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81.
The Velenje area (almost 200 km2 with over 31,000 inhabitants) is based on the Šalek Valley, which became a leading area of industrialisation and urbanisation after the Second World War, with consequent pollution problems. Various industrial plants polluted the river Paka while more serious hazards arose through the coal mine which is a still causing landscape subsidence and the thermal power station in the neighbourhood of Šoštanj which is a major source of sulphur dioxide and nitrogen oxide pollution. In 1987 there was an ecological protest which marked the beginning of a sustainable development strategy for the community. During the past decade programmes have dealt with the degradation of air, soil and water to achieve cleaner air, a transformation in landuse and enhancement the river's formerly weak self-purifying capabilities. This article examines the changes in the valley since the attention of the authorities was drawn to the deterioration of living conditions. Despite the pressures of transition which have seen unemployment rising to over ten percent, significant environmental improvements have been made and the area stands as a model for the rest of the country. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   
82.
Generation of Deccan Trap magmas   总被引:1,自引:0,他引:1  
Deccan Trap magmas may have erupted through multiple centers, the most prominent of which may have been a shield volcano-like structure in the Western Ghats area. The lavas are predominantly tholeiitic; alkalic mafic lavas and carbonatites are rare. Radioisotope dating, magnetic chronology, and age constraints from paleontology indicate that although the eruption started some 68 Ma, the bulk of lavas erupted at around 65–66 Ma. Paleomagnetic constraints indicate an uncertainty of ± 500,000 years for peak volcanic activity at 65 m.y. in the type section of the Western Ghats. Maximum magma residence times were calculated in this study based on growth rates of “giant plagioclase” crystals in lavas that marked the end phase of volcanic activity of different magma chambers. These calculations suggest that the > 1.7 km thick Western Ghats section might have erupted within a much shorter time interval of ∼ 55,000 years, implying phenomenal eruption rates that are orders of magnitude larger than any present-day eruption rate from any tectonic environment. Other significant observations/conclusions are as follows: (1) Deccan lavas can be grouped into stratigraphic subdivisions based on their geochemistry; (2) While some formations are relatively uncontaminated others are strongly contaminated by the continental crust; (3) Deccan magmas were produced by 15–30% melting of a Fe-rich lherzolitic source at ∼ 3–2 GPa; (4) Parent magmas of the relatively uncontaminated Ambenali formation had a primitive composition with 16%MgO, 47%SiO2; (5) Deccan magmas were generated much deeper and by significantly more melting than other continental flood basalt provinces; (6) The erupted Deccan tholeiitic lavas underwent fractionation and magma mixing at ∼ 0.2 GPa. The composition and origin of the crust and crust/mantle boundary beneath the Deccan are discussed with respect to the influence of Deccan magmatic episode.  相似文献   
83.
东北平原农田防护林网区土地资源系统结构及动态   总被引:2,自引:0,他引:2  
张柏 《地理学报》1992,47(4):324-343
本文在对东北平原农田防护林网区土地资源系统基本结构分析的基础上,利用典型区域的数据对该土地资源系统动态进行分析。本区的土地资源系统进入广泛的农业开发时间仅五、六十年,但经过强人工作用,已从垦殖期转入衰竭期。只有以人工再生(高投入)的方式才能保证土地资源的永续利用,维持系统的良性循环。否则,仅仅依赖自然再生(低投入)为主要的物质能量返回形式,必然导致粮畜生产带走物质能量,造成土地肥力得不到必要补充,形成土地资源日益衰竭的恶性循环系统。  相似文献   
84.
东海西湖凹陷早第三纪烃源岩生烃组分剖析   总被引:1,自引:0,他引:1  
采用有机岩石学分析方法,结合有机地球化学资料,剖析了东海盆地西湖凹陷早第三纪烃源岩。该烃源岩富镜质组,贫惰性组,含一定数量的壳质组和腐泥组(10%~30%)。壳质组+腐泥组含量与氯仿沥青、总烃和有效碳等参数密切正相关;树脂体和孢子体+藻类体分别是早期生烃和晚期生烃的重要组分。在此基础上提出了西湖凹陷烃源岩的生烃模式。  相似文献   
85.
在研究镜质组类型基础上,把富氢镜质组(荧光镜质体)作为有折扣的富氢显微组分(类脂组)对待,提出了利用荧光显微组分丰度-FMT参数作为评价不同还原类型煤生烃,排烃的定量指标。煤岩学标志,有机地球化学参数和热模拟实验产烃率数据为FMT值定量评价煤生烃排烃潜力的适用性和有效性提供了佐证。  相似文献   
86.
ABSTRACT

Power plants often use river waters for cooling purposes and can be sensitive to droughts and low flows. Water quality is also a concern, due to algal blooms and sediment loads that might clog filters. We assessed the impacts of droughts on river flow and water quality from the point of view of power plant operation. The INCA (INtegrated CAtchment) water quality model was coupled with a climate model to create a dataset of flow and water quality time series, using the River Trent (UK) as a case study. The result hints to a significant decrease in flows and an increase in phosphorus concentrations, potentially enhancing algal production. Power plants should expect more stress in the future based on the results of this study, due to reduced cooling water availability and decreasing upstream water quality. This issue might have serious consequences also on the whole national power network.  相似文献   
87.
Local governments are under pressure to develop alternative revenue sources to their already strapped property tax bases. Throughout the 1970s, municipal governments nationwide restructured their local taxes by substituing sales tax for property tax revenue. A tax accounting model identified two sources of sales-for-property tax substitution: changes in the tax rates and normal economic growth and decline. Most of the sales-for-property tax substitution experienced in Illinois city finance was attributable to economic change. The critical determinant of this substitution appreared to be the municipality's share of the regional retail market. Cities in higher density metropolitan areas were less likely to experience sales-for-property tax substitution through economic growth than those cities in lower density, less competitive environments.  相似文献   
88.
When organic matter during geological processes is affected by a variety of factors such as paleotemperature, and time, complicated chemical reactions will occur, finally resulting in the generation of petroleum and natural gas. These reactions leading to…  相似文献   
89.
The generation of natural gases is much more complicated in comparison with liquid petro-leum in that natural gases could be generated from both humic and sapropelic organic matter at different stages and that natural gases could be organic and inorganic …  相似文献   
90.
莺歌海盆地海相生物气特征及生化成气模式   总被引:11,自引:2,他引:9  
黄保家  肖贤明 《沉积学报》2002,20(3):462-468
莺歌海盆地浅层第四系-上新统存在丰富的生物气资源,已发现生物气的组成以甲烷和氮为主、干燥系数高达0.99,甲烷碳同位素轻(-65.57‰~-63.14‰)尤其是氢同位素偏重(-172.1‰~-108.5‰)是该区生物气的重要特点.研究表明,该区第四系-上新统海相沉积有机质是生物气的基质,这套源岩的平均有机碳含量约0.4%,有机质中细菌可利用基质以粗纤维、半纤维素和蛋白质为主,特别是有机质生化代谢过程中的中间产物-氨基酸、乙酸含量异常高,揭示其正处在活跃的生化成气时期;根据模拟实验结果结合本区的地质条件,初步确定生物气生成的主带在35~65℃之间、生化成气下限深度约为85℃(对应井深约2000 m,实际埋深1900 m左右),进而建立了海相生物气的形成演化模式。  相似文献   
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