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281.
Bergersen O Haarstad K 《Journal of the Air & Waste Management Association (1995)》2008,58(8):1014-1021
Hydrogen sulfide (H2S) is a major odorant in landfills. We have studied H2S production from landfill residual waste with and without sulfur-containing plaster board, including the influence of the water content in the waste. The laboratory experiments were conducted in 30-L polyethylene containers with a controlled water level. We also studied how different materials removed H2S in reactive layers on top of the waste. The organic waste produced H2S in concentrations of up to 40 parts per million (ppm) over a period of 80 days. When plaster board was added, the H2S concentration increased to 800 ppm after a lag period of approximately 40 days with a high water level, and to approximately 100 ppm after 50 days with a low water level. The methane (CH4) concentration in the initial experiment was between 5 and 70% after 80 days. The CH4 concentration in the second experiment increased to nearly 70% in the container with a high water level, slowly declining to approximately 60% between days 20 and 60. The CH4 concentrations during the experiments resembled normal landfill concentrations. Metallic filter materials were very efficient in removing H2S, whereas organic filter materials showed poor H2S removal. 相似文献
282.
Reduced take-off ability in robins (Erithacus rubecula) due to migratory fuel load 总被引:11,自引:0,他引:11
Lind Johan Fransson Thord Jakobsson Sven Kullberg Cecillia 《Behavioral ecology and sociobiology》1999,46(1):65-70
Recent studies have shown that large fuel loads in small birds impair flying ability. This is the first study to show how
migratory fuel load affects flying ability, such as velocity and height gained at take-off in a predator escape situation,
in a medium-distance migrant, and whether they adjust their take-off according to predator attack angle. First-year robins
(Erithacus rubecula) were subjected to simulated attacks from a model merlin (Falco columbarius), and take-off velocity and angle were analysed. Robins with a wing load of 0.19 g cm−2 took off at a 39% lower angle than robins with a wing load of 0.13 g cm−2, while velocity remained unaffected. The robins did not adjust their angle of ascent in accordance with the predator's angle
of attack. Since many predators rely on surprise attacks, a difference in flight ability due to varying fuel loads found in
migrating robins can be important for birds' chances of survival when actually attacked.
Received: 28 October 1998 / Received in revised form: 12 January 1999 / Accepted: 30 January 1999 相似文献
283.
Sven Ove Hansson 《Process Safety and Environmental Protection》2010,88(3):168-172
By inherent safety is meant that a hazard is eliminated rather than being managed by various add-on equipment and procedures. Practices of inherent safety have been developed in the chemical industry, and include for instance the substitution of hazardous substances by less hazardous ones. Inherently safer design strives to eliminate the possibility of major adverse events even when the probabilities of these events are small or cannot be meaningfully estimated. Considerations of security can be more easily incorporated into this approach than into most other branches of risk and safety analysis. Therefore, inherent safety has a great potential as a meeting-ground for the much-needed coordination of safety and security work. Its philosophical underpinnings are outlined, and proposals are made for more efficient promotion of its principles. 相似文献
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The long-distance dispersal of larvae provides important linkages between populations of reef-building corals and is a critical
part of coral biology. Some coral planulae have symbiotic dinoflagellates (Symbiodinium spp.) that probably provide energy in addition to the lipids provisioned within the egg. However, our understanding of the
influence of symbionts on the energy metabolism and survivorship of planulae remains limited. This study examines the relative
roles of symbiotic dinoflagellate photosynthesis and stored lipid content in the survivorship of the developing stages of
the corals Pocillopora damicornis and Montipora digitata. We found that survivorship decreased under dark conditions (i.e. no photosynthetic activity) for P. damicornis and M. digitata at 31 and 22 days after release/spawning, respectively. The lipid content of P. damicornis and M. digitata planulae showed a significant decrease, at a higher rate, under dark conditions, when compared with light conditions. When
converted to energy equivalents, the available energy provided by the depletion of lipids could account for 41.9 and 84.7%
of larval metabolism for P. damicornis (by day 31) and 38.4 and 90.1% for M. digitata (by day 21) under light and dark conditions, respectively. This finding indicates that not all energy requirements of the
larvae are met by lipids: energy is also sourced from the photosynthetic activities of the symbiotic dinoflagellates within
these larvae, especially under light conditions. In addition, the amounts of three main lipid classes (wax esters, triglycerides,
and phospholipids) decreased throughout the experiment in the planulae of both species, with the wax ester content decreasing
more rapidly under dark conditions than under light conditions. The observations that the planulae of both species derive
considerable amounts of energy from wax esters, and that symbiotic dinoflagellates enable larvae to use their stores at lower
rates, suggested that symbiotic dinoflagellates have the potential to extend larval life under light conditions. 相似文献
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Sven Hörstadius 《Die Naturwissenschaften》1932,20(21):363-363