Dependence of radon concentration in natural gas on the geological and physical parameters of the gas reservoir

Pressure of natural gas in its rock reservoir determines the final radon concentration in this gas after its decompression to normal conditions. In this investigation, radon contents of 62 natural gas samples were measured and a simple physical model of the gas reservoir was applied. The model takes into account an additional dependence of radon concentration on the natural gas pressure and on the porosity of the rock reservoir. The influence of the gas pressure on the value of the radon emanating power is discussed. The mean ²²⁶ Ra content in the source rock needed for generation of ²²² Rn concentrations observed in gas is also calculated. The calculations are made with the help of regression analysis.     

Pre-Columbian landscape impact and agriculture in the Monumental Mound region of the Llanos de Moxos, lowland Bolivia

We present a multiproxy study of land use by a pre-Columbian earth mounds culture in the Bolivian Amazon. The Monumental Mounds Region (MMR) is an archaeological sub-region characterized by hundreds of pre-Columbian habitation mounds associated with a complex network of canals and causeways, and situated in the forest–savanna mosaic of the Llanos de Moxos. Pollen, phytolith, and charcoal analyses were performed on a sediment core from a large lake (14 km²), Laguna San José (14°56.97′S, 64°29.70′W). We found evidence of high levels of anthropogenic burning from AD 400 to AD 1280, corroborating dated occupation layers in two nearby excavated habitation mounds. The charcoal decline pre-dates the arrival of Europeans by at least 100 yr, and challenges the notion that the mounds culture declined because of European colonization. We show that the surrounding savanna soils were sufficiently fertile to support crops, and the presence of maize throughout the record shows that the area was continuously cultivated despite land-use change at the end of the earth mounds culture. We suggest that burning was largely confined to the savannas, rather than forests, and that pre-Columbian deforestation was localized to the vicinity of individual habitation mounds, whereas the inter-mound areas remained largely forested.     

Understanding the evolution of a disaster��a Framework for Assessing Crisis in a System Environment (FACSE)

To understand the evolution of a disaster, we propose a Framework for Assessing Crisis in a System Environment (FACSE). FACSE is set in a multi-system environment, containing the human system as well as the various natural and technological systems that interact with people. We take a lifecycle perspective, via which we quantify rhythms of life exhibited in multiple systems, across different scales, at different times. The lifecycle perspective also implies a relative approach in that rhythms of life during time t can be compared against those during t-1. We illustrate how rhythms of life in the human system can be measured at different scales. We propose a new concept??the degree of disaster, which is a composite score that encompasses the various measurements of rhythms of life from multiple systems, across different scales. We conclude the paper by discussing the potential offered by FACSE in disaster research as well as the limitations.     

A methodology for quantifying the value of spatial information for dynamic Earth problems

We develop a methodology for assessing the value of information (VOI) from spatial data for groundwater decisions. Two sources of uncertainty are the focus of this VOI methodology: the spatial heterogeneity (how it influences the hydrogeologic response of interest) and the reliability of geophysical data (how they provide information about the spatial heterogeneity). An existing groundwater situation motivates and in turn determines the scope of this research. The objectives of this work are to (1) represent the uncertainty of the dynamic hydrogeologic response due to spatial heterogeneity, (2) provide a quantitative measure for how well a particular information reveals this heterogeneity (the uncertainty of the information) and (3) use both of these to propose a VOI workflow for spatial decisions and spatial data. The uncertainty of the hydraulic response is calculated using many Earth models that are consistent with the a priori geologic information. The information uncertainty is achieved quantitatively through Monte Carlo integration and geostatistical simulation. Two VOI results are calculated which demonstrate that a higher VOI occurs when the geophysical attribute (the data) better discriminates between geological indicators. Although geophysical data can only indirectly measure static properties that may influence the dynamic response, this transferable methodology provides a framework to estimate the value of spatial data given a particular decision scenario.     

Long length scales of element transport during reaction texture development in orthoamphibole-cordierite gneiss: Thor-Odin dome,British Columbia,Canada

First-order factors controlling the textural and chemical evolution of metamorphic rocks are bulk composition and pressure–temperature–time (P–T–t) path. Although it is common to assume that major element bulk composition does not change during regional metamorphism, rocks with reaction textures such as corona structures record evidence for major changes in effective bulk composition (EBC) and therefore provide significant insight into the scale, pathways, and mechanisms of element transport during metamorphism. Quantifying changes in EBC is essential for petrologic applications such as calculation of phase diagrams (pseudosections). The progressive growth of complex corona structures on garnet and Al₂SiO₅ porphyroblasts in orthoamphibole-cordierite gneiss Thor-Odin dome (British Columbia, Canada) reduced the EBC volume of the rock during metamorphism and therefore had a dramatic effect on the evolution of the stable mineral assemblage. These rocks contain a chemical and textural record of metamorphic reactions and preserve 3D networks (reaction pathways) connecting corona structures. These coronal networks record long (>cm) length scales of localized element transport during metamorphism. P–T, T–X, and P–X pseudosections are used to investigate the control of effective bulk composition on phase assemblage evolution. Despite textural complexity and evidence for disequilibrium, mineral assemblages and compositions were successfully modeled and peak metamorphic conditions estimated at 750°C and 9 kbar. These results illustrate how textural and chemical changes during metamorphism can be evaluated using an integrated petrographic and pseudosection approach, highlight the importance of effective bulk composition choice for application of phase equilibria methods in metamorphic rocks, and show how corona structures can be used to understand the scale of compositional change and element transport during metamorphism.     

An interdisciplinary approach to HIV/AIDS stigma and discrimination in Belize: the roles of geography and ethnicity

Belize experiences the highest rates of HIV/AIDS in Central America, ranging between 2.1 and 3.2% (World Health Organization 2008). To add to the limited literature on HIV/AIDS Stigma and Discrimination (HASD) in Belize, the authors conducted a study to assess whether stigma and discrimination is related to geography and ethnicity. One-hundred forty participants were interviewed using a structured survey instrument at three different parts of the country, and the results were analyzed quantitatively. These places were Cayo District on the western border with Guatemala, Belize City, and two cayes (Caye Caulker and Ambergris Caye). Respondents in Belize City generally held the lowest rates of stigmatizing and discriminatory attitudes towards individuals living with HIV/AIDS, highlighting a possible relationship between geography and ethnicity. Concurrently, self-identifying Afro-Belizeans and Creoles reported lower rates of HASD attitudes in some contexts than other ethnic groups. The results show that there may a relation between geography, ethnicity, and HASD, and that a randomized, controlled study is an important next step in determining the strength of that relation.     

The final Galileo SSI observations of Io: orbits G28-I33

We present the observations of Io acquired by the Solid State Imaging (SSI) experiment during the Galileo Millennium Mission (GMM) and the strategy we used to plan the exploration of Io. Despite Galileo's tight restrictions on data volume and downlink capability and several spacecraft and camera anomalies due to the intense radiation close to Jupiter, there were many successful SSI observations during GMM. Four giant, high-latitude plumes, including the largest plume ever observed on Io, were documented over a period of eight months; only faint evidence of such plumes had been seen since the Voyager 2 encounter, despite monitoring by Galileo during the previous five years. Moreover, the source of one of the plumes was Tvashtar Catena, demonstrating that a single site can exhibit remarkably diverse eruption styles—from a curtain of lava fountains, to extensive surface flows, and finally a ∼400 km high plume—over a relatively short period of time (∼13 months between orbits I25 and G29). Despite this substantial activity, no evidence of any truly new volcanic center was seen during the six years of Galileo observations. The recent observations also revealed details of mass wasting processes acting on Io. Slumping and landsliding dominate and occur in close proximity to each other, demonstrating spatial variation in material properties over distances of several kilometers. However, despite the ubiquitous evidence for mass wasting, the rate of volcanic resurfacing seems to dominate; the floors of paterae in proximity to mountains are generally free of debris. Finally, the highest resolution observations obtained during Galileo's final encounters with Io provided further evidence for a wide diversity of surface processes at work on Io.