Mapping the hydraulic connection between a coalbed and adjacent aquifer: example of the coal-seam gas resource area,north Galilee Basin,Australia     

Zhenjiao Jiang  Gregoire Mariethoz  Christoph Schrank  Malcolm Cox  Wendy Timms 《Hydrogeology Journal》2016,24(8):2143-2155

Coal-seam gas production requires groundwater extraction from coal-bearing formations to reduce the hydraulic pressure and improve gas recovery. In layered sedimentary basins, the coalbeds are often separated from freshwater aquifers by low-permeability aquitards. However, hydraulic connection between the coalbed and aquifers is possible due to the heterogeneity in the aquitard such as the existence of conductive faults or sandy channel deposits. For coal-seam gas extraction operations, it is desirable to identify areas in a basin where the probability of hydraulic connection between the coalbed and aquifers is low in order to avoid unnecessary loss of groundwater from aquifers and gas production problems. A connection indicator, the groundwater age indictor (GAI), is proposed, to quantify the degree of hydraulic connection. The spatial distribution of GAI can indicate the optimum positions for gas/water extraction in the coalbed. Depressurizing the coalbed at locations with a low GAI would result in little or no interaction with the aquifer when compared to the other positions. The concept of GAI is validated on synthetic cases and is then applied to the north Galilee Basin, Australia, to assess the degree of hydraulic connection between the Aramac Coal Measure and the water-bearing formations in the Great Artesian Basin, which are separated by an aquitard, the Betts Creek Beds. It is found that the GAI is higher in the western part of the basin, indicating a higher risk to depressurization of the coalbed in this region due to the strong hydraulic connection between the coalbed and the overlying aquifer.  相似文献   

Thermal history of the giant Qulong Cu–Mo deposit,Gangdese metallogenic belt,Tibet: Constraints on magmatic–hydrothermal evolution and exhumation     

《Gondwana Research》2016

A complete thermal history for the Qulong porphyry Cu–Mo deposit, Tibet is presented. Zircon U–Pb geochronology indicates that the mineralization at Qulong resulted from brecciation-veining events associated with the emplacement of a series of intermediate-felsic intrusions. Combined with previously published ages, our results reveal a whole intrusive history of the Qulong composite pluton. Causative porphyries were emplaced at ~ 16.0 Ma as revealed by ⁴⁰Ar–³⁹Ar dating of hydrothermal biotite (15.7 ± 0.2 Ma) and sericite (15.7 ± 0.2 Ma). Zircon and apatite (U–Th)/He (ZHe and AHe) dating of Qulong revealed that both followed similar, monotonic thermal trajectories from 900 °C (U–Pb ages: 17.5–15.9 Ma) to 200 °C (ZHe: 15.7–14.0 Ma), and that the causative porphyries experienced faster cooling at a maximum rate of greater than 200 °C/myr. The Qulong deposit was exhumed between 13.6 Ma and 12.4 Ma (AHe) at an estimated rate of 0.16–0.24 mm/y, which is consistent with previous estimates for other Gangdese Miocene porphyry deposits. Our AHe thermochronology results suggest that neither the Gangdese thrust system, nor the Yadong–Gulu graben affected or accelerated exhumation at the Qulong deposit.  相似文献   

Influence of urban expansion on the urban heat island effect in Shanghai   总被引：1，自引：0，他引：1  

Meiyan Zhao  Hongyan Cai  Zhi Qiao 《International journal of geographical information science》2016,30(12):2421-2441

The urban heat island (UHI) effect resulting from rapid urbanization is attracting increasing attention among the global scientific community. This research analyzed the relationship between urban expansion and the UHI effect utilizing an integrated approach, including urban land interpretation and retrieving land surface temperature based on remote sensing, and spatial overlay analysis for revealing the relationship for different time periods between 1984 and 2014 in Shanghai, China. The results show that (1) the spatiotemporal changes in UHI are consistent with the expansion of urban land, and rapid urban expansion leads to an expansion of the UHI, in particular along roadways. (2) The mode of urban expansion is an important factor influencing the UHI effect. Urban sprawl (urban expansion in the edge-expansion way) is a form of typical expansion that leads to the rapid increase in the UHI. When the urban compactness ratio is less than 0.15, a compact design can effectively control the expansion rate of the UHI and mitigate its range of influence and intensity. However, when the urban compactness ratio is greater than 0.15, the urban design has a marked influence on the UHI ratio index: a more compact form produces a stronger UHI effect. So, finding an equilibrium between urban compactness ratio and urban expansion rate is good for effective urban management and planning.  相似文献   

Livelihood changes and evolution of upland ethnic communities driven by tourism: a case study in Guizhou Province,southwest China     

Ya-juan Li  Hu Yu  Tian Chen  Jing Hu  Hai-yang Cui 《山地科学学报》2016,13(7):1313-1332

As an effective livelihood approach to alleviate poverty without rural population migration, ethnic tourism has become the primary choice of economic development in ethnic areas worldwide in addition to traditional livelihood approaches. This article applies the theories of livelihood to study the community evolution driven by tourism livelihood and examine three mountainous tourism communities in different stages of tourist area life cycle. Drawing on the methods of GIS spatial analysis, semi-structured interviews and questionnaires, this article proposes a sustainable livelihood framework for ethnic tourism to explore the evolution of ethnic tourism communities by identifying changes in livelihood assets (natural, financial, social, cultural and human capitals) in the process of tourism development. The results show that the development of ethnic tourism has led to changes in the increase of building land, and the diversification of land use functions with a trend of shifting from meeting local villagers' living needs to satisfying tourists, income composition and uneven distribution of tourism income spatially. Ethnic tourism also led to the deterioration of traditional social management structure, collapse of neighboring relationship, the over- commercialization and staged authenticity of ethnic culture, as well as the gradual vanish of agricultural knowledge with a trend of increasing modern business knowledge and higher education. In addition, these changes, involving livelihood assets from natural, economic, human, social and cultural aspects are interrelated and interactive, which form new evolution characters of ethnic community. This study reveals the conflicts over livelihood approaches which have formed new vulnerabilities to impact on sustainable evolution of ethnic communities. This research provides implications for achieving the sustainable development of ethnic communities with the driving force of tourism livelihood.  相似文献   

Assessment on characteristics of LUCC process based on complex network in Modern Yellow River Delta,Shandong Province of China     

Baolei Zhang  Le Yin  Shumin Zhang  Chaoyang Feng 《Earth Science Informatics》2016,9(1):83-93

Research on land use cover change (LUCC) has reached a mature stage and has formed a relatively complete scientific system. However, most studies analyzed the LUCC process from the view of land use types ignoring the integrality and systematicness of the land use system, which brought certain constraints to understanding the complexity and systematicness of land use process scientifically. Using the Modern Yellow River Delta (MYRD) of China as the study area, this research introduced the complex network analysis method to the study of the LUCC process by using 9 periods of land use data between 1976 and 2014 to build 8 stages of complex networks. The values of node degree, betweenness, changing proportions, and average shortest path in the networks were calculated to identify the key land use types, changing models of land use types, and the stability of land use system. Additionally, main parts of complex networks of the period from 1976 to 1995 and the period from 1995 to 2014 were selected to evaluate the changing characteristics of the LUCC process. The results indicated the area and proportion of natural wetland kept reducing, but the area and proportion of artificial wetland or non-wetland continued rising. The bare land, reed, bush, and cultivated land were the key land use types of the LUCC process. In the past 38 years, beach, bare land, reed and bush had been the output types, and the building land and salt pan had been the input types. The LUCC process has been a transfer process of natural wetland to artificial wetland and non-wetland in the past 38 years, which could be divided into land accretion process (1976 to 1995) and construction process (1995 to 2014). The land ecosystem was unstable for the period from 1990 to 2006.  相似文献   

New Discovery of the 341 Ma Gabbro at Xiongcun District in the Southern Margin of Lhasa Terrane,Tibet     

LANG Xinghai  LIU Dong  DENG Yulin  TANG Juxing  XIE Fuwei  YANG Zongyao  CUI Zhiwei  WANG Xuhui  LI Zhijun  ZHANG Zhong  ZHANG Jinshu  HUANG Yong 《《地质学报》英文版》2018,92(1):420-421

正Objective Lhasa terrane has recorded the geologic history concerning the formation and evolution of Paleo-Tethys and the intra-continental convergence in Qinghai–Tibet Plateau(Yin and Harrison,2000).Previous investigations have focused on the initial timing of the India-Asia collision and the Cretaceous–Cenozoic magmatism and sedimentation(Wang Tianyang et al.,2017),however,  相似文献   

阿尔金山东段阿克塞蛇绿岩地质地球化学特征及形成时代     

王军  李小强  梁明宏  王玉玺  张兵兵  潘保田 《地质通报》2018,37(4):559-569

北阿尔金蛇绿岩带是分布在阿尔金山北缘的一条蛇绿混杂岩带,超基性蛇纹岩岩块、基性岩墙、辉长岩块及基性熔岩组合是该带东段阿克塞蛇绿岩的典型组合形式。地球化学研究结果显示,阿克塞蛇绿岩超基性蛇纹岩以富MgO、贫Al_2O_3、P_2O_5、CaO和K_2O为特征,球粒陨石标准化稀土元素配分曲线表现较平缓,比值接近于1;基性熔岩类中TiO_2为0.86%～1.80%,Al_2O_3为12.00%～14.85%,CaO介于4.89%～19.23%之间,球粒陨石标准化稀土元素配分型式表现为右倾;基性岩墙中TiO_2介于1.08%～2.44%之间,Al_2O_3含量为11.07%～13.26%,Na_2O(1.20%～2.28%)K_2O(0.80%～1.38%),稀土元素总量介于48.65×10~(-6)～124.04×10~(-6)之间,平均92.95×10~(-6);轻、重稀土元素比值介于2.22～4.45之间,总体表现为大洋中脊环境,LA-ICP-MS锆石U-Pb年龄显示,阿克塞蛇绿岩形成于514.6±8.8Ma,为寒武纪,表明在早古生代北阿尔金洋已完全打开,并连通了红柳沟—阿克塞。  相似文献   

Heavy metals status,transport mechanisms,sources, and factors affecting their mobility in Chinese agricultural soils   总被引：3，自引：0，他引：3  

Feng Jing  Xiaomin Chen  Zhijiang Yang  Bilin Guo 《Environmental Earth Sciences》2018,77(3):104

Heavy metals are the focus of much interest because of their environmental persistence, toxicity, and mobility in soils. Some of the Chinese soils have been contaminated with heavy metals due to expansion of mining industries, pesticides usage, and other anthropological activities, which made the agro-ecosystem to become contaminated. The objective of this review is to illuminate the current pollution status, sources of heavy metals, transport mechanisms, and the factors affecting their mobility in Chinese soils. The additional studies in the future will present on source identification and the heavy metal transport characteristics in soil.  相似文献   

Statistical and geochemical assessment of groundwater quality in Teboursouk area (Northwestern Tunisian Atlas)     

Yosra Ayadi  Naziha Mokadem  Houda Besser  Belgacem Redhaounia  Faten Khelifi  Samia Harabi  Talel Nasri  Younes Hamed 《Environmental Earth Sciences》2018,77(9):349

Teboursouk region, Northwestern Tunisia, is characterized by the diversity of its natural resources (petroleum, groundwater and minerals). It constitutes a particular site widely studied, especially from a tectonic stand point as it exhibits a complex architecture dominated by multi-scale synclinals and Triassic extrusions. It has typical karst landform that constitutes important water resources devoted for human consumption and agriculture activities, besides to the exploitation of the Mio-Plio-Quaternary aquifer (MPQ). Thus, hydrogeological investigations play a significant role in the assessment of groundwater mineralization and the evaluation of the used water quality for different purposes. Hence, the current study based on a combined geochemical–statistical investigation of 50 groundwater samples from the multilayered aquifer system in the study area give crucial information about the principal factors and processes influencing groundwater chemistry. The chemical analysis of the water samples showed that Teboursouk groundwater is dominantly of Ca–Mg–Cl–SO₄ water type with little contribution of Ca–Mg–HCO₃, Na–K–Cl–SO₄ and Na–K–HCO₃. The total dissolved solids (TDS) values range from 0.37 to 3.58 g/l. The highest values are located near the Triassic outcrops. Furthermore, the hydrogeochemistry of the studied system was linked with various processes such as carbonates weathering, evaporites dissolution of Triassic outcrops and anthropogenic activities (nitrate contamination). Additionally, the main processes controlling Teboursouk water system were examined by means of multivariate statistical analysis (PCA and HCA) applied in this study based on 10 physicochemical parameters (TDS, pH, SO₄, HCO₃, pCO₂, Ca, Mg, Na, K, Cl and NO₃). Two principal components were extracted from PCA accounting 61% of total variance and revealing that the chemical characteristics of groundwater in the region were acquired through carbonates and evaporite dissolution besides to nitrate contamination. Similarly, according to Cluster analysis using Ward’s method and squared Euclidean distance, groundwater from the studied basin belongs to five different groups suggesting that the geochemical evolution of Teboursouk groundwater is controlled by dissolution of carbonates minerals, chemical weathering of Triassic evaporite outcrops, cation exchange and anthropogenic activities (nitrate contamination).  相似文献   

New polymorphic psyllipsocids from Burmese amber (Psocodea: Psyllipsocidae)     

《Cretaceous Research》2018

Annulipsyllipsocus andreneli gen. et sp. nov. and A. inexspectatus gen. et sp. nov., the first records of the Psyllipsocidae from the Cretaceous amber of Myanmar are described, illustrated and their taxonomic position discussed. The new genus is characterized by antennae with 16 segments; flagellomeres with secondary annulations; radial cell closed, five-angled, bulged on its R1 border; triangular pterostigma. Species belonging to Annulipsyllipsocus gen. nov. are polymorphic. The described taxa represent the earliest evidence for polymorphism in Psocodea. A checklist of all known species of Psyllipsocidae is given.  相似文献