Improving the adsorption capacity and solid structure of natural volcanic soil using a foaming-sintering process based on recycled polyethylene terephthalate (PET).

The volcanic soils of southern Chile have demonstrated a high capacity to adsorb environmental pollutants, but for an industrial application, a stable solid material is necessary. The objective of this work was to produce a stable ceramic material through a process involving volcanic soil-polyurethane foam produced with recycled polyethylene terephthalate (PET)-polyols, and further thermal treatment. The selected foam formulation with 35.4% volcanic soil (< 63 microm) seems to be the most suitable for thermal treatment, with temperature steps at 700, 850, 1000 and 1200 degrees C. The porous ceramic material obtained has a stable solid form and an improved chlorophenols adsorption capacity (comparable to natural zeolites) that makes it suitable for advanced wastewater treatment and landfill leachate depuration.     

Microbiological degradation of polycyclic aromatic hydrocarbons: Anthracene,benzo(K)fluoranthene,dibenzothiophene, benzo(H) quinoline and 2‐nitronaphthalene

Biodegradation experiments of various polycyclic aromatic hydrocarbons were studied with mixed bacteria culture under aerobic conditions. An easy‐to‐handle clean‐up procedure was developed for PAH and their metabolites simultaneously as well as a gc‐ms‐method to identify and quantify these compounds.

Anthracene and dibenzothiophene are completely degradable in an aqeous system, whereas biodegradation of benzo(k)fluoranthene and benzo(h)quinoline is possible only in an oil‐in‐water‐system with dodecane as cosubstrate. No degradation of nitronaphthalene was observed in aqueous systems. New metabolites are 2,3‐dihydroxybenzothiophene, hydroxybenzothiophenecarbonic acid and benzothiophenequinone for dibenzothiophene and hydroxyfluoranthenic acid for benzo(k)flouranthene. Whereas the former metabolites are degradable under the experimental conditions, the latter accumulates during the degradation experiment.

The results are important for microbiological wastewater treatment, since knowledge of biodegradation processes is indespensable for the successful treatment of PAH‐containing wastewater.     

The use of volcanic soil as mineral landfill liner--III. Heavy metals retention capacity.

The volcanic soil of Southern Chile was tested for its heavy metal retention capacity. The maximum uptakes for CrO4(2-) (CrVI), Cu(2+), Zn(2+) and Pb(2+) were determined to be 2.74, 5.32, 5.86 and 7.44 mg g(-1), respectively. At a slightly alkaline pH value (7.5), it seems that a precipitation-adsorption process was responsible for the Cu(2+) and Zn(2+) uptake onto volcanic soil. All the determined values are of the same order of magnitude as natural zeolites heavy metals adsorption capacities. In addition, the heavy metals diffusion model through a 1 m volcanic soil mineral liner shows breakthrough times of 21.6, 10.2 and 8.9 years, for Pb(2+), Zn(2+) and Cu(2+), respectively, confirming the trend obtained in the adsorption isotherms. The natural volcanic soil of Southern Chile is an interesting material for possible use as landfill mineral basal sealing. It has an appropriate sealing potential (average Kf value of 5.85 x 10(-9) m s(-1)) and a heavy metals retention capacity comparable with natural zeolites. About two-thirds of the agricultural land in Chile (approximately 0.4 million km2) is derived from volcanic ash, suggesting an important soil volume for future landfill projects, that could be obtained in sufficient quantities from urban building activities.     

Status and management of watersheds in the Upper Pokhara Valley,Nepal

Contributing to the debate on the causes of Himalayan environmental degradation, the status and management of four watersheds in the Upper Pokhara Valley were studied using information available from land use analysis, household surveys conducted in 1989 and 1992, deliberations held with villagers, and field observations. Accordingly, areas under forests and grazing lands were found being depleted at relatively high rates between 1957 and 1978 due mainly to the government policy of increasing national revenue by expansion of agricultural lands, nationalization of forests, steadily growing population, and dwindling household economy. Despite the steady growth of population, this process had remarkably slackened since 1978, owing primarily to remaining forests being located in very, steep slopes and implementation of the community forestry program. Forests with relatively sparase tree density, however, and grazing lands in the vicinity of settlements have been undergoing degradation due to fuelwood and fodder collection and livestock grazing. In many instances, this is aggravated by weak resource management institutions. Being particularly aware of the economic implication of land degradation, farmers have adopted assorted land management practices. Still a substantial proportion ofbari lands in the hill slopes is vulnerable to accelerating degradation, as the arable cropping system is being practiced there as well. The perpetuation of the local subsistence economy is certain to lead, to a further deterioration of the socioeconomic and environmental conditions of watersheds. To facilitate environmental conservation and ecorestructuring for sustainable development, a broad watershed management strategy is outlined with focus on alleviating pressure on natural resources.     

Design parameters for video display terminal workstations

Body dimensions are main determiners of equipment dimensions. Design for the “average user” is not suitable. Selected percentile values at the lower and upper extremes of the variable distribution determine minimum and maximum equipment dimensions or adjustment ranges. Interactions among design variables must be considered. This paper applies this rationale to the determination of major equipment dimensions of video display terminal (VDT) workstations. While the approach is generally usable, the specific data describing the U.S. population used in this paper indicate design ranges appropriate for North America. Since American body dimensions are quite comparable to most European data, the equipment dimensions should also be suitable for use in Europe.     

Effect of airborne bromoxynil-octanoate and metribuzin on non-target plants

The present study was conducted to determine the effects of airborne herbicides on the photosynthesis and growth of non-target plants. Sunflowers at different growth stages were used as test plants and exposed for 24 h in a wind tunnel to a range of concentrations of bromoxynil-octanoate and metribuzin. The quantum yield (phiPSII) and the dry weight were used as response parameters. Results indicate that young sunflower plants are affected by sublethal concentrations of both herbicides, whereas metribuzin proved to be more phytotoxic. Bromoxynil-octanoate and metribuzin concentrations > 0.265 and >0.135 microg/m(3) impair the photosynthetic activity of exposed leaves and concentrations >0.780 and >0.641 microg/m(3) of leaves developed after exposure. Effects on dry weight indicate that younger plants were more susceptible, whereby the response to metribuzin proved to be more dependent on growth stage. Based on these results and considering herbicide concentrations in ambient air, there is a reasonable probability that non-target plants are temporarily at risk of being affected.