Pentachlorotoluene and pentabromotoluene: results of a subacute and a subchronic toxicity study in the rat

Pentachlorotoluene (PCT) and pentabromotoluene (PBT) are environmental contaminants detected in the Great Lakes ecosystem. In view of the paucity of toxicity data and the potential for human exposure, a subacute (28 day) and a subchronic (91 day) study were conducted in the rat. In the subacute study, groups of 10 male and 10 female rats were fed the diet containing PCT or PBT at 0, 0.5, 5.0, 50 or 500 ppm for 28-days. In the subchronic study, the group size was increased to 15, the dose levels were 0, 0.05, 0.5, 5.0, 50 and 500 ppm in the diet and the exposure period was 91 days. Growth rate and food consumption were not affected by exposure to either chemical in the subacute and subchronic study. Clinical observations revealed no abnormalities. Decreased hemoglobin was observed in female rats fed 5.0 ppm PCT and higher levels in the subacute (28 day) study. In the same study the hematocrit value and erythrocyte numbers of females fed 5.0 or 500 ppm PCT diets were significantly lower than the control. In both subacute and subchronic studies mild dose-dependent histopathological changes were observed in the thyroid, liver and kidney of rats fed PCT and PBT diets. In general male rats were more susceptible than females to the treatment of PCT and PBT. Based on these data, it was concluded that the no observable adverse effect level for PCT was 50 ppm in the diet (3.5 mg/kg b.w./day) and that of PBT was 5.0 ppm (0.35 mg/kg b.w./day).     

Effects of two organophosphorus insecticides on some biochemical constituents in the nervous system and liver of rabbits

Male Baladi rabbits were acutely and sub-chronically intoxicated with cyanofenphos and profenophos. The levels of cholesterol, triglycerides, B-lipoproteins and total proteins were determined in the serum, brain, spinal cord and sciatic nerve of rabbits. Moreover, the activities of alkaline phosphatase, acid phosphatase and glutamic-pyruvic transaminase were determined in the liver of the animals. The whole studies revealed that the biochemical constituents were highly affected by the tested insecticides. Also, the liver function suffered from adverse effects of the tested insecticides.     

RESEARCH: Shrub Propagation Techniques for Biological Control of Invading Tree Species

Cornus stolonifera, Salix petiolaris, and Spiraea alba clones already located within the corridor of an electrical power line. To establish the efficiency of treatments, we examined the statistical differences of growth traits between species and treatments. An analysis of the effects of layering shows, after the first growth season, differences for all growth traits in only one species, Spiraea alba. After the second growth season, we observed the development of new aerial stems. Layering favors horizontal expansion of shrubs over height development. The third year after treatment, the effect of layering is reduced except for Cornus stolonifera, which continuously increases, as shown by the significant progression of the clone issued from the layer even five years after treatments. With the cutting back technique, we expected a distinct vertical growth of the shrubs at the expense of increasing the crown diameter. This technique would be best associated with the rejuvenation of clones, followed by a layering of new shoots to allow a horizontal expansion of the shrubs. Therefore, the formation of a dense shrub community by layering should be considered a valuable approach for the biological control of undesirable trees in powerline rights-of-way.     

Multicriteria Group Decision-making Model for Environmental Conflict Analysis in the Cape Region,Mexico

This paper is concerned with developing a model for group decision making under multiple criteria. The multiple criteria group decision making (MCGDM)problem involves a set of feasible land use patterns that are evaluated on the basis of multiple, conflicting and noncommensurate criteria by a group of individuals. The model integrates the Analytic Hierarchy Process (AHP) and an integer mathematical programming method. The former provides a tool for structuring the decision problem and determining land suitability for different socio-economicactivities (the uses of land), the latter is used to identify the land use pattern that maximizes consensus among interest groups. The model is used to analyze environmental conflict over land resource allocation in the Cape Region of Mexico.     

Outcomes of Collaborative Water Policy Making: Applying Complexity Thinking to Evaluation

Collaborative policy making has become increasingly significant in environmental management, but it is often evaluated by whether or not agreement is reached and implemented. The most important outcomes of such policy dialogues are often invisible or undervalued when seen through the lens of a traditional, modernist paradigm of government and accountability. These dialogues represent a new paradigm of governance that can be best understood in the light of a complex adaptive system model of society. From this perspective collaborative policy making is a way of making a system more flexible, adaptive and intelligent. The authors document such outcomes in three cases of water policy making in California, including the San Francisco Estuary Project, the CALFED Bay-Delta Program and the Sacramento Area Water Forum. The outcomes include social and political capital, agreed-on information, the end of stalemates, high-quality agreements, learning and change, innovation and new practices involving networks and flexibility.     

Physicochemical aspects of using natural scavengers in removing methylene blue (basic dye) from solution

Effluent from dyeing and finishing processes is an important source of water pollution. The effectiveness of bentonite, kaolinite and sediment from a local deposit in removing methylene blue as a cationic dye from aqueous solutions has been investigated. The adsorption equilibrium (isotherm) has been determined according to Freundlich and Langmuir equations. The optimum amount is 0.5 g for all adsorbents, and the optimum pH ranges are 2-8 for bentonite and 2-6 for kaolinite and sediment. With respect to kinetic modelling, the adsorption of methylene blue on various adsorbents was fitted to a second-order equation. Also, the thermodynamic parameters were determined. The negative free energy values indicate the feasibility of the process and spontaneous nature of adsorption. The positive ΔH° values indicate the endothermic nature of the process. Thus, Egyptian clay minerals and sediments have a great tendency to remove the dye from solutions.