A budget for continental growth and denudation

Oceanic crustal material on a global scale is re-created every 110 million years. From the data presented it is inferred that potential sialic material is formed at a rate of about 1.35 cubic kilometers per year, including hemipelagic volcanic sediments that accumulate at a rate of about 0.05 cubic kilometer per year. It is estimated that the influx of 1.65 cubic kilometers per year of terrigenous and biogenic sediment is deposited on the deep ocean, and this represents continental denudation. Because all this material is brought into a subduction zone, continental accretion rates, which could include all this material, may be as high as 3.0 cubic kilometers per year with a potential net growth for continents of 1.35 cubic kilometers per year.     

Greenland Ice Sheet: High-Elevation Balance and Peripheral Thinning

Aircraft laser-altimeter surveys over northern Greenland in 1994 and 1999 have been coupled with previously reported data from southern Greenland to analyze the recent mass-balance of the Greenland Ice Sheet. Above 2000 meters elevation, the ice sheet is in balance on average but has some regions of local thickening or thinning. Thinning predominates at lower elevations, with rates exceeding 1 meter per year close to the coast. Interpolation of our results between flight lines indicates a net loss of about 51 cubic kilometers of ice per year from the entire ice sheet, sufficient to raise sea level by 0.13 millimeter per year-approximately 7% of the observed rise.     

Resource constraints in petroleum production potential

Geologic reasons indicate that the dominant position of the Middle East as a source of conventional petroleum will not be changed by new discoveries elsewhere. The share of world crude oil production coming from the Middle East could increase, within 10 to 20 years, to exceed 50 percent, under even modest increases in world consumption. Nonconventional resources of oil exist in large quantities, but because of their low production rates they can at best only mitigate extant trends. Increased production of natural gas outside the United States, however, offers an opportunity for geographically diversified energy supplies in the near future.     

Outlook for soviet oil

Public debate about Soviet oil has become more widespread in the past 5 years, but during this period Soviet petroleum exports have ceased to be made available by volume. Soviet oil consumption has usually been estimated by deducting exports from total production. This article takes the alternative approach, using Soviet statistics from a variety of sources, to build up a sectoral pattern of Soviet oil demand and to consider this in the broader context of total Comecon energy supply and demand. From this focus future prospects for the Comecon energy balance are analyzed.     

汽车的排放污染与应对途径

随着汽车工业的快速发展,汽车的保有量在逐年增加,它在给人们的生活带来方便的同时,但排放的污染物也越来越多,给人们的生产、生活以及环境造成了日益严重的危害.随着石油资源的逐步减少和以汽油、柴油为燃料的汽车对生态环境所造成的污染,除了对以汽油、柴油为燃料的汽车在技术上进行改造和采取比较严格的控制标准以外,采用清洁燃料去替代汽油、柴油,从而减轻汽车排放的污染物对人和环境所造成的不良影响,是今后汽车发展必须进行认真探讨和研究的重要课题.     

Industrial energy in transition: a petrochemical perspective

The future growth of the petrochemical industry depends in part on the industry's ability to improve efficiency in the use of oil and gas feedstocks and to develop promising alternatives. Technological innovation is proving to be the key to the long-term viability of the industry. The next 6 to 7 years will be characterized by the commercialization of new technologies designed to improve the efficiency of petroleum as a feedstock. Union Carbide's advanced cracking reactor, now nearing the demonstration stage, exemplifies this type of effort. The increasing price of oil and gas will make coal-based synthesis gas more attractive as a feedstock, particularly for oxygenated petrochemical products. A further development involves the conversion of biomass, through fermentation, to useful chemical products and the gasification of municipal wastes to raise steam for electricity generation and as a possible, supplemental feedstock. By the year 2000, it is predicted that feedstocks from all sources other than oil and gas may constitute 10 to 14 percent of the total new material requirement for the petrochemical industry.     

A global and long-range picture of energy developments

Most studies of energy supply and demand ignore either global inter-dependence or the long time spans necessary to adjust to new energy sources. The International Institute for Applied Systems Analysis has therefore studied on a global scale, for seven major world regions, the balance between energy supply and demand for the next 50 years. Reported here are the results for two benchmark scenarios. In the "low" scenario world energy consumption increases from today's 8.2 terawatt-year per year to 22 terawatt-year per year in 2030; in the "high" scenario, consumption increases to 35 terawatt-year per year. The study showed that time will be the limiting constraint in adapting the energy supply infrastructure to changing resource availability; resources will be available until the second half of the next century, but a strong shift will be required to low-grade fossil fuels such as shale oil and tar sands. Each scenario studied indicated increased environmental problems associated with increased use of fossil fuels, and potential geopolitical problems associated with the world distribution of resources.     

The international decline in household oil use

In this article estimates are made of the permanent and reversible components of changes in heating oil use in major countries of the Organization for Economic Cooperation and Development. The components of the increase in oil use through the mid-1970's, and of the subsequent decline, are revealed. For seven countries, residential oil use decreased by 40 percent between 1972 and 1983, for a savings of about 1.2 million barrels per day (59 million metric tons of oil equivalent per year). One-third of this resulted from reductions in the number of homes heated with oil, the rest from reductions in oil use per oil-heated home. During that time, however, the size of these homes and the penetration of central heating increased significantly, so these figures underestimate the actual conservation achieved. Of the total oil savings, at least 46 percent are of a permanent nature, while the rest could be reversed with a continued slide in oil prices, although it seems likely that most of the savings will be maintained and may even increase.     

盐穴型战略储油库参数选择及稳定性分析

随着我国石油资源对外依存度的逐年增加,建立完善的战略石油储备已经成为当务之急.针对盐穴型战略储油库储存运行的关键技术,结合盐岩力学特性和我国地质状况,对战略储油库造腔设计、建腔参数选择、运行参数确定以及影响储油库稳定性因素等问题进行了详细分析.研究结果表明：当储油库安全运行时,注采速率不超过4.5 m/s,并确保运行压力符合储油库的最大内压准则;溶腔内流体的热压膨胀对战略储油库前期运行安全影响较大,在长期稳定储油后,容易造成储油库内压增大,导致储存原油发生泄漏,在储油库安全运行时应尤为重视.研究成果可为今后我国盐穴战略储油库工程实践提供理论依据和技术支持.（表1,图2,参14）     

基于Pro/E石油井口排污装置优化设计与仿真分析

目前,石油开采过程中常会出现杂质随钻井液直接喷出井口的情况,即常说"返渣"现象。针对此现象,设计了石油井口排污装置。将解决钻采"返渣"作为研究目的,应用Pro/E优化/动态仿真,建立装置三维模型,对主要几何尺寸参数进行优化设计,在此基础上进行动态仿真分析。结果表明,此装置能够引导钻井液及杂质流入规定管道中,且安全性能好、操作方便快捷,解决了钻采时任其自喷的现象。     

Can the u.s. Oil and gas resource base support sustained production?

Aggressive drilling for oil and gas in the lower 48 states of the United States over the past decade yielded reserve additions sufficient to arrest decline and to stabilize levels of production. Such positive response from a maturely explored and developed oil resource base was unpredicted and largely unanticipated. Two elements of the recent experience-maintenance of stable rates of finding and substantial levels of conventional reserve growth in older fields-indicate that the capability of the resource base to sustain production is yet considerable. The volume of domestic oil and gas production that is necessary in the national interest and the extent to which the resource base should be pursued are the central issues of public energy policy.     

Net Exchange of CO2 in a Mid-Latitude Forest

The eddy correlation method was used to measure the net ecosystem exchange of carbon dioxide continuously from April 1990 to December 1991 in a deciduous forest in central Massachusetts. The annual net uptake was 3.7 +/- 0.7 metric tons of carbon per hectare per year. Ecosystem respiration, calculated from the relation between nighttime exchange and soil temperature, was 7.4 metric tons of carbon per hectare per year, implying gross ecosystem production of 11.1 metric tons of carbon per hectare per year. The observed rate of accumulation of carbon reflects recovery from agricultural development in the 1800s. Carbon uptake rates were notably larger than those assumed for temperate forests in global carbon studies. Carbon storage in temperate forests can play an important role in determining future concentrations of atmospheric carbon dioxide.     

The silica balance in the world ocean: a reestimate

The net inputs of silicic acid (dissolved silica) to the world ocean have been revised to 6.1 +/- 2.0 teramoles of silicon per year (1 teramole = 10(12) moles). The major contribution (about 80 percent) comes from rivers, whose world average silicic acid concentration is 150 micromolar. These inputs are reasonably balanced by the net ouputs of biogenic silica of 7.1 +/- 1.8 teramoles of silicon per year in modern marine sediments. The gross production of biogenic silica (the transformation of dissolved silicate to particulate skeletal material) in surface waters was estimated to be 240 +/- 40 teramoles of silicon per year, and the preservation ratio (opal accumulation in sediment/gross production in surface waters) averages 3 percent. In the world ocean the residence time of silicon, relative to total biological uptake in surface waters, is about 400 years.     

Energy options and strategies for Western europe

Western Europe, now largely dependent on oil imports, has to prepare for strong competition for oil and energy imports in general before the year 2000. The more unlikely it is for Western Europe to secure from outside rich supplies of coal or uranium at readily acceptable economic and political conditions, the more serious this competition becomes. Even exceptionally low projections of economic growth and optimistic assumptions about energy conservation urgently call for vigorous and simultaneous development of indigenous coal and nuclear sources, including the breeder. Long-term contracts for the possession and deployment of foreign oil, gas, and coal deposits are mandatory and should be negotiated in view of the possible aggravation of north-south confrontation.     

Atmospheric input of carbon dioxide from burning wood

The atmospheric input of carbon dioxide from burning wood, in particular from forest fires in boreal and temperate regions resulting from both natural and man-made causes and predominantly from forest fires in tropical regions caused by shifting cultivation, is estimated to be 5.7 x 10(15) grams of carbon per year as gross input and 1.5 x 10(15) grams of carbon per year as net input. This is a significant amount as compared to the fossil fuel carbon dioxide produced from the utilization of oil, gas, coal, and limestone, and bears on the hypothesis of the enhanced sedimentation of marine detritus as a removal mechanism of excess atmospheric carbon dioxide.     

Impending United States energy crisis

The U.S. oil and gas industry has been dramatically weakened by the recent oil price collapse. Domestic drilling activity reached a new post-World War II low during the summer of 1986. Given a weak, unstable oil price outlook, U.S. capability will continue to deteriorate. In the last year U.S. imports of foreign oil have risen significantly, and if market forces alone dominate, U.S. dependence is expected to rise from 32% in 1983 to the 50 to 70% level in the not-too-distant future. The 1973 oil embargo and the subsequent attempts to improve U.S. energy security vividly demonstrated the huge costs and long periods of time required to change our energy system. These facts, coupled with the nation's generally short-term orientation, suggest a strong likelihood of a new U.S. energy crisis in the early to middle 1990s.     

ECOLOGY: Louisiana's Vanishing Wetlands: Going, Going ..

An ambitious $14 billion plan known as Coast 2050 attempts to protect more than 10,000 square kilometers of Louisiana's wetlands, which are disappearing at a rate of up to 90 square kilometers per year, one of the highest rates of land loss in the world. But a number of unanswered scientific questions swirl around the plan. And it could run afoul of powerful interests in the shipping, petroleum, and fishing industries.     

Carbon pools and flux of global forest ecosystems

Forest systems cover more than 4.1 x 10(9) hectares of the Earth's land area. Globally, forest vegetation and soils contain about 1146 petagrams of carbon, with approximately 37 percent of this carbon in low-latitude forests, 14 percent in mid-latitudes, and 49 percent at high latitudes. Over two-thirds of the carbon in forest ecosystems is contained in soils and associated peat deposits. In 1990, deforestation in the low latitudes emitted 1.6 +/- 0.4 petagrams of carbon per year, whereas forest area expansion and growth in mid- and high-latitude forest sequestered 0.7 +/- 0.2 petagrams of carbon per year, for a net flux to the atmosphere of 0.9 +/- 0.4 petagrams of carbon per year. Slowing deforestation, combined with an increase in forestation and other management measures to improve forest ecosystem productivity, could conserve or sequester significant quantities of carbon. Future forest carbon cycling trends attributable to losses and regrowth associated with global climate and land-use change are uncertain. Model projections and some results suggest that forests could be carbon sinks or sources in the future.     

Rapid deformation of the South flank of kilauea volcano, hawaii

The south flank of Kilauea volcano has experienced two large [magnitude (M) 7.2 and M 6.1] earthquakes in the past two decades. Global Positioning System measurements conducted between 1990 and 1993 reveal seaward displacements of Kilauea's central south flank at rates of up to about 10 centimeters per year. In contrast, the northern side of the volcano and the distal ends of the south flank did not displace significantly. The observations can be explained by slip on a low-angle fault beneath the south flank combined with dilation deep within Kilauea's rift system, both at rates of at least 15 centimeters per year.     

燕麦油的提取及精炼技术研究

[目的]为燕麦油的工业化生产提供理论指导。[方法]采用石油醚浸提法提取燕麦麸皮中的燕麦油,以料液比、浸提温度、浸提时间为因素进行正交试验优化提取工艺,通过脱胶、脱酸和脱色对燕麦粗油进行精制。[结果]3个因素对燕麦油提取率的影响由大到小依次为:料液比>浸提时间>浸提温度。脱胶燕麦油得率约为91%,脱酸燕麦油得率约为80%,脱色后精制燕麦油得率约为64%。燕麦油在精制前后酸价和游离脂肪酸含量明显下降,碘价和皂化值基本不变,密度、比重、黏度和折光率均有不同程度的提高。[结论]利用石油醚从燕麦麸皮中提取燕麦油的最佳工艺为:料液比1∶10,浸提温度80℃,浸提时间12 h。