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991.
Olivier Le Curieux-Belfond Louise Vandelac Joseph Caron Gilles-Éric Séralini 《Environmental Science & Policy》2009,12(2):170-189
Many genetically modified plants have been developed, and four of them (soya, maize, cotton, and colza) representing more than 99% of commercial crops, are widely distributed, mainly in the United States and in America [ISAAA, 2006. Report on global status on biotech/GM crops, Brief 35. International Service for the Acquisition of Agri-biotech Applications organization, US]. Yet all over the world policy is still in development in regard to authorization of modified plants and modified and/or cloned animals for food or feed and for their environmental release. The most advanced animal commercial projects concern various fish species, more easy to genetically transform, notably because conception and development take place in water and easy access to numerous eggs. A request for authorization to introduce genetically modified (GM) salmon onto the market has been presented to the Food and Drug Administration (FDA) of the US. In the interim, questions have been raised concerning the impacts of transgenic salmon, modified for productivity, on aquaculture, wildlife, ecosystems and on human health. Herein we review these scientific studies and sanitary, environmental, social and economic arguments. This paper analyses current gaps in the knowledge of the impacts of transgenic fish and proposes legislation orientations necessary for environmental and sanitary protection, should the marketing of animal genetically modified organisms (GMOs) be authorized. 相似文献
992.
Philip K. Thornton Pierre J. Gerber 《Mitigation and Adaptation Strategies for Global Change》2010,15(2):169-184
Livestock production systems will inevitably be affected as a result of changes in climate and climate variability, with impacts
on peoples’ livelihoods. At the same time, livestock food chains are major contributors to greenhouse gas emissions. Agriculture
and livestock in particular will need to play a greater role than they have hitherto in reducing emissions in the future.
Adaptation and mitigation may require significant changes in production technology and farming systems, which could affect
productivity. Given what is currently known about the likely impacts on livestock systems, however, the costs of mitigating
and adapting to climate change in the aggregate may not represent an enormous constraint to the growth of the global livestock
sector, in its bid to meet increasing demand for livestock products. Different livestock systems have different capacities
to adapt or to take on board the policy and regulatory changes that may be required in the future. Vulnerability of households
dependent on livestock, particularly in the drier areas of developing countries, is likely to increase substantially, with
concomitant impacts on poverty and inequity. The capacity of these systems to adapt and to yield up their carbon sequestration
potential deserves considerable further study. Comprehensive frameworks need to be developed to assess impacts and trade-offs,
in order to identify and target adaptation and mitigation options that are appropriate for specific contexts, and that can
contribute to environmental sustainability as well as to poverty alleviation and economic development. 相似文献
993.
刘乐 《安全.健康和环境》2010,10(12):49-50
TPM是全员生产维护的英文缩写,即全体人员,包括企业领导、生产现场工人以及办公室人员参加的生产维修、维护体制。它起源于美国,后来在日本发展成为全员生产维护。TnPM即全员规范化生产维护,是中国式的TPM。是中国设备管理发展的一种新模式,着重于生产现场的设备管理,是以提高设备综合效率为目标(全效率), 相似文献
994.
Soizic Le Fur Emmanuel Fara Hassane Taïsso Mackaye Patrick Vignaud Michel Brunet 《Die Naturwissenschaften》2009,96(5):565-574
Characterizing the paleoenvironmental context of the first hominids is a key issue for understanding their behavioral and
morphological evolution. The present study aims at reconstructing the paleoenvironment of the TM266 vertebrate assemblage
(Toros-Menalla, Northern Chad) that yielded the earliest known hominid Sahelanthropus tchadensis (7 Ma). For the first time, a quantitative analysis is carried out on the fossil mammal assemblage associated with that hominid.
Two complementary approaches were applied: (1) the analysis of the relative abundances of taxa and their habitat preferences;
and (2) the study of the distribution of taxa within three meaningful ecovariables: locomotion, feeding preferences, and body
mass. The resulting taxonomic and paleoecological structures are used to reconstruct the diversity and the relative extent
of the habitats in that part of northern Chad seven million years ago. The paleoenvironment was composed of open areas with
dry and humid grasslands, prevailing over wooded habitats. Water was also widely available as freshwater bodies and certainly
swamps. It appears that the high habitat diversity of the landscape is a common feature among paleoenvironments associated
with early hominids. 相似文献
995.
996.
Rüdiger Riesch Martin Plath Francisco J. García de León Ingo Schlupp 《Die Naturwissenschaften》2010,97(2):133-141
The majority of studies on ecological speciation in animals have investigated the divergence caused by biotic factors like
divergent food sources or predatory regimes. Here, we examined a system where ecological speciation can clearly be ascribed
to abiotic environmental gradients of naturally occurring toxic hydrogen sulfide (H2S). In southern Mexico, two genera of livebearing fishes (Poeciliidae: Poecilia and Gambusia) thrive in various watercourses with different concentrations of H2S. Previous studies have revealed pronounced genetic differentiation between different locally adapted populations in one
species (Poecilia mexicana), pointing towards incipient speciation. In the present study, we examined female reproductive life-history traits in two
species pairs: Gambusia sexradiata (from a nonsulfidic and a sulfidic habitat) and Gambusia eurystoma (sulfide-endemic), as well as P. mexicana (nonsulfidic and sulfidic) and Poecilia sulphuraria (sulfide endemic). We found convergent divergence of life-history traits in response to sulfide; most prominently, extremophile
poeciliids exhibit drastically increased offspring size coupled with reduced fecundity. Furthermore, within each genus, this
trend increased with increasing sulfide concentrations and was most pronounced in the two endemic sulfur-adapted species.
We discuss the adaptive significance of large offspring size in toxic environments and propose that divergent life-history
evolution may promote further ecological divergence through isolation by adaptation. 相似文献
997.
分别在冬季及夏季选取具有典型气候特性的两天,采集空气中总悬浮颗粒物(TSP)。根据采样前、后滤膜重量之差及采样标况体积,计算TSP质量浓度,采用液相沉降法测定粒度分布,对环境空气中总悬浮颗粒物(TSP)和可吸入颗粒物(PM10)进行粒度分布相对百分比及粒度分布累计研究。分析总悬浮颗粒物(TSP)中含有的粒度分布情况及冬夏两季可吸入颗粒物(PM10)与总悬浮颗粒物(TSP)的比例关系。更深一步了解TSP各级颗粒的粒度分布,特别是PM10以下的颗粒物的粒度分布情况。 相似文献
998.
999.
When partitioning the variation of univariate or multivariate ecological data with respect to several submodels of spatial eigenfunctions (e.g., Moran's eigenvector maps, MEM) acting as explanatory data, a problem occurs: although the submodels are constructed to be orthogonal to one another, the partitioning based on adjusted R2 statistics produces nonzero values in the intersections between spatial submodels. This phenomenon is described and two solutions are proposed. The first solution is to apportion the intersection fractions proportionally to the variation explained by each submodel. The second solution consists in creating a hierarchy among the spatial submodels, in accordance with hierarchy theory. These solutions lead to new partitioning equations that are described in the Appendix. R functions are provided to carry out partitioning with respect to environmental variables and spatial eigenfunction submodels. This development is important for the correct interpretation of spatial modeling results implying explanatory environmental data as well as submodels of spatial eigenfunctions involving two or more spatial scales. 相似文献
1000.
根据现场实测数据,应用标准k-ε模型研究了动态风场及交通流量下三维街道峡谷内的污染物扩散规律,数值模拟利用CFD软件FLUENT,其中动态风场和车流量变化信息通过用户自定义编程实现.结果发现,动态风场下空气在街道内部不断经历膨胀和压缩的过程,街道峡谷内部流场形态时刻都在变化;当风速由大变小时,空气膨胀出街谷,流型呈近似椭圆形分布;当风速由小变大时,空气压缩在街谷内部,流型呈近似圆形分布.风速的不断变化引起街谷内、外大气的压缩和膨胀过程,这种过程能够改善街谷内污染物的扩散情况.背风面行人高度处,动态来流下的平均污染物浓度要比定常来流下低17.7%;迎风面行人高度处,动态来流下的平均污染物浓度要比定常来流下低27.1%.动态环境下污染物浓度的分布和峰值由风场和车流量变化共同决定. 相似文献