Pollutant Removal from Wood and Coal Flue Gases by Soil Treatment

If many homeowners convert to solid fuels for heating, residential flue gases will be a large source of air pollution. Control of this pollution requires an inexpensive, reliable, and effective method of flue gas treatment. One such method is to force flue gases through soil beds. Such soil treatment removes all detectable smoke, odor, and polynuclear organic matter (POM), up to 97% of the CO, and at least 97% of the SO₂ from flue gases of wood and coal combustion. The technique is low cost, reliable, almost maintenance-free, and also appears suitable for other small point sources of air pollution.     

Improving Baghouse Performance at the Monticello Generating Station

At the Monticello station, operated by the Texas Utilities Generating Company, lignite coal obtained locally in Titus and Hopkins Counties fuels each of the three units. Units 1 and 2 are identical 575-MW Combustion Engineering (CE) boilers, each of which discharges its effluent to a 36- compartment shake/deflate cleaned baghouse paralleled with four electrostatic precipitators (ESP). Unit 3 is a larger boiler and is followed by an ESP and a scrubber. The Unit 1 and 2 baghouses were designed to clean 80 percent of the flue gas. Since startup, these baghouses have regularly experienced flange-to-flange pressure drops in excess of 10 in. H₂O, with large opacity spikes caused by ash bleeding through the bags after compartment cleanings. Because of higher-than-expected pressure drop, the baghouses receive only about 45-50 percent of the flue gas. Analysis has shown the Monticello lignite ash significantly differs from most other coal ashes. Testing has shown that the Monticello ash is not filtered effectively by many "standard" bag materials. However, this testing indicates that there are fabrics that show promise of eliminating the ash bleedthrough with little pressure drop penalty. Testing has also shown that injection of low concentrations (10-15 ppm) of ammonia (NH₃) into the flue gas significantly decreases ash bleedthrough, so that with NH₃ injection "standard" bag materials may perform adequately. Currently, fullcompartment testing of four fabrics, with and without NH₃ injection, is under way at the Unit 1 baghouse. The research conducted at the Monticello station is reviewed in this paper and the encouraging results from the full-compartment tests are presented.     

Perceptions of air pollution during the work-related commute by adults in Queensland,Australia

BackgroundThis study examines perceived health effect risks from air pollution during the work-related commute by socio-demographic and travel mode variables.MethodsPopulation-representative survey data were collected by telephone from 745 adults from Queensland, Australia. Variables assessed included socio-demographics, usual work travel mode, commute perceptions, and perceived health effects associated with air pollution during the work-related commute.ResultsApproximately 45% of the sample perceived air pollution negatively affected health outcomes when commuting to/from work, yet only 13% recognised air pollution as a major barrier to walking or cycling to/from work. No relationships existed between usual travel mode to/from work and perceived health risks associated with air pollution. Those higher educated or living in major cities were more likely to recognise air pollution harmed their health during their work-related commute when compared to respective referent categories (p ≤ 0.05).ConclusionsRecognition of health risks from air pollution during the work-related commute was high, and awareness did not differ by travel mode. For the majority, air pollution was not a primary barrier for walking or cycling to/from work.     

PULSED TRICKLING EFFECTS ON SOIL MOISTURE DISTRIBUTION1

ABSTRACT Laboratory experiments were conducted to study effects of trickle emitter discharge rate on the distribution of soil moisture in a silty-clay loam soil. Both pulsed and continuous irrigation treatments were studied. A simulation model was used to evaluate the results obtained in the laboratory. The agreement between the predicted and measured soil moisture distribution patterns was quite good. For both pulsed and continuous applications, increasing trickle discharge rate resulted in a decrease in the horizontal component and an increase in the vertical component of the wetted soil profile. Compared to the continuous treatments, pulsed applications resulted in significant reduction in water loss below the root zone. Pulsed applications rates can replace continuous small discharge rates to reduce irrigation water runoff problems on heavy soils and with restricted infiltration allow the use of larger emitter orifices to decrease potential clogging of the trickle system.     

Photodegradation of the herbicide EPTC and the safener dichlormid, alone and in combination

Photodegradation of the herbicide EPTC (S-ethyl-N, N-dipropylthiocarbamate), and the safener dichlormid (2,2-dichloro-N, N-diallylacetamide) has been examined in methanol and in water solutions. Irradiation of EPTC and dichlormid with UV light at 254 nm caused rapid degradation in both media. Remarkable and gradual changes in color of EPTC irradiated solution was observed from clear to yellow then to intense orange. EPTC half-life of elimination in water was 14.0, and 18.5 min, and in methanol 37.2 and 32.2 min, when irradiated with and without dichlormid, respectively. There was significant difference between rate of EPTC degradation in water and methanol in the presence or in the absence of dichlormid. Negligible degradation of EPTC or dichlormid at > 290 nm was observed. Photoproducts were separated and identified using GC or/and thin-layer chromatography then identified using mass spectrometry. It appeared that some products have high molecular weight that formed as a result of dimerization. This is possibly a result of the coupling of radicals that formed through EPTC degradation. The cleavage of C-S and C-N bonds accounted for the formation of these radicals. Gradual dealkylation of the acid chains of EPTC has also occurred. EPTC-sulfoxide, EPTC-sulfone, Propylamine and dipropylamine were detected as photoproducts of EPTC at 254 nm. Dichlormid pathways of degradation at 254 nm were characterized as dechlorination, dealkylation, and hydrolysis both in water and methanol. The findings showed that dichlormid did not significantly affect EPTC photodegradation either at 254 nm or at > 290 nm. The biological/toxicological properties of the photoproducts need further study, particularly the dimer compounds.     

Landscape Patterns of Florida Scrub Jay Habitat Use and Demographic Success

Remote sensing and geographical information systems are used to analyze landscapes important to species of conservation concern. The accuracy of the methods depends on how closely habitat mapping classes are linked to population demography. Habitat use by Florida Scrub Jays ( Aphelocoma c. coemlescens ) was quantified using circular plots. Habitat variation was mapped using high-resolution aerial photography on a site where all Florida Scrub Jays were color-banded. Nest site selection, nest success, yearling production, and breeder survival were measured within Florida Scrub Jay territories. Habitat use was lowest in areas without scrub oaks or areas within 136 m from forests. Open oak, dominated by scrub oaks and open sandy areas, had the highest use and nest success among habitats. Open oak occurred as narrow patches ( <20 m wide) in landscapes dominated by matrix habitat (palmetto-lyonia and swale marshes). Most wide patches (>50 m) of open oak were potential population sources, where reproduction exceeded mortality. Areas with patches of open oak of less than 1 ha were usually population sinks. Open oak occurred as less flammable patches in a landscape subject to frequent fires. Population sources varied temporally and spatially with fires and site potential to support scrub oaks (soils). Analyses of landscape patterns and dynamics indicated that habitat mapping should not only include patches of currently optimal habitat but should also include landscapes associated with open oak. The influences of landscape patterns on habitat use, reproductive success, survival, and territory size can be quantified at different scales starting with attributes associated with habitat patches, nest sites, and territories. Potential mapping errors occur, however, when habitats are used to quantify the areal extent of sources and sinks and similar population attributes important for species persistence.     

WalkSafe: a school-based pedestrian safety intervention program

OBJECTIVE: To evaluate the effectiveness of the WalkSafe program, an elementary school-based pedestrian safety program in a single high-risk district in Miami-Dade County. METHODS: Sixteen elementary schools were identified in a single high-risk district and enrolled in a one-year study. All schools implemented the WalkSafe program on the last week of January 2003. A pre, post, and three-month post testing of pedestrian safety knowledge was conducted. An observational component was also implemented at four schools that were randomly chosen. Engineering recommendations and law enforcement initiatives were also performed. RESULTS: A total of 6467 children from K-5th grade from 16 elementary schools participated in the program. Of these 5762 tests were collected over three different testing times. A significant difference (p-value < 0.001) was found between the pre and post testing conditions across all grade levels. There was no significant difference found between the post and three-month post testing conditions across all grade levels (p-value > 0.05). The observational data collected at four schools across the different testing times demonstrated a significant difference found between pre and post testing conditions for Group A (stop at the curb and look left, right, left) and also for Group B (midstreet crossing and darting out) (p-value < 0.05). There was no difference found between comparing the pre-test or post-test condition with the three-month post-test time. There were many environmental modifications that were recommended and actually performed. CONCLUSION: The WalkSafe program implemented in a single high-risk district was shown to improve the pedestrian safety knowledge of elementary school children. The observational data demonstrated improved crossing behaviors from pre-test to post-testing conditions. Future research will focus on sustaining the program in this district and expanding the program throughout our county.     

Prediction of cervical spine injury risk for the 6-year-old child in frontal crashes

This article presents a series of 49 km/h sled tests using the Hybrid III 6-year-old dummy in a high-back booster, a low-back booster, and a three-point belt. Although a 10-year review at a level I trauma center showed that noncontact cervical spine injuries are rare in correctly restrained booster-age children, dummy neck loads exceeded published injury thresholds in all tests. The dummy underwent extreme neck flexion during the test, causing full-face contact with the dummy's chest. These dummy kinematics were compared to the kinematics of a 12-year-old cadaver tested in a similar impact environment. The cadaver test showed neck flexion, but also significant thoracic spinal flexion which was nonexistent in the dummy. This comparison was expanded using MADYMO simulations in which the thoracic spinal stiffness of the dummy model was decreased to give a more biofidelic kinematic response. We conclude that the stiff thoracic spine of the dummy results in high neck forces and moments that are not representative of the true injury potential.     

Food and hunger in Sub-Saharan Africa

Sub-Saharan Africa is by far and away the most disadvantaged of the world's three main developing regions. Worse, its situation has mostly been deteriorating for much of the past several decades. Its agriculture is severely under-productive, and per capita food supplies have been steadily dwindling. Its environments and natural-resource base, characterised by water deficits, soil erosion, fuelwood shortages, rudimentary agro-practices, and grossly inadequate infrastructure, are generally unfavourable for sustainable agriculture. The population has expanded until it far exceeds carrying capacity, yet its growth rate is the highest in the world. The region also suffers from more disease than any other region. There is widespread and deepening poverty. As a result of these and other problems, and despite major food imports, two-thirds of the people are malnourished, one-quarter of whom endure outright hunger, even semi-starvation. Both these proportions appear set to keep on increasing both relatively and absolutely. Were these problems to persist with their decades-long trends, there could eventually arrive a stage when much larger numbers of people would succumb to terminal malnutrition, precipitating a human tragedy of unprecedented proportions. Fortunately, success stories demonstrate that solutions are available, on the part of both governments concerned and international agencies. Because of ignorance, or rather ignore-ance of the potential mortality disaster ahead, however, not nearly enough has been done to address the challenge with the energy and urgency to match its scale.     

Meaning work: reworking institutional meanings for environmental governance

Effective environmental governance requires institutional change. While some actors work to change institutions, others resist change by defending and maintaining institutions. Much of this institutional work is ‘meaning work’, which we define as the practice of crafting, adapting, connecting and performing meanings to purposively create, maintain or disrupt institutions. This paper constructs a concept of meaning work that highlights agency in carrying meanings across scales and between discursive layers, while noting the structuring role of prevailing discourses. It grounds the concept using two environmental governance cases at very different scales: a local democratic innovation employed by Noosa Council in Queensland, Australia; and the international campaign to divest from fossil fuels. The cases demonstrate the diversity of meaning work and the difficulty of achieving deep discursive change. They point to the need for environmental governance practitioners to rework existing meanings to construct compelling stories for change, taking advantage of narrative openings.