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排序方式: 共有394条查询结果,搜索用时 578 毫秒
41.
Krishna P. Paudel Keshav Bhattarai Wayne M. Gauthier Larry M. Hall 《Waste management (New York, N.Y.)》2009,29(5):1634-1643
Survey information was used to develop a minimum cost spatial dairy manure transportation model where environmental quality and crop nutrient requirements were treated as constraints. The GIS model incorporated land use types, exact locations of dairy farms and farmlands, road networks, and distances from each dairy farm to receiving farmlands to identify dairy manure transportation routes that minimized costs relative to environmental and other constraints. Our analyses indicated that the characteristics of dairy manure, its bulk and relatively low primary N, P2O5 and K2O nutrient levels limit the distribution areas or distances between the farms and the land over which the manure can be economically spread. Physical properties of the land limit the quantities of nutrients that can be applied because of excess nutrient buildup in soil and potential to harm nearby waterbodies and downstream people and places. Longer distances between dairy and farmland favor the use of commercial fertilizers due to the high cost of manure transportation. At $0.08 per ton per km transportation cost, the optimal cut-off distances for dairy manure application is 30 km for N and 15 km each for P2O5 and K2O consistent rules. An analysis of dairy manure application to different crop types suggest that, on average, 1 ha of land requires 61 tons of dairy manure to meet the recommended N, P2O5 and K2O needs. 相似文献
42.
S. L. Vehrencamp J. Yantachka M. L. Hall S. R. de Kort 《Behavioral ecology and sociobiology》2013,67(3):409-419
Acoustic displays with difficult-to-execute sounds are often subject to strong sexual selection because performance levels are related to the sender’s condition or genetic quality. Performance may also vary with age, breeding stage, and motivation related to social context. We focused on within-male variation in four components of trill performance in banded wren (Thryophilus pleurostictus) songs: note consistency, frequency bandwidth, note rate, and vocal deviation. The latter is a composite measure reflecting deviation from the performance limit on simultaneously maximizing both frequency bandwidth and note rate. We compared the changes in these song parameters at three time scales: over the course of years, across the breeding season, and at different times of the day with contrasting agonistic contexts. Vocal deviation decreased and note consistency increased between years, suggesting that experience may improve individual proficiency at singing trills. Consistency also increased across the season, confirming that practice is important for this parameter. Although there was no significant seasonal change in vocal deviation, one of its components, note rate, increased during the season. Neither vocal deviation nor consistency varied with agonistic context. However, note rate increased during playback experiments simulating territorial intrusions compared to dawn chorus singing. The magnitude of a male’s increase in note rate was positively correlated with his aggressive behavior during the playback experiment. Thus consistency, bandwidth, and vocal deviation indicate age, whereas trill rate flexibly indicates the singer’s aggressive motivation. We also found evidence of a within-male trade-off between vocal deviation and consistency. 相似文献
43.
The paper describes a programme to develop the profile of major accident risk across a large multi national oil company. It describes the concepts, tools and processes for constructing the risk profile and some of the key learnings from the exercise. 相似文献
44.
The primary goal of this study was to characterize physical habitat and benthic communities (macroinvertebrates) in the Stanislaus, Tuolumne and Merced Rivers in California’s San Joaquin Valley in 2003. These rivers have been listed as impaired water bodies (303 (d) list) by the State of California due to the presence of organophosphate (OP) insecticides chlorpyrifos and diazinon, Group A pesticides (i.e., organochlorine pesticides), mercury, or unknown toxicity. Based on 10 instream and riparian physical habitat metrics, total physical habitat scores in the Stanislaus River ranged from 124 to 188 (maximum possible total score is 200). The highest total habitat score was reported at the upstream site. Tuolumne River physical habitat scores ranged from 86 to 167. Various Tuolumne River physical habitat metrics, including total habitat score, increased from downstream to upstream in this river. Merced River physical habitat scores ranged from 121 to 170 with a significant increase in various physical habitat metrics, including total habitat score, reported from downstream to upstream. Channel flow (an instream metric) and bank stability (a riparian metric) were the most important physical habitat metrics influencing the various benthic metrics for all three rivers. Abundance measures of benthic macroinvertebrates (5,100 to 5,400 individuals) were similar among the three rivers in the San Joaquin watershed. Benthic communities in all three rivers were generally dominated by: (1) Baetidae species (mayflies) which are a component of EPT taxa generally considered sensitive to environmental degradation; (2) Chironomidae (midges) which can be either tolerant or sensitive to environmental stressors depending on the species; (3) Ephemerellidae (mayflies) which are considered sensitive to pollution stress; and (4) Naididae (aquatic worms) which are generally considered tolerant to environmental stressors. The presence of 117 taxa in the Stanislaus River, 114 taxa in the Tuolumne River and 96 taxa in the Merced River implies that the benthic communities in these streams are fairly diverse but without a clear definition of benthic community expectations it is unknown if these water bodies are actually impaired. 相似文献
45.
The reduction of SO2, HCl, and NO(x) concentrations using calcium magnesium acetate (CMA) as a novel sorbent in a simulated municipal waste incinerator flue gas was investigated. The reduction of individual SO2, HCl, and NO(x) concentrations was tested at 850 degrees C and it was found that CMA could reduce the SO2 concentration by 74%, HCl concentration by 64%, or NO(x) concentration by 94%. It was observed that individual SO2 or HCl capture increased with increasing initial oxygen concentration in the reacting gas or increasing sorbent input. NO(x) reduction decreased with increasing initial oxygen concentration in the reacting gas. The simultaneous reduction of SO2, HCl, and NO(x) concentrations by CMA was also investigated. It was found that CMA could simultaneously capture 60% SO2 and 61% HCl and reduce NO(x) concentrations by 26%, when the initial oxygen concentration in the reacting gas was 4%. During the simultaneous reduction of SO2, HCl, and NO(x), it was noted that as the initial oxygen concentration in the reacting gas increased, the efficiency of SO2 capture increased too, but the efficiency of HCl capture and the efficiency of NO(x) destruction decreased. 相似文献
46.
Abstract: Starch-gel electrophoresis was used to screen 101 bison from Badlands National Park, South Dakota, for variation at 24 genetic loci. The population was descended from founder groups of about 6 and 3 individuals, separated geographically for a minimum of 64 years. The purpose of this study was (1) to estimate levels of genic variability in this bison population, (2) to assess the extent to which descendents of the two founder groups differ genetically, and (3) to compare the genetic characteristics of the Badlands population with other bison populations. The Badlands herd was found to be polymorphic for only a single locus (MDH–1). Descendents of the founder groups were homogeneous with respect to allelic and genotypic frequencies at this locus. The MDH–1 polymorphism has not been observed in other bison populations, while several polymorphism reported in other bison populations were not detected in the Badlands herd. A mean heterozygosity of 0.012 was observed in the Badlands herd; this value is lower than that typically reported for mammals, though not as low as heterozygosities seen in other populations that have passed through severe bottlenecks in size. These results underscore the need for genetic data in planning breeding programs for species in captivity or managed in isolate reserves. 相似文献
47.
Abstract: Success in conservation biology depends upon a synergistic combination of short-term tactics and long-term strategies. Although the former are often necessary to forestall immediate habitat losses, the latter provide the critical framework of understanding needed to develop effective short-term priorities. Although many conservation biologists now emphasize short-term tactics, prudence dictates the concomitant establishment of long-term research projects aimed at answering fundamental ecological questions.
One deterrent to amassing such long-term data bases, aside from time and funding, is a lack of suitable sites where such studies can be conducted on a large scale. We describe two established major land-holding networks in the United States that could serve as appropriate places to develop long-term studies: the National Science Foundation's Long-Term Ecological Research (LTER) sites, and the US. Department of Energy's National Environmental Research Parks (NERPs). Because they consist of established research facilities, both networks can provide conservation biologists with "low-cost" baseline information on ecological processes, as well as access to a number of representative terrestrial and aquatic habitats under more or less "controlled" conditions suitable for long-term studies. We recommend that conservation biologists explore the possibility of using these or similarly available sites in their research programs. 相似文献
One deterrent to amassing such long-term data bases, aside from time and funding, is a lack of suitable sites where such studies can be conducted on a large scale. We describe two established major land-holding networks in the United States that could serve as appropriate places to develop long-term studies: the National Science Foundation's Long-Term Ecological Research (LTER) sites, and the US. Department of Energy's National Environmental Research Parks (NERPs). Because they consist of established research facilities, both networks can provide conservation biologists with "low-cost" baseline information on ecological processes, as well as access to a number of representative terrestrial and aquatic habitats under more or less "controlled" conditions suitable for long-term studies. We recommend that conservation biologists explore the possibility of using these or similarly available sites in their research programs. 相似文献
48.
49.
J C Hall L K Wilson R A Chapman 《Journal of environmental science and health. Part. B》1992,27(5):523-544
An indirect enzyme-linked immunosorbent assay (EIA) for metolachlor (2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamid e) detection in river water and soil was developed using serum obtained from rabbits immunized against the acid of metalaxyl ((N-(2,6-dimethylphenyl)-N-(methoxy-acetyl)-DL-alanine methyl ester) conjugated to bovine serum albumin. The assay had a linear working range from 1 to 50 ng/ml with a mean I50 value of 13.6 ng/ml and a lower detection limit of 2.0 ng/ml. Both the mean interwell and interassay coefficients of variation were less than 4% over the range of the standard curves for samples which had been prepared in phosphate buffered saline (PBS), river water, or soil extract. Assay cross-reactivity to the following four structurally related chloro-acetanilide pesticides were: propachlor (0%), metazachlor (0%), alachlor (23%), and metalaxyl (5,000%). Mean recoveries of metolachlor in spiked (2.0 to 32.0 ng/ml range) PBS, river water, and soil extract were 102%, 103%, and 110%, respectively. Soil samples were taken over a 56-d period from field plots treated with metolachlor and analyzed by GC and EIA. The correlation coefficient for comparison of the two methods was 0.96 with the slope of the linear regression line being 0.78. Furthermore, no statistical difference (P less than 0.05) was found between the dissipation curves of metolachlor derived from GC data versus EIA data. 相似文献
50.
Fred D. Hall John M. Bruck Diane N. Albrinck Robert A. Olexsey 《Environment international》1981,6(1-6)
The recovery of energy from the combustion of municipal solid wastes is becoming an attractive alternative as landfill space becomes scarce and the availability of fossil fuels decreases. Particulate emissions from “waste-as-fuel” processes, however, may differ significantly in chemical and physical properties from particulate emissions produced by firing only coal. Such differences can affect the design and operation of air pollution control equipment. Presented in this paper are the results of a 2-month test program at Ames, Iowa, with a mobile electrostatic precipitator (ESP) and a mobile scrubber supplied by the U.S. Environmental Protection Agency (EPA), Industrial Environmental Research Laboratory (IERL), Research Triangle Park. PEDCo Environmental, Inc., and Acurex Corporation jointly conducted the test program to examine the effect of burning refuse-derived fuel (RDF) on particulate and heavy metal control efficiencies. The mobile ESP was used only as a primary control device, whereas the mobile scrubber was tested both upstream and downstream of the existing full-scale ESP. This paper also presents a status report on a PEDCo test program with a pilot fabric filter at Ames. 相似文献