Distribution of lindane in plasma and brain after a single administration to cats

The distribution of lindane and its metabolites in the plasma and brain of the cats after 30 minutes, 1, 2, 4 and 8 hours of administration of lindane (2mg/kg, i.v.) was investigated. The compound distributes differentially in the CNS and this pattern changes with time. The pattern of distribution shows that although lindane concentration is higher in areas with a high myelin content, it disappears more rapidly from gray matter. The plasma levels were also high at 30 minutes interval and then gradually decreased. The rate of formation of the metabolite 2,4,6‐Trichlorophenol appeared to be maximum in the first 4 hours. The accumulation of the compound and its metabolite in brain during the experimental period was not evident.     

Effects of hexachlorocyclohexane administration on distribution of trace metals in rat tissues

The effects of daily administration of hexachlorocyclohexane (HCH) for 90 days on the distribution of Cu, Zn, Fe and Mn in rat tissues were investigated. The results indicated that HCH caused a significant increase in weight of liver and spleen and decrease in the weight of kidney, heart and brain. The spleen and heart demonstrated the maximum mobilization of metals. Comparing the individual trace elements, zinc appeared to be the most active element. None of the metals assayed registered change in RBC's but there was increase in Zn, Fe and Mn concentration in plasma.     

Chaos and complexity in development

SUMMARY

The paper outlines some main features of chaos theory. Examples of chaotic systems in society and the environment are given. Spontaneous interaction of components, without being planned or directed, is known as ‘self-organising behaviour’. Chaos is an essential aspect of this self organisation, occurring in many forms. A chaotic system is defined as one that shows sensitivity to initial conditions. If the errors relative to the initial conditions become too great, the system will eventually collapse. Development projects are sensitive to such initial conditions. In particular, two examples in development are outlined in some detail and commented upon. One is the occurrence of a project promoting self-organising systems among the poorest of the poor. The other outlines how rehabilitation after resettlement in a power project has transgressed the ‘edge of chaos’ socio-emotionally, in spite of the socioeconomic development being good.     

Risk homeostasis theory, utility and accident loss in a simulated driving task

The suggestion that utility is logically necessary for behavioural adjustments to be made in response to changes in intrinsic risk is fundamental to risk homeostasis theory (RHT). However, the methodology used to investigate RHT — analysis of road traffic accidents — is ill-suited to the investigation of this assertion. The role of utility and intrinsic risk as possible determinants of behavioural compensation were therefore examined experimentally across 14 specific behaviours using the Aston Driving Simulator. RHT predicts that these two factors act in a multiplicative way to form a statistical interaction. It also predicts that the behavioural pathways through which the effect manifests itself should be reconcilable with the concept of utility. Both predictions received little support in this experiment, suggesting that utility and intrinsic risk operate as independent factors: both factors produced significant main effects across a number of behaviours. This finding, if it can be generalised, implies that, contrary to mathematically-based models of danger compensation and the traditional model of risk homeostasis, utility is not logically necessary for behavioural compensation in response to a change in intrinsic risk.     

Testing of a GIS model ofEucalyptus Iargiflorens health on a semiarid,saline floodplain

Irrigated agriculture has resulted in substantial changes in water flows to the lower reaches of the River Murray. These changes have led to large-scale occurrences of dieback inEucalyptus largiflorens (black box) woodlands as well as increased inputs of salt to the river. Management options to address problems of this scale call for the use of spatial data sets via geographic information systems (GIS). A GIS exists for one floodplain of the River Murray at Chowilla, and a simple model predicted six health classes ofEucalyptus largiflorens based on groundwater salinity, flooding frequency, and groundwater depth.To determine the usefulness of the model for vegetation management, the quality of both the model and the GIS data sets were tested. Success of the testing procedure was judged by the degree of spatial matching between the model's predictions of health and that assessed from aerial photographs and by field truthing. Analyses at 80 sites showed that tree health was significantly greater where groundwater salinity was less than 40 dS/m or flooding occurred more frequently than 1 in 10 years or depth to groundwater exceeded 4 m. Testing of the GIS data sets found that vegetation was misclassified at 15% of sites. Association was shown between GIS-predicted values and field-truthed values of groundwater salinity but not groundwater depth. The GIS model of health is a useful starting point for future vegetation management and can be further improved by increasing the quality of the data coverages and further refining of the model to optimize parameters and thresholds.     

CONTINUOUS SIMULATION FOR WATER QUALITY PLANNING1

ABSTRACT: This paper describes a methodology for the evaluation of water quality plans analogous to procedures used in flood control planning, where flood damage frequency curves provide the basis for determining flood control benefits. The proposed method uses continuous water quality simulation to develop long term information from which water quality frequency curves can be obtained. This frequency information allows the evaluation of the impact of proposed water quality control plans taking into consideration the variable nature of the water resource. Using treatment costs and other economic indicators of water quality, the frequency information can be used to estimate the cost-effectiveness and economic efficiency of alternative plans. The method is demonstrated in a semi-hypothetical environment; real hydrologic and climatic characteristics are assigned to a hypothetical watershed configuration. Alternative management plans are simulated and analyzed for both physical and economic impacts. The advantages of continuous simulation and its use in water quality planning are explored.     

Modeling of gas-phase photodegradation of chloroform and carbon tetrachloride

The relationship between the irradiance in a photoreactor and the rate of photodegradation of organics is essential in the scaling-up of photoreactors to treat large volumes of air contaminated with organic pollutants. In this study, the analysis is adopted to compare results obtained from two different photoreactors. Initially, the applicability of two light models in calculating the irradiance in two photoreactors was evaluated. Thereafter, kinetic models of ultraviolet (UV) photooxidation of chloroform (CHCl3) and carbon tetrachloride (CCl4) from the archived literature were tested using experimental data under various operating conditions and different irradiances. Sensitivity analyses were conducted using different values of model parameters to determine the significance of each parameter on the photodegradation of the two chlorinated organics. For compounds that undergo photolysis as a primary mode of degradation, the rate of photodegradation at low initial concentrations can be predicted easily by the following equation: d[C]/dt = -2.303Iave, lambdaepsilonlambdaphilambda[C]. Although the photodegradation of chlorinated organic compounds in dry and humid air can be predicted well, it is difficult to predict the Cl* sensitized oxidation occurring at high initial concentrations. A good agreement between the simulated and experimental data provides a sound basis for the design of large-scale reactors.     

INFLUENCING WATER LEGISLATWE DEVELOPMENT WHAT TO DO AND WHAT TO AVOID1

ABSTRACT: Whomever would affect water policy development must influence the water legislative process. This paper discusses in the context of the Model State Water Allocation Code the following ten ideas about doing that: (1) seek the right timing for enactment; (2) set modest goals; (3) prepare a well-drafted proposal; (4) recognize diversity by offering legislative choices; (5) consider the impacts of adoption; (6) make alliances; (7) respect executive influence; (8) become involved in legislative interaction; (9) be flexible; and (10) persist. Heeding these ideas, although not guaranteeing enactment, is sure to be educational for participants and useful to legislators.     

Smart Growth and Sustainable Development: challenges, solutions and policy directions

In this paper, we focus on the issues related to development densities that emerged from our study of sprawl and development issues in three regions of British Columbia, Canada. We chose to focus on this aspect of the Smart Growth agenda because, while many of its other elements enjoy wide support across social interests, the goal of achieving a higher density urban fabric is highly controversial. We proceeded by collecting data on development densities and 13 indicators of community sustainability in 26 municipalities. The results suggest that the density of communities is associated with efficiencies in infrastructure and with reduced automobile dependence, with the ecological and economic implications which flow from that. However, it does not necessarily correlate with greater affordability of housing or more access to green space. In fact, if anything, we discovered a negative relationship between housing affordability and green space per capita and higher land-use densities. In a second stage of the research, we conducted a qualitative analysis of a subset of six municipalities and identified key policy issues for moving ahead with the Smart Growth agenda. The paper concludes with a discussion of the policy issues that emerged from these case studies.