Ammonium-dependent regulation of aerobic methane-consuming bacteria in landfill cover soil by leachate irrigation

The impacts of landfill leachate irrigation on methane oxidation activities and methane-consuming bacteria populations were studied by incubation of landfill cover soils with leachate and (NH₄)₂SO₄ solution at different ammonium concentrations. The community structures and abundances of methane-oxidizing bacteria (MOB) and ammonia-oxidizing bacteria (AOB) were examined by PCRDGGE and real-time PCR. Compared with the pure (NH₄)₂SO₄ solution, leachate addition was found to have a positive effect on methane oxidation activity. In terms of the irrigation amount, ammonium in leachate was responsible for the actual inhibition of leachate. The extent of inhibitory effect mainly depended on its ammonium concentration. The suppression of the predominant methaneconsuming bacteria, type I MOB, was responsible for the decreased methane oxidation activity by ammonium inhibition. Methaneconsuming bacteria responded diversely in abundance to ammonium. The abundance of type I MOB decreased by fivefold; type II MOB showed stimulation response of fivefold magnification upon the first addition but lessened to be lower than the original level after the second addition; the amount of AOB was stimulated to increase for 20-30 times gradually. Accumulated nitrate from nitrification strengthened the ammonium inhibition on type I and type II MOB, as a result, repetitive irrigation was unfavorable for methane oxidation.     

澳大利亚昆士兰的下地壳捕虏体:大陆玄武岩地壳深部同化作用和分离作用的证据

<正> 前言对下地壳捕虏体系列进行的综合性岩石学、地球化学及同位素研究,为下地壳某些部分是怎样和什么时候形成的提供了直接的信息。此外,堆积作用形成的捕虏体能提供有关沉淀出它们的熔融体的成因和演化信息。我们     

埃塞俄比亚的地震危险性

<正> 1 地震危险性评定历史当1961年6月M6.7级地震完全摧毁了Afar盆地西部边缘附近的一个小镇时,人们强烈地意识到进行地震危险性评定的重要性。此后,又发生了若干破坏性地震,使得进一步增强了对地震危险性评定工作的要求。随后,在1973年,埃塞俄比亚的第一部建筑规范中,增加了地震区域设计要求和可采用的地震危险性图。Gouin(1979)对埃塞俄比亚和非洲角进行了综合地震研究,这项研究结果所产生的地震目录是该地区目前进行地震危险性评定的最重要的基础资料。Gouin(1976)采用一系列烈度衰减曲线,出版了北非西部和东部的地震概率图。Gouin的工作得到了修正,主要是采用了区域烈度衰减关系,并增加和修订了该地区的地震目录(Asfaw,1988)。目前,在建设中已广泛采用了地震危险性评定。     

陆壳与地壳中Nd和Sr同位素的分别演化

从整体来看,Nd和Sr同位素在碎屑沉积岩和陆壳中是独立演化的,因为Sr优先从大陆再循环到地幔中去。结果,由陆壳的Sr同位素和平均Rb-Sr年龄推导出的地慢的分异年龄都比其真实年龄要小。     

Use of lysimeters to estimate leaching of pesticides in agricultural soils

In this review of lysimeters, different aspects concerning soil-filling technique, lysimeter size and materials, and drainage-system type are discussed. The placement of lysimeters in the field is dealt with, as are other types of field measurements that can provide complementary information. Evaluations of various properties are based on the assumption that the lysimeters are to be used for estimating pesticide leaching. Guidelines for use in designing a suitable lysimeter experiment for this purpose are described, with special emphasis placed on using the results as a basis for pesticide registration. In this context, some general recommendations are identified. Concerning the lysimeter itself, stress is placed on the importance of using undisturbed soil monoliths. It is recommended that two soil types, i.e. sand and clay, be used and that the management practices carried out closely resemble normal farming practices. Further recommendations include weekly water sampling, two watering regimes, and use of the normal and double the normal application rate of pesticides.     

Effect of gamma-irradiated sludge on the growth and yield of rice (Oryza sativa L. var. GR-3)

The effects of gamma-irradiated sludge on the growth and yield of rice (Oryza sativa L. var. GR-3) in pot cultures have been studied. Compared to plants grown only in soil, shoot length, root length, fresh weight, dry weight, total proteins, total soluble sugars, starch and chlorophyll content of plants grown in soil supplemented with unirradiated or gamma-irradiated sludge were found to be significantly increased. Irradiation of sludge significantly stimulated the linear growth of shoot and root systems as well as fresh and dry weights of plants, compared to those grown in soil containing unirradiated sludge. There was also an improvement in the grain yield (weight of seed) when plants were grown in soil supplemented with irradiated sludge. The results obtained suggest that the gamma-irradiated sewage sludge can be beneficially recycled for agricultural uses.     

1975年国际粘土会议

1975年国际粘土会议将于1975年7月16—23日在墨西哥的墨西哥城举行。会议内容包括地质学和成岩作用、晶体化学、地球化学、胶体性质、表面化学、分析化学以及粘土与污染相互作用等。会议还将召开关于高岭石、沸石、粘土和土壤力学、粘土和农业土壤等的专题讨论会。     

大气增温影响及对策

科学家预测,在以后的几十年中,由于大气中二氧化碳和其它产生“温室效应”的气体的增加,地球的温度将升高到史无前例的水平。温度的增加,降雨量规律的变化及海平面的上升所带来的问题将严重阻碍工业国和发展中国家的经济发展。例如,要维持正常的粮食生产,仅调整灌溉格局一项,全世界可能要投资近二千亿美元。据估计,全世界用于应付气候变化的费用达到经济总产值的3%。这也许会葬送经济增长的全部利润。由于工厂,交通运输工具,发电厂及     

The effects of selected NOx reduction scenarios on long-term nitrogen deposition and episodic ozone levels in Europe

For computational reasons, evaluations of NO(x) emission controls usually concentrate on either episodic or annual impacts on pollution or deposition levels. However, previously published model results indicate that the consequences of NO(x) controls can be quite different on these different time scales. In this paper we analyse the impact of a consistent set of NO(x) control scenarios on both the episodic and annual time-scales. Using similar models, we compute levels of episode peak O(3) and NO(2) and annual NO(y)-N and total N deposition at three locations in Europe due to six emission scenarios derived from OECD estimates. An NO(x) control scenario which reduces European emissions by 63%, only results in total annual N deposition reductions of 19, 36 and 26% at the three locations examined because of the influence of ammonia-nitrogen deposition. The same scenario results in either increases or decreases in episode peak O(3) due to the influence of hydrocarbons. Emission reduction strategies should take into account not only NO(x) emissions, but emissions of other pollutants, such as hydrocarbons and ammonia.     

Pollutant loads from the drainage basin to the Venice Lagoon (Italy)

In order to assess the actual pollutant loads from the drainage basin, the twelve major tributaries of the Venice Lagoon were monitored and studied in the period 1998-2000 in the framework of the DRAIN project. A specific sampling scheme was designed to investigate the effects of the different regimes, including floods, in the transport of total and dissolved metals, nitrogen and phosphorous species as well as organic micropollutants. The loads were calculated from data collected during the year of 1999, since this year displayed a value close to the mean in terms of the distribution of total rainfall on the drainage basin. The annual values for the different pollutants are reported and discussed. A comparison with the estimates of previous investigations highlights the significant advancement provided by the DRAIN project results in the understanding of the drainage basin contribution to the pollution of the lagoon. Finally, the importance of flood events on the overall balance of materials and pollutants delivered to the lagoon is emphasized.