Metamorphic waters from the pacific tectonic belt of the west coast of the United States

Waters unusually rich in ammonia, boron, carbon dioxide, hydrogen sulfide, and hydrocarbons are found in more than 100 localities along the Pacific coast of the United States. The waters are believed to be products of low-grade metamorphism of marine sediments. The marine sedimentary rocks would have to be tectonically emplaced below crystalline rocks in many places. Mercury ore deposits are probably also products of the low-grade metamorphism.     

Extension of northeastern-pacific fracture zones

The great fracture zones of the northeastern Pacific extend into the central Pacific. At a relatively constant distance of 4500 to 4900 kilometers west of the crest of the East Pacific Rise and of its projection through North America, the typically straight and simple fracture zones branch and become more complex. However, the Clipperton fracture zone, including one branch, follows a great circle for almost 10,000 kilometers, a quarter of Earth's circumference.     

Origins of the 1988 north american drought

The 1988 summer drought in the United States was the most extensive in many years. Because the drought developed in different places at different times, not all regional effects can be traced to the same cause. Along the West Coast and in the northwestern United States drought conditions developed during 1987 in association with the 1986 to 1987 El Ni?o in the tropical Pacific Ocean. Record low rainfalls from April to June 1988 led to rapid development of drought in the North Central United States. Strong anticyclonic conditions and a northward displaced jet stream in the upper atmosphere over North America throughout this period were only part of pronounced and distinctive wavetrain of anomalies in the atmospheric circulation that appeared to emanate from the tropical Pacific. Below average sea surface temperatures along the equator in the Pacific in the northern spring of 1988, combined with warmer than normal water from 10 degrees to 20 degrees N, led to a northward displaced but still active intertropical convergence zone (ITCZ) southeast of Hawaii. Results from a steady-state planetarywave atmospheric model indicate that the atmospheric heating anomalies associated with the displaced ITCZ can force an anomalous wavetrain across North America similar to that observed. Land surface processes probably contributed to the severity and persistence of the drought; however, the large-scale atmospheric circulation perturbations associated with natural variations in the coupled atmosphere-ocean system in the tropical Pacific were most likely the primary cause.     

Climatic anomalies in the tropical pacific ocean and corn yields in the United States

The association between climatic anomalies in the tropical Pacific Ocean, often called El Ni?o events, and annual corn production in the United States was investigated. Temperature and atmospheric pressure in parts of the United States have been correlated with El Ni?o events. This research suggests that in years in which an El Ni?o event causes surface temperatures in the tropical Pacific to become warmer than normal, there is a higher probability of an above-average corn crop in the United States. For years when sea surface temperatures are average or cool, no significant association is observed.     

Evolving subduction zones in the Western United States, as interpreted from igneous rocks

Variations in the ratio of K(2)O to SiO(2) in andesitic rocks suggest early and middle Cenozoic subduction beneath the western United States along two subparallel imbricate zones dipping about 20 degrees eastward. The western zone emerged at the continental margin, but the eastern zone was entirely beneath the continental plate. Mesozoic subduction apparently occurred along a single steeper zone.     

Oceanic sediment volumes and continental drift

The volume of sediment off the Atlantic Coast of the United States is at least six times as great as that off the Pacific Coast. This disparity is readily accounted for if the continent is drifting westward and has overrun large volumes of sediment on a former Benioff zone. Such an overrunning is also consonant with many features of the geology of the western United States.     

Reduction of permeability in granite at elevated temperatures

The addition of hydrothermal fluids to heated, intact granite leads to permeability reductions in the temperature range of 300 degrees to 500 degrees C, with the rate of change generally increasing with increasing temperature. The addition of gouge enhances the rate of permeability reduction because of the greater reactivity of the fine material. Flow rate is initially high in a throughgoing fracture but eventually drops to the level of intact granite. These results support the fault-valve model for the development of mesothermal ore deposits, in which seals are formed at the base of the seismogenic zone of high-angle thrust faults. The lower temperature results yield varying estimates of mineral-sealing rates at shallower depths in fault zones, although they generally support the hypothesis that such seals develop in less time than the recurrence interval for moderate to large earthquakes on the San Andreas fault.     

Rana pipiens complex: mating call structure and taxonomy

Geographic variability in call structure indicates that four largely allopatric populations of leopard frogs are present in the central United States. These forms appear to maintain their distinctness in narrow zones of sympatry, and most adult males can be separated morphologically. It is suggested that the four forms represent distinct species and that the idea of gradual clinal variability in one wide-ranging species is wrong.     

耦合视角下生产性服务业与智慧农业发展的研究 ——基于美国的经验与启示

为了推进农业生产性服务业与智慧农业的耦合,进而为我国小农户衔接智慧农业提供桥梁。本文选取美国为典型案例,分析美国生产性服务业与智慧农业耦合发展的模式和措施。采用比较研究法,归纳中美生产性服务业与智慧农业耦合发展的异同。研究表明,美国生产性服务业与智慧农业发展具有服务耦合、产业耦合和利益耦合三种模式,美国为推进其耦合发展而采取了立法保障、信息化建设、农业大数据利用和高素质人才培养等一系列措施。中美两国在智慧农业的高门槛、农业人口流失与老龄化问题、突发性公共卫生危机等方面存在共同点。但与美国相比,中国的生产性服务业与智慧农业之间的关系尚处于并行分离的状态,存在耦合层次较低,创新驱动力不足等问题。因此,为推动生产性服务业与智慧农业耦合发展,提出健全相关配套支持机制、加强大数据平台建设和信息化技术研发、完善农业产业链条和加强专业性人才的培养力度等对策建议。     

Computer simulations of the atmospheric chemistry of sulfate and nitrate formation

Simulations of the atmospheric chemistry of sulfate and inorganic nitrate formation have been carried out by means of a detailed gas phase-liquid phase chemical kinetic mechanism. Consideration has been given to the effect of changes in sulfur dioxide, nitrogen oxides, and reactive hydrocarbon concentrations on sulfate and nitrate formation for conditions typical of the midwestern and northeastern United States. The results indicate significant nonlinearities in the chemistry of acid formation, particularly between sulfur dioxide and sulfate concentrations.     

Sea levels 7,000 to 20,000 years ago

Relative sea levels for early post-Pleistocene time are best known from radiocarbon dates of sediments on the continental shelves off Texas and off northeastern United States. Differences in indicated rates of the rise of relative sea level and in depths of the shelf-breaks reveal differential vertical movement of the two shelves during this time, with the result that the Atlantic shelf has sunk with respect to the Texas shelf.     

Fracture-controlled paleo-fluid flow in Candor Chasma, Mars

Color observations from the High Resolution Imaging Science Experiment on board the Mars Reconnaissance Orbiter reveal zones of localized fluid alteration (cementation and bleaching) along joints within layered deposits in western Candor Chasma, Mars. This fluid alteration occurred within the subsurface in the geologic past and has been exposed at the surface through subsequent erosion. These findings demonstrate that fluid flow along fractures was a mechanism by which subsurface fluids migrated through these layered deposits. Fractured layered deposits are thus promising sites for investigating the geologic history of water on Mars.     

On the sources of summertime haze in the eastern United States

The summertime haze transported from the Gulf Coast northward in maritime tropical air masses is partially formed from emissions in the midwestern and northeastern United States. Several cases are documented in which sulfate particulates, formed from emissions in the Midwest and Northeast, traveled to the Gulf of Mexico and, in some cases, returned to their source regions.     

Littoral of the northeastern United States: late quaternary warping

Isobases constructed from recently published data are strikingly parallel to both the edge of the continental shelf off the northeastern United States and the Fall Zone. Our analyses suggest that the downwarping recorded by these isobases may be explained by Daly's hypothesis of a collapsing peripheral or marginal "bulge."     

Causes of Decadal Climate Variability over the North Pacific and North America

The cause of decadal climate variability over the North Pacific Ocean and North America is investigated by the analysis of data from a multidecadal integration with a state-of-the-art coupled ocean-atmosphere model and observations. About one-third of the low-frequency climate variability in the region of interest can be attributed to a cycle involving unstable air-sea interactions between the subtropical gyre circulation in the North Pacific and the Aleutian low-pressure system. The existence of this cycle provides a basis for long-range climate forecasting over the western United States at decadal time scales.     

Xenon-133: ambient activity from nuclear power stations

The average activity of xenon-133 within and at approximately 100 kilometers from Albany, New York, from April to July 1975 was 2.6 picocuries per cubic meter of air. The source was gaseous effluents from boiling water reactors located in the northeastern United States. Its 5.29-day half-life makes xenon-133 an appropriate isotope to observe for the study of regional and hemispheric dispersion of pollutants.     

Acid Precipitation in the Northeastern United States: pH and Acidity

Detailed chemical analyses reveal that acid precipitation (pH < 5.6) in the northeastern United States is caused by the strong mineral acids sulfuric and nitric. There is a large array of other proton sources in precipitation, weak acids and Bronsted acids; however, although these other acids contribute to the total acidity of precipitation, they have a minimal influence on the free acidity (ambient pH) of acid precipitation.     

Climatic Anomaly over the United States during the 1960's

The past cool decade over the eastern United States is attributed to increased deployment of polar air masses set in motion by responses of the upper-air wind circulation of the Northern Hemisphere to large-scale air-sea coupling over the North Pacific.     

The structure and dynamics of mid-ocean ridge hydrothermal systems

Sub-seafloor hydrothermal convection at mid-ocean ridges transfers 25% of the Earth's heat flux and can form massive sulfide ore deposits. Their three-dimensional (3D) structure and transient dynamics are uncertain. Using 3D numerical simulations, we demonstrated that convection cells self-organize into pipelike upflow zones surrounded by narrow zones of focused and relatively warm downflow. This configuration ensures optimal heat transfer and efficient metal leaching for ore-deposit formation. Simulated fluid-residence times are as short as 3 years. The concentric flow geometry results from nonlinearities in fluid properties, and this may influence the behavior of other fluid-flow systems in Earth's crust.     

The perfect ocean for drought

The 1998-2002 droughts spanning the United States, southern Europe, and Southwest Asia were linked through a common oceanic influence. Cold sea surface temperatures (SSTs) in the eastern tropical Pacific and warm SSTs in the western tropical Pacific and Indian oceans were remarkably persistent during this period. Climate models show that the climate signals forced separately by these regions acted synergistically, each contributing to widespread mid-latitude drying: an ideal scenario for spatially expansive, synchronized drought. The warmth of the Indian and west Pacific oceans was unprecedented and consistent with greenhouse gas forcing. Some implications are drawn for future drought.