Effect of adsorbed iron on thermoluminescence and electron spin resonance spectra of Ca-Fe-exchanged montmorillonite     

Coyne LM  Banin A 《Clays and clay minerals》1986,34(6):645-650

The electron spin resonance (ESR) spectra and the natural and gamma-induced thermoluminescence (TL) glow curves of a series of variably cation-exchanged Fe-Ca-clays prepared from SWy-1 montmorillonite were examined. The ESR signal (g = 2) intensity associated with the surface Fe was found to increase linearly with surface Fe content up to a nominal concentration of 50% exchangeable Fe. At > 50% exchangeable Fe, no appreciable increase in the signal was noted. The TL intensity decreased linearly with increasing surface Fe up to 50% nominal exchangeable Fe. At > 50%, the signal was not appreciably further diminished. The natural TL showed only a high-temperature peak, but irradiation produced an additional low-temperature peak. One month after gamma-irradiation, the integrated TL signal was still 10-100 times higher than that from the non-irradiated material. Thus, (1) surface iron clusters may form above a certain critical Fe concentration; (2) the Fe clusters are probably less effective in quenching TL than are single Fe atoms, implying interaction between surface Fe and the stored energy content of the material; and (3) the electronic energy stored in the material as the result of gamma-irradiation is only slowly dissipated.  相似文献   

东非裂谷系中一个场地的地震危险分析     

Asfaw  LM 傅征祥 《地震科技情报》1993,(8):30-33

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"The Bush is No More": Insights on Institutional Change and Natural Resource Availability in Rural South Africa     

Kirkland T  Hunter LM  Twine W 《社会与自然资源》2007,20(4):337-350

The past decade has brought substantial transition to South Africa. The introduction of democracy in 1994 has yielded important political and socioeconomic transformations affecting millions of people. Here, we explore the impact of institutional and structural changes on the availability and management of fuelwood, a key natural resource in rural South Africa. As in other developing regions, many households depend on natural resources for both sustenance and energy needs. Drawing on qualitative data from 32 interviews, our objective is to describe, from the perspective of the respondents, (1) resource scarcity, (2) the underlying causes of resource scarcity, (3) the role of traditional authority in managing resources, and (4) strategies used by community members in the face of resource scarcity. The results have important implications for the well-being of both social and natural systems in many transitional, rural developing societies.  相似文献   

“竺可桢精神与西部大开发”座谈会在兰举行     

倪建红 《高原气象》2000,(2):165

今年恰逢我国一代宗师 ,杰出的气象学家、地理学家和教育家竺可桢先生诞辰 1 1 0周年 ,由中国地理学会冰川冻土分会和沙漠分会、甘肃省气象学会及甘肃省地理学会联合主办 ,“竺可桢精神与西部大开发”座谈会于 4月 1 7日下午在中科院寒区旱区环境与工程研究所冻土工程国家重点实验室学术厅举行 ,会议由施雅风院士主持。与会代表来自兰州分院 ,兰州大学及省气象局等 ,与会者既有年过半百的专家学者 ,也有年轻的师生 ,共一百余人。会上首先放映了有关竺可桢先生的文献记录片 ,然后施雅风院士介绍了竺老如何为国办学 ,如何呕心力血地为规划新中…  相似文献   

南撒哈拉干旱研究的进展     

Druy.  LM 倪建红 《世界沙漠研究》1990,(1):35-39

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利用高分辨率地震反射技术圈定煤矿地下断层     

Goch.  LM 朱希安 《国外煤田地质》1990,(4):30-35

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Biodegradation of toxic chemicals in Guayanilla Bay,Puerto Rico   总被引：1，自引：0，他引：1  

Zaidi BR  Hinkey LM  Rodríguez NR  Govind NS  Imam SH 《Marine pollution bulletin》2003,46(4):418-423

Studies were conducted to assess the factors that may influence the rate and extent of biodegradation of biphenyl, naphthalene, phenanthrene, pentachlorophenol (PCP) and p-nitrophenol in water samples collected from the Guayanilla Bay (18 degrees N; 67.45 degrees W), southwest of Puerto Rico. In vitro studies mediated slow degradation of biphenyl, naphthalene and phenanthrene substrates by natural microbial flora present in the Bay. Addition of KNO(3) as a source of inorganic N greatly enhanced the degradation of phenanthrene but not of naphthalene, suggesting that effects on degradation due to nutrient limitation were compound specific. The rate and extent of degradation of naphthalene and PCP were higher in water samples collected closer to the source of contamination, i.e. the petrochemical complex. The identity of a phenanthrene degrading bacterium, previously identified by conventional phenotypic method (Zaidi et al., Utilizing Nature's Advanced Materials, Oxford Unviersity Press, 1999) as Alteromonas sp., was confirmed by partial DNA sequencing of the small subunit rRNA gene.  相似文献   

Milking the Plains: movement of large dairy operations into southwestern Kansas     

Harrington LM  Lu M  Kromm DE 《Geographical review》2010,100(4):538-558

Western Kansas has an historical identification with cattle, with a focus on cattle ranching and more specifically since the 1950s, beef-cattle feedlots. Since the mid-1990s large dairy operations have moved into southwestern Kansas. Today more than twenty large dairies house more than 70,000 milk cows. These operate as confined feeding operations similar to beef-cattle feedlots. Regional advantages for the dairy industry include affordable land with wide-open space, local residents' cattle- and dairy-friendly attitudes, and other factors. Regional promoters have actively recruited dairies, and a dairy-business support system has emerged. The prospects for continued expansion of dairies in southwestern Kansas are unclear; despite the locational advantages and the possibility that the industry may continue to relocate here, as did the cattle-feeding industry several decades ago, further moves into the area may depend on continued resources availability and additional infrastructure development.  相似文献   

Copper and sewage inputs from recreational vessels at popular anchor sites in a semi-enclosed Bay (Qld, Australia): estimates of potential annual loads     

Leon LM  Warnken J 《Marine pollution bulletin》2008,57(6-12):838-845

Environmental impacts of vessels are well documented; Cu pollution as result of Cu based antifouling paints and nutrient pollution (such as N) from marine sewage are two examples of such disturbances. Understanding environmental impacts as well as the use of coastal waterways by recreational vessels is of concern to regulatory authorities, waterway users and local residents. In this study more than 55 aerial surveys were conducted of selected popular anchorages in eastern Moreton Bay, Queensland, Australia. Numbers of recreational vessels at certain times during the year were used in multiple linear regression analyses to develop predictive models for recreational vessel numbers. Over one year approximately 10,000 locally registered recreational craft (>6m length overall) generated an estimated 59,000 vessel nights. With Cu leaching rates from the literature, and estimates of sewage inputs (assuming little or no use of pump-out facilities), load estimates associated with overnight use of 20 popular anchor sites were calculated as 141+/-46 kg of Cu and 1.17+/-0.38 t of nitrogen (N) annually. More importantly, the models showed vessel activity to be highly variable, and focused at peak holiday times, with 14% of vessel activity and associated pollutant loads entering the environment during Christmas and Easter. This study highlighted the inherent difficulties in managing a popular maritime amenity and Marine Parks such as the Moreton Bay Marine Protected Area, Queensland, Australia with its variety of stakeholders and types and intensities of uses.  相似文献   

2.67Ma时近北极的北太平洋地区冰川环境的快速起动：因果关系的线索     

Prue.  LM 周立君 《海洋地质前沿》1999,(6):6-7

ＯＤＰ１４５航次从近北极的北太平洋取得的重叠液压活塞岩心使得该地区首次有了晚上新世气候变化的高分辨率沉积记录。太平洋最北端的上新生代深海沉积物以快速堆积的硅质软泥和硅质粉砂粘土为主。沉积物中作为物理风化和侵蚀尺度的大量陆源组分在２．６Ｍａ之前突然增加...  相似文献