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921.
922.
A Bayesian framework for stable isotope mixing models 总被引:1,自引:0,他引:1
Stable isotope sourcing is used to estimate proportional contributions of sources to a mixture, such as in the analysis of animal diets and plant nutrient use. Statistical methods for inference on the diet proportions using stable isotopes have focused on the linear mixing model. Existing frequentist methods provide inferences when the diet proportion vector can be uniquely solved for in terms of the isotope ratios. Bayesian methods apply for arbitrary numbers of isotopes and diet sources but existing models are somewhat limited as they assume that trophic fractionation or discrimination is estimated without error or that isotope ratios are uncorrelated. We present a Bayesian model for the estimation of mean diet that accounts for uncertainty in source means and discrimination and allows correlated isotope ratios. This model is easily extended to allow the diet proportion vector to depend on covariates, such as time. Two data sets are used to illustrate the methodology. Code is available for selected analyses. 相似文献
923.
Pomacea insularum were collected from polluted and unpolluted freshwater ecosystems in Malaysia. Besides the shells, the soft tissues were dissected and pooled into cephalic tentacle, foot, mantle, operculum, digestive tract, penial sac, lung sac, and remainder. These tissues were analyzed for the concentrations of Cu, Cd, Fe, Ni, and Zn. The present work resulted in three interesting findings. First, the concentrations of Cu, Cd, Fe, and Zn found in most of the different parts of P. insularum collected from the polluted Juru River were significantly (P < 0.05) higher than those found in the snails from the other four sites. Second, positive and significant correlation coefficients were found for sediment-lung sac for Cd, Fe, and Zn while sediment-digestive tract for Cu. These correlation results indicated that lung sacs could reflect the environmental concentrations of Cd, Fe, and Zn, while the digestive tract could do the same for Cu. Third, the different concentrations of heavy metals found in the different parts indicated different metal regulation and binding sites in these organs. The significant correlation coefficients between different tissues indicated that they might be caused by similar metal regulation and sequestration. Based on the above findings, P. insularum are a potential biomonitor of Cd, Cu, Fe, and Zn pollution in freshwater ecosystems. 相似文献
924.
Sarah Mellish Jillian C. Ryan Elissa L. Pearson Michelle R. Tuckey 《Conservation biology》2019,33(1):40-52
Zoos and aquariums are increasingly incorporating conservation education into their mission statements and visitor experiences to address global biodiversity loss. To advance knowledge and practice in the field, research is being conducted to evaluate the effect of zoo conservation-education experiences on visitor psychosocial outcomes (e.g., knowledge, attitude, emotions, motivations, behavior). Following recent discussions among scholars and practitioners concerning logistical and methodological challenges that likely undermine the conclusions of such research, we identified and reviewed the methods and reporting practices in peer-reviewed articles published in English from May 1998 to June 2016 that focused on adult visitor samples (47 articles, 48 studies). We examined elements of internal, external, construct, and statistical conclusion validity. Methodological quality of quantitative methods and reporting practices was determined using the Effective Public Health Practice Project Quality Assessment Tool. Each study was coded as either strong (no weak ratings), moderate (1 weak rating), or weak (≥2 weak ratings). The quantitative methods of 83.3% of studies were weak. The remaining 16.7% had methods of moderate quality. Using an existing checklist, we also assessed the quality and rigor of qualitative methods and reporting practices and found that some aspects of these methods were reported more comprehensively than others. For example, 69.6% of articles discussed methods for identifying key themes from the data, whereas only 34.8% reported how data verification was performed. We suggest increased application of intensive longitudinal methods (e.g., daily diary) to strengthen self-reported data, experimental and repeated-measures designs, and mixed-methods approaches. Our findings and recommendations could strengthen and guide the research and evaluation agenda for the field and ultimately enhance the contribution zoos make to global biodiversity conservation. 相似文献
925.
Matt W. Hayward Alex Callen Benjamin L. Allen Guy Ballard Femke Broekhuis Cassandra Bugir Rohan H. Clarke John Clulow Simon Clulow Jennifer C. Daltry Harriet T. Davies-Mostert Peter J. S. Fleming Andrea S. Griffin Lachlan G. Howell Graham I. H. Kerley Kaya Klop-Toker Sarah Legge Tom Major Ninon Meyer Robert A. Montgomery Katherine Moseby Daniel M. Parker Stéphanie Périquet John Read Robert J. Scanlon Rebecca Seeto Craig Shuttleworth Michael J. Somers Cottrell T. Tamessar Katherine Tuft Rose Upton Marcia Valenzuela-Molina Adrian Wayne Ryan R. Witt Wolfgang Wüster 《Conservation biology》2019,33(4):760-768
Compassionate conservation focuses on 4 tenets: first, do no harm; individuals matter; inclusivity of individual animals; and peaceful coexistence between humans and animals. Recently, compassionate conservation has been promoted as an alternative to conventional conservation philosophy. We believe examples presented by compassionate conservationists are deliberately or arbitrarily chosen to focus on mammals; inherently not compassionate; and offer ineffective conservation solutions. Compassionate conservation arbitrarily focuses on charismatic species, notably large predators and megaherbivores. The philosophy is not compassionate when it leaves invasive predators in the environment to cause harm to vastly more individuals of native species or uses the fear of harm by apex predators to terrorize mesopredators. Hindering the control of exotic species (megafauna, predators) in situ will not improve the conservation condition of the majority of biodiversity. The positions taken by so-called compassionate conservationists on particular species and on conservation actions could be extended to hinder other forms of conservation, including translocations, conservation fencing, and fertility control. Animal welfare is incredibly important to conservation, but ironically compassionate conservation does not offer the best welfare outcomes to animals and is often ineffective in achieving conservation goals. Consequently, compassionate conservation may threaten public and governmental support for conservation because of the limited understanding of conservation problems by the general public. 相似文献
926.
Martha Stallard Vern Hodge Edward D. Goldberg 《Environmental monitoring and assessment》1987,9(2):195-220
Butyltins were monitored at over eighty sites, primarily marinas, in surface waters and sediments of the California coast. Values of tributyltin (TBT) in marina waters ranged from 20 to 600 ppt while lower values were usually found in harbors and on the coast. The origin of the tributyltin is in its use as an antifouling agent in marine paints. In those marinas where the concentrations are greater than about 100 ppt, there is usually a conspicuous absence of native organisms, especially molluscs, which are among the most sensitive animals to the highly toxic TBT. The impact of TBT upon not-target organisms recalls the DDT episode of the 1970s. Increasing uses of TBT-containing antifouling paints in the future may have even more drastic effects on coastal organisms than those observed today. The conclusion is inescapable that TBT should be banned for use in commercially available marine paints. 相似文献
927.
Edward L. Stockton Winthrop C. Shook 《Journal of the Air & Waste Management Association (1995)》2013,63(3):162-163
This year an automatic monitoring system will supplement existing air sampling stations in Allegheny County (Pittsburgh). This system will measure pollutant levels and weather conditions at several remote sites. “On-site” recorders are equipped to telemeter the data in analog form to a central station. At the central, a multipoint recorder is supplied for each pollutant measured. This basic system, purchased for a modest initial investment, has complete capabilities for future expansion. An estimated fifteen sites will provide representative pollution data for Allegheny County. However, the basic system can be expanded to include industry installed monitoring stations—a possibilty now being considered. Further expansion to a complete Data Management system including a computer based data logger to calculate emission inventory, peak averages, and other control data is also provided for. 相似文献
928.
David L. Brooman Edward Edgerley Jr. 《Journal of the Air & Waste Management Association (1995)》2013,63(1):25-29
Activated carbon filters were used to concentrate atmospheric mixtures of acrolein, methyl sulfide, and n-propyl mercaptan. Removal efficiency and carbon capacity for each of the odor compounds were investigated using two different carbons, Cliff char {4-10 mesh) and Barnebey-Cheney (C-4). A closed system was devised to establish a known atmospheric odor concentration for each filter run. Solvent extraction techniques were employed to desorb and recover the odor compounds from the carbon filters. All quantitative analyses were conducted with gas liquid chromatography utilizing the hydrogen flame ionization detector. The removal studies conducted indicate that the efficiency of removal of a carbon filter is essentially 100 percent up to the point of filter breakthrough. This breakthrough point is governed by the filter’s capacity for a particular compound. This study indicated that the filter capacity is dependent both on the type of carbon employed and the particular odor compound adsorbed. Solvent recovery of the odor compounds from the carbons varied from 0 to 4.5 percent for the mercaptan up to 96 to 98 percent for acrolein. Percent recovery was found to vary for a given odor compound with different carbons and for a given carbon with different odor pollutants. 相似文献
929.
Edward R. Frederick 《Journal of the Air & Waste Management Association (1995)》2013,63(11):1086-1089
Encouraged by the successes attained with fly ash control by fabric filters in Pennsylvania Power & Light and Colorado Ute, other utilities are installing, planning, and/or considering baghouses as a practical and economical means for controlling emissions from the burning of low sulfur coals. Where deposits of alkaline reagents (i.e. nahcolite) are available, some power plants are also considering a process for dry scrubbing SO2 from the flue gas. By introducing such reagents with the emission ahead of the fabric collector, both partlculates and SO2 are removed. 相似文献
930.
William S. Linn Edward L. Avol Deborah A. Shamoo Jill D. Whynot Karen R. Anderson Jack D. Hackney 《Journal of the Air & Waste Management Association (1995)》2013,63(12):1323-1328
Young asthmatic adult volunteers (N = 27) were exposed in an environmental chamber to sulfuric acid aerosol at concentrations near 0, 122, 242, and 410 μg/m3, in purified background air at 22° C and 50 percent relative humidity. The polydisperse aerosol had a mass median aerodynamic diameter near 0.6 μm. Exposures occurred in random order at one-week intervals. Each lasted 1 h, during which subjects exercised (mean ventilation 42 L/min) and rested during alternate 10-min periods. Specific airway resistance and forced expiratory function were measured pre-exposure, after the initial exercise, and at end-exposure. Bronchial reactivity was determined by challenge with cold air immediately post-exposure. Symptoms were monitored during exposure for one week afterward. Exercise-induced bronchospasm was observed under all conditions. Physiologic and symptom changes possibly attributable to sulfuric acid exposure were small and not statistically significant. Our largely negative results contrast with positive findings elsewhere at lower acid doses. Possible explanations include different clinical characteristics of subjects and different routes of breathing. 相似文献