Geomicrobiological in-situ containment of uranium in subsurface and its long-term stability     

Won-Kyoung Ha Jong-Un Lee 《中国地球化学学报》2006,25(B08):110-111

Uranium is a redox-sensitive element. While U （Ⅵ）, the oxidized form of uranium, is soluble and thus mobile in groundwater, U （Ⅳ） readily forms UO2（s） and is precipitated. Recent geomicrobiological researches demonstrated that dissimilatory metal reducing bacteria can effectively remove uranium fi＇om contaminated groundwater by reducing soluble U （Ⅵ） to relatively insoluble U （Ⅳ）. This novel form of microbial reduction of U （Ⅵ） is reported to be much faster than abiological reduction. The objective of this work was to investigate U （Ⅵ） reduction by indigenous bacteria in uranium-bearing black shale sediment and to determine whether microbially-precipitated uranium has long-term stability in subsurface. Through this study, fundamental information on the effects of microorganisms on the fate of redox-sensitive elements in natural settings will be provided. Soil and sediment samples were collected from uranium-bearing black shale in the Dukpyung area in Korea. Microbial inoculum was prepared from soil and sediment slurry supernatant. The reactors were purged with N2 ： CO2 gas （80 ; 20） to maintain anaerobic condition. Glucose, acetate or lactate was added as an electron donor at a final concentration of 5 mM.  相似文献   

A Promising style of growth velocity model of green algae and diatoms in local lake area     

Zhihong WANG Fuyi CUI Jie JIA Wenxuan CHEN 《中国地球化学学报》2006,25(B08):162-163

A serious and difficult problem confronting those water plants which use reservoirs as water resources is how to predict the time when algae bloom would happen. A series of experiments have been designed and finished after efforts of nearly one year, and achieved some important and useful regulations which can do great help to the problem. In order to study the correlation between changes of several typical indices and growth regulation, algae were cultivated in an artificial environment. The raw water of these experiments came from subsurface water at the Dashahe Reservoir in Guangdong Province, China. During the cultivating process, it strictly controlled original indexes as trophic factors, ecological factors and topographic factors, and has successfully achieved 64 sets of experiment data, which indicate some suggested conclusions. Water temperature and light intensity are the prime inducements of algae bloom when water environment is nutritionally sufficient. It has proved that original trophic status, light intensity and water temperature have important effects on algae growth velocity. It has analyzed different algae growth velocities due to different original total nitrogen and total phosphorus, as well as light intensity, and used the data of algae biomass in lag phase and log phase to study the correlation between time and algal biomass with SPSS software. Results indicated that both under different original nutritional conditions and under different light intensities, the relationship between algae biomass and time matches an exponential function very well. So, it proposes a very promising style algal growing velocity model, which can be expressed as：dDdt = kent. According to the model, original trophic status, light intensity and water temperature will affect the concrete values of variants k and n.  相似文献   

The free jet as a means to improve water quality: Destratification and oxygen enrichment     

Jürgen Michele  Volker Michele 《Limnologica》2002,32(4):329-337

Rivers, lakes, and coastal waters are chaotic systems — physical, chemical, and biological parameters influence their development. Each parameter itself is influenced by the system. Human interaction has led to fast eutrophication. Oxygen input and artificial mixing have been considered as tools to overcome the biggest problems of fish kills, algal blooms, and bad odour. The favoured technology for destratification and oxygen input so far is the bubble curtain. This technology has been applied successfully in several cases. But often, this technology could not be implemented because of high investment and operating costs.

Alternatively, the free jet is discussed as an efficient and low investment and operating cost technology. The free jet may transport oxygen-rich water from the surface down into the hypolimnion, thereby destratifying a water system. A free jet entrains on its way down even more oxygen rich and warm epilimnic water. This water will finally — if some mixing with the cold hypolimnic water occurs — be transferred to the metalimnion. The density differences will make this water travel long distances.

The energy input may be very low and the objective must not be to totally overturn a system. A jet started in early spring may help a lake to have a deep enough epilimnion, relatively large in volume in respect to the hypolimnion, and the normal wind will recirculate the water transferring enough oxygen to the deeper part, thus expanding the fish habitat and enabling benthic fauna. Literature also shows that the occurrence of massive algal blooms may be reduced.

The oxygen efficiency can be multifold compared to standard technologies.  相似文献   

巢湖、太湖蓝藻湖靛及其提取物的动物毒性初步研究   总被引：1，自引：0，他引：1  

瞿文川  苏晨伟 《湖泊科学》1996,8(2):156-160

对国内淡水湖泊巢湖、太湖中的蓝藻湖靛及其提取物（藻胆蛋白），进行了动物毒性实验。实验动物为昆明种小白鼠，采用灌胃法给药。给药后小白鼠均无中毒症状，一周内无死亡。说明巢湖、太湖中蓝藻湖靛及其提取物，对以小白鼠为代表的哺乳类动物消化系统，基本不产生毒性。这对于开发两湖中的蓝藻作为鱼、家禽等饲料和提取其中的植物蛋白（藻胆蛋白）作为营养食品添加剂等有一定意义。  相似文献   

沙暴天气的云图特征分析   总被引：9，自引：1，他引：9       下载免费PDF全文

郑新江  刘诚  崔小平  耿树民  赵亚民 《气象》1995,21(2):27-31

在研究我国沙暴分布特征的基础上，通过两次沙暴天气的对比分析，给出了沙暴天气的云图特征。  相似文献   

吉林省中、新生代黑色页岩（油页岩）中某些金属元素富集特征     

李红  王东坡  高福红  杨瑞英  李盛华 《吉林大学学报(地球科学版)》1994,(3)

吉林省中、新生代黑色页岩（油页岩）中Ａｇ、Ｕ、Ｃｏ、Ｎｉ等元素含量偏高；黑色页岩（油页岩）中古生物组合丰富，有机碳含量很高（＞２％）．研究了吉林省中、新生代黑色页岩（油页岩）中稀、贵金属元素富集特征，初步探讨了其富集机理，为吉林省中、新生代含金属的黑色页岩（油页岩）的综合利用提供参考。  相似文献   

武汉东湖微囊藻水华形成及消失原因的探讨——围圈放养实验   总被引：3，自引：1，他引：3  

刘学君  谢平  王少梅  王建 《湖泊科学》1994,6(3):245-256

采用围圈试验的方法,将东湖微囊藻水华的形成和消失过程重现。根据有关生物调控(Biomanipulation)的原理,我们设计了鲢鳙草鱼的放养试验。实验结果表明:放养鲢鳙的围圈,水华在很短时间(约15天)内消失,放养草鱼的围圈,水华几乎不受影响,而没有放养的围圈,其水华日趋浓厚。这一结果显示出滤食性鱼类对围圈内浮游生物群落结构的影响是巨大的。在实验过程中通过测定碳、氮、磷等营养元素的变化,重点探讨了它们对微囊藻水华形成与消失过程的影响。  相似文献   

Race and Primary,Return, and Onward Interstate Migration     

K. Bruce Newbold 《The Professional geographer》1997,49(1):1-14

This paper uses the U.S. 1990 Public Use Micro Sample to characterize the 1985-1990 primary, return, and onward interstate migration patterns for blacks and whites. The classification of these three types of migration is based on the state of birth and state of residence at the start and end of the census interval. Major migration streams, migration rates, and net migration are evaluated for each migrant type and compared for blacks and whites. Overall, the migration patterns of blacks resemble those of whites, with an attraction to the South and the Southwest and movement out of the Northeast and the Midwest. Some differences were observed, however, between the two races. Return migration rates were somewhat higher for black migrants as compared with whites, and onward migration rates were lower. Black primary out-migrants represented a larger proportion of the total flows from the southern states as compared with white out-migrant flows, and they represented a larger share of the out-migrants from the rust belt states. The major migration streams also had different regional and national patterns by race and migrant type.  相似文献   

白果园黑色岩系型银（钒）矿床沉积古环境与银（钒）初始富集   总被引：9，自引：0，他引：9  

庄汉平  卢家烂 《地质论评》1997,43(4):373-380

白果园银（钒）矿产于震旦系陡山沱组黑色色岩系中。矿床的地球化学和有机地球化学研究表明，黑色页岩含丰富以低等海生生物为主的腐泥型有机质，黑色页岩形成于局限的滞留海盆。  相似文献   

“5·5"黑风暴过程初步探讨   总被引：3，自引：0，他引：3  

杨克明  韩建钢  顾秋瑾  赵梅 《气象》1993,19(12):23-28

利用实测资料,采用有限区数值预报模式计算的物理参数,对1993年5月5日特大黑风暴天气过程形成的物理条件及成因进行了诊断分析研究。探讨了变温梯度、动量下传、地形特征等因子的重要作用,给出了诸物理量的分布特征和黑风暴形成条件的模型及具有预报意义的一些判据。  相似文献