Chemical species in fly ash from coal-burning power plants

Fly ash specimens from four power plants in the Tennessee Valley Authority system have been separated into three matrices: glass, mullite-quartz, and magnetic spinel. Chemical species of trace elements are defined to a large extent by the matrices that contain them. The magnetic component of fly ash is ferrite. The mullite-quartz phase is relatively pure and can be recovered as a resource.     

Off-design performance of power plants: an integrated gasification combined-cycle example

Fossil-fueled power plants typically operate below their design capacities for a large fraction of their service life. In the United States, increased fuel and capital costs attributable to this off-design operation are considerable. This article describes the reasons for off-design operation and its importance in designing and selecting new power plants. Recent studies of coal gasification combined-cycle power plants show how computer simulations of off-design performance can aid in the design process, and they suggest that such simulations can be useful in reducing the cost of building and operating new power plants.     

抗氧化酶活性作为植物抗盐性 评价指标的有效性

以5个抗盐性不同的树种河南白榆、新疆枸杞、南蛇藤、小叶丁香、樟子松的1年生实生苗为试验材料,通过测定盐胁迫下5个树种叶片丙二醛含量和超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)、抗坏血酸氧化酶(APX)等抗氧化酶活性的变化,研究抗氧化酶活性作为植物抗盐性评价指标的有效性.结果表明:盐胁迫下5个树种叶片丙二醛含量显著增加,丁香和樟子松增加幅度明显大于枸杞和白榆.SOD、CAT可以作为不同树种抗盐性评价标准,其中SOD、CAT更为有效.各胁迫时期抗盐性较强的枸杞和白榆SOD活性随胁迫强度的增加逐渐升高,而抗盐性较弱的丁香和樟子松SOD活性却不断下降;长期胁迫下抗盐性较强的枸杞和白榆CAT活性随胁迫强度的增加逐渐升高,而抗性相对较弱的丁香和樟子松CAT活性轻度胁迫下升高,较重胁迫下却降低.POD和APX不是评价不同树种抗盐性的可靠指标.POD活性增加是一种胁迫症状,而不是一种抗性表现.随胁迫强度的增加,抗盐碱性较弱的丁香和樟子松POD活性增加,而抗盐碱性较强的枸杞和白榆POD活性却降低.     

Large groundwater strontium flux to the oceans from the Bengal Basin and the marine strontium isotope record

Strontium concentration and isotopic data for subsurface flowing groundwaters of the Ganges-Brahmaputra (G-B) delta in the Bengal Basin demonstrate that this is a potentially significant source of strontium to the oceans, equal in magnitude to the dissolved strontium concentration carried to the oceans by the G-B river waters. The strontium concentrations of groundwaters are higher by a factor of about 10 than typical G-B river waters and they have similar 87Sr/86Sr ratio to the river waters. These new data suggest that the present contribution of the G-B system to the rise in 87Sr/86Sr ratio in seawater is higher by at least a factor of 2 to 5 than the average over the past 40 million years.     

Sulfur dioxide emissions from power plants: their effect on air quality

A modeling study of atmospheric diffusion indicates that emission from power plants contributed only a modest percentage of the yearly average concentration of sulfur dioxide at ground level in the most polluted areas of Cook County, Illinois, during 1968.     

Deuterium content of snow as an index to winter climate in the sierra nevada area

The winter of 1968-69 produced two to three times the amount of precipitation in the Sierra Nevada area, California and Nevada, as the winter of 1969-70. The deuterium content in snow cores collected at the end of each winter at the same sites, which represents the total snowfall of each interval, shows a depletion in 1968-69 of approximately 20 per mil. The higher snowfall in 1968-69 and the depletion of deuterium can be explained by an uncommonly strong westward flow of cold air over and down the western slopes of the Sierras, which interacted with an eastward flow of moist Pacific air that overrode and mixed with the cold air; this resulted in precipitation that occurred in greater than normal amounts and at a lower than normal temperature. Pluvial periods of the Pleistocene may have had the same shift in air-mass trajectory as the wet 1968-69 year. Snow cores collected in the norrmal 1970-71 winter have deuterium concentrations that resemble those of the normal 1969-70 winter. Small and nonsystematic differences in samples from these two normal winters are due to variations in climatic character as well as to factors inherent in the sampling sites.     

Seawater strontium isotopic variations from 2.5 million years ago to the present

Measurements of marine carbonate samples indicate that during the past 2.5 million years the (87)Sr/(86)Sr ratio of seawater has increased by 14 x 10(-5). The high average rate of increase of (87)Sr/(86)Sr indicates that continental weathering rates were exceptionally high. Nonuniformity in the rate of increase suggests that weathering rates fluctuated by as much as +/-30 percent of present-day values. Some of the observed shifts in weathering rates are contemporaneous with climatic changes inferred from records of oxygen isotopes and carbonate preservation in deep sea sediments.     

含钴废水的粉煤灰处理效果初报

为解决含钴工业废水的污染问题,实验以热电厂废弃物粉煤灰为吸附剂,采用EDTA滴定法,对含钴废液进行了吸附研究。模拟测定了影响粉煤灰吸附特性的几种因素,即吸附时间、待吸附液pH值、温度、加灰量以及振动速度等,并分析了粉煤灰处理废水的机理。结果显示,在其它条件相同的情况下,随着吸附温度的降低,振荡速率的增加,加灰量的增加,吸附时间的适当延长,pH的升高,去除率逐渐升高。研究表明,采用粉煤灰吸附含钴工业废水,可以得到较好的处理效果,能达到以废治废的目的。     

应用H指数及G指数对科研人员的绩效进行评价研究——以华北煤炭医学院学者为例

利用《中国学术文献网络出版总库》的检索数据,通过对华北煤炭医学院著者发表论文的被引用情况分析,应用H指数、G指数对本校著者的影响力进行了较为合理的评价和分析,并且应用SPSS软件对H指数、G指数和总被引频次之间的相关性进行了分析。     

象山港滨海电厂温排水对浮游生物的生态影响

应用海洋数值模式ECOM-si耦合一个可用于实时计算的太阳辐射强度和海面热通量计算模块,采用N2P2ZD型生态模型,研究评估了象山港海域的浮游生物量受港内两大滨海电厂(国华电厂和乌沙山电厂)温排水的影响程度。数值模式的模拟结果表明,温排水及其卷载和余氯杀伤效应对海域的浮游生物量有显著影响,一定程度上改变了象山港浮游生物量的季节变化规律和空间分布特征。在春季和初夏等增温季节,温排水的存在可使藻华的发生期提前;夏季高温期,水温超过最佳生长温度,则使浮游植物生物量下降,且可降低赤潮发生的风险;在秋季降温期和冬季低温期,水温低于最佳生长温度,温排水有助于缓解水温的下降,有助于提高该时期海域的初级生产力。除了季节变化上有增有减外,浮游植物和浮游动物量年均水平由于温排水的温升和杀伤效应而降低,碎屑量随之上升,总体上弥补了海域水体总有机体含量的损失,但海域的年均总有机体变化量仍为负值。国华电厂温排水的影响大于乌沙山电厂。无论从温升范围和浮游生物量变化幅度上,国华电厂对铁港的影响都大于黄墩港。     

Crop water stress index derived from multi-year ground and aerial thermal images as an indicator of potato water status

Potato yield and quality are highly dependent on an adequate supply of water. In this study, 3 years of information from thermal and RGB images were collected to evaluate water status in potato fields. Irrigation experiments were conducted in commercial potato fields (Desiree; drippers). Two water-deficit scenarios were tested: a short-term water deficit (by suppressing irrigation for a number of days before image acquisition), and a long-term cumulative water deficit. Ground and aerial images were acquired in various phenological stages along the potato growing season. Effects of irrigation treatments were recorded by thermal indices and biophysical measurements of stomatal conductance (SC), leaf water potential, leaf osmotic potential and gravimetric water potential in soil. Canopy temperature was delineated from the thermal images with and without fused information from the RGB image. Crop water stress index (CWSI) was calculated, using three forms of minimum baseline temperature: empirical, theoretical and statistical. An empirical evaluation of maximum baseline temperature of Tair + 7 °C was used in all CWSI forms examined. Statistical tests and comparison of CWSI with biophysical measurements were performed to evaluate the responses to irrigation treatments. The results indicated a high correlation of CWSI with SC from tuber initiation to maturity based on ground and aerial data (0.64 ≤ R² ≤ 0.99). Similar trends of increasing CWSI from well to deficit-irrigated treatments were found in all three growing seasons. The results also showed that CWSI may be calculated based merely on thermal imagery data.     

七种植物粗提物对常见植物病菌的抑菌作用研究

用生长速率法以辣椒丝核病菌、黄瓜黑星病菌、番茄早疫病菌和黄瓜枯萎病菌为供试菌种,对7种植物的12种二氯甲烷提取物进行了抑菌活性测定。结果表明:龙葵全株粗提物对辣椒丝核和黄瓜黑星病菌、龙葵果实提取物对黄瓜枯萎病菌、苍耳果实提取物对辣椒丝核病菌的抑制率均为100 %;黄花蒿(全株)提取物对黄瓜枯萎病菌、番茄早疫病菌和辣椒丝核病菌的菌丝抑制率都分别达到了78.5 %以上。     

农林生物质直燃电厂灰渣资源化技术分析与展望

近年来我国农林生物质直燃电厂发展迅速,日益增长的灰渣带来了越来越大的环境压力。生物质电厂灰渣是一类富有价值的可回收资源,亟待有效利用。有必要寻找一种合理的资源化手段整体处理灰渣。本研究综述了我国农林生物质直燃发电的发展现状、生物质灰渣的理化性质及其在基础设施建设、土壤修复改良、元素回收、吸附材料与复合材料制备等领域的应用,进而提出了依据灰渣粒径差异资源化处理电厂灰渣的一体化方案。不同粒径的生物质灰渣经过细分处理,可提高灰渣的资源利用率,有利于农林生物质直燃电厂的可持续发展。     

Transgenic plants as tools to study the molecular organization of plant genes

Transgenic plants are generated in nature by Agrobacterium tumefaciens, a pathogen that produces disease through the transfer of some of its own DNA into susceptible plants. The genes are carried on a plasmid. Much has been learned about how the plasmid is transferred, how the plasmid-borne genes are organized, regulated, and expressed, and how the bacteria's pathogenic effects are produced. The A. tumefaciens plasmid has been manipulated for use as a general vector for the transfer of specific segments of foreign DNA of interest (from plants and other sources) into plants; the activities of various genes and their regulation by enhancer and silencer sequences have been assessed. Future uses of the vector (or others like it that have different host ranges) by the agriculture industry are expected to aid in moving into vulnerable plants specific genes that will protect them from such killers as nonselective herbicides, insects, and viruses.     

Endophytic insect-parasitic fungi translocate nitrogen directly from insects to plants

Most plants obtain nitrogen through nitrogen-fixing bacteria and microbial decomposition of plant and animal material. Many vascular plants are able to form close symbiotic associations with endophytic fungi. Metarhizium is a common plant endophyte found in a large number of ecosystems. This abundant soil fungus is also a pathogen to a large number of insects, which are a source of nitrogen. It is possible that the endophytic capability and insect pathogenicity of Metarhizium are coupled to provide an active method of nitrogen transfer to plant hosts via fungal mycelia. We used soil microcosms to test the ability of M. robertsii to translocate insect-derived nitrogen to plants. Insects were injected with (15)N-labeled nitrogen, and we tracked the incorporation of (15)N into amino acids in two plant species, haricot bean (Phaseolus vulgaris) and switchgrass (Panicum virgatum), in the presence of M. robertsii. These findings are evidence that active nitrogen acquisition by plants in this tripartite interaction may play a larger role in soil nitrogen cycling than previously thought.     

龟纹瓢虫对茶树挥发物的行为反应

以洁净空气为对照,源于茶树的27个单一挥发物及其中芳樟醇、反-2-己烯醛和顺-3-己烯-1-醇的混合物和8个“绿叶组分”的混合物为味源,设10^-6,10^-4,10^-2g/ml 3个剂量,用Y形嗅觉仪测定了这29种味源对龟纹瓢虫的引诱效应。结果表明：（1）当剂量是10^-6g/ml时,选择烯丙基异硫氰酸酯的瓢虫数显著高于选择对照的（P〈0.05）;（2）当剂量是10^-4g/ml时,选择芳樟醇、苯甲醛、水杨酸甲酯、正己醇、1-戊烯-3-醇、（＋）-3-蒈烯和苯甲醇的瓢虫数分别高于选择对照的（P〈0.05）;（3）当剂量是10^-2g/ml时,选择所有单一挥发物的瓢虫数分别与选择对照的瓢虫数的差异均未达显著水平;（4）龟纹瓢虫趋向2组混合物,其数量分别与趋向对照的数量差异不显著。分析认为,茶树挥发物对该瓢虫有引诱效应,其中苯甲醛和水杨酸甲酯等互利素的引诱效应更强;该瓢虫对信息物的趋向性存在着阈值,但高剂量信息素有抑制效应;不恰当的信息物组配不能引起该瓢虫显著趋性。可供信息物调控龟纹瓢虫行为的参考。