Hormesis and stage specific toxicity induced by cadmium in an insect model,the queen blowfly,Phormia regina Meig

Hormesis is an adaptive response, commonly characterized by a biphasic dose-response that can be either directly induced, or the result of compensatory biological processes following an initial disruption in homeostasis [Calabrese and Baldwin, Hum. Exp.Toxicol., 21 (2002), 91]. Low and environmentally relevant levels of dietary cadmium significantly enhanced the pupation rate of blowfly larvae, while higher doses inhibited pupation success. However, dietary cadmium at all exposure levels adversely affected the emergence of the adult fly from the pupal case. Such findings represent the first report of a heavy metal displaying a hormetic-like biphasic response for pupation success, while at the same time displaying stage-specific toxicity at a later developmental period.These conclusions are based on substantial experimentation of over 1750 blowflies, in seven replicate experiments, involving 10 concentrations per experiment. These findings indicate the need to assess the impact of environmental stressors over a broad range of potential exposures as well as throughout the entire life cycle.     

An environmental assessment of enhanced oil recovery

The objective of this assessment is to quantify some of the environmental effects of a significant increase in United States oil production by tertiary or enhanced oil recovery (EOR) methods. The problems associated with each EOR technology are discussed and controls and regulations are briefly summarised. A tertiary oil production scenario for the United States was developed focussing only on mainland fields in the lower 48 states. It included all of the EOR methods expected to be in use during the next two decades. The environmental impacts, including water requirements, air emissions and generation of solid wastes, are then scaled to this scenario. The effects of control technologies and state regulations are considered. A comparison is also made between the impacts of EOR as an energy source and impacts associated with coal and synthetic fuels which concludes that EOR is preferable in many respects. There are environmental risks associated with EOR technologies, specific projects and specific fields in the production scenario; however, most problems are solvable by responsible regulation, enforcement of regulations and application of the best professional engineering by project operators.     

Empowered native community, modified SIA: The case of hydaburg, alaska

This paper reviews a social impact assessment of Hydaburg, Alaska, to illustrate the modifications of non-NEPA SIAs in response to “empowered” Native communities. Hydaburg has been influenced by three organizations designed to promote greater self-determination: the Native Village Corporation, a Native municipal government, and the Native Sovereignty Movement. The Hydaburg SIA incorporated community-based research, cultural assessment, and advocacy mitigation to accommodate the demands of this“empowerment”. The paper suggest that modified SIAs of this sort are likely to become more prevalent as self-determination among Native communities increases.     

Design guidelines for an optimum scrubber system

The revised New Source Performance Standards (NSPS) for the utility industry mandates reduced particulate matter and sulfur dioxide emissions from new utility boilers. A wet scrubber system can be an advantage in controlling both of these emissions. Existing wet scrubber systems may meet the new standards with significant increase in power consumption. A careful design of the entire scrubber system, based on the experience gained at the existing installations, is necessary to ensure cost effectiveness. The experience with existing wet scrubber systems used on coal-fired utility boilers is reviewed and their performance is correlated with power consumptions. Based on a correlation of scrubber pressure drop against outlet concentration, conventional scrubber systems would be able to meet the revised NSPS for particulate matter with a theoretical scrubber pressure drop of 43±5 cm H₂O. Overall system pressure drop, however, could easily run as high as 76 cm H₂O. Novel scrubber systems such as the electrostatically augmented scrubber may provide the necessary collection performance at lower pressure drops. The performance of the various scrubber components such as mist eliminators and reheaters is reviewed. Operating problems are also discussed.     

USE OF SYNOGRAPHIC TECHNIQUES IN RESEARCH AND DISSEMINATION OF HYDROLOGICAL INFORMATION1

ABSTRACT: Application of synographic techniques to four separate nonrelated research tasks demonstrated the usefulness of such an approach in interpreting and communicating hydrologic survey data especially when large geographic areas are involved. Nutrient exchange and biotic indicators in coastal estuaries were analyzed to determine residence times in different seasons of the year. Man induced changes in urban runoff patterns were shown to increase the probability of flooding with different recurrences of storm events. Nitrate and indicator bacteria in private wells were analyzed on a county-wide basis to determine the sources and extent of natural occurrence versus contamination origins. Water wells and the surface supply of metropolitan Houston were analyzed for sodium content to assist citizens and physicians with data which are needed for derivation of sodium restricted therapeutic diets.     

UNSATURATED FLOW THROUGH SOLID WASTE LANDFILLS: MODEL AND SENSITIVITY ANALYSIS1

ABSTRACT: The movement of precipitation water infiltrating through the material (refuse) of solid waste landfills is examined via numerical solution of the equations of continuity, and motion (Darcy's Law). The solution of the equations is obtained by a fully implicit, finite-difference scheme. Both unsaturated and saturated surface conditions are considered, making the scheme suitable for real-time simulation of net precipitation and moisture redistribution events. A sensitivity analysis showed that for unsaturated surface conditions the solution is primarily affected by hydraulic conductivity and capillary diffusivity, and is relatively independent of the space and time steps. In addition, the precipitation averaging process is shown to be critical in the correct computation of moisture transport during the time period where the transition from unsaturated to saturated conditions occurs. The model presented herein is suitable for analysis of water movement through landfills, and the design of bottom collection systems.     

HYDROLOGIC ENGINEERING TECHNIQUES FOR REGIONAL WATER RESOURCES PLANNING1

The emphasis upon comprehensive regional water resources planning in the past decade has encouraged the hydrologic engineer to take advantage of improvements in technology to develop new hydrologic engineering techniques for use in regional planning studies. The new techniques are necessary because the traditional hydro-logic engineering techniques are not always consistent with the increased scope and diversified objectives of regional planning studies. The Hydrologic Engineering Center has been involved in aiding in the development of some of these new techniques as the result of studies that have been made in cooperation with other Corps of Engineers offices. Most of the new techniques being developed emphasize computational procedures developed specifically for use with electronic computers. Applications of new techniques range from framework studies to planning of day-to-day operation criteria. Studies recently completed or in progress include: (1) development of a regional flood control site screening plan for the North Atlantic Region study; (2) use of streamflow simulation for planning and operation of the Missouri River mainstem projects; (3) development of an operation plan for the Arkansas-White-Red Rivers Reservoir System; (4) standard project flood and flood frequency estimates for the Colorado River Basin Framework Study; and several other projects which are described in more detail in the following paragraphs. One of the initial efforts in regional analysis was the formulation of procedures for determining standard project flood estimates for southern California coastal streams using generalized criteria. Techniques were developed that were readily adaptable to the computer and which would determine representative unit hydrographs, losses and standard project precipitation for any location in the study area. The resulting standard project flood estimates were consistent with the accuracy required for framework studies; however, they could be refined easily for design studies. As a result of the recent drought in the Northeastern United States, a study was made to evaluate both present and future water supply reservoirs in that region. The study consisted of computerized studies of the hypothetical operation of a large number of reservoirs as a system. The reservoirs were on many different streams throughout the region and had varying constraints, depending upon the stream and the state in which the reservoir was located. Since only preliminary data was available on the proposed reservoirs, it was not possible to refine the studies to a large degree. However, the models of each system can be easily refined as more accurate design data become available. The development of a computer-aided screening procedure for use in evaluating several hundred potential reservoir sites for the Missouri River Basin Comprehensive Framework Study is a third example of regional analysis. The adopted procedures used available physical, hydrologic, and climatologic data in estimating reservoir storage requirements throughout the basin. Because the procedure is based upon the techniques often used in more refined studies, it is expected that the results of the screening study will be very useful in future planning and design work. Shortcomings of some of the traditional techniques have helped in the development of new techniques. For maximum usefulness the new techniques should: (1) be consistent with the scope, objectives, and requirements of the overall study; (2) use all available physical, hydrologic, and climatologic data without requiring extensive data which may not be available; (3) take full advantage of the capabilities of the computer and associated data processing systems; and (4) produce results which form a firm basis for future, more detailed, planning and design studies instead of being limited in usefulness largely to the study at hand.     

Natural vs. plantation forests: A case study of land reclamation strategies for the humid tropics

Biomass and productivity were compared in two plantations and in one stand of natural regeneration on similar sites in a premontane moist forest region of Puerto Rico. While initial growth rates of plantation species were higher, after four decades productivity of the natural regeneration plots was equal to or greater than productivity of the plantations. For the first 44 years, aboveground biomass of natural regeneration increased at an average annual rate of 3.8t·ha^–1·yr^–1, but the last year of the study it was 14.7t·ha^–1. Biomass increment of a pine plantation averaged between 8 and 10.5t·ha^–1·yr^–1 except for one year when the rate was much lower, possibly because of hurricane damage. A tropical hardwood plantation averaged close to 4t·ha^–1·yr^–1 for 41 years. It is suggested that in countries where funds for land reclamation are limited, intensive plantations may not always be the best strategy. Natural regeneration or shelterbelt plantations may be suitable alternatives.     

AIRPORT WASTES AND WATER QUALITY1

ABSTRACT: Waste waters from various operations at the Miami International Airport are characterized. Servicing, maintenance, overhauling, and washing of aircraft seem to be the most significant waste water producing operations. Pollutional constitutents commonly found in the airport wastes include acids, alkalis, detergents, oil, grease, and oxygen demanding substances. Phenols are of concern when stripping and repainting operations occur. Although most airport wastes may be treatable, a great reduction in influent load can be achieved by proper housekeeping methods.