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11.
Robert G. Bailey 《Environmental management》1988,12(1):11-17
As part of the planning process, maps of natural factors are often superimposed in order to identify areas which are suitable or unsuitable for a particular type of resource management. Overlay maps may also be used to identify analysis areas for predictive modeling of resource productivity and ecological response to management. Current interest in applying computer-assisted mapping technology to making overlay maps is drawing attention to geographic information systems for this purpose. The resultant maps, however, may be so inaccurate or unable to capture significant units of productivity and ecological response that they could lead to imperfect or false conclusions. Recommendations are made on how to proceed in light of these problems. 相似文献
12.
Will Limits of the Earth's Resources Control Human Numbers? 总被引:1,自引:1,他引:0
David Pimentel O. Bailey P. Kim E. Mullaney J. Calabrese L. Walman F. Nelson X. Yao 《Environment, Development and Sustainability》1999,1(1):19-39
The current world population is 6 billion people. Even if we adopted a worldwide policy resulting in only 2.1 children born per couple, more than 60 years would pass before the world population stabilized at approximately 12 billion. The reason stabilization would take more than 60 years is the population momentum – the young age distribution – of the world population. Natural resources are already severely limited, and there is emerging evidence that natural forces already starting to control human population numbers through malnutrition and other severe diseases. At present, more than 3 billion people worldwide are malnourished; grain production per capita has been declining since 1983; irrigation per capita has declined 12% during the past decade; cropland per capita has declined 20% during the past decade; fish production per capita has declined 7% during the past decade; per capita fertilizer supplies essential for food production have declined 23% during the past decade; loss of food to pests has not decreased below 50% since 1990; and pollution of water, air, and land has increased, resulting in a rapid increase in the number of humans suffering from serious, pollution-related diseases. Clearly, human numbers cannot continue to increase. 相似文献
13.
Markéta Julinová Marie Dvořáčková Jan Kupec Jitka Hubáčková Martina Kopčilová Jaromír Hoffmann Pavol Alexy Anna Nahálková Ida Vašková 《Journal of Polymers and the Environment》2008,16(4):241-249
Improving biodegradability of PVA/starch blends is a reality already documented by a number of works. Admittedly, mechanical
properties of products (for example, tensile strength) are somewhat worse, but suitable composition optimizing or chemical
modifying of starch may eliminate the problem to a large degree. This work is an attempt to find another potential effect
influencing biodegradability, that of technological procedure for producing films from these blends on an extruder. The procedure
with a so-called pre-extrusion step (two-stage) and dry-blend (single-stage) produced blends of slightest differences in achieved
biodegradability (virtually within limits of experimental error) in aerobic (76 vs. 79%) as well as anaerobic breakdown (48
vs. 52%). Conversely, morphological analysis exhibited superior homogeneity of films prepared by the two-stage process; their
tensile strength was also higher. 相似文献
14.
Darryl T. Gwynne Winston J. Bailey Amanda Annells 《Behavioral ecology and sociobiology》1998,42(3):157-162
In katydids such as Kawanaphilanartee, a female bias in the operational sex ratio (OSR) results in female competition for mates and male choice of mates. Previous
work showed that the excess of sexually active females occurs when food availability is low, in part because less food increases
the propensity of females to mate as they forage for the large edible spermatophores produced by males. In this study with
K.nartee, a pollen-feeding species, we estimate natural variation in numbers of sexually active males and females by assessing male
calling activity and the propensity of females to respond to experimental calling males. We found an excess of sexually active
males at a site with many flowers and an excess of sexually active females at a site with few flowers about 900 m away. Between-site
differences in gut masses of calling males were consistent with the hypothesis that pollen availability controls OSR. Finally,
at a third site where flowers were at first scarce, we found that the initial excess in sexually active females changed to
an excess of sexually active males after a clump of grass-trees flowered. The mean gut mass of all sampled males from this
site increased after flowering. The large variation in OSR that we document for K. nartee highlights the importance of identifying the appropriate spatial and temporal scales over which OSRs are measured in studies
of factors controlling sexual selection.
Received: 13 May 1997 / Accepted after revision: 27 October 1997 相似文献
15.
Essential and non-essential element concentrations in two sleeper shark species collected in arctic waters 总被引:1,自引:0,他引:1
McMeans BC Borgå K Bechtol WR Higginbotham D Fisk AT 《Environmental pollution (Barking, Essex : 1987)》2007,148(1):281-290
A number of elements/metals have increased in arctic biota and are of concern due to their potential toxicity. Most studies on elements in the Arctic have focused on marine mammals and seabirds, but concentrations in the Greenland shark (Somniosus microcephalus) and Pacific sleeper shark (Somniosus pacificus), the only two shark species known to regularly inhabit arctic waters, have never been reported. To address this data gap, concentrations and patterns of 25 elements were analyzed in liver of Greenland sharks collected about Cumberland Sound (n=24) and Pacific sleeper sharks collected about Prince William Sound (n=14). Several non-essential elements differed between species/locations, which could suggest geographical exposure differences or ecological (e.g., diet) differences between the species. Certain essential elements also differed between the two sleeper sharks, which may indicate different physiological requirements between these closely related shark species, although information on such relationships are lacking for sharks and fish. 相似文献
16.
17.
Clemens Gros Evan Easton-Calabria Meghan Bailey Kadirbyek Dagys Erin Coughlan de Perez Munguntuya Sharavnyambuu Andrew Kruczkiewicz 《Disasters》2022,46(1):95-118
This paper presents evidence relating to a forecast-based cash and non-food item distribution among vulnerable herder households during the 2017–18 dzud (extreme winter) season in Mongolia, and analyses the results of a quasi-experimental study evaluating its impacts. An innovative approach in disaster risk reduction, forecast-based financing (FbF) can have short- and long-term benefits to vulnerable households but remains understudied. The paper contributes information on a multimodal FbF programme offering one-off cash grants and in-kind veterinary kits. The data found significant effects of reduced mortality and increased offspring survival in some types of livestock, and that the timing of FbF assistance is crucial, as reported early assistance correlated to positive outcomes in terms of reduced animal mortality. These findings can be used to design more effective FbF interventions, to understand better the appropriateness of FbF designs, and to use early warnings and early actions to help people prepare and withstand disasters such as dzuds. 相似文献
18.
H. T. Schreuder R. Czaplewski R. G. Bailey 《Environmental monitoring and assessment》1999,56(3):269-291
A forest ecological inventory and monitoring system combining information derived from maps and samples is proposed based on ecosystem regions (Bailey, 1994). The system extends the design of the USDA Forest Service Region 6 Inventory and Monitoring System (R6IMS) in the Pacific Northwest of the United States. The key uses of the information are briefly discussed and expected results are illustrated with examples. The system is flexible, allowing regions based on ecological considerations to be modified. Sampling intensities that are affordable are likely to be insufficient to provide meaningful estimates for key parameters relating to rare and endangered species, watersheds, and other ecological units. Methods are proposed for collecting additional information in follow-up surveys and combining it with relevant information obtained in R6IMS. Near-continuous information on weather and possible pollution variables recorded by instruments at sampling sites is needed to develop meaningful models to understand what is happening in the ecoregions. R6IMS and the proposed additions constitute a dynamic system which will be modified further as data are analyzed. 相似文献
19.
Maria C. Dzul Philip M. Dixon Michael C. Quist Stephen J. Dinsmore Michael R. Bower Kevin P. Wilson D. Bailey Gaines 《Environmental monitoring and assessment》2013,185(1):405-414
We used variance components to assess allocation of sampling effort in a hierarchically nested sampling design for ongoing monitoring of early life history stages of the federally endangered Devils Hole pupfish (DHP) (Cyprinodon diabolis). Sampling design for larval DHP included surveys (5 days each spring 2007–2009), events, and plots. Each survey was comprised of three counting events, where DHP larvae on nine plots were counted plot by plot. Statistical analysis of larval abundance included three components: (1) evaluation of power from various sample size combinations, (2) comparison of power in fixed and random plot designs, and (3) assessment of yearly differences in the power of the survey. Results indicated that increasing the sample size at the lowest level of sampling represented the most realistic option to increase the survey’s power, fixed plot designs had greater power than random plot designs, and the power of the larval survey varied by year. This study provides an example of how monitoring efforts may benefit from coupling variance components estimation with power analysis to assess sampling design. 相似文献
20.
Ionela Birloaga Ida De Michelis Francesco Ferella Mihai Buzatu Francesco Vegliò 《Waste management (New York, N.Y.)》2013,33(4):935-941
The present lab-scale experimental study presents the process of leaching waste printed circuit boards (WPCBs) in order to recover gold by thioureation. Preliminary tests have shown that copper adversely affects gold extraction; therefore an oxidative leaching pre-treatment was performed in order to remove base metals. The effects of sulfuric acid concentration, hydrogen peroxide volume and temperature on the metal extraction yield were studied by analysis of variance (ANOVA). The highest copper extraction yields were 76.12% for sample A and 18.29% for sample D, after leaching with 2 M H2SO4, 20 ml of 30% H2O2 at 30 °C for 3 h. In order to improve Cu removal, a second leaching was performed only on sample A, resulting in a Cu extraction yield of 90%. Other experiments have shown the negative effect of the stirring rate on copper dissolution. The conditions used for the process of gold extraction by thiourea were: 20 g/L thiourea, 6 g/L ferric ion, 10 g/L sulfuric acid, 600 rpm stirring rate. To study the influence of temperature and particle size, this process was tested on pins manually removed from computer central processing units (CPUs) and on waste CPU for 3½ h. A gold extraction yield of 69% was obtained after 75% of Cu was removed by a double oxidative leaching treatment of WPCBs with particle sizes smaller than 2 mm. 相似文献