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911.
912.
William O. Rasmussen 《Environmental management》1994,18(1):129-137
The percentage of the cross-sectional area of two objects (e.g., vehicles, hikers, or animals) that can be seen from each
of their locations in a forested area is generally not the same. There is a directionality to the visibility between them.
This is due to the relative positions and sizes of the vegetation and other view-blocking features between the objects. An
analytical technique has been developed to help understand bidirectional visibility. Its use entails the construction of a
visibility diagram containing the basic visibility information between observers in a given setting.
An example is presented showing the use of the visibility diagram to determine visibility between two moving observers in
a forested environment. The diagram is also used to determine the differences in the percentage each observer has of the other's
visible cross-sectional area (bidirectional visibility). A discussion of the application of the technique in the planning
or development of new facilities, as well as in forest and wildlife management, is provided. 相似文献
913.
Administrative machinery has been set up to regulate and control most of the emissions that are known to have severe local
consequences, such as the discharge of raw sewage into rivers and lakes and the smokestack emission of air pollutants. Now,
the nature of environmental degradation is usually different. We are faced with pollutants and effects with more subtle cause-effect
relationships, often characterized by larger geographic areas of interest and longer term potential damage; the potential
risk is now more chronic than acute. Acid rain and climate change are good examples, in that they are associated with a variety
of pollutants from a number of sources and damage to ecosystems occurs over many years. It is argued that monitoring programs
should evolve to reflect the changing nature of the environmental problems they are addressing. It is now necessary to consider
interactions among many pollutants, mixing among the various media, and potentially affecting many components of the ecosystem
in both indirect and direct ways. Here, integrated monitoring and analysis is presented as a unifying strategy to bring together
different measurement methodologies in different disciplines, addressing environmental questions of complexity beyond the
scope of many existing activites that have a classical narrower focus. The underlying concept is of nested networks, each
tier being composed of sites selected for specific purposes but arranged to maximize the number of common sites where more
multidisciplinary questions can be addressed. 相似文献
914.
Helmut Karl 《Environmental management》1994,18(4):617-621
environmental auditing must be rejected if the aim is to make companies introduce a specific management concept. Rather, it
is preferable to leave the search for effective environmental protection strategies to the competitive system, especially
since the criteria for environment-oriented management in the European Community audit proposal are without substance. Environmental
auditing can, however, assume a complementary function in the framework of an overall environmental policy if it is designed
as an information tool with which companies provide information on the development of environmental problems deriving from
their manufacturing processes and products. However, the model required to establish a framework of quantity and evaluation
criteria is not available. Further, auditing does not cover products. Similarly, there are no proposals defining the evaluation
procedure for ecological resource scarcity. Thus, the attempt of the Commission of the European Communities to create the
elementary prerequisites for consistent and verifiable environmental auditing in the corporate sector has failed. 相似文献
915.
Estrogenic effects of water from the Yangtze River (Nanjing section) on goldfish (Carassius auratus) after an early life stage exposure 总被引:1,自引:0,他引:1
Effects of river water from the Yangtze River (Nanjing section) on fish development, vitellogenin (VTG) induction, gonado-somatic
index (GSI) and sex ratio were investigated by exposing goldfish (Carassius auratus) in the early life stage (from fertilization to 28 days
post-hatch) to water samples (25%, 50% and 100%) collected from three representative sections. The results showed that there was no
significant effect on hatching success for any of the exposure groups, but survival was significantly reduced when compared with the
control (P < 0.05). Body lengths, weights of all treated fish did not differ significantly from those of the control. Condition factors (CF)
of larval fish exposed to 50% and 100% river water from the Jiangxinzhou section and 100% river water from the Daqiao section were
significantly lower than that of the control (P< 0.05). VTG inductions were significant in larval fish exposed to all the dilution series
of river water. No significant difference in CF value was observed in any exposure group after 150 days of depuration. VTG was fully
eliminated after 75 days of depuration. For both female and male, GSI did not significantly differ between exposure groups and the
control after 150 days of convalescence. The highest female:male ratios were observed in response to the treatment with 50% or 100%
river water from the Jiangxinzhou section and 100% river water from the Daqiao section (53:47, 56:44 and 54:46, respectively), but no
significant difference in sex ratio was observed in any treated group when compared to the control. The results showed that early life
stage exposure of river water from the Yangtze River (Nanjing section) had adverse effects on goldfish development and reproductive
health, and the effects on CF and VTG were reversible after depuration in clean water. 相似文献
916.
917.
918.
Suiliang Huang Yafei Jia Sam S. Y. Wang 《Frontiers of Environmental Science & Engineering in China》2009,3(2):178-185
The effects of chemical spills on aquatic nontarget organisms were evaluated in this study. Based on a review of three types
of current eco-toxicological models of chemicals, i.e., ACQUATOX model of the US-EPA, Hudson River Model of PCBs, and critical
body residual (CBR) model and dynamic energy budget (DEBtox) model, this paper presents an uncoupled numerical ecotoxicological
model. The transport and transformation of spilled chemicals were simulated by a chemical transport model (including flow
and sediment transport), and the mortalities of an organism caused by the chemicals were simulated by the extended threshold
damage model, separately. Due to extreme scarcity of data, this model was applied to two hypothetical cases of chemical spills
happening upstream of a lake. Theoretical analysis and simulated results indicated that this model is capable of reasonably
predicting the acute effects of chemical spills on aquatic ecosystems or organism killings. 相似文献
919.
3种不同功效医药品活性成分对发光菌的毒性作用 总被引:1,自引:0,他引:1
因药物活性成分的环境残留引发的风险和健康问题成为公众关注的焦点。本文以海洋发光细菌为受试生物,研究了布洛芬、阿奇霉素、三氯生3种医药品的单一和联合毒性作用。结果表明,3种医药品对发光菌的EC_(50)值分别为:36.5×10~(-5)、30.26×10~(-5)和0.0155×10~(-5)mol·L~(-1);二元及多元混合体系对发光菌的EC_(50)值高于单一体系的毒性作用,进一步采用相加指数法(AI)、毒性单位法(TU)、混合毒性指数法(MTI)评价3种医药品多元体系的联合毒性的作用类型,取得了一致的评价结果。3种医药品的二元混合体系及多元混合体系的作用类型均属于拮抗作用,但拮抗作用的强弱不同,这与医药品不同药效官能团结构可影响其对微生物生理生化反应过程有关。研究3种医药品对发光菌急性毒性作用可为该类新型污染物的环境风险评价提供基础数据。 相似文献
920.