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71.
Accounting for the Mesoscale Effects on the Air Pollution in Some Cases of Large Sulfur Pollution in Bulgaria or Northern Greece 总被引:1,自引:0,他引:1
Ganev Kostadin Dimitrova Reneta Syrakov Dimiter Zerefos Christos 《Environmental Fluid Mechanics》2003,3(1):41-53
The objective of the present work is to demonstrate the influence of the meso-scale dynamic phenomena on the larger scale air pollution characteristics. A limited set of episodes with very large sulphur pollution in Bulgaria or Northern Greece is chosen for the study. A 3D quasi-hydrostatic model of the meso-scale dynamics, based on the Businesque approximation (the formulation of Guthman) is used for the purpose. Some numerical experiments for the Balkan Peninsula are carried out under different background (synoptic) conditions. The simulated flow systems outline the main topography effects, typical for the region, such as slope winds, channelling of the air flows or blocking effects. Numerical simulations of the air pollution transport are also carried out, with and without accounting for the meso-scale deformations of the wind field. The comparison of the air pollution characteristics, obtained in both the cases demonstrates that the underlying surface heterogeneity in some of the synoptic situations may have influence not only on the detailed air pollution field in the region, but also on some larger scale pollution characteristics – the total pollution quantity in the air above the countries, the mean surface concentration, the pollution fluxes trough the country boundaries, dry and wet deposition. 相似文献
72.
[CO2]和温度增加的相互作用对植物生长的影响 总被引:4,自引:3,他引:4
CO2 和温度是影响植物生长、发育和功能的两个关键因子 .在过去一个世纪中 ,[CO2 ]从 2 80 μmol/mol增加到 36 0μmol/mol且每年增长速率为 1~ 5 μmol/mol,到 2 0世纪末达到更高的浓度[1] .最近的模型预测表明 ,到 2 10 0年 ,全球表面温度可能会增加 1~ 4 .5℃ [2 \〗.CO2 是光合作用的底物 ,而且还是初级代谢过程 (气孔反应和光合作用 )、光合同化物分配和生长的调节者 .温度几乎影响植物所有的生物学过程 .因此 ,在全球气候变化要素中 ,大气 [CO2 ]和温度升高对植物的生理过程和生物量及产量具有极为重要的… 相似文献
73.
74.
Tyler Mehler W Schuler LJ Lydy MJ 《Environmental pollution (Barking, Essex : 1987)》2008,152(1):217-224
The joint toxicity of chlorpyrifos and atrazine was compared to that of chlorpyrifos alone to discern any greater than additive response using both acute toxicity testing and whole-body residue analysis. In addition, acetylcholinesterase (AChE) inhibition and biotransformation were investigated to evaluate the toxic mode of action of chlorpyrifos in the presence of atrazine. The joint toxicity of atrazine and chlorpyrifos exhibited no significant difference in Lepomis macrochirus compared to chlorpyrifos alone; while studies performed with Pimephales promelas and Chironomus tentans, did show significant differences. AChE activity and biotransformation showed no significant differences between the joint toxicity of atrazine and chlorpyrifos and that of chlorpyrifos alone. From the data collected, the combination of atrazine and chlorpyrifos pose little additional risk than that of chlorpyrifos alone to the tested fish species. 相似文献
75.
Gita R. Kolluru Gregory F. Grether Heidy Contreras 《Behavioral ecology and sociobiology》2007,61(5):689-701
Food availability is expected to influence the relative cost of different mating tactics, but little attention has been paid
to this potential source of adaptive geographic variation in behavior. Associations between the frequency of different mating
tactics and resource availability could arise because tactic use responds directly to food intake (phenotypic plasticity),
because populations exposed to different average levels of food availability have diverged genetically in tactic use, or both.
Different populations of guppies (Poecilia reticulata) in Trinidad experience different average levels of food availability. We combined field observations with laboratory “common
garden” and diet experiments to examine how this environmental gradient has influenced the evolution of male mating tactics.
Three independent components of variation in male behavior were found in the field: courtship versus foraging, dominance interactions,
and interference competition versus searching for mates. Compared with low-food-availability sites, males at high-food-availability
sites devoted more effort to interference competition. This difference disappeared in the common garden experiment, which
suggests that it was caused by phenotypic plasticity and not genetic divergence. In the diet experiment, interference competition
was more frequent and intense among males raised on the greater of two food levels, but this was only true for fish descended
from sites with low food availability. Thus, the association between interference competition and food availability in the
field can be attributed to a genetically variable norm of reaction. Genetically variable norms of reaction with respect to
food intake were found for the other two behavioral components as well and are discussed in relation to the patterns observed
in the field. Our results indicate that food availability gradients are an important, albeit complex, source of geographic
variation in male mating strategies. 相似文献
76.
Jesús M. Avilés Bård G. Stokke Arne Moksnes Eivin Røskaft Anders P. Møller 《Behavioral ecology and sociobiology》2007,61(3):475-485
The outer layer of the eggshell in birds is in many cases covered by pigments that are assumed to be genetically determined traits with a negligible environmental component. To test the hypothesis that spring environmental conditions (i.e., temperature and rainfall) may affect bird egg pigmentation, we measured by spectrophotometry and photography egg coloration and spottiness on reed warbler (Acrocephalus scirpaceus L.) clutches parasitized by the common cuckoo (Cuculus canorus L.) collected over a period of 24 years and preserved in the Zoological Museum, Copenhagen, Denmark. In addition, we investigated whether spring environmental conditions may influence the coevolutionary relationship between the cuckoo and its host via changes in cuckoo–host egg matching. Generalized mixed models revealed that reed warbler eggs were more brilliant in those springs with a higher rainfall and tended to be bluer and greener in springs with a lower relative temperature. On the other hand, cuckoo eggs were bluer and greener in springs with a higher rainfall. Cuckoo–host egg matching in blue-greenness and spottiness was better in springs with a higher rainfall. These results provide support for the existence of an environmental component on bird egg coloration and suggest that environmental factors may potentially affect the outcome of important features of the arms race between cuckoos and reed warblers. 相似文献
77.
78.
Peter G. Ashton James B. Pickens Coryell Ohlander Bruce Benninghoff 《Journal of the American Water Resources Association》1980,16(4):738-744
ABSTRACT: Decisionmaking associated with the Nation's 1.7 billion acres of forest and range land has become increasingly complicated because of the rise in competition for resource use and in the awareness of environmental and social effects. This system analysis approach uses four models to synthesize pertinent masses of information into measures of economic, environmental, and social impacts. The system results can be used to help evaluate alternative national programs. The models are:
79.
从二维空间的角度出发,提出了系统的结构特征;联系紧密和联系松散;复杂式相互作用和直线式相互作用的概念及其特点,并探讨了系统结构特征在系统事故致因中的应用分析。 相似文献
80.
地表水中抗生素与农药的混合暴露及其潜在生态与健康风险受到广泛关注。然而,目前关于抗生素与农药混合毒性研究大多仅考虑急性毒性,缺乏其长期毒性相互作用的研究。以较为广泛使用的2种抗生素土霉素(OXY)、环丙沙星(CIP)和1种三唑类杀菌剂农药戊唑醇(TCZ)及其二元混合物为研究对象,以生态系统中初级生产者绿藻(羊角月牙藻)为受试生物,研究目标混合物在暴露时间为96、120、144和168 h的长期毒性相互作用。结果表明,单一物质及其混合物随暴露时间延长而毒性增大;同一暴露时间点的单一污染物毒性大小顺序为OXYTCZCIP;混合物毒性相互作用与浓度、混合物组分和暴露时间三者密切相关;混合体系的拮抗作用均出现在高浓度区域,而中、低浓度区域呈协同作用或加和作用; OXY-CIP与CIPTCZ混合体系的协同作用随着暴露时间延长而协同作用逐渐增大。研究结果对水环境中抗生素与农药复合污染生态风险评估具有重要的现实意义。 相似文献