Seismic expression of sedimentary volcanism on the continental slope,northern Gulf of Mexico

High-resolution geophysical data define acoustically amorphous, mounded structures on the upper, middle, and lower continental slope of the northern Gulf of Mexico. Physical samples and observations within this unique seismic facies show gassy sediments, sometimes in hydrated form and, in places, as chemosynthetic communities. The geologic setting of these mounds suggests that the process of formation falls on the continuum of mud volcanoes to mud diapirs.     

Comparison of high-resolution seismic profiles and the geoacoustic properties of Eckernförde Bay sediments

High-resolution seismic profiles of Eckernförde Bay and the adjacent Baltic Sea were collected, and the geoacoustic properties of sediments there were measured. Bulk densities averaged ~ 1.35 g cm^–3 and ranged from ~ 1.2 to ~ 1.7 g cm^–3. Compressional wave velocities in gas-free sediments averaged ~ 1460 m s^–1 and ranged from ~ 1425 to ~ 1555 m s^–1. In nongassy sediments, bulk density variations typically controlled changes of acoustic impedance. Impedance changes were usually too small and closely spaced to be resolved seismically, although, at certain sites, significant impedance changes are far apart enough that they correlate one-to-one with seismic reflectors. Where free gas is present, velocity decreases and wave energy is scattered, causing a prominent seismic reflector.     

Hopane,sterane and n-alkane distributions in shallow sediments hosting high arsenic groundwaters in Cambodia

The presence of elevated As in ground waters exploited for drinking water and irrigation in South-East Asia is causing serious impacts on human health. A key mechanism that causes the mobilization of As in these waters is microbially mediated reductive transformation of As-bearing Fe(III) hydrated oxides and the role of degradable organic matter (OM) in this process is widely recognized. A number of different types of OM that drive As release in these aquifers have been suggested, including petroleum derived hydrocarbons naturally seeping into shallow sediments from deeper thermally mature source rocks. However, the amount of information on the characteristics of the OM in South-East Asian aquifers is limited. Here the organic geochemical analyses of the saturated hydrocarbon fractions and radiocarbon analysis, of two additional sites in SE Asia are reported. The results show that the OM in a given sedimentary horizon likely derives from multiple sources including naturally occurring petroleum. The importance of naturally occurring petroleum as one of the sources was clearly indicated by the n-alkane CPI of approximately 1, the presence of an unresolved complex mixture, and hopane (dominated by 17α(H),21β(H) hopanes) and sterane distribution patterns. The results also indicate that the OM in these aquifers varies tremendously in content, character and potential bioavailability. Furthermore, the presence of petroleum derived OM in sediments at both sites doubles the number of locations where their presence has been observed in association with As-rich, shallow aquifers, suggesting that the role of petroleum derived OM in microbially mediated As release might occur over a wider range of geographical locations than previously thought.     

三维航标监测与管理系统的设计与实现

设计了三维航标监测与管理系统的整体框架和功能结构,研究了其涉及的若干关键技术,开发实现了系统功能.     

Giant Maps as Pedagogical Tools for Teaching Geography and Mathematics

Giant maps offer a potentially useful pedagogical tool for teaching mathematics and map skills. In this pilot study, giant maps were distributed to elementary schools in Colorado and New Hampshire and teachers were provided with guided activities designed to integrate mathematics and geography skills. In an assessment of student skills, it was found that there were improvements in map-use skills and that students improved in some skills more than others. Additionally, there were differences in gender; girls improved more in their scores for some skills and less than boys in others. The teaching benefits of giant maps merit additional investigation.     

Factors influencing surface runoff generation from two agricultural hillslopes in central Pennsylvania

The variable source area (VSA) concept provides the underlying paradigm for managing phosphorus losses in runoff in the north‐eastern USA. This study sought to elucidate factors controlling runoff along two hillslopes with contrasting soils, including characterizing runoff generation mechanisms and hydrological connectivity. Runoff monitoring plots (2 m × 1 m) were established in various landscape positions. Footslope positions were characterized by the presence of a fragipan that contributed to seasonally perched water tables. In upslope positions without a fragipan, runoff was generated primarily via the infiltration‐excess (IE) mechanism (96% of events) and was largely disconnected from downslope runoff. Roughly 80% of total runoff originated from the north footslope landscape position via saturation‐excess (SE) (46% of events; 62% of runoff) and IE (54% of events; 38% of runoff) mechanisms. Runoff from the north hillslope was substantially greater than the south hillslope despite their proximity, and apparently was a function of the extent of fragipan representation. Results demonstrate the influence of subsurface soil properties (e.g. fragipan) on surface runoff generation in variable source area hydrology settings, which could be useful for improving the accuracy of existing runoff prediction tools. Published in 2009 by John Wiley & Sons, Ltd.     

The Morávka meteorite fall: 3. Meteoroid initial size,history, structure,and composition

Abstract— The properties and history of the parent meteoroid of the Morávka H5–6 ordinary chondrites have been studied by a combination of various methods. The pre‐atmospheric mass of the meteoroid was computed from fireball radiation, infrasound, seismic signal, and the content of noble gases in the meteorites. All methods gave consistent results. The best estimate of the pre‐atmospheric mass is 1500 ± 500 kg. The fireball integral bolometric luminous efficiency was 9%, and the acoustic efficiency was 0.14%. The meteoroid cosmic ray exposure age was determined to be (6.7 ± 1.0) × 10⁶ yr. The meteorite shows a clear deficit of helium, both ³He and ⁴He. This deficit can be explained by solar heating. Numerical backward integration of the meteoroid orbit (determined in a previous paper from video records of the fireball) shows that the perihelion distance was probably lower than 0.5 AU and possibly as low as 0.1 AU 5 Ma ago. The collision which excavated Morávka probably occurred while the parent body was on a near‐Earth orbit, as opposed to being confined entirely to the main asteroid belt. An overview of meteorite macroscopic properties, petrology, mineralogy, and chemical composition is given. The meteorites show all mineralogical features of H chondrites. The shock level is S2. Minor deviations from other H chondrites in abundances of trace elements La, Ce, Cs, and Rb were found. The ablation crust is enriched with siderophile elements.     

基于Erdas2013的Pleiades卫星影像区域网平差设计与实现

介绍了Pleiades卫星影像数据及基于Erdas 2013的Pleiades卫星影像应用的可行性和区域网平差技术,为该卫星影像应用于相关测绘工程提供了技术依据。     

“Is there a bubble to burst?”-college students’ spatial perception of campus and the city,a case study of rhodes college in memphis,TN

ABSTRACT

This paper builds on the study of student geography by critically examining college students’ perceived space of a university campus and the surrounding urban space. Rhodes College is a liberal arts college situated in the city of Memphis. As a campus with a majority white population located in a predominately black city, Rhodes College exists within but often separate from the city. It serves as a perfect case study to investigate how the college students build relationships with the environment within and beyond the campus. By using mental mapping and focus groups, this research unpacks four spatialities that shape college students’ perception of the urban space: (in)activity space, (im)mobility, boundaries, and center. This research demonstrates that student geography can be gendered, classed and racialized. The perceived space is socially constructed, and is reinforced by the lived and material space. Finally, this paper provides implications to facilitate deeper connections between students, the campus, and the city.