Accelerated transport of (90)Sr following a release of high ionic strength solution in vadose zone sediments

Numerical simulation of cation exchange and mineral precipitation/dissolution reactions using the multiphase reactive geochemical transport code TOUGHREACT has provided important insight into the distribution of (90)Sr among layers of geologic strata in a complex vadose zone at the U. S. Department of Energy's Idaho National Laboratory. During a transfer operation in November 1972, 70.4 m(3) of acidic, high ionic strength liquid containing 15,900 Ci of (90)Sr was released over five days into alluvial gravels 137 m above the Snake River Plain Aquifer. Sampling data from perched water zones 33 m below the release contain very high levels of (90)Sr as do soil samples obtained nearer the point of release. Use of traditional simulation approaches using laboratory-measured constant partitioning coefficients (K(d)) cannot simultaneously explain perched water and soil concentrations. To address the discrepancy, a reactive transport approach was adopted to include competitive cation exchange, dissolution/precipitation of calcite, carbon dioxide gas production and transport, and gibbsite precipitation. Simulation results using this model suggest that some of the (90)Sr could have been transported very rapidly immediately after the release with the acceleration facilitated by competition for cation exchange sites with high sodium concentrations in the released liquid and calcium dissolved from calcite, and to a lesser extent by formation of aqueous complexes with nitrate. Once the leading edge of the liquid assemblage was flushed from the alluvium, the mobility of the remaining (90)Sr decreased significantly in the absence of the competing cations. Calculations indicate that there should be a net increase in calcite, suggesting that (90)Sr could be entrained in the mineral lattice, but insufficient field data exist for confirmation. Sensitivity studies show that the cation exchange selectivity coefficients were the most sensitive individual parameters determining the (90)Sr distribution. However, the most sensitive overall quantity was the total ion exchange capacity which is a function of the moles of exchange sites per volume of pore water, the cation exchange capacity, and the total volume wetted by the infiltrating solution. In contrast, the future mobility of (90)Sr was found to be relatively insensitive to the normal range in the composition of influxing precipitation and anthropogenic waters.     

Fine particulate chemical composition and light extinction at Meadview, AZ

The concentration of fine particulate nitrate, sulfate, and carbonaceous material was measured for 12-hr day-night samples using diffusion denuder samplers during the Project Measurement of Haze and Visibility Effects (MOHAVE) July to August 1992 Summer Intensive study at Meadview, AZ, just west of Grand Canyon National Park. Organic material was measured by several techniques. Only the diffusion denuder method measured the semivolatile organic material. Fine particulate sulfate and nitrate (using denuder technology) determined by various groups agreed. Based on the various collocated measurements obtained during the Project MOHAVE study, the precision of the major fine particulate species was +/- 0.6 microg/m3 organic material, +/- 0.3 microg/m3 ammonium sulfate, and +/- 0.07 microg/m3 ammonium nitrate. Data were also available on fine particulate crustal material, fine and coarse particulate mass from the Interagency Monitoring of Protected Visual Environments sampling system, and relative humidity (RH), light absorption, particle scattering, and light extinction measurements from Project MOHAVE. An extinction budget was obtained using mass scattering coefficients estimated from particle size distribution data. Literature data were used to estimate the change in the mass scattering coefficients for the measured species as a function of RH and for the absorption of light by elemental carbon. Fine particulate organic material was the principal particulate contributor to light extinction during the study period, with fine particulate sulfate as the second most important contributor. During periods of highest light extinction, contributions from fine particulate organic material, sulfate, and light-absorbing carbon dominated the extinction of light by particles. Particle light extinction was dominated by sulfate and organic material during periods of lowest light extinction. Combination of the extinction data and chemical mass balance analysis of sulfur oxides sources in the region indicate that the major anthropogenic contributors to light extinction were from the Los Angeles, CA, and Las Vegas, NV, urban areas. Mohave Power Project associated secondary sulfate was a negligible contributor to light extinction.     

New Models for Implementation Theory: Striking a Consensus on Windfarms

The UK Government has provided financial support to developing renewable technologies through the Non-fossil Fu el Obligation imposed on the regional electricity companies. Several hundred renewable energy schemes have come forward to be assessed for their environmental suitability by local level regulators in a very poorly developed national policy framework. This study examines the development control decisions on windfarm applications since 1983 by the largest district council in Wales, and seeks to highlight the role played by clusters of public and private organizations in policy and programme implementation. With the multiple and sometimes conflicting objectives advanced by these organizations, it was in the interests of the district council to strike a negotiated consen sus between landscape conservation and inward investment concerns. The case study shows the crucial importan ce of the socio-political context for understanding the dynamics of policy making.     

Addressing identity-related barriers to collaboration for conservation through self-affirmation theory and moral foundations theory

The natural resource management literature documents many reasons for pursuing collaborative processes, offering useful insights on how to manage conflict and facilitate productive deliberation in complex multistakeholder collaborative efforts. Moral foundations theory and self-affirmation theory can further help collaborative efforts mitigate conflicts caused by identity threats and the identity-protective reasoning these threats provoke. Moral foundations theory suggests an approach to increase collaboration by minimizing triggering language and helping people appreciate opposing viewpoints. Self-affirmation theory suggests a practical intervention that could be used to increase collaboration by desensitizing people to identity threats and reducing defensiveness. Taken together, these theories can contribute substantially to the understanding and practice of collaboration and conflict management for conservation.     

Managing OHS: A route to a new negotiating order in high-performance work organizations?

Contrary to a widely held view, rather than seeing the certification of Occupational Health and Safety (OHS) as a barrier to increasing employee participation, this article views new ways of structuring participation as a necessary step towards making improvements in OHS management systems. The article first considers how work organization has changed and then in a similar way traces how bargaining has shifted from being distributive to become integrative to create a fundamental change in the negotiation regime. Finally, by analyzing an OHS-certified firm in greater depth, the article shows how solutions for improvements in OHS management and notable bottom-up formulations of OHS benchmarks may help us discover how the organizational form of firms with high-performance work organization can be developed through new participatory structures.     

International mining taxation issues and comparisons

This paper presents the quantitative results of recent research on Canada's minerals and metals industry, and its international competitiveness for mineral investment. The information and analysis presented are derived from the work of a Canadian government-industry task force that was created in 1991, under the auspices of the Intergovernmental Working Group on the Mineral Industry (IGWG). Much of this work deals with mining taxation in several Canadian provinces. More importantly, an attempt is made to evaluate the total tax burden that the mining industry must bear, on a project basis, at all levels from exploration through refining operations in many important competitor countries. While the focus of the paper is on an international comparison of mining taxation, some non-tax issues relating to Canada's competitiveness for mineral investment are addressed .     

How Perceived Exposure to Environmental Harm Influences Environmental Behavior in Urban China

Rapid environmental degradation in China makes understanding how perceived exposure to environmental harm influences environmental attitudes and participation in pro-environmental behaviors among the Chinese people crucial. We used a nation-wide survey dataset in urban China to test two hypotheses: experiencing environmental harm directly affects environmental behavior; environmental attitudes mediate the relationship between experiencing environmental harm and environmental behavior. We found respondents who experienced environmental harm had more pro-environmental attitudes. Experiencing environmental harm positively influenced pro-environmental behavior both directly and indirectly through the mediation of pro-environmental attitudes. Among the pro-environmental behaviors, environmental litigation was most strongly related with exposure to environmental harm. Our results suggest that more participation in pro-environmental behaviors may be expected as rapid economic development increases public exposure to environmental harm in urban China.     

Fine Particulate Chemical Composition and Light Extinction at Meadview,AZ

Abstract

The concentration of fine particulate nitrate, sulfate, and carbonaceous material was measured for 12-hr day-night samples using diffusion denuder samplers during the Project Measurement of Haze and Visibility Effects (MOHAVE) July to August 1992 Summer Intensive study at Meadview, AZ, just west of Grand Canyon National Park. Organic material was measured by several techniques. Only the diffusion denuder method measured the semivolatile organic material. Fine particulate sulfate and nitrate (using denuder technology) determined by various groups agreed. Based on the various collocated measurements obtained during the Project MOHAVE study, the precision of the major fine particulate species was ±0.6 μg/m³ organic material, ±0.3 μg/m³ ammonium sulfate, and ±0.07 μg/m³ ammonium nitrate. Data were also available on fine particulate crustal material, fine and coarse particulate mass from the Interagency Monitoring of Protected Visual Environments sampling system, and relative humidity (RH), light absorption, particle scattering, and light extinction measurements from Project MOHAVE. An extinction budget was obtained using mass scattering coefficients estimated from particle size distribution data. Literature data were used to estimate the change in the mass scattering coefficients for the measured species as a function of RH and for the absorption of light by elemental carbon. Fine particulate organic material was the principal particulate contributor to light extinction during the study period, with fine particulate sulfate as the second most important contributor. During periods of highest light extinction, contributions from fine particulate organic material, sulfate, and light-absorbing carbon dominated the extinction of light by particles. Particle light extinction was dominated by sulfate and organic material during periods of lowest light extinction. Combination of the extinction data and chemical mass balance analysis of sulfur oxides sources in the region indicate that the major anthropogenic contributors to light extinction were from the Los Angeles, CA, and Las Vegas, NV, urban areas. Mohave Power Project associated secondary sulfate was a negligible contributor to light extinction.     

The Relationship Between the Chemical Structure of Poly(alkylene glycol)s and Their Aerobic Biodegradability in an Aqueous Environment

The relationship between the chemical structure of poly(alkylene glycol)s (PAGs) and their biodegradability was studied using a set of polymeric fluids that included poly(ethylene glycol), poly(propylene glycol) (PPG), random copolymers of ethylene oxide (EO) and propylene oxide (PO) differing in the EO/PO ratio as well as PAGs capped with ether or acyl moieties. The PAGs that were tested had an average molecular weight (MW) in the range of 350–3,600 Da and differed in their polymer backbones by either linear (diol type) or branched (triol type) molecules. The ultimate biodegradability of the PAGs was determined according to ISO 14593 (CO₂ headspace test) with a non-pre-exposed (as in OECD 310 test) and pre-exposed (adapted) inoculum. PAGs with the structure of PPG and copolymers of EO/PO of diol or triol structures with average molecular weights lower than 1,000 Da can be considered as readily biodegradable. Their ultimate biodegradation exceeds the limit of 60 % (according to the criteria of the OECD 310 test). PAGs with a copolymer structure and MW values ranging between 1,000 and 3,600 Da are not readily biodegradable, but they can be considered as those of inherent ultimate biodegradability. The increased EO content in PAG structures and the acylation of the terminal hydroxyl groups with carboxylic acids favourably influenced their biodegradability. Capped PAGs containing terminal ether groups appeared to be resistant to biodegradation.     

Detection of Jarcho–Levin syndrome at 12 weeks' gestation by nuchal translucency screening and three-dimensional ultrasound

Jarcho–Levin syndrome (JLS) or spondylothoracic dysotosis causes early newborn death from respiratory insufficiency. Prenatal diagnosis is possible using fetal ultrasound, but requires a high level of suspicion and definitive diagnosis may be delayed well into the second trimester. We present a case in which a combination of three-dimensional ultrasound and measurement of nuchal translucency thickness allowed successful detection of recurrent JLS at 12 weeks' gestation. Copyright © 2001 John Wiley & Sons, Ltd.