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531.
An expert system, PASSSFA, has been developed to help select the most appropriate variables for monitoring the effects of extensive land use activities, particularly forestry, on streams. PASSSFA was initially developed for headwater streams in the northwestern U.S. and Alaska, but the consistency of the underlying principles make it much more broadly applicable. The selection process is based on the designated beneficial uses of concern, the type of management activity, accessibility during high flows, frequency of sampling, and the costs for equipment, data collection, and sample analysis. A total of thirty potential monitoring variables are considered, and these were selected because of their sensitivity to land management activities and their effects on key designated uses. Problems in developing PASSSFA and the use of expert systems are discussed. 相似文献
532.
Charles S. ReVelle Justin C. Williams John J. Boland 《Environmental Modeling and Assessment》2002,7(2):71-80
Five classes of zero–one programming models for discrete facility location problems are compared to counterpart models for the selection of conservation reserves. The basic problem of siting facilities to cover demand for services is analogous to the problem of selecting reserves to support species diversity. The classes of models include the set covering and maximal covering models, as well as models for backup and redundant coverage. Issues of reliability and uncertainty are addressed by chance constrained covering models and maximal expected covering models. Exact and heuristic solution approaches are discussed. Multi-objective and economic issues are considered. 相似文献
533.
Bridget N. Bero Margrit C. Von Braun Charles R. Knowles John E. Hammel 《Environmental monitoring and assessment》1993,27(1):17-33
The recognition of the hazards to young children of low-level lead intoxication and the widespread distribution of lead in
the urban environment have resulted in massive federal, state, and local lead awareness and abatement programs. Two of the
most significant exposure routes of lead to young children are the soils and dusts found within the child's home. Most state
and federal lead abatement programs deal with lead-based paint contamination but often do not address the issue of soft-surface
contamination, such as that of carpets, furniture, and draperies. Carpets can be a reservoir of contaminated soils and dusts;
currently, there exists no standard method to test carpeted surfaces for lead contamination.
This paper describes a study that uses X-ray fluorescence (XRF) to test carpeted surfaces for lead contamination. XRF technology
is the standard technology used in lead-based paint testing and is known to be an accurate technique to test for lead in soils.
This study uses a controlled laboratory atmosphere to evaluate this technology; the objectives are to determine: (1) a lower
limit of detection for the instrument; and (2) whether soil loading levels can be differentiated by XRF using trace elements
also present in the soil. Results indicate that XRF can easily differentiate soil loading levels (g soil/m2 carpet). The lower limit of detection of soil lead concentration on the carpet is a function of both soil lead concentration
and soil loading; therefore, lead loading (mg Pb/m2) is a better indicator of detection limit than soil lead concentration. Lead loading detection levels from 108–258 mg Pb/m2 were obtained, as compared to a level of 10 000 mg/m2 (1 mg/cm2) for lead on painted surfaces as required by theLead-Based Paint Poisoning Prevention Act.
XRF technology has the potential to be a fast, inexpensive screening technique for the evaluation of lead contamination on
carpeted surfaces. 相似文献
534.
The NOAA National Status and Trends (NS&T) Program has been monitoring chemical contamination in fish livers, and surface sediments since 1984 and in molluscan tissue and sediments since 1986. Data from fine-grained sediment at 175 sites are used to describe the spatial distribution of contamination throughout the coastal and estuarine United States. Highest levels are generally found in, and considered representative of, urban areas. It should be noted, however, that these levels are not as high as have been found near discharge pipes or in isolated industrial areas through other monitoring efforts. Dramatic biological responses, such as liver tumors in fish or apparently toxic contaminant levels in sediment, are found infrequently. Subtle biological changes, especially those that affect reproductive ability, are being sought. Data from three annual collections of mollusks have been used to identify early signals of temporal trends in contamination at NS&T sites. 相似文献
535.
Charles A. Menzie Jerome J. Cura William F. Skinner 《Environmental monitoring and assessment》1982,2(3):301-308
A realistic approach to thermal impact assessment is presented which employs a two-dimensional thermal plume model, a large data base for river flow and temperature, and accounts for nonuniform spatial distribution of habitats and seasonal differences in fish behavior. The end result portrays real effects of the thermal impact rather than an artificially constructed worst-case scenario. 相似文献
536.
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539.
Rodolfo Jaffé Fabiana C. Pioker-Hara Charles F. dos Santos Leandro R. Santiago Denise A. Alves Astrid de M. P. Kleinert Tiago M. Francoy Maria C. Arias Vera L. Imperatriz-Fonseca 《Die Naturwissenschaften》2014,101(3):261-264
High genetic diversity is important for the functioning of large insect societies. Across the social Hymenoptera (ants, bees, and wasps), species with the largest colonies tend to have a high colony-level genetic diversity resulting from multiple queens (polygyny) or queens that mate with multiple males (polyandry). Here we studied the genetic structure of Trigona spinipes, a stingless bee species with colonies an order of magnitude larger than those of polyandrous honeybees. Genotypes of adult workers and pupae from 43 nests distributed across three Brazilian biomes showed that T. spinipes colonies are usually headed by one singly mated queen. Apart from revealing a notable exception from the general incidence of high genetic diversity in large insect societies, our results reinforce previous findings suggesting the absence of polyandry in stingless bees and provide evidence against the sperm limitation hypothesis for the evolution of polyandry. Stingless bee species with large colonies, such as T. spinipes, thus seem promising study models to unravel alternative mechanisms to increase genetic diversity within colonies or understand the adaptive value of low genetic diversity in large insect societies. 相似文献
540.
Ian Calder Ashvin Gosain M. S. Rama Mohan Rao Charles Batchelor James Garratt Emma Bishop 《Environment, Development and Sustainability》2008,10(4):427-440
This paper recognises the need for a revision of watershed development policy in India in relation to the planning of development
interventions involving agricultural intensification and rainwater harvesting and the need for new approaches to assist the
planning process. Building on, and using as an example, the results of biophysical and societal impact studies carried out
on two watershed development projects in Karnataka three new management/dissemination tools, are suggested. These are (1)
the web-based geographical information systems exploratory, climate land assessment and impact management tool dissemination
tool for disseminating to policymakers and non-specialist stakeholders the downstream impacts of watershed interventions,
(2) the ‘quadrant’ approach for ensuring that sustainability criteria are met and (3) Bayesian networks to investigate the
biophysical and societal impacts of interventions.
Readers should send their comments on this paper to BhaskarNath@aol.com within 3 months of publication of this issue 相似文献