首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 0 毫秒
1.
The Tarim River is the longest continental river in China. During the past five decades, intensive human exploitation of natural resources, especially water resources in this area has caused serious eco-environmental problems. The Green Corridor in the lower reaches of the Tarim River is situated on the brink of the grave. To save the Green Corridor, emergency water transportation measure was taken by the local government from the year 2000. The landscape pattem and hydrological & geochemical characteristics had changed greatly after emergency water transportation in the lower reaches of the Tarim River. After processing the remote sensing images in the years 2000 and 2005 using ARCGIS 9.0 software, which present the landscape pattems before and after the emergency water transportation, characteristics of dynamic change of landscape pattem were analyzed. The landscape pattern change is described as follows: The forest land, waters, cultivated land and construction landscape area increased, particularly the forest land, which increased by 23.03% during the last 5 years. The water landscape change was only inferior to the forest land, which increased by 16.04%. The lawn, sand and Gobi saline-alkali land area was reducing; lawn and cultivated land had made the biggest contribution to the increase of forest land by 6.46% and 4.79%. In the year 2005, landscape diversity index, evenness index, ffactal dimension and general fragmentation values increased, but dominance index reduced. Furthermore, the eco-hydrological process, hydrological & geochemical characteristics were analyzed based on the monitoring data in this paper. The results showed the hydrological & geochemical characteristics changed greatly after emergency water transportation. Hydrological geochemical characteristics were influenced earlier in the upper part than in the lower part in the lower reaches of the Tarim River. Variations in the concentration of some major ions and hydrological chemical types are obvious.  相似文献   

2.
The Vado Carranza dump, located in the Mexicali Valley, Baja California, northwest Mexico, was operated for more than 15 years receiving about 30 tons/day of solid wastes. The disposed wastes were periodically burned in open air. The presence of a shallow aquifer in the area makes the groundwater vulnerable to contamination processes. The purpose of this study was the evaluation of heavy metals content (Cu, Cd, Ni, Pb and Zn) in soil and groundwater in the vicinity of this dump. The results indicate high content of metals in soil, mainly at a superficial level, with the highest concentrations in the areas where burning of wastes occurred. Elevated concentrations of cadmium and copper were detected in groundwater with the highest concentrations occurring in monitoring wells located in the north side of the dump, downward of groundwater flow. Although the high content of metals in soil can be attributed to the burning of waste, other sources of pollution could be the agricultural irrigation in the vicinity of the dump. The program PHREEQC was used to model the geochemical evolution of groundwater. Results suggest that evaporation of the contaminated waters circulating below the landfill is one of the key processes that explain the increased concentration of contaminants in groundwater and its seasonal variations. As groundwater flows away from the dump, evaporation can concentrate the chemicals making the water more toxic. These results are important because they illustrate processes that are likely to occur in landfills located in other desert areas of the world.  相似文献   

3.
Groundwater, as a precious resource hidden underground, is an important component of the global water system. Transboundary aquifers containing substantial amount of groundwater often carry crucial ecological and social implications. Yet, it is unfortunate that transboundary aquifers have hardly been in the forefront of political and scientific discussions, and have not received due attention by policymakers. This article attempts to summarize the investigation on the eight transboundary aquifers that China shares with the neighboring countries. An overview on the groundwater resources in China, including its distribution, exploitation and challenges is also provided. Hydrogeological condition of the Heilongjiang-Amur River Basin aquifer, which is one of the eight major aquifers, is further elaborated. Cooperative activities carried out by China and Russia on monitoring and management of this aquifer are also presented.  相似文献   

4.
This study reveals the changes and evolution of rainstorm-driven intermediate floods occurring and driving multiple damaging hydrological events in the Rhone River Basin (RRB), since 1500 until 2010. A parsimonious approach was developed to simulate the major hydroclimatological flood-producing forcing, the Multiscale Rainstorm Climate Model (STORMCLIMM). We collected the frequency of intermediate floods—a type of particularly hazardous floods commonly taking place between June and beginning of November—from the RCB to be compared to STORMCLIMM estimates. The latter, smoothed by a moving window of 21 years, results in a high-pass filter in the time domain, which magnifies the signal of forcing variations causing intermediate floods. The RRB showed large temporal variations in both extreme rainstorms and associated multidecadal intermediate-floods (MUDIF) frequency at different climatic periods and land-use systems through historical times. An important peak was observed in the Maunder Minimum (1645–1715 AD). The model allowed detecting MUDIF occurred in the historical times. The situation becomes interesting with respect to recent times, because the Rhone landscape looks more vulnerable in the last decades as a consequence of land-use changes and climate shift towards more erratic and intensive storms. This evidence suggests that the interactions of land-use and climatic changes may turn into considerable vulnerability to fluvial flooding and agro-ecosystem connected to them for upcoming years. The Rhone, for example, provides basis for use of hydrological indicators (such as the one represented by STORMCLIMM) for one site or region and which, through minor modifications, can be made relevant to specific needs.  相似文献   

5.
Almost all the oil and gas reservoirs developed in marine sedimentary strata of China have undergone processes of multi-phase reservoir formation and later modification. The irregular reservoirs are classified into three types as the Naxi, Tahe and Renqiu ones, increasing successively in the development degree of karstificated pores and fissures and the connection degree of independent reservoirs. In these reservoirs, the unity in the fluid feature, pressure and oil-gaswater interface also increases successively from the Naxi to the Renqiu type. The main body of Ordovician reservoirs of the Tahe Oilfield in the Tarim Basin is a network pool rather than a stratified, massive, stratigraphically-unconformed or weathering-crust one. The fluid nature of oil, gas and water, the interface positions and the pressures, as well as the dynamic conditions of fluids within the reservoirs during the production are all different from those in stratified or massive oil and gas reservoirs. Carbonates in the Akekule uplift and the Tahe Oilfield are assemblages of various types of reservoirs, which have an overall oH-bearing potential and obvious uneven distribution. Testing and producing tests are the major means to evaluate this type of reservoirs and acid fracturing improvement is a key link in petroleum exploration and development.  相似文献   

6.
7.
正The Junggar Basin in the northern part of Xinjiang is the second largest inland basin in China.It is located between the Altai and Tianshan Mountains,which is bounded by the Junggar bounded Mountain in the northwest,the Altai Mountains in the northeast and the North Tianshan Mountains in the south.It belongs to a triangular close inland basin,and extends 700 km in EW  相似文献   

8.
We investigated major ions, stable isotopes, and radiocarbon dates in a Quaternary aquifer in semi-arid northwestern China to gain insights into groundwater recharge and evolution. Most deep and shallow groundwater in the Helan Mountains was fresh, with total dissolved solids <1,000 mg L?1 and Cl? <250 mg L?1. The relationships of major ions with Cl? suggest strong dissolution of evaporites. However, dissolution of carbonates, albite weathering, and ion exchange are also the major groundwater process in Jilantai basin. The shallow desert groundwater is enriched in δ18O and intercepts the local meteoric water line at δ18O = ?13.4 ‰, indicating that direct infiltration is a minor recharge source. The isotope compositions in intermediate confined aquifers resemble those of shallow unconfined groundwater, revealing that upward recharge from intermediate formations is a major source of shallow groundwater in the plains and desert. The estimated residence time of 10.0 kyr at one desert site, indicating that some replenishment of desert aquifers occurred in the late Pleistocene and early Holocene with a wetter and colder climate than at present.  相似文献   

9.
10.
C2-carbazole isomers have been investigated in crude oils from the Hui-Liu Structure Ridge (HLSR) in the Pearl River Mouth Basin (PRMB), South China Sea. The NH shielded isomer, as well as the NH partially shielded isomers, was detected in high abundance and the NH exposed isomers in lower abundance. A small-enrichment trend of 1,8-dimethylcarbazole (DMC) was observed in crude oils along the western part of HLSR (WPHLSR), which may indicate little effect of migration on the C2-carbazole distributions. Two strikingly different distribution patterns of NH partially shielded isomers were observed in the reservoirs along the WPHLSR: one with a preference of 1,3- and 1,6-DMCs and the other with a preference of 1,4- and 1,5-DMCs. All of the oils occurring in the Upper reservoirs have a preference of 1,3- and 1,6-DMCs, whereas those trapped in the Lower reservoirs show a preference of 1,4- and 1,5-DMCs, which may indicate there are two petroleum migration systems in the WPHLSR.  相似文献   

11.
The geothermal field is mainly controlled by the regional tectonic framework characterized by alternationsof uplifted and depressed basement. and exhibits a similar zoned distribution of temperatures. In the upliftedarea the geothermal gradient (G) and terrestrial heat flow value(q) of the Cenozoic sedimentary cover are rela-tively high, with G=3.5-5.0℃/100m and q=63-84mW/m~2; whereas in the depressions they are rela-tively low, with G=2.7-3.5℃/100m and q=46-59mW/m~2. In the whole region, G=3.58℃/100m and q=61.5±13.4nW/m~2, indicating a comparatively high geothermal background and the presence of localgeothermal anomalies. A comparison of the results of mathematical simulation of the geothermal field with themeasured values shows a good agrecment between them. The geothermal difference between various tectonicunits is caused chiefly by the lateral and vertical variation of thermal properties of shallow crustal rocks. Thisphenomenon can be regarded as the result of redistribution of relatively uniform heat flows from the deep crustin the surficial part of the crust in the process of their upward conduction.  相似文献   

12.
1 Introduction In recent years rapid economic developmentbadly needs energy resources. Exploration andexploitation of more kinds of energy resources shouldbe intensified to meet this need. According to presentliterature, oil/gas fields, coal fields as we…  相似文献   

13.
Street vending faces uncertain state responses in contemporary Chinese cities, though it plays an important role in sustaining the livelihood of urban migrants. Building on the critical perspective that understands informality as a production of the state, this paper explores the nature of the regulation of street vending in Guangzhou since 1949. The state’s regulatory practices are characterized by what we call historical ambivalence and geographical ambivalence, which refer to the inconsistency in policies, which fluctuate between soft and hard approaches over time, and the mix of contradictory regulatory measures applied in different urban spaces, respectively. Ambivalence is generated because the state addresses street vending in ways that attain the overarching objective of urban policies. In particular, the exclusion of street vendors in present-day China is not historically natural but driven and sustained by the government’s pursuit of a good city image favorable for attracting capital in the context of intensifying inter-urban competition. The definition of informality is not a neutral classification. Rather, declaring when and to what extent an informal practice is tolerable depends on what the state desires in a specific historical circumstance.  相似文献   

14.
Sixty-five natural gas samples were collected from 19 oil-gasfields in the Qaidam basin, China. The chemical composition and carbon isotope values of the samples were measured, and the geochemical characteristics and origin of the natural gases were studied. The gases can be divided into biogenic gases, sapropelic oil-type gases, mixed type oil-type gases, coal-type gases and mixed gas. The δ13Ci values of the biogenic gases are very small and the C2+ contents of them are very low, ranging from -68.2‰ to -61.8‰ and 0.06% to 0.20% respectively. They have heavy δD and δ13Cco2> showing a CC>2 reduction pathway. They are distributed in the East depression region and derived from the Quaternary source rocks. The sapropelic oil-type gases have small δ13C2 values and high C2+ ranging from -36.6‰ to -28.6‰ and from 33.01% to 47.15% respectively. The mixed type oil-type gases have <5I3C2 values and C2+ contents varying from -28.6‰ to -24.8‰ and from 4.81% to 26.06% respectively. Both sapropelic oil-typ  相似文献   

15.
Bulk mineral resources of iron ores, copper ores, bauxite, lead ores, zinc ores and potassium salt play a pivotal role on the world’s and China’s economic development. This study analyzed and predicted their resources base and potential, development and utilization and their world’s and China’s supply and demand situation in the future 20 years. The supply and demand of these six bulk mineral products are generally balanced, with a slight surplus, which will guarantee the stability of the international mineral commodity market supply. The six mineral resources(especially iron ores and copper ores) are abundant and have a great potential, and their development and utilization scale will gradually increase. Till the end of 2014, the reserveproduction ratio of iron, copper, bauxite, lead, zinc ores and potassium salt was 95 years, 42 years, 100 years, 17 years, 37 years and 170 years, respectively. Except lead ores, the other five types all have reserve-production ratio exceeding 20 years, indicative of a high resources guarantee degree. If the utilization of recycled metals is counted in, the supply of the world’s six mineral products will exceed the demand in the future twenty years. In 2015–2035, the supply of iron ores, refined copper, primary aluminum, refined lead, zinc and potassium salt will exceed their demand by 0.4–0.7 billion tons(Gt), 5.0–6.0 million tons(Mt), 1.1–8.9 Mt, 1.0–2.0 Mt, 1.2–2.0 Mt and 4.8–5.6 Mt, respectively. It is predicted that there is no problem with the supply side of bulk mineral products such as iron ores, but local or structural shortage may occur because of geopolitics, monopoly control, resources nationalism and trade friction. Affected by China’s compressed industrialized development model, the demand of iron ores(crude steel), potassium salt, refined lead, refined copper, bauxite(primary aluminum) and zinc will gradually reach their peak in advance. The demand peak of iron ores(crude steel) will reach around 2015, 2016 for potassium salt, 2020 for refined lead, 2021 for bauxite(primary aluminum), 2022 for refined copper and 2023 for zinc. China’s demand for iron ores(crude steel), bauxite(primary aluminum) and zinc in the future 20 years will decline among the world’s demand, while that for refined copper, refined lead and potassium salt will slightly increase. The demand for bulk mineral products still remains high. In 2015–2035, China’s accumulative demand for iron ores(crude steel) will be 20.313 Gt(13.429 Gt), 0.304 Gt for refined copper, 2.466 Gt(0.616 Gt) of bauxite(primary aluminum), 0.102 Gt of refined lead, 0.138 Gt of zinc and 0.157 Gt of potassium salt, and they account for the world’s YOY(YOY) accumulative demand of 35.17%, 51.09%, 48.47%, 46.62%, 43.95% and 21.84%, respectively. This proportion is 49.40%, 102.52%, 87.44%, 105.65%, 93.62% and 106.49% of that in 2014, respectively. From the supply side of China’s bulk mineral resources, it is forecasted that the accumulative supply of primary(mine) mineral products in 2015–2035 is 4.046 Gt of iron ores, 0.591 Gt of copper,1.129 Gt of bauxite, 63.661 Mt of(mine) lead, 0.109 Gt of(mine) zinc and 0.128 Gt of potassium salt, which accounts for 8.82%, 13.92%, 26.67%, 47.09%, 33.04% and 15.56% of the world’s predicted YOY production, respectively. With the rapid increase in the smelting capacity of iron and steel and alumina, the rate of capacity utilization for crude steel, refined copper, alumina, primary aluminum and refined lead in 2014 was 72.13%, 83.63%, 74.45%, 70.76% and 72.22%, respectively. During 2000–2014, the rate of capacity utilization for China’s crude steel and refined copper showed a generally fluctuating decrease, which leads to an insufficient supply of primary mineral products. It is forecasted that the supply insufficiency of iron ores in 2015–2035 is 17.44 Gt, 0.245 Gt of copper in copper concentrates, 1.337 Gt of bauxite, 38.44 Mt of lead in lead concentrates and 29.19 Mt of zinc in zinc concentrates. China has gradually raised the utilization of recycled metals, which has mitigated the insufficient supply of primary metal products to some extent. It is forecasted that in 2015–2035 the accumulative utilization amount of steel scrap(iron ores) is 3.27 Gt(5.08 Gt), 70.312 Mt of recycled copper, 0.2 Gt of recycled aluminum, 48 Mt of recycled lead and 7.7 Mt of recycled zinc. The analysis on the supply and demand situation of China’s bulk mineral resources in 2015–2035 suggests that the supply-demand contradiction for these six types of mineral products will decrease, indicative of a generally declining external dependency. If the use of recycled metal amount is counted in, the external dependency of China’s iron, copper, bauxite, lead, zinc and potassium salt will be 79%, 65%, 26%, 8%, 16% and 18% in 2014, respectively. It is predicted that this external dependency will decrease to 62%, 64%, 20%,-0.93%, 16% and 14% in 2020, respectively, showing an overall decreasing trend. We propose the following suggestions correspondingly.(1) The demand peak of China’s crude steel and potassium salt will reach during 2015–2023 in succession. Mining transformation should be planned and deployed in advance to deal with the arrival of this demand peak.(2) The supply-demand contradiction of China’s bulk mineral resources will mitigate in the future 20 years, and the external dependency will decrease accordingly. It is suggested to adjust the mineral resources management policies according to different minerals and regions, and regulate the exploration and development activities.(3) China should further establish and improve the forced mechanism of resolving the smelting overcapacity of steel, refined copper, primary aluminum, lead and zinc to really achieve the goal of "reducing excess production capacity".(4) In accordance with the national strategic deployment of "One Belt One Road", China should encourage the excess capacity of steel, copper, alumina and primary aluminum enterprises to transfer to those countries or areas with abundant resources, high energy matching degree and relatively excellent infrastructure. Based on the national conditions, mining condition and geopolitics of the resources countries, we will gradually build steel, copper, aluminum and lead-zinc smelting bases, and potash processing and production bases, which will promote the excess capacity to transfer to the overseas orderly.(5) It is proposed to strengthen the planning and management of renewable resources recycling and to construct industrial base of renewable metal recycling.(6) China should promote the comprehensive development and utilization of paragenetic and associated mineral species to further improve the comprehensive utilization of bulk mineral resources.  相似文献   

16.
Ecological security evaluation is an important way to identify the need for improvement in a watershed and to assess the degree of regional sustainable development. Using a driver–pressure–state–exposure–response model, a comprehensive system of ecological security indicators was developed, and it was demonstrated in a case study of the main ecological problems facing the Qinghai Lake Basin. Indicators of the status of the natural ecological environment, socioeconomic pressure, and the degree of environmental damage were chosen to develop the model, and comprehensively evaluated the basin’s ecological security in 2000, 2004, 2009, and 2013 to reveal changes in the ecological security in response to changing climate and land use. The overall ecological security of the basin improved from 2000 to 2013, with considerable restoration and reconstruction of the ecosystem. From 2000 to 2004, environmental deterioration increased slightly as a result of pollution caused by human activities, excess land reclamation for agriculture, land desertification, and grassland degeneration. However, the obvious effect of ecological protection policies, such as conversion of farmland into grassland and stall feeding of livestock instead of grazing, led to improvement of the ecological environment from 2004 to 2013. Ecological security in the basin increased with increasing precipitation during the study period.  相似文献   

17.
The geological structure and tectonophysics of the Gusinoozersky Basin—a tectonotype of Mesozoic depressions in the western Transbaikal region—is discussed. New maps of the fault-block structure and state of stress in the Earth’s crust of the studied territory are presented. It is established that the Gusinoozersky Basin was formed in a transtensional regime with the leading role of extension oriented in the NW-SE direction. The transtensional conditions were caused by paths of regional tension stresses oriented obliquely to the axial line of the basin, which created a relatively small right-lateral strike-slip component of separation (in comparison with normal faulting) along the NE-trending master tectonic lines. The widespread shear stress tensors of the second order with respect to extension are related to inhomogeneities in the Earth’s crust, including those that are arising during displacement of blocks along normal faults. Folding at the basin-range boundary was brought about by gravity effects of normal faulting. The faults and blocks in the Gusinoozersky Basin remained active in the Neogene and Quaternary; however, it is suggested that their reactivation was a response to tectonic processes that occurred in the adjacent Baikal Rift Zone rather than to the effect of a local mantle source.  相似文献   

18.
Tessema  Israel  Simane  Belay 《GeoJournal》2021,86(4):1767-1783
GeoJournal - Climate variability and change make agricultural sector a risky venture for smallholders’ farmers. This paper presents an assessment of smallholder farmers’ perceptions of...  相似文献   

19.
This article examines changing water governance modalities in the context of the neoliberalization of nature. Specifically, it focuses on Brazilian water sector reforms passed in 1997 that mandate decentralized and participatory decision-making at the river basin scale. Critics have suggested that rescaling, decentralization, and participatory governance mechanisms – supposedly intended to render decision-making more equitable, accessible, and relevant – can serve to legitimate, facilitate, and thus further embed processes of neoliberalization. Examining the impact of Brazil’s water sector reforms on the state–society relationship, this article presents a case study of water governance in the São Francisco River Basin and finds that the reforms – despite their neoliberalizing potential – have not significantly contributed to the neoliberalization of governance therein. Instead, water governance continues to be characterized by longstanding patterns of traditional elite control. Through an institutional and socio-natural analysis, this article describes and accounts for the continued dominance of these patterns relative to neoliberalization and explores activists’ efforts to use water sector reforms to pursue more progressive possibilities. The article concludes with a discussion of the implications for variegation and contestation in ongoing debates over neoliberal natures.  相似文献   

20.
To promote the rational development and use of clean coal resources in China, data on the regional and age distribution of sulfur, arsenic and other harmful elements in Chinese coal was broadly collected, tested for content, and analyzed. Coal in northwestern China is characterized by low to extremely low levels of sulfur; the coal of the Taiyuan Formation in northern China mainly has high-sulfur content; that of the Shanxi Formation is mainly characterized by low sulfur coal; and the Late Permian coal in southern China has overall higher sulfur content; other regions have low sulfur coal. The average content of harmful trace elements in the bulk of China's coal is similar to the corresponding content in the coal of the North America and the rest of the world, whereas the content of various elements (Hg, Sb and Se) is different in magnitude to the corresponding percentage in the crust. The average content of the elements Cr, Se, Co, Be, U, Br in Late Permian coal in S China ranks first in the country whereas the average content of Hg and CI in the coals of Late Carboniferous to Early Permian age in N China are the highest. The average content of Mn in Early and Middle Jurassic coal is higher in NW China. The high content of harmful elements in some coal should cause particular concern both in the development and utilization of coal.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号