环渤海地区城市规模扩张与质量增长的时空演变及耦合特征   总被引：1，自引：0，他引：1  

曲衍波  王霞  王世磊  朱伟亚  平宗莉  王森 《地理研究》2021,40(3):762-778

城市规模扩张与质量增长是当前中国城镇化发展所面临的重要矛盾,如何推动两者的协同演进成为区域城市系统可持续发展的重要命题。本文以中国经济第三个增长极——环渤海地区为研究区,在城市系统理论认识的基础上,构建多维度融合的城市规模与质量测度体系,利用泰尔指数和脱钩模型对城市规模扩张与质量增长的时空演变过程及其耦合关系进行深入分析,并从系统内部性和外部性角度探讨了城市系统高质量运行的影响机制。研究表明：①2000—2019年环渤海地区城市规模扩张与城市质量增长均持续攀升,并呈现出一定的空间格局特征,其中京津冀呈“同心圆”的高-中值分异格局,山东半岛呈“中轴-两翼”的中-高值集聚格局,辽东半岛呈“突变式”的低-中-高三区共存格局。②环渤海地区城市规模扩张与质量增长的区域差异性总体降低,并以区域内差异占据主导,城市规模扩张的差异性降幅为山东半岛>京津冀>辽东半岛,城市质量增长的差异性降幅为京津冀>辽东半岛>山东半岛,不同区域内城市系统演化趋势复杂多样。③环渤海地区城市规模扩张与质量增长的脱钩类型经历了“SND-WD”为主向“WD-SD”为主的变化过程,脱钩状态整体趋于耦合的良性发展,脱钩程度表现为京津冀>山东半岛>辽东半岛。④环渤海地区城市规模扩张与质量增长及其耦合趋优是城市系统内部性和外部性要素综合作用的表现,不同要素通过长效调控、有条件作用和缓慢调节等过程性影响和有效性干预的方式,驱动不同城市系统由规模扩张转向质量增长。  相似文献   

Distinct export dynamics for dissolved and particulate phosphorus reveal independent transport mechanisms in an arable headwater catchment          下载免费PDF全文

Rémi Dupas  Chantal Gascuel‐Odoux  Nicolas Gilliet  Catherine Grimaldi  Gérard Gruau 《水文研究》2015,29(14):3162-3178

This paper investigates particulate phosphorus (PP) and soluble reactive phosphorus (SRP) concentrations at the outlet of a small (5 km²) intensively farmed catchment to identify seasonal variability of sources and transport pathways for these two phosphorus forms. The shape and direction of discharge‐concentration hystereses during floods were related to the hydrological conditions in the catchment during four hydrological periods. Both during flood events and on an annual basis, contrasting export dynamics highlighted a strong decoupling between SRP and PP export. During most flood events, discharge‐concentration hystereses for PP were clockwise, indicating mobilization of a source located within or near the stream channel. Seasonal variability of PP export was linked to the availability of stream sediments and the export capacity of the stream. In contrast, hysteresis shapes for SRP were anticlockwise, which suggests that SRP was transferred to the stream via subsurface flow. Groundwater rise in wetland soils was likely the cause of this transfer, through the hydrological connectivity it created between the stream and P‐rich soil horizons. SRP concentrations were the highest when the relative contribution of deep groundwater from the upland domain was low compared with wetland groundwater. Hence, soils from non‐fertilized riparian wetlands seemed to be the main source of SRP in the catchment. This conceptual model of P transfer with distinct hydrological controls for PP and SRP was valid throughout the year, except during spring storm events, during which PP and SRP exports were synchronized as a consequence of overland flow and erosion on hillslopes. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

闽西南地区印支期隆起-伸展构造的厘定及其控矿作用     

聂童春 《福建地质》2010,29(4):315-322

在闽西南地区隆起-伸展构造主要活动于印支期,经历了挤压隆起和伸展拆离过程,以拆离体系极为发育为特征,形成的构造形式较为多样,对该区域的矿产分布具有明显的控制作用。  相似文献   

U–Th–Pb–REE systematics of organic-rich shales from the ca. 2.15 Ga Sengoma Argillite Formation, Botswana: Evidence for oxidative continental weathering during the Great Oxidation Event     

Gerald D. Pollack  Eirik J. Krogstad  Andrey Bekker   《Chemical Geology》2009,260(3-4):172-185

The redox-sensitive geochemical behavior of uranium permits the use of Th/U ratios as a geochemical proxy for the oxidation state of the atmosphere during deposition. Due to the effects of post-depositional uranium mobility on Th/U ratios during events involving oxygenated fluids, direct measurements of Th/U ratios are often misleading even for drill core samples. Because both of these elements radioactively decay and produce lead isotopes, the Pb isotope composition may reflect the depositional Th/U ratio, although the Th/U ratios induced by changes shortly after deposition may not be distinguished from the true depositional Th/U ratios. In order to effectively evaluate the time-integrated Th/U ratio (κ_a), values for the initial depositional Pb isotope composition must be determined or accepted from the models for the whole Earth.While the timing for the rise of atmospheric oxygen is reasonably well constrained now, its effect on continental weathering and ocean redox state remains poorly constrained and debated. The ca. 2.15 Ga Sengoma Argillite Formation of Botswana contains organic-rich shales deposited during the Great Oxidation Event. The slope of the ²⁰⁷Pb/²⁰⁴Pb–²⁰⁶Pb/²⁰⁴Pb array of shales from the Sengoma Argillite Formation corresponds to a Pb–Pb age that is within analytical error of the depositional age and is, therefore, inferred to be the time by which the time-integrated thorogenic and uranogenic lead growth started. The time-integrated lead growth corresponds to an average κ_a of 2.63 (± 0.62, 1σ) for the organic-rich shales of the Sengoma Argillite Formation. This is lower than Th/U ratios measured in Archean shale suites or estimated for the Archean–Proterozoic average upper continental crust [Taylor, S.R. and McLennan, S.M., 1985. The Continental Crust: Its Composition and Evolution. Blackwell, Oxford, 312 pp.], which indicates that these samples were enriched in uranium with respect to thorium (and perhaps lead) at the time of deposition. In the modern ocean, sediments are enriched in uranium under reducing conditions by reduction of the water-soluble uranyl ion, which is delivered to the ocean by oxidative weathering of continental crust. To evaluate the potential mobility of Th, U, and Pb during post-depositional processes, the concentrations of the rare earth elements (REE) were also determined. Interelement ratios of the largely immobile REE (in this study, La/Nd and Gd/Er) can be used as a proxy for the Th/U ratio, as the geochemical behavior of the lanthanide and actinide elements is similar under a variety of conditions. Furthermore, close similarity in the chondrite-normalized REE patterns and small range in La/Nd and Gd/Er ratios in studied samples indicate that variations in κ_a values are not likely to have been controlled by mixing of one or more REE-, Th-, and U-rich heavy minerals from the multiple detrital sources. Our study of shales from the ca. 2.15 Ga Sengoma Argillite Formation indicates that decoupling of U from Th, most likely related to the oxidative continental weathering, began by 2.15 Ga, at the latest.  相似文献   

Geomorphic coupling between hillslopes and channels in the Swiss Alps     

Sara Savi  Michelle Schneuwly‐Bollschweiler  Bastian Bommer‐Denns  Markus Stoffel  Fritz Schlunegger 《地球表面变化过程与地形》2013,38(9):959-969

The coupling relationships between hillslope and channel network are fundamental for the understanding of mountainous landscapes' evolution. Here, we applied dendrogeomorphic methods to identify the hillslope–channel relationship and the sediment transfer dynamics within an alpine catchment, at the highest possible resolution. The Schimbrig catchment is located in the central Swiss Alps and can be divided into two distinct geomorphic sectors. To the east, the Schimbrig earth flow is the largest sediment source of the basin, while to the west, the Rossloch channel network is affected by numerous shallow landslides responsible for the supply of sediment from hillslopes to channels. To understand the connectivity between hillslopes and channels and between sources and sink, trees were sampled along the main Rossloch stream, on the Schimbrig earth flow and on the Rossloch depositional area. Geomorphic observations and dendrogeomophic results indicate different mechanisms of sediment production, transfer and deposition between upper and lower segments of the channel network. In the source areas (upper part of the Rossloch channel system), sediment is delivered to the channel network through slow movements of the ground, typical of earth flow, shallow landslides and soil creep. Contrariwise, in the depositional area (lower part of the channel network), the mechanisms of sediment transfer are mainly due to torrential activity, floods and debris flows. Tree analysis allowed the reconstruction of periods of high activity during the last century for the entire catchment. The collected dataset presents a very high temporal resolution but we encountered some limitations in establishing the source‐to‐sink connectivity at the catchment‐wide scale. Despite these uncertainties, for decennial timescales the results suggest a direct coupling between hillslopes and neighbouring channels in the Rossloch channel network, and a de‐coupling between sediment sources and sink farther downstream, with connections possible only during extraordinary events. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Decoupling of cobalt and nickel in high-temperature magmatic processes and its metallogenic indicationSCIEI北大核心CSCD     

Su BenXun  Cui MengMeng  Yuan QingHan  Wang Jing  Bai Yang 《岩石学报》2023,(10):2867-2878

Cobalt ( Co) and nickel (Ni) have similar geochemical behaviors and commonly co -vary in nature, but they may undergo decoupling in certain geological processes, especially in ore -forming processes, and the decoupling mechanism is not yet clear. This paper analyzes the distribution characteristics and migration behaviors of Co and Ni in major rock -forming minerals in different types of mafic-ultramafic rocks. The Ni (2500 x 10(-6) 3400 x 10(-6)) and Co (110 x 10(-6) 160 x 10(-6)) contents of mantle olivine are both higher than those of the primitive mantle. The Ni content shows no obvious correlation with the Fo value, while the Co content has a strong negative correlation with both the Fo value and the Ni/Co ratio. This indicates that partial melting does not cause significant changes in Ni content of olivine, but can control the Co content and the Ni/Co ratio, mainly due to the differences in compatibility between the two elements in olivine. Melt-rock reactions can cause significant Co-Ni decoupling between minerals and within minerals, but the mechanisms differ. In the process of reacting with basaltic magma, olivine mainly absorbs Co and loses Ni, while being affected by coexisting spinet minerals. When reacting with carbonatite melt, olivine loses Co, but Ni remains almost unchanged. As mantle derived basaltic magma intrudes into the lower crust, the migration of Co and Ni in pyroxenes is controlled by concentration gradients and sulfide crystallization. The local enrichment of Co provides an important material basis for the formation of Co -rich melts in deep crustal melting. During the differentiation and evolution of mafic-ultramafic magma, the chromite fractional crystallization and sulfide segregation can cause Co-Ni decoupling at both rock and/or mineral scales. Meanwhile, the enriched hydrous fluids released during chromite aggregation and sulfide melt solidification can significantly promote the efficiency of element exchange in sub-solidus state, especially strengthening the activity of Co, thus causing negative correlations between Co and Ni in olivine and even in chromite. Comparative studies show that the trends of Co and Ni content changes in mineral assemblages are evidently different, or even opposite, between mineralized and barren bodies and between ore -bearing and ore -free rocks, which provides a basis for identifying mineralization in rock bodies and guiding prospecting.  相似文献   

城镇化与资源环境的耦合过程与解耦分析——以北京为例   总被引：2，自引：0，他引：2  

郭莎莎  陈明星  刘慧 《地理研究》2018,37(8):1599-1608

探索城镇化与资源环境之间的相互作用与复杂关系具有重要意义。从可持续城镇化视角,构建城镇化发展指数和资源环境压力指数,分析评估了2003-2015年北京市城镇化发展对资源环境压力的影响,借鉴解耦模型进一步研究了北京市城镇化与资源环境压力的耦合关系。结果表明：① 北京城镇化进入了后期成熟阶段,人口、经济和社会城镇化均呈现出较高水平且增速放缓的特征,人口城镇化率从79.05%上升到86.51%。② 资源消耗总量仍在不断增加,而环境污染的治理效果相对较为明显,工业废水、工业固体废物等污染物排放量趋于降低,城镇化发展的资源环境压力总体处于中等水平且呈波动性逐步上升趋势。③ 12年间,北京市城镇化发展与资源环境压力呈现由弱解耦—强解耦—弱解耦—扩张性耦合—扩张性负解耦—强解耦—弱解耦—强解耦的演变轨迹,耦合与解耦关系反复,这种反复体现了城镇化发展与资源环境之间复杂关系及其动态演化特征。资源环境可持续性将是北京建设国际一流的和谐宜居之都的关键瓶颈因素之一。  相似文献   

Green growth and climate change: conceptual and empirical considerations     

Miklós Antal  Jeroen C.J.M. Van Den Bergh 《Climate Policy》2016,16(2):165-177

The feasibility of green growth is studied in the context of climate change. As carbon emissions are easier to quantify than many other types of environmental pressure, it will be possible to reach a more definite conclusion about the likelihood of green growth than has been possible in the long-standing historical debate on growth versus the environment. We calculate the rate of decoupling between gross domestic product (GDP) and GHG emissions needed to achieve internationally agreed climate targets. Next, eight arguments are considered that together suggest that fast decoupling will be very difficult. Subsequently, we examine the main lines of research used by proponents of green growth to support their viewpoint, including theoretical arguments, exercises with integrated assessment models, and studies of the environmental Kuznets curve hypothesis. It will be concluded that decoupling as a main or single strategy to combine economic and environmental aims should be judged as taking a very large risk with our common future. To minimize this risk we need to seriously consider reducing our dependence on growth. This requires a fundamental change of focus in both economic research and policy.

Policy relevance

Currently, green growth is the only strategy of mainstream economists and policy makers to address climate change. This article demonstrates that such an exclusive focus is very risky due to the scale of the challenge and the existence of various barriers to the fast decoupling of GHG emissions from economic output. It seems that the only option to combine environmental and economic objectives is reducing the dependence of our economies on growth. Finding strategies in line with this requires a fundamental change of focus in both economic research and policy.  相似文献   

中国旅游业碳排放脱钩效应及影响因素研究     

翁钢民  李聪慧  潘越  李建璞 《地理与地理信息科学》2021,37(2):114-120

以中国30个省域为研究对象,采用Tapio脱钩模型测算2008-2017年旅游业碳排放脱钩指数,结合ESDA和LMDI方法,对旅游业碳排放脱钩的时空格局演变及影响因素进行研究。结果表明:中国旅游业碳排放脱钩指数整体处于弱脱钩状态,在0.4380~0.8758之间波动,碳排放脱钩指数分布不均衡,脱钩水平表现出“东高西低”的空间分布格局;旅游业碳排放脱钩指数呈显著负相关,但空间分布的集聚程度较低;随着时间推移,空间集聚程度有所提高,其中,H-H类型的省域集中分布在中部地区,L-L类型省域数量较少,呈零星分布;技术效应、游客规模效应分别是促进和抑制旅游业碳排放脱钩的主导因素,能源结构效应表现为先抑制后促进的作用,经济效应的影响较小。最后针对中国旅游业碳排放脱钩现状提出相关应对措施,以期为制定科学的减排政策提供决策依据。  相似文献   

Lithospheric composition and structure beneath the northern margin of the Qinling orogenic belt   总被引：1，自引：0，他引：1  

Lu?FengxiangEmail author  Wang?Chunyang  Zheng?Jianping 《中国科学D辑(英文版)》2004,47(1):13-22

Swarms of mafic-intermediate volcaniclastic bodies occur in the Minggang region of Henan Province, a tectonic boundary between the North Qinling and the North China Block, and emplaced at (178.31±3.77) Ma. These volcanic rocks are subalkaline basaltic andesites and contain abundance of lower crust and mantle xenoliths. Thus this area is an ideal place to reveal the lithospheric composition and structure beneath the northern margin of the Qinling orogenic belt. Geochemical data indicate that these mafic granulites, eclogites and metagabbros have trace elemental and Pb isotopic characteristics very similar to those rocks from the South Qinling Block, representing the lower part of lower crust of the South Qinling which subducted beneath the North China Block. Talcic peridotites represent the overlying mantle wedge materials of the North China Block, which underwent the metasomatism of the acidic melt/fluid released from the underlying lower crust of the South Qinling Block. Deep tectonic model proposed in this paper is that after the Late Paleozoic South Qinling lithosphere subducted northward and decoupled, the upper part of the lithosphere emplaced under the North Qinling and the lower part continuously subducted northward under the North China Block. In Early Mesozoic, the North Qinling Block obducted northward and the North China Block inserted into the Qinling orogenic belt in a crocodile-mouth shape.  相似文献