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31.
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安徽省含山县土地整理耕地质量评价及其变化研究 总被引:1,自引:0,他引:1
土地整理是改善土地利用条件,提高土地质量的有效措施,对土地整理后的耕地质量进行评价是土地整理重要工作之一。从耕地质量的内涵和土地整理项目的基本要求出发,选取耕地自然条件和耕地利用条件2个基本因素和12个影响因子,将特尔斐法与层次分析法相结合,确定各因子权重,构建基于土地整理的耕地质量评价指标体系。以安徽省含山县铜闸镇土地整理项目为例,采用传统的土壤调查与3S技术相结合的方法,分析土地整理复垦过程中耕地质量时空格局变化,得出整理前、后耕地质量的级别变化。研究结果表明,通过土地整理,研究区的耕地质量空间分布和级别发生了很大变化,整理后一级、二级、三级质量的土地比整理前分别增加了7.20%,11.95%和0.65%,四级、五级则分别减少了15.65%和4.16%,整理后的耕地质量总体水平是整理前的1.291倍。 相似文献
33.
Zhang Jiji Zhang Qingshan Dian Changgong Liu Cheng Dong Chaohua 《Acta Meteorologica Sinica》1989,3(4):562-568
From May 6 to June 2,1987,a huge forest fire broke out and raged for 28 days in Da Hinggan Lingregion in far Northeast China,causing heavy loss of life and property,which claims the biggest forest firedisaster in Chinese history.The fire drew attention of the whole of China and was also concerned by manyother countries.How were the meteorological satellites used in the detection of the forest fire?This paperelaborates the principles and methods of the fire detection using meteorological satellites,so that to sum upthe experience and to increase the ability of forest fire detection. 相似文献
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Carbon and Noble Gas Isotopes in the Tengchong Volcanic Geothermal Area, Yunnan, Southwestern China 总被引:1,自引:0,他引:1
Carbon and noble gas isotope analyses are reported for bubbling gas samples from the Tengchong volcanic geothermal area near the Indo-Eurasian suture zone. All samples contain a resolvable component of mantle-derived 3He. Occurrence of mantle-derived 3He coincides with surface volcanism. However, 3He occurs over a larger geographic areathan do surface volcanics. δ13C values for CO2 and CH4 vary from -33.4‰ to 1.6 ‰ and from -52.8‰ to -2.8‰, respectively. He and C isotope systematics indicate that CO2 and CH4 in the CO2-rich gases originated predominantly from magmatic component mixed with crustal CO2 produced from carbonate. However, breakdown of organic matter and near-surface processes accounts for the CH4 and CO2 in N2-rich gases. 3He/4He ratio distribution pattern suggests that mantle-derived He and heat sources of high-temperature system in central Tengchong originate from a hidden magma reservoir at subsurface. CO2-rich gases with the highest 3He/4He ratio (5.2 Ra) may be representative of the 相似文献
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CHEN Biying FANG Luji LANG Yunchao XU Sheng LIU Congqiang ZHANG Luyuan HOU Xiaolin 《《地质学报》英文版》2024,98(1):207-219
The knowledge of the residence time of formation water is fundamental to understanding the subsurface flow and hydrological setting. To better identify the origin and evolution of coal seam water and its impact on gas storage and production, this study collected coalbed methane co-produced water in the southeast Qinshui Basin and detected chemical and isotopic compositions, especially 36Cl and 129I concentrations. The calculated tracer ages of 129I (5.2–50.6 Ma) and 36Cl (0.13–0.76 Ma) are significantly younger than the age of coal-bearing formation (Pennsylvanian - Cisuralian), indicating freshwater recharge after coal deposition. The model that utilises 129I/I and 36Cl/Cl ratios to constrain the timing of recharge and the proportion of recharge water reveals that over 60% of pre-anthropogenic meteoric water entered coal seams since 10 Ma and mixed with residue initial deposition water, corresponding to the basin inversion in Cenozoic. The spatial distribution of major ion concentrations reveals the primary recharge pathway for meteoric water from coal outcrops at the eastern margin to the basin center. This study demonstrates the occurrence of higher gas production rates from wells that accept water recharge in recent times and suggests the possible potential of the non-stagnant zones for high gas production. 相似文献
38.
Junfeng Wu Yunsheng Wang Simeng Dong Yun Chen Lei Wang 《Journal of the Geological Society of India》2013,82(3):277-282
This paper presents a case study on the Mogangling landslide and its characteristics and geological mechanism. The Mogangling landslide is a giant rock landslide located at the intersection of Dadu river and Moxi river. It is a landslide triggered by an earthquake with large magnitude that occurred in 18th century. Based on detailed site investigation, it shows the Mogangling landslide developed in the Kangding complex strata, composed of completely decomposed aggregates of massive-block stone, debris and soil with some gravels, pebbles and sand layer found distributed in front of the landslide. The control factor of the deformation of this landslide is the combined effect of Detuo fault which is located under the slope, and the regional stress formed along structural planes as well as the free surfaces formed by river cutting. Therefore, when the Kangding-Moxi earthquake (Ms =7.7) occurred on 1st June, 1786, due to seismic shaking, topographic amplification effects and back slope effects, the Mogangling landslide occurred. The Dadu River is the most important river for hydropower development in China; large-scale seismic landslides along the Dadu River are the most important geological issue during the construction of hydropower stations. Therefore, this research is important from the point of view of economic and social benefits. 相似文献
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Sheng Jifu Zhang Dequan Li YanInstitute of Mineral Deposits Chinese Academy of Geological Sciences Beijing Jiang M inxi 《《地质学报》英文版》1995,69(3):289-302
Physicochemical parameters of mineralization such as temperature, pressure, salinity, density, composition and boiling of ore fluids as well as pH, Eh, fo2 and reducing parameter in theprocess of mineralization of major ore deposits in the study district have been obtained by the authors through systematic observation and determination of characteristics and phase changes of fluid inclusions at different temperatures and analysis of gaseous and liquid phase compositions of the inclusions, thus providing a scientific basis for the division of mineralization-alteration stages, types of mineral deposits and minerogenetic series and the deepening of the knowledge about the ore-forming processes and mechanisms of mineral deposits. It is indicated that the deposits of the same type have similar fluid inclusion geochemical features and physicochemical parameters though they belong to different minerogenetic series, while the compositions of inclusions are not conditioned by deposit types but closely related to 相似文献