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891.
There is an apparent disconnect between geography and education for sustainable development (ESD), with geography underrepresented in publications and curricula related to sustainability though the discipline embraces the need to foment positive change. To bridge this schism, this article introduces advances in education for sustainable development (ESD-2) and a three-dimensional key competence-based model that can be deployed in tandem with economic geography theory. Deploying the theme of solar PV in Korea, a competency-based lesson planning exercise is presented to demonstrate the potential for this learning paradigm to generate agency and empower change for a sustainable future. 相似文献
892.
We have determined the rupture history of the March 28, 1964, Prince Williams Sound earthquake (M
w=9.2) from long-period WWSSNP-wave seismograms. Source time functions determined from the long-periodP waves indicate two major pulses of moment release. The first and largest moment pulse has a duration of approximately 100 seconds with a relatively smooth onset which reaches a peak moment release rate at about 75 seconds into the rupture. The second smaller pulse of moment release starts at approximately 160 seconds after the origin time and has a duration of roughly 40 seconds. Because of the large size of this event and thus a deficiency of on-scale, digitizableP-wave seismograms, it is impossible to uniquely invert for the location of moment release. However, if we assume a rupture direction based on the aftershock distribution and the results of surface wave directivity studies we are able to locate the spatial distribution of moment along the length of the fault. The first moment pulse most likely initiated near the epicenter at the northeastern down-dip edge of the aftershock area and then spread over the fault surface in a semi-circular fashion until the full width of the fault was activated. The rupture then extended toward the southwest approximately 300 km (Ruff andKanamori, 1983). The second moment pulse was located in the vicinity of Kodiak Island, starting at 500 km southwest of the epicenter and extending to about 600 km. Although the aftershock area extends southwest past the second moment pulse by at least 100 km, the moment release remained low. We interpret the 1964 Prince William Sound earthquake as a multiple asperity rupture with a very large dominant asperity in the epicentral region and a second major, but smaller, asperity in the Kodiak Island region.The zone that ruptured in the 1964 earthquake is segmented into two regions corresponding to the two regions of concentrated moment release. Historical earthquake data suggest that these segments behaved independently during previous events. The Kodiak Island region appears to rupture more frequently with previous events occurring in 1900, 1854, 1844, and 1792. In contrast, the Prince William Sound region has much longer recurrence intervals on the order of 400–1000 years. 相似文献
893.
Group Sunspot Numbers: A New Solar Activity Reconstruction 总被引:1,自引:0,他引:1
In this paper, we construct a time series known as the Group Sunspot Number. The Group Sunspot Number is designed to be more internally self-consistent (i.e., less dependent upon seeing the tiniest spots) and less noisy than the Wolf Sunspot Number. It uses the number of sunspot groups observed, rather than groups and individual sunspots. Daily, monthly, and yearly means are derived from 1610 to the present. The Group Sunspot Numbers use 65941 observations from 117 observers active before 1874 that were not used by Wolf in constructing his time series. Hence, we have calculated daily values of solar activity on 111358 days for 1610–1995, compared to 66168 days for the Wolf Sunspot Numbers. The Group Sunspot Numbers also have estimates of their random and systematic errors tabulated. The generation and preliminary analysis of the Group Sunspot Numbers allow us to make several conclusions: (1) Solar activity before 1882 is lower than generally assumed and consequently solar activity in the last few decades is higher than it has been for several centuries. (2) There was a solar activity peak in 1801 and not 1805 so there is no long anomalous cycle of 17 years as reported in the Wolf Sunspot Numbers. The longest cycle now lasts no more than 15 years. (3) The Wolf Sunspot Numbers have many inhomogeneities in them arising from observer noise and this noise affects the daily, monthly, and yearly means. The Group Sunspot Numbers also have observer noise, but it is considerably less than the noise in the Wolf Sunspot Numbers. The Group Sunspot Number is designed to be similar to the Wolf Sunspot Number, but, even if both indices had perfect inputs, some differences are expected, primarily in the daily values. 相似文献
894.
895.
Variations in hydraulic conductivity with scale of measurement during aquifer tests in heterogeneous, porous carbonate rocks 总被引:4,自引:3,他引:1
Previous studies have shown that hydraulic conductivity of an aquifer seems to increase as the portion of the aquifer tested
increases. To date, such studies have all relied on different methods to determine hydraulic conductivity at each scale of
interest, which raises the possibility that the observed increase in hydraulic conductivity is due to the measurement method,
not to the scale. This study analyzes hydraulic conductivity with respect to scale during individual aquifer tests in porous,
heterogeneous carbonate rocks in southeastern Wisconsin, USA. Results from this study indicate that hydraulic conductivity
generally increases during an individual test as the volume of aquifer impacted increases, and the rate of this increase is
the same as the rate of increase determined by using different measurement methods. Thus, scale dependence of hydraulic conductivity
during single tests does not depend on the method of measurement. This conclusion is supported by 22 of 26 aquifer tests conducted
in porous-flow-dominated carbonate units within the aquifer. Instead, scale dependency is probably caused by heterogeneities
within the aquifer, a conclusion supported by digital simulation. All of the observed types of hydraulic-conductivity variations
with scale during individual aquifer tests can be explained by a conceptual model of a simple heterogeneous aquifer composed
of high-conductivity zones within a low-conductivity matrix.
Received, January 1997 Revised, August 1997, November 1997 Accepted, November 1997 相似文献
896.
Long-term homogeneous observations of solar activity or many solar cycles are essential for investigating many problems in solar physics and climatology. The one key parameter used in most long-term studies is the Wolf sunspot number, which is susceptible to observer bias, particularly because it is highly sensitive to the observer's ability to see the smallest sunspots. In this paper we show how the Wolf sunspot number can be derived from the number of sunspot groups alone. We utilize this approach to obtain a Group Wolf number. This technique has advantages over the classical method of determining the Wolf number because corrections for observer differences are reduced and long-term self-consistent time series can be developed. The level of activity can be calculated to an accuracy of ± 5% using this method. Applying the technique to Christian Horrebow's observations of solar cycles 1, 2, and 3 (1761–1777), we find that the standard Wolf numbers are nearly homogeneous with sunspot numbers measured from 1875 to 1976 except the peak of solar cycle 2 is too low by 30%. This result suggests that further analyses of early sunspot observations could lead to significant improvements in the uniformity of the measurements of solar activity. Such improvements could have important impacts upon our understanding of long-term variations in solar activity, such as the Gleissberg cycle, or secular variations in the Earth's climate. 相似文献
897.
Compositional zonation in garnets in peridotite xenoliths 总被引:1,自引:0,他引:1
Garnets in 42 peridotite xenoliths, most from southern Africa, have been analyzed by electron probe to seek correlations between compositional zonation and rock history. Xenoliths have been placed into the following 6 groups, based primarily upon zonation in garnet: I (12 rocks)-zonation dominated by enrichment of Ti and other incompatible elements in garnet rims; II (10 rocks)-garnet nearly homogeneous; III (8 rocks)-rims depleted in Cr, with little or no related zonation of Ti; IV (3 rocks)-slight Ti zonation sympathetic to that of Cr; V (3 rocks)-garnet rims depleted or enriched in Cr, and chromite included in garnet; VI (6 rocks)-garnets with other characteristics. Element partitioning between olivine, pyroxene, and garnet rims generally is consistent with the assumption of equilibrium before eruption. Although one analyzed rock contains olivine and pyroxene that may have non-equilibrated oxygen isotopes, no corresponding departures from chemical equilibrium were noted. Causes of zoning include melt infiltration and changes in temperature and pressure. Zonation was caused or heavily influenced by melt infiltration in garnets of Group I. In Groups III, IV, and V, most compositional gradients in garnets are attributed to changes in temperature, pressure, or both, and gradients of Cr are characteristic. There are no simple relationships among wt% Cr2O3 in garnet, calculated temperature, and the presence of compositional gradients. Rather, garnets nearly homogeneous in Cr are present in rocks with calculated equilibration temperatures that span the range 800–1500 °C. Although the most prominent Cr gradients are found in relatively Cr-rich garnets of rocks for which calculated temperatures are below 1050 °C, gradients are well-defined in a Group IV rock with T1300 °C. The variety of Cr gradients in garnets erupted from a range of temperatures indicates that the zonations record diverse histories. Petrologic histories have been investigated by simulated cooling of model rock compositions in the system CaO–MgO–Al2O3–SiO2–Cr2O3. Proportions and compositions of pyroxene and garnet were calculated as functions of P and T. The most common pattern of zonation in Groups III and IV, a decrease of less than 1 wt% Cr2O3 core-to-rim, can be simulated by cooling of less than 200 °C or pressure decreases of less than 1 GPa. The preservation of growth zonation in garnets with calculated temperatures near 1300 °C implies that these garnets grew within a geologically short time before eruption, probably in response to fast cooling after crystallization of a small intrusion nearby. Progress in interpreting garnet zonations in part will depend upon determinations of diffusion rates for Cr. Zonation formed by diffusion within garnet cannot always be distinguished from that formed by growth, but Ca–Cr correlations unlike those typical of peridotite suite garnets may document diffusion. 相似文献
898.
Douglas G. Brookins 《Environmental Geology》1992,19(1):11-15
Background radiation levels in the Albuquerque, New Mexico, area are elevated when compared to much of the United States. Soil K, U, and Th are somewhat elevated compared to average values in this country and generate roughly 60 mrem per year to the average resident. Cosmic ray contribution, due to the mean elevation of 5,200 ft above sea level, is 80 mrem/yr—well over the average for the United States. Thirty percent of the homes in Albuquerque contain indoor radon levels over the EPA action level of 4 pCi/ compared to 10–12 percent of homes for the entire United States. Indoor radon contributes about 100–300 mrem/yr. Food, beverages, and x-ray doses are assumed at an average-equivalent for the United States and locally yield 96 mrem/yr. Total contributions from other minor sources (color TV, coal, weapons fallout, etc.) are under 10 mrem/yr. Thus total background radiation received by Albuquerque residents is about 330–530 mrem/yr, well in excess of the rest of the United States. The spread in mrem values is due to variations in the contribution from indoor radon.Douglas G. Brookins, Professor of Geology and former Chairman of the Department, 1976–1979, passed away unexpectedly on April 30, 1991. He was a man of passion, intellect, and conviction. He left us at the peak of his productive career, but he leaves behind a legacy of exceptional accomplishments and contributions to his friends, family, students, and profession. He was a member of the Faculty Senate at the time of his death and had served two previous terms in 1984 and 1986.Doug's academic accomplishments were of world class, beginning with an AB degree, Summa Cum Laude, from U.C. Berkeley in 1958 and a PhD from MIT in 1963. He came to UNM as a full professor in 1971, having previously served at Kansas State University, and built a first class program in isotope geochemistry. He wrote five books and had a sixth in progress, edited several others, and authored or coauthored approximately 500 technical papers, book chapters, and reports.—Bruce M. Thomson and Wolfgang E. Elston, University of New Mexico. 相似文献
899.
In laboratory tests, manganese accumulation by the appendages of the sediment burrowing Norway lobster. Nephrops norvegicus (L.) (including the lateral antennules) was approximately three times greater [600 microg Mn g(-1) (dry weight) after 5 days in 20 mg Mn l(-1)] than that by the carapace. The accumulation was linearly dose-dependent (10-40 mg Mn l(-1)) and duration-dependent (2-30 days). and showed no decrease after 3 weeks in undosed seawater. A high manganese uptakc to the lateral antennules during hypoxia in the field was verified from the SE Kattegat, Sweden. These results indicate that accumulation of Mn on the mobile appendages of the Norway lobster fulfils most of the criteria for a biomarker of exposure to hypoxia. Using these measurements in conjunction with Mn concentrations in the internal tissues, it may be possible to resolve both the timing and the extent of the Mn exposure and the underlying hypoxic event. 相似文献
900.
The results summarized herein are based on subaerial beach profiles taken on the Atlantic Ocean at Sandbridge, Virginia (USA). The shoreline has experienced an average, historic recession rate of about 2 m/yr for more than 120 years before seawall construction began in 1978. The purpose of this study is to determine whether or not the 16 walled sections increase the existing erosional trend at adjacent, non-walled beaches. Fifteen years of survey data are employed with 8–9 years of data taken before wall construction peaked in 1989. The main focus of these results is on five full wave years of monthly and post-storm survey data taken at 28 locations (16 walled, 4720 m, 62% and 12 non-walled, 2950 m, 38%) since October 1990. Three time scales (historic, seasonal, storms) and three analysis methods were used to address three questions concerning the effects of seawalls on adjacent beaches.It has been determined that volume erosion rates are not higher in front of seawalls (Question No. 1). However, the seasonal variability of the sand volume in front of walls is generally greater than at non-walled locations. Winter season waves drag more sand offshore in front of walls but also summer swell waves pile more sand up against walls in beach rebuilding.Walled beaches were found to recover about the same time as non-walled beaches for both seasonal transitions (winter to summer) and following erosional storm events (Question No. 2).At a few non-walled locations, the sand volume landward of adjacent walls was found to be eroding at a faster rate after wall construction. At some other non-walled locations, the sand volume landward remained constant or increased in time after nearby walled construction. The evidence for Sandbridge beach as a whole was considered inconclusive for Question No. 3.After wall construction, sand trapped behind the wall is not available for transport to adjacent beaches during and after storm events. The loss of this sand volume is felt to be in the initial stage of detection at Sandbridge. More full years of profile data are needed to confirm and quantify the effect. Sand is also trapped beneath the road (baseline) at non-walled locations. The study is continuing. 相似文献