Dense Nonaqueous Phase Liquid Tracer Tests: Experimental Results

Two dense nonaqueous phase liquid (DNAPL) tracer tests werecarried out in a shallow aquifer north of Fort Worth, TX. i-Propanolwas used as the nonpartitioning tracer; n-hexanol and n-octanol werethe partitioning tracers. Field data, mathematical modeling, theresults of column tests, and field tracer tests with NaCl were usedin designing the DNAPL tracer tests. The results indicated the presenceof DNAPL at both sites tested; semi-quantitative estimates of theamounts of DNAPL present were obtained by mathematical modeling.Interpretation was complicated by heterogeneity of the aquifer andmass transport effects.     

The Climate Impacts of Sulfate Aerosols

Sulfate aerosols (SO₄) from anthropogenic emissions of sulfur dioxide (SO₂) generally have a cooling effect. However, if SO₂ emissions fall over time, accounting for sulfate aerosols will increase the predicted warming from greenhouse gases. This paper integrates the four marker emission scenarios for CO₂ and SO₄ from the Special Report on Emissions Scenarios (SRES), the UIUC general circulation model (GCM), and a country-specific impact model (GIM) to calculate the impacts of sulfate aerosols. By 2100, lower SO₂ emissions slightly increase warming in the temperate and polar regions causing small damages in the former and small benefits in the latter. If SO₂ emissions are also lower in tropical regions, temperatures will rise causing small damages there as well. However, if SO₂ emissions rise in tropical regions, temperatures will fall leading to small benefits. This revised version was published online in July 2006 with corrections to the Cover Date.     

Detailed and reduced chemistry for hydrogen autoignition

Reaction-rate parameters are given for the detailed chemistry of gas-phase hydrogen combustion, involving 21 reversible elementary steps. It is indicated that, when attention is restricted to specific combustion processes and particular conditions of interest, fewer elementary steps are needed. In particular, for calculating autoignition times over a wide range of pressures for temperatures between about 1000 and 2000 K, five irreversible elementary steps suffice, yielding a remarkable reduction in complexity. It is explained that, from a mathematical viewpoint, in terms of global reaction-kinetic mechanisms, the hydrogen–oxygen system in principle comprises only six overall steps. Rational reduced chemical mechanisms for hydrogen combustion therefore necessarily must have fewer than six overall steps. For autoignition over the range of conditions specified above, ignition times can be determined accurately by considering, in addition to an elementary initiation step and an elementary termination step, at most three overall steps for reaction intermediaries, which reduce to two for very fuel-lean conditions and to one for stoichiometric or fuel-rich conditions. The resulting reductions can simplify computations that need to be performed in risk analyses for hydrogen storage and utilization.     

Comparison of Field Performance of Multiple Soil Moisture Sensors in a Semi‐Arid Rangeland1

Abstract:  Automated electronic soil moisture sensors, such as time domain reflectometry (TDR) and capacitance probes are being used extensively to monitor and measure soil moisture in a variety of scientific and land management applications. These sensors are often used for a wide range of soil moisture applications such as drought forage prediction or validation of large‐scale remote sensing instruments. The convergence of three different research projects facilitated the evaluation and comparison of three commercially available electronic soil moisture probes under field application conditions. The sensors are all installed in shallow soil profiles in a well instrumented small semi‐arid shrub covered subwatershed in Southeastern Arizona. The sensors use either a TDR or a capacitance technique; both of which indirectly measure the soil dielectric constant to determine the soil moisture content. Sensors are evaluated over a range of conditions during three seasons comparing responses to natural wetting and drying sequences and using water balance and infiltration simulation models. Each of the sensors responded to the majority of precipitation events; however, they varied greatly in response time and magnitude from each other. Measured profile soil moisture storage compared better to water balance estimates when soil moisture in deeper layers was accounted for in the calculations. No distinct or consistent trend was detected when comparing the responses from the sensors or the infiltration model to individual precipitation events. The results underscore the need to understand how the sensors respond under field application and recognize the limitations of soil moisture sensors and the factors that can affect their accuracy in predicting soil moisture in situ.     

Enhancing polychlorinated biphenyl dechlorination in fresh water sediment with biostimulation and bioaugmentation

Polychlorinated biphenyls (PCBs) are toxic compounds ubiquitously distributed in ecosystems. Microbial attenuation of these contaminants is a potential means of remediation. Two promising microbial PCB remediation technologies, biostimulation and bioaugmentation, were investigated in different sediments. Biostimulation experiments in which electron donor was supplied (H2 via elemental iron, Fe(0)) resulted in only a marginal improvement in the dechlorination of amended 2,3,4,5-tetrachlorobiphenyl (2,3,4,5-CB), likely because of an inadequate population of indigenous H2-utilizing dechlorinators. Extensive dechlorination was observed, however, after bioaugmenting microcosms with a PCB-dechlorinating enrichment culture. Dechlorination of 2,3,4,5-CB began prior to the 20th day of incubation and proceeded to 2-chlorobiphenyl. This extensive dechlorination activity was maintained in both sediments over 70d at 10 and 25 degrees C. This research demonstrates that although past studies of biostimulation were promising, a great deal must be known about the PCB-dechlorinating organisms present before successful biostimulation is expected. Bioaugmentation, however, appears to be a promising PCB remediation strategy and should be further pursued.     

Innovative solutions for averting a potential resource crisis—the case of one-person households in England and Wales

This paper seeks to test the hypothesis that growth in one-person households will increase the domestic consumption of energy, land and household goods in England and Wales. It concludes that if current consumer behaviour of one-person households persists there will be a significant increase in the consumption of all three resources in the future. However, it argues that that many opportunities exist in England and Wales for tackling this problem. For example the new housing programme, increasing ability amongst one-person households to afford “green alternatives” and the search amongst some one-person households for alternative lifestyles (which could be potentially more resource efficient). The paper suggests that providing one-person households with opportunities to live in more resource efficient housing and adopt pro-environmental behaviour could significantly reduce their future environmental impact. Various design, fiscal and awareness-raising solutions are presented in the paper and their viability is assessed. These include ecological homes, collective housing forms, occupancy tax, relocation packages, educational programmes and targeted advertising campaigns. The paper proposes that using a combination of these more innovative solutions to the problem could significantly reduce the future environmental impact of one-person households.     

Tetrasomy 12p—unusual presentation in CVS

CVS direct preparations usually achieve limited resolution and are better at detecting numerical rather than structural abnormalities. A CVS direct preparation analyzed using G-banding revealed a 47,XY,+G karyotype in 5 of 11 cells and was reported as mosaic for trisomy 21. Subsequent analysis of the CVS culture found only normal male cells. Amniocentesis revealed both normal male cells and cells with an extra F-group chromosome. Fluorescence in situ hybridization (FISH) identified this chromosome to be an isochromosome from the short arm of chromosome 12 [i(12)(p10)]. The amniocyte karyotype was reported as 47,XY,+i(12)(p10)[12]/46,XY[8].ish i(12)(p10)(wcp12+), which is associated with Pallister–Killian syndrome. Reexamination of the CVS direct preparation by FISH with a chromosome 12 centromere probe confirmed the karyotype of this tissue to be 47,XY,+mar[5]/46,XY[6].nuc ish 12cen(D12Z3 × 3)/12cen(D12Z3 × 2). Thus, multiple studies, including amniocentesis and fluorescence in situ hybridization, may be required to fully and accurately evaluate abnormalities detected by CVS. This case also indicates that mosaicism for supernumerary isochromosomes may have a complex origin. Copyright © 2003 John Wiley & Sons, Ltd.     

Book reviews

French Land Use Planning in the Fifth Republic: Real or imagined decentralisation?

Irene B. Wilson, Nijmeegse Planologische Cahiers No. 27, Geografisch en Planologisch Instituut, Katholieke Universiteit Nijmegen, Netherlands, 1988. 228pp. ISBN 90–70219–23–9.

Environmental and Resource Economics: an Introduction

Common, M. (1988). Longman i‐xiv 1–319.

The Greening of Aid: Sustainable Livelihoods in Practice.

C. Conroy & M. Litvinoff (Eds.) Earthscan Publications Ltd, London, 1989, pp.293, £8.95 (pb).

Private Supply of Public Services: Evaluation of Real Estate Exactions, Linkage, and Alternative Land Policies.

Rachelle Alterman (Ed), New York University Press, 1988. 273pp, ISBN 0–8147–0589–8.

City Politics

Hegemonic Projects and Discourse, by Maarten A. Hajer, published by Avebury Press, the Gower Publishing Company Ltd 1989, 140 pp.

The Genius Of The Place

The English Landscape Garden 1620–1820

John Dixon Hunt and Petér Willis. Price £12.50 (Paperback) & £26.95 (Cloth). M.I.T. Press.

Vacationscape

Designing Tourist Regions — 1988 2nd Ed.

Clare A. Gunn, New York, Van Nostrand Reinhold, $34.95 (cloth)

Loft Living — Culture and Capital in Urban Change

Sharon Zukin. Published, British Edition ‘Radius (Century Hudson) London, 1988 Price £8.95.

First Pub. U.S. John Hopkins University Press, 1982. Note: The British Edition has an added Chapter ’More Market Forces’.

William Kent Landscape Garden Designer

John Dixon Hunt. A. Zwemmer Ltd London. 1987, 176pp.

The Pattern of Landscape

Sylvia Crowe and Mary Mitchell (1988). Packard Publishing Ltd, Chichester. 127pp, 161 photographs. Price £30. ISBN 185341 020.

International Environmental Diplomacy

Edited by J. E. Carroll