Microbial release of potassium from K-bearing minerals by thermophilic fungus Aspergillus fumigatus

A strain of thermophilic fungus Aspergillus fumigatus was cultured with K-bearing minerals to determine if microbe-mineral interactions enhance the release of mineralic potassium. Experiments were carried out in two settings, one with the mineral grains and the fungal cells in direct contact, and the other employing a membrane (pore size 0.22 μm) to separate the two. Measurements over a period of 30 days showed that, irrespective of the experimental setup, the concentration of free K in the culture was drastically higher than those in any of the control experiments where no living organism was present. Moreover, the occurrence of mineral-cell physical contact enhanced potassium release by an additional factor of 3 to 4 in comparison to the separation experiments. For contact experiments, Electron Probe Microanalysis revealed the formation of mycelium-mineral aggregates, and Atomic Force Microscopy imaging further indicated the possible ingestion of mineral particles by the fungus cells. Contrasting to what was observed and expected in control experiments, the potassium solubilization rate showed a positive dependence upon pH when fungi and minerals were mixed directly, and exhibited no correlations with solution acidity if cell-rock contact was restrained. These results appear to suggest that A. fumigatus promoted potassium release by means of at least three likely routes, one through the complexation of soluble organic ligands, another appealing to the immobile biopolymers such as the insoluble components of secretion, and the third related to the mechanical forces in association with the direct physical contact between cells and mineral particles.     

Integrating diverse methods to understand climate-land interactions in East Africa

The questions of how land use change affects climate, and how climate change affects land use, require examination of societal and environmental systems across space at multiple scales, from the global climate to regional vegetative dynamics to local decision making by farmers and herders. It also requires an analysis of causal linkages and feedback loops between systems. These questions and the conceptual approach of the research design of the Climate-Land Interaction Project (CLIP) are rooted in the classical human-environment research tradition in Geography.This paper discusses a methodological framework to quantify the two-way interactions between land use and regional climate systems, using ongoing work by a team of multi-disciplinary scientists examining climate-land dynamics at multiple scales in East Africa. East Africa is a region that is undergoing rapid land use change, where changes in climate would have serious consequences for people’s livelihoods, and requiring new coping and land use strategies. The research involves exploration of linkages between two important foci of global change research, namely, land use/land cover (LULC) and climate change. These linkages are examined through modeling agricultural systems, land use driving forces and patterns, the physical properties of land cover, and the regional climate. Both qualitative and quantitative methods are being used to illustrate a diverse pluralism in scientific discovery.     

Numerical modeling of tide-surge interaction along Orissa coast of India

The Orissa coast of India is one of the most vulnerable regions of extreme sea levels associated with severe tropical cyclones. There was extensive loss of life and property due to the October 1999 super cyclone, which devastated large part of the Orissa coast. The shallow nature of the head bay, presence of a large number of deltas formed by major rivers of Orissa such as Mahanadi and Dhamra, and high tidal range are responsible for storm surge flooding in the region. Specifically, rising and falling tidal phases influence the height, duration, and arrival time of peak surge along the coast. The objective of the present study is to evaluate the tide-surge interaction during the 1999 Orissa cyclone by using nonlinear vertically integrated numerical models. The pure tidal solution for the head bay region of the Bay of Bengal provides the initial condition for the fine resolution nested grid Orissa model. However, the feedback from the Orissa model does not affect the head bay model as the study provides a one-way interaction. Numerical experiments are performed to study the tide-surge interaction by considering various relative phases of the tidal waves with the surge-wave produced by 1999 Orissa cyclone. The comparison, although utilizing only the limited estimates of tidal data, appears adequate to assert that the principal features are reproduced correctly.     

Finite Element Modeling of Swelling Soil Pressures Using Joint/Interface Elements

There could be some discontinuities in a soil media such as layers, earth structures, cracks, and fissures so that estimation of stresses and deformations in these types of soil masses are somewhat different from continuous masses. The discontinuities in a soil mass could be considered as a special link between two blocks. Transmitted swelling pressures affected by the soil properties of the backfill especially at the interface between the backfill and retaining wall. In order to estimate the transmitted swelling pressure distribution behind a retaining wall, using with interface element, a new finite element model and a code (SWELPRES) have been developed. To evaluate the effect of backfill characteristics and interface element from the transmitted lateral swelling pressures, four cases of thickness of backfills with or without interface elements are investigated.     

强降雨条件下土质边坡瞬态稳定性分析

基于实际降雨气象资料,设计了单峰降雨和8个不同时间间隔的双峰降雨计算方案,利用非饱和土力学理论,对边坡的瞬态稳定性进行了计算和分析,研究了水分在坡体内的运移对边坡稳定性的时间空间影响效应,同时考察了降雨入渗造成的土性渗透特性的改变。分析发现：一次降雨的影响历时约12 d,降雨后约0.5 d该类土质边坡最危险;不同时间间隔的两次降雨对边坡稳定的影响比单峰降雨的最小安全系数滞后约0.3 d～0.8 d,影响历时基本保持不变;土体物理力学性质、边坡最危险滑动面及其对应的安全系数随水分在坡体内渗透运移而变化。     

橄榄岩—熔体相互作用过程中Re-Os体系的变化趋势: 对华北新生代地幔橄榄岩Re-Os年龄含义的启示

橄榄岩的Re-Os同位素体系作为探讨岩石圈地幔形成年龄的重要手段已受到人们越来越多的重视。然而,Re-Os体系是否会受到橄榄岩的低温蚀变如蛇纹石化和地幔交代作用或橄榄岩—熔体相互作用的影响并不十分清楚。本文在总结国际上典型造山带橄榄岩剖面研究和地幔橄榄岩捕虏体研究的基础上,发现橄榄岩的Re-Os同位素体系基本不受蛇纹石化等低温蚀变作用的影响; 但橄榄岩—熔体相互作用会造成橄榄岩的Re-Os体系的变化即Re或Os的带入。当熔体/岩石比例较小时(≤1),橄榄岩—熔体相互作用会造成橄榄岩的Re含量显著增加,而放射成因的Os同位素即¹⁸⁷Os增量有限。但当熔体/岩石比例很大时(≥1),会造成¹⁸⁷Os同位素显著增加。同时,橄榄岩的Re含量与中等程度不相容主、微量元素如Al、Ti、Yb的正相关关系可以通过橄榄岩的两阶段演化模式来解释,即早期的部分熔融残留和后期的橄榄岩—熔体相互作用共同影响的结果。橄榄岩的Re含量与Cr含量的正相关关系进一步说明了这一问题。上述结果对华北东部岩石圈地幔的演化过程有重要的启示作用。因为华北东部古生代时期的确存在太古宙岩石圈地幔,然而新生代时期地幔橄榄岩捕虏体普遍具有元古宙而非太古宙的事实证明橄榄岩—熔体的相互作用的确广泛存在,从而造成岩石圈地幔橄榄岩变年轻。因此,新生代地幔捕虏体的Re-Os同位素年龄并不是岩石圈地幔的形成年龄,而是混合作用的结果。汉诺坝地幔橄榄岩的Re含量和Sr、Nd同位素组成符合橄榄岩—多元熔体相互作用的混合趋势,其橄榄岩的全岩Al₂O₃含量和橄榄石Fo的反相关性能够通过橄榄岩—熔体相互作用来解释。     

西藏西南部拉昂错地幔橄榄岩的地球化学特征及其构造意义

拉昂错蛇绿岩位于西藏西南部雅鲁藏布缝合带(YZSZ)的西段,由地幔橄榄岩和侵入其中的基性岩墙组成.拉昂错地幔橄榄岩普遍发育碎斑结构及熔体注入和交代结构,尖晶石的Cr#值具有较广泛的变化(0.32～0.70),大多数样品富集LREE并伴随HFSE的明显增加,少数亏损LREE,前者部分熔融程度为15%～23%,后者为10%左右,这表明它们并不是地幔单阶段部分熔融的残余物,而是MORB型亏损橄榄岩在俯冲过程中再度部分熔融后熔体与残余地幔相互作用的产物,由于熔体不同程度的混合与交代,形成了各种再饱满程度不同的橄榄岩.对拉昂错地幔橄榄岩岩石学和地球化学特征的研究,为探讨YZSZ蛇绿岩带所代表的特提斯洋盆的形成和演化提供了新的证据.     

鲢鱼(Hypophthalmichthys molitrix)摄食强度和节律的实验研究

报道用室内实验方法对鲢鱼摄食强度和摄食节律的研究结果,探讨了影响它们的因子。提出鲢鱼在不同水温、不同花粉密度及不同鱼规格下的摄食量的统计分析。指出:食粒密度和水温与摄食量正相关,而鱼规格与摄食量负相关;食粒密度对摄食量影响最大(P<0.01),其次为水温;水温和食粒密度在影响摄食量的过程中可能有一定的交互作用。鲢鱼摄食强度在室内条件下也具明显的昼夜节律。在食粒规格较小、密度较低且溶氧充足条件下,鲢鱼夜晚非但不停食且出现摄食率次高峰。在本实验条件下,鲢鱼的日摄食节律与水温和光照无关,可能受饵料可得性和自身的生物钟节律等制约。     

南黄海灾害地质因素及分区

尝试性地将南黄海灾害地质因素分为4大类。同时参考地貌沉积界线和其他因素将南黄海分成4个灾害地质区：即海岸带、苏北浅滩、海州湾和南黄海东部灾害地质区，并时各灾害地质区进行了定性评价，苏北浅滩灾害地质区是研究区内灾害地质环境最不稳定的区域。