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1.
The soft uppermost sediments in lakes and wetlands contain important records of past environmental change. Although the technology
for coring these sediments is relatively well established, there has been a continuing effort to improve the design of equipment
that can provide the precise volumetric samples required for high-resolution dating and elemental analysis. Soft-sediment
cores are usually sectioned near a coring site under a wide range of field conditions creating a challenge for both field
crews and equipment. A new field extruder was therefore designed to simplify the process of fine-sectioning these cores in
the field while improving volumetric-sampling accuracy. The new extruder is relatively light, stable, and easy to use, but
sufficiently strong to extrude long continuous cores of stiff sediment if required. The key features of this extruder minimize
sampling errors by enabling an operator to automate the measurement and extrusion of a pre-determined volume of sediment.
The extruder was successfully field tested on a variety of sediment types in a large wetland from southern Florida, USA and
proved easy to master by even inexperienced field crews. 相似文献
2.
Kurt A. Haberyan 《Journal of Paleolimnology》2001,26(2):219-223
Materials for constructing a simple piston corer are available at most well-stocked hardware stores, primarily using galvanized fence post for the barrel, and pipe for the drive rod and head. These are assembled with a modicum of machinist skills. In the field, this VolksCorer operates like similar corers; it is limited to relatively shallow water (about 10–15 m) and is poorly suited for down-the-hole coring, but it requires few specialized tools. Likewise, materials to construct the VolksExtruder are widely available; this extruder, although simple, allows very precise extrusion control. The very low cost of the corer and extruder (less than US$50 each) make them suitable for investigators operating with low budgets without sacrificing sample quality. 相似文献
3.
Gravity corers have been in use for a long time and in many different configurations. There are, however, reasons for improvements
since new manufacturing materials have become available, and demands for accurate coring and sub-sampling in both research
and environmental monitoring have increased. The HTH-coring equipment, which has been tested for >10 years by several users,
is a further development of the Kajak-corer concept and has some unique features which are described here. To avoid contamination
in pollution studies, the equipment is made of stainless steel and plastic (polyoxymethylene and polyethylene), and the use
of these materials also makes the equipment more durable. The extruding device is the main improvement over previous versions.
It consists of a piston that seals perfectly to the core tube wall, a threaded rod that can be mounted on a foot plate, and
an extruder head with a stationary upper-half and a rotatable lower-half that is screwed along the rod. One 360°-turn gives
a 5-mm thick sediment increment that is scraped off using the sectioning tray. Sub-sampling is quick and accurate and can
be performed by one person. The equipment is constructed to allow coring and sub-sampling both in summer and winter. 相似文献
4.
以地域经济系统理论为指导,以福建省300强企业为研究样本,以县级行政区为基本的地域单元,以根据区域所有制数量的动态变化所划分的4种区域所有制结构类型为研究的结构框架,以300强企业的所有制及企业主要产品的行业属性为研究起点,分析了区域所有制结构的空间变化特征,并探究了区域所有制结构与区域产业结构之间的关系,揭示了区域所有制结构与区域经济发展水平的关系。研究的结果显示：4种所有制结构类型的区域工业经济发展梯度已经形成,其中,始终多于3种所有制的区域所有制结构和区域产业结构最复杂,工业经济发展水平最高。 相似文献
5.
小城镇土地集约利用水平综合评价探讨——以重庆市北碚区为例 总被引：37，自引：2，他引：37
小城镇土地集约利用水平综合评价直接反映小城镇土地利用的集约程度，文章对小城镇土地集约利用水平综合评价的方法有益的探索，构建了一套小城镇土地集约利用水平综合评价的指标体系，采用多因素综合评价的方法，得到集约利用综合指数F，并通过比较分析探讨小城镇土地集约利用的空间分异特征及成因，从而达到定量衡量小城镇土地集约利用水平的目的。以重庆市北碚区为例的研究表明，小城镇土地集约利用水平综合评价采用多因素综合评价法是比较适宜的。 相似文献
6.
O. M. Khlystov E. E. Kononov H. Minami A. V. Kazakov A. V. Khabuev N. A. Gubin A. G. Chenskii 《Geography and Natural Resources》2018,39(1):33-38
A high-resolution bathymetric survey of the entire underwater slope in South Baikal was carried out for the first time by means of the multibeam echosounder. New elements were revealed in the underwater relief of the southern slope of the basin from the Kultuchnaya river to the Mysovka river, and a relevant regionalization was carried out into three areas according to the presence of ancient landforms and the intensity of the processes of their reworking, with the boundaries along the delta-front and the river fan of the Utulik and Pereemnaya. We reconstructed the formation process of the modern relief of this area of the underwater slope and determined a dominant role of the underwater-erosion processes in the formation of the modern relief, with the tectonic movements served as the “trigger” for them. The study revealed a direct correlation between the reworking of the ancient geomorphological surfaces and the occurrence of separate large underwater elevations or group ridges (remnants), canyons and linear depressions. It is determined that the pivotal role in the appearance of the modern relief of the underwater slope in the second area of extensive plano-convex (in section) and fan-shaped (in plan) delta-fronts of large rivers and debris fans enveloping the remnants. The existence of a steep underwater slope from the mouth of the Pereemnaya to the mouth of the Bol’shaya Tel’naya and of two large benches, and also the proximity of the maximum depths of the southern basin at the foot of this slope are explained by a more intense step-like lowering of this part of the lake when compared with the western part of the basin. This also accounts for the absence of large remnants in this part of the slope. The area of occurrence of lacustrine-fluvial and lacustrine-delta deposits of the Tankhoi paleobasin within the southern basin of Baikal is reconstructed. Four new hydrate-bearing structures associated with these deposits and morphologically pronounced in the vertex parts of the remnants were discovered. The morphological exploration indicators of the presence of new accumulations of gas hydrates on the underwater slopes of Baikal have been expanded. 相似文献
7.
旅游与文化生态保护研究进展 总被引：1，自引：0，他引：1
郑玉玉 《云南地理环境研究》2012,24(1):105-110
旅游可持续发展与文化生态保护的良性互动机制成为学界的研究热点。运用文献分析法分析了旅游与文化生态保护研究进展,按研究内容将已有研究主要归纳为文化生态理念在旅游开发规划中的应用、旅游对文化生态保护的效应及文化生态保护模式3个方面,研究方法以结合具体案例的定性研究为主。在此基础上,提出未来旅游与文化生态保护的研究趋势：加强旅游与文化生态保护作用机制、旅游开发共性与文化生态保护个性模式、旅游与文化生态保护测评、旅游利益相关者与文化生态保护主体等方面的研究。 相似文献
8.
荒漠河岸植被的受损过程与受损机理分析 总被引：9，自引：0，他引：9
以塔里木河多年平均地下水位数据为依据,将地下水位划分为6个环境梯度,各梯度上6次重复采集植被样地数据。从物种多样性、植被盖度与群落类型等几方面分析了植被的受损过程,以及导致此过程的受损机理。结果表明：(1) 草本植物丰富度受损发生在地下水埋深大于4 m,而木本植物丰富度受损发生在地下水埋深大于8 m。(2) 植被盖度减少始于草本植物盖度受损,与群落多样性受损的临界地下水位相同,发生在地下水埋深大于4 m;在地下水埋深大于6 m之后,植被盖度不断减少则是由木本植物盖度的减少所引起。(3) 群落类型受损体现在芦苇群落和胡杨林群落的结构与类型变化上,芦苇群落的衰退演变出现了优势种的更替,而胡杨林群落中优势种的优势地位没有变化。(4) 此受损过程是由荒漠河岸生态系统脆弱的生态基质和外界干扰共同作用的结果,起因于人口的增加、需求的增长。植被退化是人类干扰作用于植被赖以生存的环境主导因子所致。在生态受损过程中,植物功能型差异与所承受的干扰强度差异对植被退化的程度有一定影响。 相似文献
9.
论山地旅游资源分区与开发布局原则：—以湖南省为例 总被引：3，自引：0，他引：3
本文以湖南省山地旅游资源为例，论述了山地旅游资源的六个分区原则和四个开发布局原则。依据这些原则，编制了湖南省山地旅游的资源分区图和开发布局图。 相似文献
10.
城乡一体化发展的动力机制研究——以成都市为例 总被引：3，自引：0，他引：3
城乡一体化是当前研究的热点问题之一。成都市从2003年开始，在全市范围内开展城乡一体化试点。正确认识城乡一体化的基本内涵、准确把握城乡一体化发展的动力机制是深化理论研究、加快城乡一体化发展的前提和基础。以成都市作为城乡一体化研究的实证对象，采用因子分析法和灰色关联度法，对成都市城乡一体化的动力机制进行了初步探讨。研究结果表明：经济发展水平、工业化水平、社会人口动力因素是其主要驱动力。并对各影响因素进行了深入分析。 相似文献
11.
新疆经济区划与天山南北坡经济带的形成 总被引：3，自引：0，他引：3
天山北坡经济带是新疆维吾尔自治区的中心区域，天山南坡经济带则是新疆经济发展中仅次于天山北坡经济带的一个具有发展优势和潜力的经济区域。1955年新疆维吾尔自治区成立以来其经济区划的演变和区域经济发展重心的转移是两大经济带形成的主要因素；20世纪末至21世纪初新疆区域经济发展战略、经济区与行政区界限关系的协调、经济中心的有效辐射距离、支柱产业的聚集优势、城市辐射效应，以及两地带水同源的生态依据等是天山南北坡经济带区域范围形成的主要依据。 相似文献
12.
关于沙漠化地图编制的原则与方法 总被引：13，自引：3，他引：10
沙漠化是当前一个世界性的重要环境问题,其结果造成生物生产量的下降,土地生产潜力的衰退和可利用土地资源的丧失。它影响到全球陆地面积的1/3和占世界14%的人口,而且每年还以5-7万平方公里面积的速度在蔓延,因此沙漠化的防治便成为全球所关心的一个生态问题和环境保护问题。 相似文献
13.
杭州市人口密度空间分布及其演化的模型研究 总被引：56，自引：8，他引：56
基于四次人口普查数据 ,本文探讨了杭州城市人口密度的空间分布及其演化规律。首先提取了不同年份城市人口密度的空间分布数据 ;然后根据人口分布的曲线特征对各种可能出现的数学模型进行拟合、比较 ,发现杭州市的人口分布服从Clark模型的修正形式———加幂指数模型 ;借助模型参数进行城市增长及其空间动力学分析 ,发现反映信息熵的约束参数波动升高、渐次逼近于 1,从而揭示 :改革开放以来 ,随着城市演化过程中自组织能力的加强以及郊区化的发展 ,城市空间复杂性程度增高 ,城市内各功能单元的效用增强 ,城市的空间结构进一步趋向新的有序状态。本文借助前沿科学思想及郊区化理论 ,尝试提出一个分析城市人口时空变化规律的完整范例 ,对城市规划和管理工作也具借鉴意义 相似文献
14.
青藏高原生态环境问题研究 总被引：55，自引：5，他引：50
论述青藏高原生态环境现状和面临的严重问题,从人口、资源和环境角度阐述造成高原严重生态环境问题的自然和社会根源。分析解决高原生态环境问题所面临的巨大的自然和社会经济障碍,给出重新认识和评价高原资源优势的新视点,并提出适合于高原自然和社会经济环境的优先产业。 相似文献
15.
Main directions of development of the Baku urban agglomeration 总被引：1，自引：0，他引：1
E. S. Badalov 《Geography and Natural Resources》2016,37(2):174-180
An analysis is made of the historical development and formation of the major Baku urban agglomeration. The theoretical and methodological foundations of population distributions are considered, and an analysis is made of the influence of the natural, historical and economic factors on the formation of this region. The historical development of the major urban agglomeration and productive forces is investigated, which involves a high level of concentration of production and mining industries as well as with infrastructural development. A study is made of the dynamics of demographic processes, the characteristics of natural and migration movement of the population, and of the age/gender and marriage/family population composition which form the social-demographic structure of population and have an important practical significance in the determination of long-term development of the Baku agglomeration. The structural and dynamical formations of new settlements of Baku depended on their functional characteristics as well as on the distance from the center. An analysis is made of the Soviet and post-Soviet periods of population growth in the agglomeration. The dynamics of the demographic processes of the population in the agglomeration shows that the growth rates of the settlements in the outer zone are substantially higher than in Baku itself; therefore, pendulum migration is taking shape between the city and the suburb, which creates serious problems. Urbanization and its influence on the settlement process, and the problems of development of urban settlements are investigated. The ways of long-term socioeconomic development, and the transformation of the territorial organization of the Baku agglomeration are outlined. Also, an analysis is made of the population dynamics and formation of labor resources, and the problems of using and employing them in the region are considered. Based on the research done, recommendations are made for the regulation of demographic processes across the territory under investigation. 相似文献
16.
文章强调我国解决"三农"问题的焦点是粮食生产流通体制的改革。在我国当前存在的多个严峻条件的刚性约束之下,粮食的生产流通改革必须按市场经济规律进行。以对粮食生产流通所需要素的科学评估为依据,以粮食流通体制的改革为核心,以按市场化机制运行的各类企业为市场主体,以政府的引导和扶持政策为基本保障,形成良性运行模式,以尽快解决对粮食主产区农民的组织问题,达到粮食生产及流通直接与市场对接的目的。 相似文献
17.
18.
黄海北部长山群岛海洋农牧化分区探讨 总被引：7，自引：0，他引：7
本文采用主成分-聚类分析等定量方法,并通过对长山群岛海域的资源、环境、生产条件等的相似性和差异性分析,将其划分为三个海洋农牧化区域,为海水养殖业的合理布局提供科学依据。 相似文献
19.
I.S. Vasiliev 《Geography and Natural Resources》2009,30(1):92-95
An analysis is made of the spectrum of altitudinal zonality of mountain permafrost landscapes of Yakutia. The intervals of the values of characteristics of particular landscape altitudinal zones are provided, namely, the marks of their boundaries in accordance with a change in the latitude of the locality, the indices of freezing and thawing, mean yearly air temperatures, the pattern of occurrence, the thickness and temperature of permafrost, the thickness of the active layer as well as the accompanying permafrost-geological processes and phenomena. 相似文献
20.
高速城镇化背景下山地城镇空间拓展问题的分析——以云南临沧为例 总被引：1，自引：0，他引：1
在高速城镇化背景下,临沧市的山地城镇在空间扩展中遇到了诸如城镇周边耕地被大量侵蚀、新城空置、城镇地质灾害隐患加大、城镇外围生态景观破坏,城镇地域特色丧失等一系列问题。这些问题主要是由于以下几个方面的原因造成的：（1）城镇建设中总是优先选择建设成本低廉的农田导致对耕地的侵蚀;（2）落后的工业化进程制约城镇化的持续发展导致新城空置、经济活力不足;（3）城镇空间采用蔓延式的拓展模式导致城镇地质灾害隐患加大和城镇外围生态景观破坏;（4）缺乏对城市特色的提炼导致山地城镇地域特色丧失。 相似文献