at the downstream end of the North Arm to over 100 d further upstream. When averaged over the entire North Arm, the integral renewal time (IRT) is estimated to vary only from 8 to 21 d depending on the season. The LRT and IRT estimates are major improvements over conventional renewal estimates using tidal prism methods.  相似文献   

7.
Metropolitan growth and labor markets in Mexico   总被引:1,自引:0,他引:1  
The objective of this paper is to examine the main changes in the metropolitan labor markets associated with economic restructuring in Mexico during the late 1980s and beginning of the 1990s. The analysis refers particularly to the four largest metropoles of the country, Mexico City, Guadalajara, Monterrey and Puebla, looking for common characteristics in their emergent employment structures now strongly differentiated in terms of rewards, stability in employment relations and conditions of access to jobs. The analysis reveals that largest metropolitan areas have been the most profoundly affected by the economic restructuring resulting from globalization, through a rapid de-industrialization and the expansion of the tertiary sector. Metropolitan labor markets in Mexico, at the time that show signs of social polarization in the formal sector, put in evidence a general process of precarization – less labor stability, replacement of permanent by part-time jobs, and increasing subcontracting –, segmentation of the labor force, and an increasing informal conditions of economic activities with small businesses and unskilled, temporarly and poorly paid jobs. The labor force segmentation and its more precarious and casual conditions are mostly explained by the impact of recent neoliberal policies, and recurrent economic crisis during the 1980s and 1990s which highly contributes to social inequality.  相似文献   

8.
John Holmes 《Geoforum》2004,35(1):9-21
Historically, political struggles to define the geographical scale at which labour relations and collective bargaining will be conducted have been of crucial significance to the labour movement. Today, workers and their unions face very difficult challenges. In many manufacturing industries changes in the organizational structure of production at different geographical scales have undermined the effectiveness of the organizing and collective bargaining strategies associated with traditional industrial unionism. This paper focuses on collective bargaining strategies developed by North American autoworkers’ unions to respond to the extensive restructuring of the automotive industry that took place during the 1990s. These strategies include innovations in the structure and content of collective bargaining and efforts to redefine the scale at which collective bargaining takes place. Following a brief discussion of the challenge posed by the integration of Mexico into a continent-wide production system, the analysis focuses on the strategies devised by the Canadian Auto Workers (CAW) union during the 1996 and 1999 rounds of collective bargaining to address issues raised by outsourcing and modular manufacturing. With outsourcing, the automakers are not so much eliminating jobs as they are deciding who gets to do them, at what price, and under what working conditions. With modular manufacturing, the organizational boundaries between firms are blurring and the terms and conditions of work in one firm arguably are becoming dependent upon management decisions made in another firm. The CAW’s response has been to develop new collective bargaining strategies including the concepts of ‘work ownership’ and ‘satellite bargaining’ which involves redefining the traditional geographical extent of the bargaining unit. While the empirical focus is on the North American automobile industry, the general issues related to the re-scaling of production, and especially outsourcing and modular manufacturing, are common across a range of manufacturing industries.  相似文献   

9.
《Quaternary Science Reviews》2005,24(10-11):1123-1149
A prominent, abrupt climate event about 8200 years ago brought generally cold and dry conditions to broad northern-hemisphere regions especially in wintertime, in response to a very large outburst flood that freshened the North Atlantic. Changes were much larger than typical climate variability before and after the event, with anomalies up to many degrees contributing to major displacement of vegetative patterns. This “8k” event provides a clear case of cause and effect in the paleoclimatic realm, and so offers an excellent opportunity for model testing. The response to North Atlantic freshening has the same general anomaly pattern as observed for older events associated with abrupt climate changes following North Atlantic freshening, and so greatly strengthens the case that those older events also reflect North Atlantic changes. The North Atlantic involvement in the 8k event helps in estimating limits on climate anomalies that might result in the future if warming-caused ice-melt and hydrologic-cycle intensification at high latitudes lead to major changes in North Atlantic circulation. Few model experiments have directly addressed the 8k event, and most studies of proxy records across this event lack the time resolution to fully characterize the anomalies, so much work remains to be done.  相似文献   

10.
Doug Ramsey  Barry Smit 《Geoforum》2002,33(3):367-384
In this paper we develop a model of changes in rural community well-being. The model conceptualizes four interrelated dimensions of rural community well-being: physical, psychological, social, and economic. The model recognizes that a range of external forces (political, economic, etc.) exert pressures on rural communities, of which changes in well-being are one outcome. The paper then applies the model to changes which occurred in the tobacco growing region of southern Ontario, Canada. It is argued that this region was impacted by a variety of forces, some general to farming, others specific to tobacco farming, particularly between 1979 and the early 1990s. The empirical application is based on a personally administered farm survey (n=63) conducted between July 1996 and January 1997 and agricultural census data for the years 1981, 1986, 1991, and 1996. The paper concludes by suggesting that the model provides a useful framework for analysing the forces and changing conditions of other rural communities, not only in Canada, but beyond.  相似文献   

11.
Paleobiologists generally agree that within the past 10,000 yr North American black bears (Ursus americanus) have decreased in body and tooth size. Some researchers infer that diminution was gradual and continuous; thus, one might infer that a specimen is old if it is larger than an average-size modern bear. Ursid remains recovered in the 1950s from Lawson Cave, Missouri, that are larger than some modern bears have been reported to date to the late Pleistocene, but association with modern taxa, taphonomic considerations, and a radiocarbon date of 200 yr B.P. indicate that they are modern. Modern specimens from Lawson Cave and other parts of the American Midwest are relatively large compared to modern North American black bears from other areas, suggesting that many supposed late Pleistocene bears from the area might be modern also.  相似文献   

12.
Joanna Kinsey 《Geoforum》1981,12(4):331-347
Liverpool developed round the Port which brought prosperity to the region dating from the 18th century. Over the last twenty years, however, changes in trading patterns and cargo-handling methods have had a distinct and drastic impact upon the Port. Today it is struggling to compete with South and East coast rivals. Its economic impact on the local economy is also declining. Through examining activity linked with the Port it was found that (a) jobs totally dependent upon the Port number less than 15,000, (b) firms supplying the Port are generally only dependent upon it for an extremely small proportion of their total turnover and (c) the Port's customers, which tend to be located in the North West, West Midlands and Yorkshire-Humberside, are decreasing in number and are frequently constrained by shipping companies for their choice of port.  相似文献   

13.
The development of settlement and building activity is the result of socioeconomic, political and demographic changes in the past. However, accurate information on temporal variation in building activity is rather limited. Dendrochronological databases containing dated historical wooden constructions provide an important resource. We used 6514 tree-felling dates to reconstruct building activity in the Czech lands for the period 1450–1950. Comparing felling dates with historical events demonstrated that building activity was negatively associated with intense wars, particularly during the Thirty Years' War (1618–1648). After the Peace of Westphalia (1648), socioeconomic renewal and demographic growth were reflected in an upsurge of building activity, especially ecclesiastical buildings. While the construction of ecclesiastical and noble buildings culminated around the 1720s, rural buildings peaked in the 1780s and the 1820s. Although no direct effect of climate was demonstrated, adverse climatic conditions leading to harvest failures and subsequent famines (e.g. the ‘Hunger Years’ 1770–1772) significantly contributed to declines in building activity. In contrast, a higher number of felling dates were detected when strong and/or frequent windstorms occurred. This study provides a comprehensive understanding of building activity in Central Europe and advocates the use of dendrochronological databases for the investigation of human activities in history.  相似文献   

14.
额尔齐斯河流域中游地区是哈萨克斯坦共和国重要的水资源富矿与战略经济区, 资料表明这一地区过去几十年来气候与水资源均发生了显著变化, 分析研究其气候变化及其对水资源的影响, 对水资源合理利用具有重要的指导意义.利用研究区7个气象站1926-2009年84 a逐月降水和气温资料, 应用高桥浩一郎公式计算研究区月平均蒸发量及可利用降水量, 分析了1926-2009年研究区气候变化及其对水资源的影响.结果表明: 1)与全球气候变暖一致, 过去84 a来研究区平均气温呈较快的升高趋势, 且自20世纪80年代末以来进入快速升温变暖期; 2)84 a来, 研究区降水总体呈增加趋势, 随着温度的升高, 蒸发量同步增加. 因此, 研究区可利用降水量尽管有波动但总体变化不大; 3)降水是影响研究区可利用降水量的最重要的影响因素, 二者呈现显著的正相关关系, 1%的降水变化可导致1.68%的可利用降水量变化.研究区是全球气候变化的敏感区域, 水资源开发利用需切实做好应对气候变化的适应性对策.  相似文献   

15.
Iris Grossmann 《Geoforum》2008,39(6):2062-2072
During recent decades, most European river-port cities and also many seaport cities have undergone a major transition towards a service-centred, rather than industrially-based metropolis, offering a high quality urban environment with a revitalised waterfront. Hamburg is one of the few river-port cities that have chosen the course of port expansion instead. This paper discusses the consequences of current global technological, organisational and economic developments for the port. Changing requirements imply rising monetary and land-use costs and environmental and social impacts, and also entail the risk that the port may not be able to fulfil new requirements and could thus lose market shares to coastal competitors. More importantly, the world-wide economic shift towards the service sector has affected port-dependent jobs in two ways: Directly port-dependent jobs have been reduced to a fraction, while many indirectly port-dependent jobs no longer require physical proximity of the port. Those benefits that continue to arise tend to spread over a much larger geographical region, while the port’s costs remain locally concentrated. Given the increasing competition between world-wide metropolitan regions that seek to establish themselves in new sectors and attract a qualified workforce, it is particularly relevant for Hamburg to account for these changes and to incorporate an assessment of the port’s changing costs and benefits into planning processes. To date, this task has received little attention from the city.  相似文献   

16.
Antimony is an element that is becoming of increasing concern as an environmental contaminant. Geothermal systems are a source of Sb into some fresh waters of New Zealand’s North Island. The purpose of this research was to determine the factors controlling the behaviour of geothermally-derived Sb in the large lowland Waikato River system. The Waikato River is New Zealand’s longest and most utilised river. Antimony in the system exhibited mainly conservative behaviour, and seasonally variable dilution was found to be the most important control on Sb concentrations. The most significant potential removal process was identified as adsorption of Sb onto suspended particulate material (SPM). The adsorption of Sb onto the SPM is enhanced at low (<5) pH conditions, and in the anoxic base of stratified lakes. There was evidence that the adsorption of Sb is mainly onto Fe oxides in SPM, and changes with changing Fe concentrations. Therefore, Sb adsorption was higher in winter (when Fe concentrations in SPM were higher) than in summer. In Lake Ohakuri, which was stratified during the late summer/early autumn of 2007, there was also potential for removal of Sb as Sb2S3 in the presence of sulfide formed in the anoxic layer. The behaviour of Sb was conservative through the estuary at the mouth of the river.  相似文献   

17.
As hydrogeological conditions of coal field in North China are complicated, coal mine water hazards have been occurring frequently. Nearly 80% of coal mines are affected by Ordovician and Permo-Carboniferous Karst water. According to rough statistics, 200 incidents of water inrush have occurred since 1950, 1,500 persons have died, and there is an economic loss of 3 billion Yuan (RMB). The climate of North China belongs to drought or semi-drought zone. So the recharge amount of ground water by infiltration of precipitation is limited. Stronger coal mine water drainage has brought a series of environmental problems, such as water resource and lots of famous Karst springs exhausted, surface collapse emerged, mine water contaminated. Coal mine water hazards are so serious that the economic benefit of coal mines is dropping. Sustainable development of coal mines is affected. So, preventing coal mine water hazards and protecting geological environment are essential. This thesis focuses on preventing coal mine water hazards technologies. The technologies include four aspects: exploration of hydrogeological conditions; prediction and forecast of water inrush; mining under safe water pressure; and sealing off groundwater by grouting.  相似文献   

18.
Over the past 50 years, containerization has both enabled and reflected the articulation of increasingly concentrated and complex global trade flows. Once close infrastructural, economic and institutional ties between seaports and port cities have been loosened, since major ports now serve producers and consumers in widely dispersed hinterlands. This process has been especially intense in North America, where west coast ports serve markets across the continent. At the same time, many of the external costs of increased port activity are incurred in port cities. Hence, questions about the changing nature of employment in port and related goods-handling sectors have become increasingly important for understanding the share of economic benefits received by port cities. This paper focuses on the effects of containerization, and related changes in transportation regulation, on port-logistics worker earnings in major United States port cities since 1975. A difference-in-differences framework is used to examine the relative annual earnings of dock, trucking and warehouse workers in major container port cities. The analysis shows that, with notable exceptions, port-logistics worker earnings in major container ports are not necessarily higher than those of comparable workers. The findings provide further insights into the strained relationship between seaports and port cities in the era of containerization and economic globalization.
Peter V. HallEmail:
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19.
This paper reviews housing policy development in Lithuania in the light of previous literature which reinterprets Esping-Andersen’s work on welfare regimes and adopts it to study housing policy. It seeks to highlight the major features of the Lithuanian housing policy. The findings of this paper reveal that the Lithuanian housing regime exhibits many features which are common under the liberal one. Most significant of these are low de-commodification for those who have to buy or rent a home for the market price, increasing stratification based on income and the dominant position of the market in housing production, allocation and price determination. However, a detailed examination of the Lithuanian housing policy reveals that the housing policy system, despite having many features similar to the liberal one, has been operating in different social and economic settings as a result of unique historical experience of the communist housing policy (massive production of low quality apartment blocks during the communist era, which currently need substantial renovation) and consequently drastic changes in the housing field since 1990s (massive privatization of the housing stock and decentralization of the housing management system). The Lithuanian housing policy regime could be characterized as a regime with the higher owner-occupation compared to other welfare state regimes, but the lower economic power of the owners to take care of their property maintenance, repair and renovation.  相似文献   

20.
Nabil Kamel 《Geoforum》2012,43(3):453-463
This paper reveals the contingent aspect associated with the actualization of a neoliberal space. The paper examines the material, institutional, and economic conditions necessary for a neoliberal agenda to transform its urban policy objectives into a material reality. The study follows changes in housing conditions in Santa Monica, California from 1990 to 2008. During this period, the confluence of three sets of events led to the actualization of a neoliberal space. First, housing damage from the 1994 Northridge earthquake removed “dead capital” from the housing sector. Second, subsequent administrative actions at the local level and more importantly deregulation legislation at the state level eliminated rent control regulations and created market incentives that favored upscale development. Finally, the state’s economic recovery generated a substantial flow of private investments into the real estate market. These combined factors led not only to the dismantling of affordable housing in Santa Monica, but also to the erosion of residents’ and local authorities’ ability to manage housing choices and, consequently, to a historic restructuring of Santa Monica’s physical and social space. These changes had a disproportionately and negative effect on low-income and minority renters.  相似文献   

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