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Dowty RA Shaffer GP Hester MW Childers GW Campo FM Greene MC 《Marine environmental research》2001,52(3):195-211
Research was conducted to assess the impact of oiling on fresh-marsh plant communities and to test the efficacy of techniques that may be used to enhance the bioremediation of crude oil spills in these environments while minimizing secondary anthropogenic impacts. To emulate field conditions, a mesocosm facility was used that houses 120 mesocosm vessels, each of 200-1 capacity. A five-way factorial treatment arrangement was used that included two substrates (inorganic, organic), two nutrient regimes (fertilized, not fertilized), two aeration levels (substrate aeration, no aeration), three oiling concentrations (0-, 5-, 10-1 m(-2) of South Louisiana Sweet Crude oil), and four vascular plant species (Alternanthera philoxeroides, Panicum hemitomon, Phragmites australis, Sagittaria lancifolia, and an unplanted control). Under the 5- and 10-1 m(-2) oiling concentrations, S. lancifolia displayed a short-term response of increased productivity, whereas P. hemitomon had the highest biomass production and photosynthetic rates at the end of the 18-month experiment. Overall plant growth and productivity, as well as oil degradation, were significantly higher in the inorganic substrate, indicating that biodegradation of oil spills in organic substrates may require a longer time period. Time-released fertilizer also stimulated plant productivity and resulted in higher soil respiratory quotients, suggestive of greater microbial activity, particularly in aerated mesocosms. The amount of oil remaining after 18 months was lowest in aerated and fertilized mesocosms containing either P. hemitomon or S. lancifolia and a substrate of low organic matter content. 相似文献
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A study using multiple techniques provided insight into tectonic influences on ground water systems; the results can help to understand ground water systems in the tectonically active western United States and other parts of the world. Ground water in the San Bernardino Valley (Arizona, United States and Sonora, Mexico) is the main source of water for domestic use, cattle ranching (the primary industry), and the preservation of threatened and endangered species. To improve the understanding of ground water occurrence, movement, and sustainability, an investigation was conducted using a number of complementary methods, including major ion geochemistry, isotope hydrology, analysis of gases dissolved in ground water, aquifer testing, geophysics, and an examination of surface and subsurface geology. By combining information from multiple lines of investigation, a more complete picture of the basin hydrogeology was assembled than would have been possible using fewer methods. The results show that the hydrogeology of the San Bernardino Valley is markedly different than that of its four neighboring basins in the United States. The differences include water quality, chemical evolution, storage, and residence time. The differences result from the locally unique geology of the San Bernardino Valley, which is due to the presence of a magmatically active accommodation zone (a zone separating two regions of normal faults with opposite dips). The geological differences and the resultant hydrological differences between the San Bernardino Valley and its neighboring basins may serve as a model for the distinctive nature of chemical evolution of ground water in other basins with locally distinct tectonic histories. 相似文献
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本文根据唐山主震、强余震震源参数、强余震迁移规律以及地面破坏分布等多方面资料,论证唐山地震障碍体的存在,给出了宁河、滦县—卢龙断层面上障碍体的大致位置.并用障碍体模式对唐山连发式强震的震源过程进行了讨论.笔者认为,唐山主震即是主震断层面上的障碍体破裂所致.主震断层的破裂传播在宁河、滦县—卢龙受阻于障碍体而终止,在这两处形成新的应力集中区.这两个应力集中区在障碍体的阻挡和主震区的挤压下产生两次最大强余震. 相似文献
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本文用非线性方法分析了吉林省１９８９年以来的地震活动图像,认为１９８９年至１９９４年吉林省内发生的一系列４．０级左右的地震,显示出时间和空间上的有序性,而这种有序的地震活动图象,很可能是未来中强地震的中期背景。１９９４年后,省内再没有发生４．０级以上地震,而小震频度开始上升,１９９６年则高达４０余次,其中可定位的２．０级以上地震２８次。与此同时,多项地学指标出现同步异常。根据以上情况,我们认为吉林 相似文献
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挪威某些铜镍矿石中单斜磁黄铁矿出溶体的退火和粗化 总被引：4，自引：0，他引：4
在挪威某些正岩浆铜镍矿床的矿石中，六万磁黄铁矿基质内的单斜磁黄铁矿叶片是高温时形成的磁黄铁矿固溶体在降温过程中出溶的产物。出溶叶片宽度和间距的加大、叶片的带状分布、楔形尖端、箱状扭曲和复杂叶片等结构，表明出溶产物在不高于单斜-六方转变温度（254℃）的条件下发生过显著的退火和粗化。重结晶的六方磁黄铁矿基质中所保存的单斜变种甚少，表明变质作用所引起的矿石重结晶，可使磁黄铁矿吸收其中的单斜出溶体而发生均匀化。 相似文献
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吉林省汪清两次深源地震的研究 总被引：1，自引：0，他引：1
本文在给出了发生在吉林省汪清的两次深源地震的基本参数、CMT解及有感范围等基本情况的基础上，总结了对2002年6月29日汪清7．2级深源地震的预测情况。对汪清两次深震前出现的水位、水化学异常进行了分析，初步认为异常可能与深源地震孕育过程中引起的大区域应力场调整有关。对6月29日汪清7．2级深源地震前长春净月地震台体应变仪记录到的前驱波机理进行了分析，认为对前驱波机理的研究，可能成为地震预测的一个突破点。 相似文献