Field demonstration of the combined effects of absorption and evapotranspiration on septic system drainfield capacity.

Drainfields for disposal of septic tank effluents are typically designed by considering the loss of water by either upward evapotranspiration into the atmosphere or lateral and downward absorption into the adjacent soil. While this approach is appropriate for evapotranspiration systems, absorption systems allow water loss by both mechanisms. It was proposed that, in areas where high evapotranspiration rates coincide with permeable soils, drainfield sizes could be substantially reduced by accounting for both mechanisms. A two-year field demonstration was conducted to determine appropriate design criteria for areas typical of the Texas High Plains. The study consisted of evaluating the long-term acceptance rates for three different drainfield configurations: evapotranspiration only, absorption only, and combined conditions. A second field demonstration repeated the experiments for additional observation of the combined evapotranspiration and absorption and achieved similar results as the first study. The field tests indicated that the current design loading criteria may be increased by at least a factor of two for the Texas High Plains region and other Texas areas with similar soil composition and evapotranspiration rates, while still retaining a factor of safety of two.     

Nitrous oxide (N2O) emissions from waste and biomass to energy plants.

Following the Kyoto protocol with respect to reducing emissions of greenhouse gases emissions, and EU energy policy and sustainability in waste management, there has been an increased interest in the reduction of emissions from waste disposal operations. From the point of view of nitrous oxide (N2O) emissions, waste incineration and waste co-combustion are very acceptable methods for waste disposal. In order to achieve very low N2O emissions from waste incineration, particularly for waste with higher nitrogen content (e.g. sewage sludge), two factors are important: temperature of incineration over 900 degrees C and avoiding the selective non-catalytic reduction (SNCR) de-NO(X) method based on urea or ammonia treatments. The more modern selective catalytic reduction (SCR) systems for de-NO(X) give rise to negligible sources of N2O.     

Influence of flue-gas desulfurization systems on coal combustion by-product quality at kentucky power stations burning high-sulfur coal

Two Kentucky power plants burning similar blends of high-sulfur western Kentucky and southern Indiana coal provide a unique opportunity to examine the variations in coal combustion by-products due to differences in the method of wet flue-gas desulfurization (FGD). One plant employed carbide lime-based scrubbing for two units and a dual-alkali process for the third unit. The second plant employed a Mississippian limestone from Kentucky for all four units. This study provides an example of optical and SEM petrographic techniques, supplemented by chemical analyses, applied to the study of, at least from the geologic perspective, non-traditional materials. The coal sources comprise a blend of high volatile C and B bituminous, high vitrinite (85–90%, mmf), high-sulfur (> 3%, dry) coals. The fly ash is dominated by glassy phases (70–80%) with about 5–10% spinel (predominately magnetite), 3–10% quartz, and 4–10% isotropic coke comprising the remaining portion of the ash. SEM observations indicate that the glassy particles exhibit a bimodal size distribution with sub-micron glass spheres and a population of larger (several 10s of microns) spheres. The bottom ash has higher proportions of spinels and mullite, with negligible carbon forms, compared to the fly ash from the same units. Fly ashes were observed to be lower in Fe and higher in Al, Si, and S compared to the bottom ashes. Carbide lime, a by-product of acetylene manufacture, soda ash, and limestone were the reagents used in the flue-gas desulfurization processes. The primary FGD by-product is a calcium sulfite slurry which is vacuum filtered and mixed with fly ash and, usually, lime, to form a stable product for disposal. The FGD by-products have some potential, as yet unrealized, for utilization.     

The Development of Environmental Action Plans: Turning Statements into Actions

The Midlands Region of the Environment Agency has developed a management system, in the form of an Environmental Action Plan (EAP) to ensure that the constraints and mitigation measures identified in the Environmental Statement document are delivered on the ground. The reasons are considered for developing such procedures and examples are provided of the environmentalobjectives and targets which lie at the heart of the new procedures. The EAP is designed to provide a summary of the environmental constraints, adverse effects and their associated mitigation measures, and monitoring requirements, in an easily accessible document for both technical and non-technical readers.     

The Mersey Basin and its River Valley Initiatives: an appropriate model for the management of rivers?

Concepts of sustainable development have stimulated innovation in the delivery of environmental management. In particular, new partnership approaches have been developed in recognition of the need to adopt more holistic perspectives and facilitate multi-sectoral and cross-sectoral working. River catchments are complex systems and have been one particular focus of experimentation in environmental management mechanisms. This paper provides a brief overview of river management experience in the UK, charting changing approaches in terms of scope and organisation since the 1970s. This sets the context for a more detailed examination of the Mersey Basin Campaign and, in particular, its River Valley Initiatives. The paper concludes with an evaluation of the merits of this approach in relation to sustainable river management.     

Molecular Genetic Consequences of a Population Bottleneck Associated with Reintroduction of the Mauna Kea Silversword (Arg yroxiphium sandwicense ssp. sandwicense [Asteraceae])

The endangered Mauna Kea silversword (Argyroxiphium sandwicense ssp. sandwicense) has experienced a severe decline in distribution and abundance because of predation by alien ungulates. By the late 1970s only a small remnant natural population persisted on the Mauna Kea volcano on the Island of Hawaii. The Hawaii Department of Land and Natural Resources, Division of Forestry and Wildlife, initiated an outplanting program in the 1970s to promote recovery of A. sandwicense ssp. sandwicense. Intermittent outplanting since 1973 has generated an outplanted population of over 450 plants on Mauna Kea, but the program has unintentionally resulted in a major population bottleneck. All plants in the outplanted population appear to be first- or subsequent-generation offspring of only two maternal founders from the natural population. Genetic variation in the natural and outplanted populations was assessed for 90 random amplified polymorphic DNA loci. Eleven loci were detectably polymorphic in the natural population, whereas only three loci were detectably polymorphic in the outplanted population. Thus, the population bottleneck has been accompanied by a 73% reduction in the level of detectable polymorphism. In addition, for eight loci, the population bottleneck has resulted in the loss of the marker allele in the outplanted population. A management strategy involving manual pollen transfer has recently been implemented to incorporate additional founders from the natural population into the outplanting program. As a supplement to the outplanting program, the strategy also includes a program promoting direct seedling establishment following manual pollen transfer. Incorporating additional founders may serve to overcome the legacy of the population bottleneck, especially if founder representation can be equalized.     

Advisory Committee: A Powerful Tool for Helping Decision Makers in Environmental Issues

/ It has been suggested that the general public should be moreinvolved in environmental policy and decision making. It is important forthem to realize that they will have to live with the consequences ofenvironmental policies and decisions. Consequently, policy makers shouldconsider the concerns and opinions of the general public before makingdecisions on environmental issues. This raises questions such as: How can weintegrate the perceptions and reactions of the general population inenvironmental decisions? What kind of public participation should weconsider? In the present study, using a new regional ecosystem model, weattempted to integrate these aspects in its decision making model byincluding the formation of an advisory committee to resolve problems relatedto waste management. The advisory committee requested the activeparticipation of representatives from all levels of the community: economic,municipal, and governmental intervenors; environmental groups; and citizens.Their mandates were to examine different management strategies available inthe region, considering all the interdisciplinary aspects of each strategy,elaborate recommendations concerning the management strategies that are mostsuitable for all, and collaborate in communication of the information to thegeneral population. The results showed that at least in small municipalitiessuch an advisory committee can be a powerful tool in environmental decisionmaking. Conditions required for a successful consultation process, such aseveryday lay language and the presence of a facilitator other than ascientific expert, are discussed.KEY WORDS: Public consultation; Environmental policies;Interdisciplinary aspects; Municipal sewage sludge management; Generalpopulation; Decision-making process