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711.
Five priority areas of potential impact by contaminants (API) were investigated at the Presidente Bernardes Refinery in Cubatão, São Paulo, Brazil with the following aims: (i) to identify both organic and inorganic contaminants present in soil and groundwater; (ii) to define the environmental conditions relevant for microbial activity at the site and (iii) to evaluate the feasibility of employing natural attenuation for treatment of the hydrocarbon contamination. One area (API 1) was an uncontrolled landfill, where waste materials from the refinery were deposited between 1954 and 1986, and four areas (API 4, 5, 7 and 11) were located in the operational section of the refinery. Soil contamination by regulated BTEX compounds (benzene, toluene, total xylenes) was restricted to two samples from API 1. Nonregulated ethylbenzene was detected in one soil sample from API 4, one from API 5 and two from API 1. No soil contained regulated PAH above threshold levels. Several nonregulated PAHs were found in 6 soil samples from API 1, 3 soil samples from API 4 and 1 soil sample from API 5. Site soils contained very high aluminium concentrations, but metal contamination was restricted to one soil sample from API 1, which contained nickel above threshold limits. BTEX contamination of groundwater was due mostly to benzene. Of the 17 PAH molecules tested, only naphthalene and 2-methylnaphthalene occurred in groundwater. The sum of total BTEX and total PAH exceeded 200 μg/L in only a few monitoring wells in API 4, 5 and 11 and was always below 2.640 μg/L. Be, Cd, Cr, Cu, Hg, Ni, Se, Ag, Tl and Zn were not detected in groundwater, which was contaminated in a few locations by aluminium (mostly below 1 mg/L), lead (<0.066 mg/L) and arsenic (<0.056 mg/L). S, K, Ca, Mg and Fe were present in groundwater in excess of physiological requirements for microbial growth, but low concentrations of N and P could become growth limiting. However, BTEX were efficiently degraded in saturated and unsaturated zone microcosms and nutrient amendments did not stimulate biodegradation rates measurably. The inorganic carbon pool in groundwater was up to one order of magnitude larger than the organic carbon pool. Total inorganic carbon (TIC) in API groundwater exceeded TIC of clean groundwater by factors of 2 (API 4), 6 (API 5, 7 and 11) or 10 (API 1). Most of the inorganic carbon incorporated into groundwater beneath the refinery originated from biodegradation in the unsaturated soil, which contained a microbiota (106 cells/g on average) capable of growth with most of the pure (benzene, toluene, ethylbenzene and xylene) and mixed hydrocarbons tested (diesel oil, gasoline, naphtha, condensate, aromatic residue and fuel oil). A viscous hydrocarbon paste uncovered in API 1 was insoluble in water but dissolved in dichloromethane. Many organic components of this paste were biodegradable as evidenced by weight reduction of the hydrocarbon paste and by the growth of suspended and attached biomass in saturated zone microcosms, where the paste was the only carbon source. This study indicates that monitored natural attenuation may be a technically feasible and efficient means for plume control in API 1, 4 and 5, provided the plumes in API 4 and 5 are not expanding. This technique is not suitable for contaminant reduction in API 11.  相似文献   
712.
Lake Vela, located in the Portuguese littoral-centre, is a temperate shallow lake exhibiting a high trophic status. This aquatic ecosystem has been potentially exposed to contamination generated by agricultural and livestock activities held in their drainage basin, which seriously compromise their health. This work summarizes some background information and presents the problem formulation step of the ERA. Therefore, it evaluates the characteristics of the stressor(s), describes the ecological system and receptors and suggests a conceptual model, which predicts the potential exposure pathways, relating suspected sources to the defined endpoints. This introductory step also described an analysis plan on the entire study, which includes a delineation of the assessment design, data needs, measures, and methods for conducting the analysis phase of the risk assessment process.  相似文献   
713.
The sperm-shape abnormality bioassay in mice was used to determine whether chemical mutagens in diesel exhaust reach the testes. Strain A male mice (30 per group from 4 to 6 weeks of age) were exposed for 31 or 39 weeks to either diesel exhaust or clean air. After exposure, Eosin Y-stained, air-dried smears of cauda epididymal sperm were scored for changes in sperm-head abnormalities in three different laboratories. There was no difference in the proportion of abnormally shaped sperm in controls and mice exposed to diesel exhaust.  相似文献   
714.
The mode of action, extent of use, and the current knowledge on environmental fate and toxicity of three biological insecticides [Bacillus thuringiensis (B.t.), nucleopolyhedrosis virus (NPV), and pheromones] are reviewed. Data gaps, environmental uncertainties in any large-scale use, and proposed registration guidelines which may lead to more extensive use are discussed. B.t. disappears rapidly from plant foliage on exposure to sunlight and/or moisture, although it may persist in dry soil for several months or years. Foliar-applied NPVs are also inactivated by sunlight; the halflife on cotton leaves is 20–25 h. In the soil, NPVs may remain active for several years. Pheromones volatilize readily and do not persist in plant or in soil. Limited available data indicate that B.t. and pheromones do not persist in aquatic environments; quantitative data are unavailable for NPVs. Based on bioassay data, the three insecticides exhibit undetectable to low toxicity to nontarget organisms; there are also no reports of human disease or injury due to exposure to these pesticides and no bioaccumulation is expected with normal application. Except for B.t. which has been used in a limited large-scale applications, pest control uses of NPVs and pheromones are still in experimental stages. Areas of uncertainties requiring research and development include potential adverse health and ecological impacts in any large-scale and widespread use and efficacy and cost relative to synthetic chemical pesticides.  相似文献   
715.
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717.
This study explores ecological vulnerability to land-use change in the U.S. Mid-Atlantic Region by spatially extrapolating land and economic development, and overlaying these projections with maps of sensitive ecological resources. As individual extrapolations have a high degree of uncertainty, five methods with different theoretical bases are employed. Confidence in projections is increased for counties targeted by two or more projection methods. A county is considered at risk if it currently supports three or more sensitive resources, and is projected to experience significant growth by the year 2010 by two or more methods. Analysis designated 19 counties and two cities as at risk, highlighting within a large region the priority areas where state and regional efforts would contribute the most to integrating environmental considerations into the process of land development. The study also found that potentially severe ecological effects of future land-use change are not limited to the outskirts of major urban areas. Recreational demands on smaller communities with mountain and coastal resources are also significant, as are initiatives to promote economic development in rural areas of high ecological quality. This approach provides a comprehensive overview of potential regional development, leading to an objective prioritization of high-risk areas. The intent is to inform local planning and decision-making so that regional and cumulative ecological degradation are minimized.  相似文献   
718.
719.
This article covers the strategic, organizational, and operational decisions involved in one automobile manufacturer's efforts to balance its goals of productivity and high quality with the more elusive goal of environmental responsibility. The case material is based on the real-life experiences of Honda of America's two manufacturing plants in East Liberty and Marysville, Ohio. The case unfolds as the environmental manager in charge of the two plants faces the pending visit of her corporate boss from Tokyo, who has made it clear that environmental issues are of growing importance in Honda's overall direction. ISO 14000, the new environmental quality standards being adopted by some other manufacturers, serves as a focusing issue for the environmental manager's thinking, but this issue is really representative of a wider challenge facing the Ohio plants: balancing Honda's core mission of producing the best cars at the lowest cost possible, and being a responsible actor in the environmental arena. Complicating this challenge, the environmental manager has to negotiate another tension common in global manufacturing firms today: balancing the influence of Honda's corporate headquarters in Japan with the local and regional context at its American plant sites.  相似文献   
720.
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