Deposition and biological availability of diesel particles and their associated mutagenic chemicals

To estimate the human health risk of inhaled diesel particles, it is necessary to know their deposition and retention in the respiratory tract and the rate of dissociation of mutagenic compounds associated with the particles. The deposition of a chain aggregate aerosol of ⁶⁷Ga₂O₃ with size and shape characteristics similar to diesel exhaust particles has been evaluated using Beagle dogs. Approximately one-third of the inhaled activity is deposited in the respiratory tract with most of the particles deposited in the lung. The mutagenic activity present in dichloromethane, dog serum, dog lung lavage fluid, saline, dipalmitoyl lecithin (DPL) and albumin following incubation of these fluids with diesel exhaust particles was determined in the Ames Salmonella system. As observed by other investigators, large quantities of mutagenic activity were removed by dichloromethane. A very small amount of mutagenic activity was removed by the serum and lavage fluid over a 3-day incubation period. No activity was detected following elution with the other solvents. The finding that minimal mutagenic activity could be demonstrated in the biological media following incubation with diesel exhaust particles may be due to a lack of removal of mutagens from the particles or an inactivation of removed mutagens by protein binding or other processes.     

Containment facilities for pathological material

Microbiological Safety Cabinets are designed to provide protection to an operator from aerosol hazards that may be generated when handling infectious material. In addition, some types of cabinet can provide protection to the work being handled. Several national standards have been published in recent years which define the construction and performance of these devices; the three types of safety cabinet designated Classes I, II, and III are defined and described in this paper. A measured degree of operator protection is required at the front aperture of Class I and II cabinets, and a new method for assessing operator protection factor based upon a challenge aerosol of potassium iodide is described. Cabinet performance is discussed in relation to containment test results using this system. Working procedures and unsuitable environments can prejudice the containment performance of open-fronted cabinets by several orders of magnitude, and various aspects of this problem are discussed and illustrated. The importance of on-site commissioning tests to ensure adequate operator protection is emphasised. The application of safety cabinet testing techniques has been extended to assess the performance of fume cupboards (hoods), complete laboratories, and special “hybrid” installations such as may be used for handling carcinogenic or radiopharmaceutical material.     

Preliminary investigation of air bubbling and dietary sulfur reduction to mitigate hydrogen sulfide and odor from swine waste

When livestock manure slurry is agitated, the sudden release of hydrogen sulfide (H(2)S) can raise concentrations to dangerous levels. Low-level air bubbling and dietary S reduction were evaluated as methods for reducing peak H(2)S emissions from swine (Sus scrofa) manure slurry samples. In a first experiment, 15-L slurry samples were stored in bench-scale digesters and continuously bubbled with air at 0 (control), 5, or 10 mL min(-1) for 28 d. The 5-L headspace of each digester was also continuously ventilated at 40 mL min(-1) and the mean H(2)S concentration in the outlet air was <10 microL L(-1). On Day 28, the slurry was agitated suddenly. The peak H(2)S concentration exceeded instrument range (>120 microL L(-1)) from the control treatment, and was 47 and 3.4 microL L(-1) for the 5 and 10 mL min(-1) treatments, respectively. In a second experiment, individually penned barrows were fed rations with dietary S concentrations of 0.34, 0.24, and 0.15% (w/w). Slurry derived from each diet was bubbled with air in bench-scale digesters, as before, at 10 mL min(-1) for 12 d and the mean H(2)S concentration in the digester outlet air was 11 microL L(-1). On Day 12, the slurry was agitated but the H(2)S emissions did not change significantly. Both low-level bubbling of air through slurry and dietary S reduction appear to be viable methods for reducing peak H(2)S emissions from swine manure slurry at a bench scale, but these approaches must be validated at larger scales.     

FOOD QUALITY OF AUFWUCHS FROM ARTIFICIAL STREAMS RECEIVING LOW LEVELS OF PERTURBATIONS1

ABSTRACT: Protein, carbohydrate, and organic content of Aufwuchs samples from artificial streams dosed separately With chlorine, copper, or dextrose were altered by changes in the taxonomic composition or physiological condition of the community. Protein content increased as community composition shifted toward a dominance. by blue-green algae or heterotrophs. Bluegreens or cyanobacteria were dominant most often in Aufwuchs developing under copper or chlorine treatments and when water temperatures approached the seasonal maximum (22.8 C-25.8 0, while heterotrophs proliferated in the dextrose-enriched stream. Due to the associated extracellular mucilage, carbohydrate content also tended to be higher when blue-green algae or bacteria were abundant. However, carbohydrate content decreased in communities developing under chlorine or copper treatments at low or moderate temperatures (3 C-22.8 C), indicating a utilization of stored photosynthetic products to adapt to the stress. The organic content of Aufwuchs was related to the extent of mucilage production and the tendency of the community to accumulate detritus and suspended inorganic sediment. Protein and carbohydrate estimates were significantly correlated with dry weight and ash-free dry weight, a result of the copious extracellular mucilage associated with rapidly growing blue greens and other bacteria. Estimates of Aufwuchs food quality are important in evaluating the impact of pollutants on higher trophic levels; however, the tendency of change with both taxonomic shifts and physiological adaptations tends to confound interpretations for water quality assessment.     

Lessons for ecological policy design: A case study of ecosystem management

This paper explores the prospects for combining elements of the ecological and policy sciences to form a substantive and effective science of ecological policy design. This exploration is made through a case study whose specific focus is the management problem posed by competition between man and an insect (the spruce budworm, Choristoneura fumiferana) for utilization of coniferous forests in the Canadian Province of New Brunswick. We used this case study as a practical testing ground in which we examined the relative strengths, weaknesses, and complementarities of various aspects of the policy design process. Where existing approaches proved wanting, we sought to develop alternatives and to test them in turn. In particular, we used a combination of simulation modeling and topological approaches to analyze the space-time dynamics of this ecosystem under a variety of natural and managed conditions. Explicit consideration was given to the development of invalidation tests for establishing the limits of model credibility. An array of economic, social, and environmental indicators was generated by the model, enabling managers and policy makers to evaluate meaningfully the performance of the system under a variety of management proposals. Simplified versions of the models were constructed to accomodate several optimization procedures, including dynamic programming, which produced trial policies for a range of possible objectives. These trial policies were tested in the more complex model versions and heuristically modified in dialogue with New Brunswick's forest managers. We explored the role of utility functions for simplifying and contrasting policy performance measures, paying special attention to questions of time preferences and discounting. Finally, the study was shaped by a commitment to transfer the various models and policy design capabilities from their original academic setting to the desks and minds of the practicing managers and politicians. An array of workshops, model gaming sessions, and nontraditional communication formats was developed and tested in pursuit of this goal.This paper reports some specific management policies developed, and some general lessons for ecological policy design learned in the course of the study.     

Seasonal and geographic variation in chlorophyll level of Elysia tuca (Ascoglossa: Opisthobranchia)

Elysia tuca Marcus were collected from the Florida Keys (USA) during 1978–1979, with the aim of clarifying the physiological significance of their kleptoplastids by studying variations in the chlorophyll content of the slugs. The chlorophyll levels in the field populations varied seasonally, with peak levels in autumn. Peak reproductive activity coincided with maximum chlorophyll levels, carbon fixation, and rate of macromolecular conversion of kleptoplastid (= symbiotic chloroplast) photosynthates. Changes in chlorophyll level are probably controlled by rate of feeding, which is in turn governed by such factors as algal density and climatic factors (light and temperature). Chlorophyll level and individual weight varied with location, with significant differences between sites in the Upper Keys and the Lower Keys. Environmental factors control benefits of kleptoplastid retention, and suggest that photosynthate yield is an important subsidy of reproductive output.     

Impacts of disturbance from construction work on the densities and feeding behavior of waterbirds using the intertidal mudflats of Cardiff Bay,UK

The impact of disturbance from construction work around Cardiff Bay, south Wales, on the densities and feeding behavior of seven waterbird species was studied over an 11-year period. Construction of a barrage across the mouth of the bay has subsequently resulted in its impoundment; other major works included the construction of a bridge carrying a divided highway. Construction work disturbance significantly reduced the densities of five species—green-winged teal (Anas crecca), Eurasian oystercatcher (Haematopus ostralegus), dunlin (Calidris alpina), Eurasian curlew (Numenius arquata), and common redshank (Tringa totanus)—on adjacent intertidal mudflats, and thus the overall carrying capacity of the bay. Construction work also reduced the feeding activity of Eurasian oystercatcher, dunlin, and common redshank on these mudflats. The possible impact of the loss of birds from these mudflats upon the populations that the bay supported is discussed. Evidence from other local studies suggests that the displacement of common redshank from these mudflats did not contribute to a decline in this species.     

High-performance teams in wildlife conservation: A species reintroduction and recovery example

Reintroduction of animals to the wild to establish free-ranging viable populations is a valuable conservation tool, but ecological skills alone are not enough to ensure a successful reintroduction; also needed to do the work are effectively designed and managed programs. This article suggests general guidelines for organizing and managing reintroduction programs, reviews some basic organizational issues, and considers ways to develop high-performance teams The need to integrate reintroduction programs into their larger interorganizational context is discussed. The reintroduction program's structure must be appropriate for its function and should be properly staffed, led, and buffered from its political environment It should process information well, learn rapidly from its own mistakes, and be creative A high-performance team devotes most of its energies to solving external rather than internal problems     

A model of the antecedents of early union commitment: The role of socialization experiences and steward characteristics

The present study aimed at investigating the influence of shop steward characteristics and early union socialization experiences on new members' attitudes toward unions and their affective commitment to the union. Two thousand surveys were mailed to the most recent members of the National Association of Letter Carriers. Of these, 658 (33 per cent) were returned. Focusing on those individuals who had joined the union within the past 12 months yielded a usable sample of 585. A two-stage, structural equation modeling approach indicated a satisfactory goodness-of-fit for both the measurement and structural models. Individual socialization experiences significantly affected union attitudes. The latter variable was a significant predictor of union commitment. These results are discussed in the context of the organizational socialization literature and union commitment research.