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11.
Two simplified versions of a numerical life cycle model for diazotrophic cyanobacteria (of the order Nostocales) are developed and evaluated. Both consider two-life cycle stages, one growing, nitrogen-fixing stage and one stage that combines the resting, germinating and vegetative stages. The versions differ in the vertical resolution of the non-diazotrophic stage: version 1 collects the biomass in one layer at the bottom, version 2 considers sinking and rising of biomass explicitly. The results of the two versions are compared with a complex cyanobacteria life cycle model which describes four different life cycle stages each with two internal quotas for energy and nitrogen. The two simplified approaches show a good agreement with respect to the main characteristics of cyanobacteria dynamics (timing and duration of blooms, magnitude of nitrogen fixation, interannual variability). Our model study shows that both simplified approaches are suitable to be implemented into three-dimensional coastal or lake models.  相似文献   
12.
Carlman I 《Ambio》2005,34(2):163-168
This article confronts present main stream planning approaches against the perspective of ecological sustainability, as relevant for Rule of Law countries and based on a modern environmental law approach. It discusses the setting and implementation of environmental goals against the general experience of massive implementation deficits regarding environmental policies all over the world. In this confrontation, environmental planning, with at least some principles picked up from New Zealand's Resource Management Act, and much more taken from modern environmental law theory on legal operationalisation, is compared to adaptive management approaches which also allow for modifying the environment related goal if implementation fails or seems very difficult. The concept of adaptive environmental planning (AEP) is suggested as a possible road to choose for planning for sustainability, while maximizing development within the framework legally defined by means of environmental limits. This article presents five criteria, all of which must be met by AEP planning. One of these relates to a planning hierarchy which, among other things, leads to the conclusion that coastal planning, if it is intended to aim at sustainability, can not be dealt with in isolation, although such planning might have to meet very complex problems at the regional level.  相似文献   
13.
Oviposition by butterflies on young leaves: Investigation of leaf volatiles   总被引:2,自引:0,他引:2  
Bergström  Gunnar  Rothschild  Miriam  Groth  Inga  Crighton  Cathy 《Chemoecology》1994,5(3-4):147-158
Summary Various butterflies select young foliage on which to lay their eggs; volatiles emitted by young and old leaves have been compared (by sorption enrichment, followed by GC-MS) to gauge possible qualitative and quantitative differences between the two age groups. The plants investigated are cabbage (Brassica oleracea), two milkweeds (Asclepias syriaca andA. curassavica), the bitter orange (Citrus aurantium) and the lime (C. aurantiifolia). The chemical compounds identified belong to three classes, isoprenoids, fatty acid derivatives and benzenoids. Quantitative differences were found between young and old leaves, of which a few may be characteristic of young leaves only. Thirty-four single trials withDanaus plexippus exposed to volatiles from young and old leaves are recorded.  相似文献   
14.
Two closely related forms ofOphrys insectifera were observed in the field to attract different pollinator species selectively.O. i. ssp.insectifera attracted males of two species ofArgogorytes (Sphecidae, Hymenoptera Aculeata) andO. i. ssp.aymoninii attractedAndrena combinata males (Andrenidae, Apoidea, Hymenoptera Aculeata). A third form,O. aff.i. ssp.insectifera, attracted none of these three species. Volatile compounds from flowers and inflorescences of the three forms (originating from Öland, Sweden, and Aveyron, France) were collected, using entrainment, enfleurage, and solvent extraction techniques, and identified by gas chromatography — mass spectrometry. Scent differences between the three forms were confirmed in the amounts of aliphatic hydrocarbons (C11–C19), methyl esters (C14–C18), short chain aliphatic 1-alcohols (C6–C12), and monoterpene alcohols (C10).  相似文献   
15.
这篇文章根据生态可持续性的观点,挑战当前主流规划办法,适用于法治国家并建立在现代环境法办法的基础之上.这篇文章根据全世界环境政策大规模实施不利的一般经验,讨论了环境目标的设定和实施.在此,把环境规划与自适应管理办法作比较.环境规划中至少有一些法则来源于新西兰的<资源管理法>,更多则取自法律操作化的当代环境法律理论;而自适应管理办法在实施失败或似乎很难实施的情况下,允许考虑调整环境相关目标.自适应环境规划(AEP)观念被建议作为在通过环境限度合法界定框架内最大限度地发展的同时,选择可持续性规划的一个可能的路径.这篇文章提出了5个标准,这些标准是在自适应环境规划中必须要符合的.这些标准之一涉及到规划的层次,规划的层次与其它情况一起导致这样的结论:如果海岸带规划的目标是可持续性,就不能孤立地来对待,尽管在区域一级上这样的规划可能不得不面对非常复杂的问题.  相似文献   
16.
Hydrocarbon emissions from gas turbine engines can be divided into unreactive and reactive components. The unreactive component consists of paraffins which do not take part in smog producing reactions with NOx. The reactive portion includes olefins, aro-matics and oxygenated derivatives of hydrocarbons which take part in smog producing reactions with NOx. Odor is attributed normally to the aromatics and oxygenates.

Previous work led to the development of a high temperature subtractive analyzer (APCA 22, 696 (1972) which separates hydrocarbon emissions into a) paraffins and b) aromatics, olefins, and oxygenates. Liquid chromatographic techniques have also been used to separate the hydrocarbons into a) aliphatics, b) aromatics, and c) oxygenates. These aliphatics include olefins.

In this work, engine emissions have been analyzed by these two techniques as a function of engine type, engine thrust (power) and fuel type. Specific engines tested were JT4, JT3D and JT9D. Fuels studied were JP5, and Jet A fuel. Power settings ranged from sub idle to high power. Results using the high temperature subtractive analyzer indicate that the % unreactive hydrocarbons ranges from 30 % at idle to near zero at high power for these engine types and fuels. In general, the higher the total hydrocarbon level, the higher the % unreactive hydrocarbons. Total hydrocarbons decrease sharply with increase in thrust. The emissions from different types of engines at various power settings were collected on an adsorbent Chromosorb 102 and the adsorbate analyzed by liquid chromatographic techniques at A. D. Little, Inc. These results showed similar trends from low power to high power. The oxygenate fraction increased and aliphatic portion decreased. However, the data for this portion of the work were very limited and no firm conclusions can be drawn.  相似文献   
17.
The overall measurement of farm level greenhouse gas (GHG) emissions in dairy production is not feasible, from either an engineering or administrative point of view. Instead, computational model systems are used to generate emission inventories, demanding a validation by measurement data. This paper tests the GHG calculation of the dairy farm-level optimization model DAIRYDYN, including methane (CH4) from enteric fermentation and managed manure. The model involves four emission calculation procedures (indicators), differing in the aggregation level of relevant input variables. The corresponding emission factors used by the indicators range from default per cow (activity level) emissions up to emission factors based on feed intake, manure amount, and milk production intensity. For validation of the CH4 accounting of the model, 1-year CH4 measurements of an experimental free-stall dairy farm in Germany are compared to model simulation results. An advantage of this interdisciplinary study is given by the correspondence of the model parameterization and simulation horizon with the experimental farm’s characteristics and measurement period. The results clarify that modeled emission inventories (2,898, 4,637, 4,247, and 3,600 kg CO2-eq. cow?1 year?1) lead to more or less good approximations of online measurements (average 3,845 kg CO2-eq. cow?1 year?1 (±275 owing to manure management)) depending on the indicator utilized. The more farm-specific characteristics are used by the GHG indicator; the lower is the bias of the modeled emissions. Results underline that an accurate emission calculation procedure should capture differences in energy intake, owing to milk production intensity as well as manure storage time. Despite the differences between indicator estimates, the deviation of modeled GHGs using detailed indicators in DAIRYDYN from on-farm measurements is relatively low (between ?6.4 % and 10.5 %), compared with findings from the literature.  相似文献   
18.
Data were retrieved from 25 ocean sunfish (Mola mola) that were tagged with pop-up satellite archival tags in the southern Gulf of Maine (n = 6), off Nantucket Island (n = 17), and off the coast of Georgia (n = 2) between September 2005 and March 2008. Tags remained attached from 7 to 242 days, with a mean attachment period of (X ± SD) 107.2 ± 80.6 days. Ocean sunfish tagged in the Gulf of Maine and southern New England left those areas in the late summer and early autumn and moved south along the continental shelf break. Fish traveled as far south as the Bahamas and the Gulf of Mexico. By moving south, sunfish experienced similar mean sea surface temperatures throughout the tagging period. The maximum straight-line distance traveled by a tagged Mola mola was 2,520 km in 130 days. Two tagged ocean sunfish entered the Gulf of Mexico, one in the December and one in July. Movements were associated with frontal features created by the Gulf Stream and fish moved farther offshore in 2007 when the Gulf Stream was deflected from the shelf break.  相似文献   
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