共查询到20条相似文献，搜索用时 62 毫秒
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以彭州川芎种植区的菜园土、稻田翻耕土、稻田免耕土和旱地(未种过川芎和蔬菜)四种土壤为研究对象,探讨了不同耕作方式下川芎对土壤中Cd、Pb的富集特征。结果表明:在四种耕作方式下,菜园土中Cd、Pb含量显著高于其他三种土壤,分别为1.10mg·kg-1和29.78mg·kg-1;土壤Cd综合污染指数和Hacanson系数分别为3.76和133.07,处于重污染和强生态危害状态。稻田翻耕土、稻田免耕土和旱地三种类型土壤在Cd含量上差异显著,依次为稻田免耕土(0.86mg·kg-1)稻田翻耕土(0.59mg·kg-1)旱地(0.37mg·kg--1),在Pb含量上三者差异不显著。川芎植株对Cd的富集在菜园土中显著高于其他土壤,表现为菜园土稻田免耕土旱地稻田翻耕土;川芎植株对Pb的富集以在稻田免耕土中最大,依次为稻田免耕土旱地稻田翻耕土菜园土。在四种土壤中,川芎叶片对Cd、Pb的富集能力均大于根茎,其中川芎叶片对Cd的富集能力是根茎的1.37倍,对Pb的富集能力是根茎的1.42倍,二者对Cd的富集能力在菜园土中差异最大(叶/根为1.56),对Pb的富集能力在稻田免耕土中差异最大(叶/根为1.98)。川芎对Cd、Pb的富集主要受轮作作物种类和耕作措施的影响。 相似文献
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耕作侵蚀研究回顾和展望 总被引：1，自引：0，他引：1
《地球科学进展》2019,(12)
耕作侵蚀是土壤侵蚀的重要组成,会导致地形、土壤性质和坡面水文过程的变化,已被证实是一个重要的土壤退化过程。利用科学文献计量法,总结了耕作侵蚀的发展历程、影响因子和研究方法。在此基础上,分析研究热点和趋势,对研究中存在的问题和挑战进行总结和讨论。耕作侵蚀的发生是耕作侵蚀力和景观可蚀性共同作用的结果,前者主要受人为因子影响,而后者主要由自然因子决定。为了科学认识耕作侵蚀过程及其发生和作用机制,长期以来开展了大量不同空间尺度和时间尺度的研究,并构建了多种独立的耕作侵蚀模型。随着对耕作侵蚀认识的逐步深化,耕作侵蚀从最初的独立研究逐步发展为与水蚀结合的综合土壤侵蚀研究,构建了大量科学评估区域和长时间尺度土壤侵蚀和地形演化的综合模型。然而,耕作侵蚀的多尺度综合研究有待进一步突破,与其他形式侵蚀的交互作用还有待进一步深入探索。构建精确的耕作侵蚀评估和预测模型,编制耕作侵蚀防治标准,协调耕作和土壤保护之间的关系是未来的重要发展方向。 相似文献
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137Cs示踪技术在土壤侵蚀估算中的应用研究进展 总被引：20，自引：2，他引：18
137Cs示踪技术目前已被广泛用于长期的土壤侵蚀(水蚀)估算。该技术要解决的两个关键问题是土壤137Cs基准值的确定,以及土壤的137Cs损失量与土壤侵蚀量之间的定量模型的建立。对现有的主要的定量模型进行了简述,并提出了各自的局限性。这些模型可分为经验模型和理论模型两大类,其中以理论模型中的质量平衡模型较为成熟,综合考虑了较多的侵蚀因子,如137Cs年沉降分量、土壤颗粒粒径分布差异、地表富集作用、耕作土壤在耕作活动前新沉降137Cs的侵蚀损失等。对现有模型的改进也进行了探讨,并提出了今后的一些研究重点。 相似文献
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辽河油田是一个有着40多年开发历史的老油田,其稠油产量占据原油产量的半壁江山,其稠油开采工艺主要为蒸汽吞吐、蒸汽驱、SAGD和火驱。以加热原油温度降低其粘度的方法,在多轮次生产之后套管都会不同程度地受到损坏。套管整形技术是套管修复主体技术之一。针对梨形胀管器整形技术难应用于近井口井段、液压整形技术单次整形的长度有限等问题,研制了一种新型的机械液压复合套管整形工具。新型机械液压复合套管整形工具主要由高强度合金钢多级胀头、加长管柱（选配）、液压增力器、水力锚、安全泄压装置等部分组成。通过理论计算,给出了胀头的材料强度、液压增力器推力、水力锚锚爪数量及压力阀值等建议值,通过梨形胀管器技术和复合套管整形技术现场应用对比,证实使用机械液压复合套管整形技术,可将作业时间大幅度缩短,具有良好的应用前景和推广价值。 相似文献
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Emily Keeble David I. Whiteside Michael J. Benton 《Proceedings of the Geologists' Association. Geologists' Association》2018,129(2):99-119
Pant-y-ffynnon Quarry in South Wales yielded a rich cache of fossils in the early 1950s, including articulated specimens of new species (the small sauropodomorph dinosaur Pantydraco caducus and the crocodylomorph Terrestrisuchus gracilis), but no substantial study of the wider fauna of the Pant-y-ffynnon fissure systems has been published. Here, our overview of existing specimens, a few described but mostly undescribed, as well as freshly processed material, provides a comprehensive picture of the Pant-y-ffynnon palaeo-island of the Late Triassic. This was an island with a relatively impoverished fauna dominated by small clevosaurs (rhynchocephalians), including a new species, Clevosaurus cambrica, described here from a partially articulated specimen and isolated bones. The new species has a dental morphology that is intermediate between the Late Triassic Clevosaurus hudsoni, from Cromhall Quarry to the east, and the younger C. convallis from Pant Quarry to the west, suggesting adaptive radiation of clevosaurs in the palaeo-archipelago. The larger reptiles on the palaeo-island do not exceed 1.5?m in length, including a small carnivorous crocodylomorph, Terrestrisuchus, and a possible example of insular dwarfism in the basal dinosaur Pantydraco. 相似文献
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Gilles Serge Odin 《Comptes Rendus Geoscience》2002,334(6):409-414
Lithostratigraphy, physicochemical stratigraphy, biostratigraphy, and geochronology of the 77–70 Ma old series bracketing the Campanian–Maastrichtian boundary have been investigated by 70 experts. For the first time, direct relationships between macro- and microfossils have been established, as well as direct and indirect relationships between chemo-physical and biostratigraphical tools. A combination of criteria for selecting the boundary level, duration estimates, uncertainties on durations and on the location of biohorizons have been considered; new chronostratigraphic units are proposed. The geological site at Tercis is accepted by the Commission on Stratigraphy as the international reference for the stratigraphy of the studied interval. To cite this article: G.S. Odin, C. R. Geoscience 334 (2002) 409–414. 相似文献
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The effect of water on accessory phase solubility in subaluminous and peralkaline granitic melts 总被引：4，自引：0，他引：4
The solubilities of columbite, tantalite, wolframite, rutile, zircon and hafnon were determined as a function of the water contents in peralkaline and subaluminous granite melts. All experiments were conducted at 1035 °C and 2 kbar and the water contents of the melts ranged from nominally dry to approximately 6 wt.% H2O. Accessory phase solubilities are not affected by the water content of the peralkaline melt. By contrast, solubilities are affected by the water content of the subaluminous melt, where the solubilities of all the accessory phases examined increase with the water content of the melt, up to 2 wt.% H2O. At higher water contents, solubilities are nearly constant. It can be concluded that water is not an important control of accessory phase solubility, although the water content will affect diffusivities of components in the melt, thus whether or not accessory phases will be present as restite material. The solubility behaviour in the subaluminous and peralkaline melts supports previous spectroscopic studies, which have observed differences in the coordination of high field strength elements in dry vs. wet subaluminous granitic glasses, but not for peralkaline granitic glasses. Lastly, the fact that wolframite solubility increases with increasing water content in the subaluminous melt suggests that tungsten dissolved as a hexavalent species. 相似文献
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Muriel Rocher Stéphane Baize Stéphane Jaillet Edward Marc Cushing Yannick Lozac&#x;h Francis Lemeille 《Comptes Rendus Geoscience》2003,335(8):701-708
Calcite samples were extracted both from the rock matrix and the superficial coating of a karstified fault plane of an underground quarry, located in the eastern border of the Paris basin. The karstification is dated as Quaternary. Analysis of mechanical calcite twinning reveals that only the calcite matrix has also undergone a compression trending WNW that can be attributed to the Mio-Pliocene alpine collision. Both coating and matrix have undergone a strike-slip regime with σ1 roughly trending north–south, that could correspond to the regional present-day state of stress, a strike-slip compression rather trending NNW, modified by local phenomena. To cite this article: M. Rocher et al., C. R. Geoscience 335 (2003). 相似文献
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正20141756 Chen Ruige(Mathematical College,China University of Geosciences,Beijing100083,China);Zhou Xun Numerical Simulation of Groundwater Level Fluctuation in a Coastal Confined Aquifer with Sloping Initial Groundwater Level Induced by the Tide(Geological Bulletin of China,ISSN1671-2552,CN11-4648/P,32(7),2013,p.1099-1104,6 illus.,16 refs.) Key words:confined water,groundwater level 相似文献
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正20141408 Cai Jia(Institute of Geology,Chinese Academy of Geological Sciences,Beijing100037,China);Liu Fulai Petrogenesis and Metamorphic P-T Conditions of Garnet-Spinel-Biotitebearing Paragneiss in Danangou Area,Daqingshan-Wulashan Metamorphic Complex Belt(Acta Petrologica Sinica,ISSN1000-0569,CN11-1922/P,29(7), 相似文献
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正20142386An Guoying(China Aero Geophysical Survey and Remote Sensing Center for Land and Resources,Beijing 100083,China)Application of Satellite Remote Sensing in Regional Hydrogeological Investigation:Taking Cenozoic Strata in Wenquan Sheet(1∶250 000)of Karakoram Range as an Example(Geosci- 相似文献
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正20141016An Chengbang(Key Laboratory of Western China’s Environmental Systems,Ministry of Education,Lanzhou University,Lanzhou 730000,China);Zhao Yongtao Lake Records during the Last Glacial Maximum from Xinjiang,NW China and Their Climatic Impli- 相似文献
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正20141538 Cao Qing(School of Earth Sciences and Engineering,Xi’an Petroleum University,Xi’an 710065,China);Zhao Jingzhou Characteristics and Significance of Fluid Inclusions from Majiagou Formation,Yichuan Huangling Area,Ordos Basin(Advances in Earth Science,ISSN1001-8166,CN62-1091/P,28(7),2013,p.819-828,7 illus.,3 tables,43 refs.) 相似文献