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151.
Steven C. Richtsmeier Neil Goldstein Fritz Bien Chris Schuch Jack Buckley Robert R. Bennett 《Journal of the Air & Waste Management Association (1995)》2013,63(12):981-988
Abstract An instrumentation system employing an RPV (remotely piloted vehicle) platform was developed for temporally and spatially resolved air pollution measurements, and was used to measure the evolution of gas-phase HC1 in exhaust clouds from a solid rocket motor firing and fuel pit burns. A thermistor and a sensitive (ppmv-level), rapid-response (<0.1 sec) infrared absorption sensor for HC1 were mounted in a flow channel in the RPV, permitting concentration and temperature measurements to be made in the cloud on a several-meter scale. The RPV system was flown in a series of field tests at Thiokol Corporation’s Elkton, MD division to evaluate the HC1 content of the exhaust products of a new Mg-based fuel formulation. Measurements were made in the clouds from Al-based and Mg-based solid fuel pit burns and a Mg-fueled motor firing over periods of several minutes. Elevated temperatures and HC1 concentrations were found to be temporally correlated with video images of the particulate cloud. Cl originating from the ammonium perchlorate oxidizer appeared in the exhaust as HC1 in each of the tests. Both the macroscopic and local cloud parameters indicate that the Mg-based fuel may provide some reduction in HC1 concentration compared to the standard Al-based fuel. 相似文献
152.
Jeffrey Wielgus Leah R. Gerber Enric Sala Jeff Bennett 《Journal of environmental management》2009,90(11):3401-3409
Stated-preference surveys for the economic valuation of environmental resources typically assume no uncertainty in the hypothetical valuation scenarios. However, the outcomes of environmental policies are uncertain. We explored the effects of including information on probabilities of attribute improvement and provision in choice experiments. Our results suggest that stating explicitly a high probability for the occurrence of the valuation scenario can improve the goodness of fit of choice models and the consistency of choices. As the general public becomes more aware of the uncertainty of environmental outcomes under global change, omitting information on scenario risk may contribute to hypothetical bias and impair the validity of stated-preference valuations. 相似文献
153.
The high degree of heterogeneity within sediments can make interpreting one-dimensional measurements difficult. The recent development and use of in situ techniques that measure two-dimensional distributions of porewater solutes have facilitated investigation of the role of spatial heterogeneity in sediment biogeochemistry. A colourimetric diffusive equilibration in thin films method has been developed that allows two-dimensional, high-resolution measurement of reactive phosphate in sediment porewaters. A method detection limit of 0.22 μM, an effective upper limit of ∼1000 μM and relative standard deviations typically below 5% were achieved. This method was evaluated by deployment in seagrass (Zostera capricorni) colonised sediments, as part of combined probes with similar colourimetric methods for sulfide and iron(II). The two-dimensional, high resolution distributions obtained provide a highly representative measurement of the co-distributions of porewater solutes, allowing heterogeneous features and biogeochemical processes to be observed and interpreted. Microniches of high phosphate concentration >100 μM were observed throughout the distributions and were interpreted to be due to localised zones of rapid organic matter mineralisation, possibly using electron acceptors other than iron(III) oxyhydroxides (e.g. aerobic respiration) as often they did not correspond with microniches of higher Fe(II) concentration. 相似文献
154.
155.
Fish ages are often estimated by assuming an annual frequency of the band-like, growth-zones recorded in the largest of their otoliths, the sagittae. The total number of growth-zones are normally determined either by counting external growth-zones (whole otolith technique) or by examining otolith cross-sections (otolith section technique). The two techniques do not always yield the same age, however, particularly in older specimens of certain fishes. To resolve this problem, otoliths of the splitnose rockfish Sebastes diploproa were examined morphologically and were assayed for their natural radionuclide concentrations. Four age groups of otoliths were identified based on growth-zone counting; in the first three, whole otolith and otolith section age estimates agreed, while in the fourth, the otolith section age substantially exceeded the whole otolith age. Radiometric analysis demonstrated that all otoliths were deficient in 210Pb activity relative to 226Ra activity with the deficiency decreasing with increasing number of growth-zones. The magnitude of the 210Pb/226Ra radioactive disequilibrium in each otolith group, when compared to the number of growth-zones and the otolith weight histories derived with the two techniques, identifies the growth-zones revealed by otolith sections as annual features. Thus when otolith section age exceeds whole otolith age (usually occurring after 20 to 25 yr of age for this species), the otolith section technique is the correct method of age determination. Estimates of longevity in the genus Sebastes near 80 yr are therefore confirmed. 相似文献
156.
B. G. Bennett 《Environmental monitoring and assessment》1982,2(1-2):85-93
Exposure commitment is a measure of the concentration and duration of a pollutant in an environmental medium. It is the basis of a time-independent method of pollutant pathway analysis. Applied to environmental mercury, contributions to concentrations in the human body from inhalation and from ingestion of terrestrial and aquatic foods areevaluated.Staff member of the United Nations Environment Programme (UNEP). The author's views do not necessarily represent those of UNEP. 相似文献
157.
Perceptions of Species Abundance,Distribution, and Diversity: Lessons from Four Decades of Sampling on a Government-Managed Reserve 总被引:2,自引:0,他引:2
J. Whitfield Gibbons
Author to whom correspondence should be addressed. Vincent J. Burke Jeffrey E. Lovich Raymond D. Semlitsch Tracey D. Tuberville J. Russell Bodie Judith L. Greene Peter H. Niewiarowski Howard H. Whiteman David E. Scott Joseph H. K. Pechmann Christopher R. Harrison Stephen H. Bennett John D. Krenz Mark S. Mills Kurt A. Buhlmann John R. Lee Richard A. Seigel Anton D. Tucker Tony M. Mills Trip Lamb Michael E. Dorcas Justin D. Congdon Michael H. Smith David H. Nelson M. Barbara Dietsch Hugh G. Hanlin Jeannine A. Ott Deno J. Karapatakis 《Environmental management》1997,21(2):259-268
/ We examined data relative to species abundance, distribution, anddiversity patterns of reptiles and amphibians to determine how perceptionschange over time and with level of sampling effort. Location data werecompiled on more than one million individual captures or observations of 98species during a 44-year study period on the US Department of Energy's(DOE) Savannah River Site National Environmental Research Park (SRS-NERP) inSouth Carolina. We suggest that perceptions of herpetofaunal speciesdiversity are strongly dependent on level of effort and that land managementdecisions based on short-term data bases for some faunal groups could resultin serious errors in environmental management. We provide evidence thatacquiring information on biodiversity distribution patterns is compatiblewith multiyear spatially extensive research programs and also provide aperspective of what might be achieved if long-term, coordinated researchefforts were instituted nationwide.To conduct biotic surveys on government-managed lands, we recommend revisionsin the methods used by government agencies to acquire and report biodiversitydata. We suggest that government and industry employees engaged inbiodiversity survey efforts develop proficiency in field identification forone or more major taxonomic groups and be encouraged to measure the status ofpopulations quantitatively with consistent and reliable methodologies. Wealso suggest that widespread academic cooperation in the dissemination ofinformation on regional patterns of biodiversity could result byestablishment of a peer-reviewed, scientifically rigorous journal concernedwith status and trends of the biota of the United States. KEY WORDS: Abundance; Amphibian; Biodiversity; Distribution; Landmanagement; Reptile 相似文献
158.
Anthony Bennett 《Natural resources forum》1998,22(3):193-199
This article defines three kinds of public/private partnership, lists their potential benefits and explains common issues and problems in their operation with examples from developing countries. It then defines and discusses the concepts of social sustainability and financial sustainability in relation to public/private partnerships, and emphasizes the importance of applying sustainability criteria to each partner. It is argued that essentially the same criteria apply to non-profit NGOs as to for-profit firms, despite their differences in goals and values. The article concludes with some suggested strategies for effective international technical co-operation in the establishment of public/private partnerships. 相似文献
159.
Environmental forensics is an established discipline in North America, but has yet to make an impact within Europe and more specifically within the UK. In this paper we explore the reasons for this and explore the nature and fundamental philosophy that underlies this discipline. Case studies can be used to explore the complexity that can be associated with an environmental forensic investigation and we argue that there is a demand for professionals with skills in forensic practice within the environmental sector today. The paper finishes by suggesting that environmental forensics is a discipline of its moment within Europe for which the Higher Education sector must now cater. 相似文献
160.
Elizabeth L. Bennett 《Conservation biology》2001,15(2):308-310
Editor's note: This Conservation Forum begins with a reprinted editorial by Elizabeth Bennett from the August 2000 issue of Conservation Biology . Several papers were submitted in repsonse to that piece, and it is reprinted here to start this forum. 相似文献