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941.
Should I stay or should I go? Testing optimality models of stopover decisions in migrating birds 总被引:1,自引:0,他引:1
Thomas P. Weber Thord Fransson Alasdair I. Houston 《Behavioral ecology and sociobiology》1999,46(4):280-286
Time-minimizing migrants should leave a stopover site if the instantaneous speed of migration drops to the average speed
of migration in the environment. This argument has been used in two different ways: either there is local variation in the
fuel deposition rate and a fixed expected speed or there is global variation in the fuel deposition rate, i.e. locally experienced
variation represents global variation along the route. The first case leads to a far steeper relationship between departure
load and fuel deposition rate than the second case. So far, data on departure loads have mainly been analysed within the concept
of local variation of the fuel deposition rate and the result that the observed slopes are much lower than predicted has been
explained by changes in the expected speed along the route or by individual differences in the expected speed. We show here
that the observed relationships generally fall close to the predictions for global variation. We propose that migrants use
a behavioural rule which projects the current experience into the future and therefore interprets local variation as global
variation.
Received: 3 April 1999 / Received in revised form: 22 April 1999 / Accepted: 26 April 1999 相似文献
942.
A. Bulgakov A. Konoplev J. Smith G. Laptev O. Voitsekhovich 《Journal of environmental radioactivity》2009
During the coming years, a management and remediation strategy for the Chernobyl cooling pond (CP) will be implemented. Remediation options include a controlled reduction in surface water level of the cooling pond and stabilisation of exposed sediments. In terrestrial soils, fuel particles deposited during the Chernobyl accident have now almost completely disintegrated. However, in the CP sediments the majority of 90Sr activity is still in the form of fuel particles. Due to the low dissolved oxygen concentration and high pH, dissolution of fuel particles in the CP sediments is significantly slower than in soils. After the planned cessation of water pumping from the Pripyat River to the Pond, significant areas of sediments will be drained and exposed to the air. This will significantly enhance the dissolution rate and, correspondingly, the mobility and bioavailability of radionuclides will increase with time. The rate of acidification of exposed bottom sediments was predicted on the basis of acidification of similar soils after liming. Using empirical equations relating the fuel particle dissolution rate to soil and sediment pH allowed prediction of fuel particle dissolution and 90Sr mobilisation for different remediation scenarios. It is shown that in exposed sediments, fuel particles will be almost completely dissolved in 15–25 years, while in parts of the cooling pond which remain flooded, fuel particle dissolution will take about a century. 相似文献
943.
Chromosomal aberrations and DNA damage in human populations exposed to the processing of electronics waste 总被引:1,自引:0,他引:1
Qiang Liu Jia Cao Ke Qiu Li Xu Hong Miao Guang Li Fei Yue Fan Yong Cheng Zhao 《Environmental science and pollution research international》2009,16(3):329-338
Background, aim, and scope It has been known that the pollutants of electronic wastes (E-wastes) can lead to severe pollution to the environment. It
has been reported that about 50% to 80% of E-wastes from developed countries are exported to Asia and Africa. It has become
a major global environmental problem to deal with ‘E-wastes’. E-waste recycling has remained primitive in Jinghai, China.
This not only produces enormous environmental pollution but also can bring about toxic or genotoxic effects on the human body,
threatening the health of both current residents and future generations living in the local environment. The concentration
of lead in the blood of children in the E-waste polluted area in China is higher than that of the control area. But little
is known about the cytogenetic effect to human beings caused by the pollution of E-wastes. In the present study, experiments
have been performed to investigate the genetics of permanent residents of three villages with numerous E-waste disposal sites
and to analyze the harmful effects of exposure to E-wastes.
Materials and methods In total, 171 villagers (exposed group) were randomly selected from permanent residents of three villages located in Jinghai
County of Tianjin, China, where there has been massive disposal of E-wastes. Thirty villagers were selected from the neighboring
towns without E-waste disposal sites to serve as controls. Chromosomal aberrations and cytokinesis blocking micronucleus were
performed to detect the cytogenetic effect, dic + r (dicentric and ring chromosome), monomer, fragments (acentric fragments,
minute chromosomes, and acentric rings), translocation, satellite, quadriradial, total aberrations, and micronuclear rate
were scored for each subject. DNA damage was detected using comet assay; the DNA percentage in the comet tail (TDNA%), tail
moment (TM), and Olive tail moment (OTM) were recorded to describe DNA damage to lymphocytes.
Results The total chromosome aberration rates (5.50%) and micronuclear rates (16.99%) of the exposure group were significantly higher
than in the control group (P = 0.000). The percentage of DNA in the comet tail, tail moment, and Olive tail moment detected by comet assay showed that
there was a significant difference in DNA damage in the exposure group (P = 0.000). The chromosome aberration, micronucleus rate, and DNA damage observed in women were significantly higher than those
in men. Chromosome aberration and micronuclear rates of both smokers and non-smokers in the exposure group are obviously higher
than that in the control group (P = 0.000).
Discussion The use of outdated (and unsafe) ways to deal with E-wastes can lead to exposure to a variety of substances harmful to human
health. The components of pollution may enter the human body through the air, drinking water, and food chain to damage human
genetic material, resulting in genomic instability. The rates of chromosomal aberration, micronucleus formation, and the degree
of DNA damage in women in the group exposed to electronic waste were significantly higher than in men. The reason for this
may be concerned with the traditional lifestyle of the local residents or the difference of sensitivity to the exposure to
E-wastes or any others. Further investigations are needed to provide evidence to demonstrate this.
Conclusions Here, we report the obviously cytogenetic toxicity to the exposure population by the E-waste pollution for the first time.
E-waste pollution may be a potential agent of genetic mutation, and may induce cytogenetic damage within the general population
exposed to the pollution. These findings need to be considered, and steps should be taken to protect the current population
and future generations from the effects of pollution with E-wastes.
Recommendations and perspectives The above results remind us that the impact of E-waste recycling on environmental quality of Jinghai should be evaluated soon.
Moreover, it is urgent for the government to prohibit E-waste import and its processing by outdated ways. The future studies
such as pollutant details of drinking water, air, and soil in the area as well as epidemiological investigations on the harmful
effect to children must be performed eagerly. All the data available do provide a compelling case for immediate action in
both countries to address workplace health and safety and waste management.
Qiang Liu and Jia Cao contributed equally to this study and share the first authorship. 相似文献
944.
模拟了车用工况下燃料电池发动机脉冲式排氢的特点,设计开发了一套质子交换膜燃料电池的尾气净化系统,并以5 kW燃料电池的尾气排放为例,研究其净化效果。研究了电池阳极排放氢气缓冲前后尾气中氢气浓度的变化,以及不同空速条件下氢气的去除效果。结果表明:电堆阳极排放氢气经过缓冲处理后,尾气中氢气浓度趋于平稳,大部分工况下处在2%以下,达到了安全处理的要求;尾气中氢气的去除效果与空速密切相关。对自制的整体式催化剂而言,当空速低于20 000 h-1时,氢气的去除率能达到约95%,而当空速达到39 270 h-1时,氢气的去除率仅为10.9%。鉴于这一问题,提出通过采用尾排空气的分流手段调整催化燃烧反应器对空速的要求,以提高尾气中氢气的去除率。 相似文献
945.
Oral ingestion of contaminated soil is an important pathway of human exposure to hydrophobic organic contaminants (HOCs), particularly for children in developing countries. The mobilization potential of various contaminants from ingested soil is often characterized using an in vitro gastrointestinal model, based on the quantities of contaminants remaining in digestive fluid after digestion and separation. Recently, it was experimentally demonstrated that a large fraction of mobilized contaminants sorbed on the digested residue could be released if the dissolved fraction was removed by intestinal absorption. This hypothesis was further tested in this study. Soil spiked with dichlorodiphenyltrichloroethane and its metabolites (DDXs) and polycyclic aromatic hydrocarbons (PAHs) was digested using an in vitro gastrointestinal model. A human colon carcinoma cell line (Caco-2) was cultured in digestive fluid with or without soil residue (pre-equilibrated with the soil) for 2 h. A large proportion of the contaminants (37-68%) was sorbed on the digested residue. Without this residue, 66 ± 13% of DDXs and 73 ± 14% of PAHs dissolved in the fluid, as means and standard deviations, were absorbed by the cell monolayer after exposure. With both digestive fluid and residue, the sorbed fraction of PAHs and DDXs decreased by 38-92%, while the ratios of the cellular to the dissolved concentrations were 2.7-2.8 times higher than those without the residue. This supported the hypothesis that the cell absorption of dissolved HOCs induces desorption of the sorbed fraction from digestive residue, and the desorbed HOCs can be absorbed as well. 相似文献
946.
947.
化学防护服的氢氧化钠渗透性能离子色谱检测方法的研究 总被引:1,自引:1,他引:0
渗透性能是化学防护服最重要的防护性能指标之一.本文利用PTC200型渗透测试池、蠕动泵和离子色谱仪等装置,研究并建立了NaOH溶液的渗透性能离子色谱仪的检测方法.结果表明,利用该装置可以方便准确地实现服装面料NaOH溶液渗透性能测试,是一种具有重要应用价值的检测方法. 相似文献
948.
核基因组在细胞质雄性不育中的作用研究:背景与现状 总被引:6,自引:0,他引:6
郭骁才 《应用与环境生物学报》2001,7(3):297-301
细胞质雄性不育 (cytoplasmicmalesterility ,CMS) ,表现为小孢子发育异常、不能产生花粉或花粉败育 ,但卵细胞发育正常、可接受外来花粉而正常结实 ,系母性遗传 ,即细胞质遗传[1~ 4 ] .CMS的重要性 ,首先表现为在农业生产上的巨大经济应用价值[2~ 4 ] .杂种优势的发现和利用为粮食生产带来了革命 ,但杂种种子的生产过程却是很繁杂的 ,核心是要阻止母本的自花授粉结实、保证母本植株上所结的种子全部是杂种 ,即种子的纯度很高才能保证农业生产上的应用 .CMS ,由于其不能产生可育的花粉 ,即无自花授粉结… 相似文献
949.
Outdoor power performance measurements of silicon (Si) solar cells and its assembled module were carried out at the coastal site of geographical location of 12.0107° Latitude and 79.856° Longitude, of Puducherry, India. Measurements were analyzed in comparison with the daily solar illumination data obtained by an optical pyranometer deployed with global measurement condition. It was found that the module required ~3 times more illumination to stabilize in its output voltage than the requirement of an individual cell and exhibited 11.35% loss in its efficiency compared to its STC value. Proposed operation of 5.30 hours was found resulting in an output rating fixed at ~40% from its 100% full capacity. 相似文献
950.
We estimate a model of vehicle choice and kilometers driven to analyze the long-run impacts of fuel conservation policies in the Indian car market. We simulate the effects of petrol and diesel fuel taxes and a diesel car tax, taking into account their interactions with the pre-existing petrol fuel tax and car sales taxes. At levels sufficient to reduce total fuel consumption by 7%, the increased diesel and petrol fuel taxes both yield deadweight losses (net of externalities) of about 4 (2010) Rs./L. However, at levels sufficient to reduce total fuel consumption by 2%, the increased petrol fuel tax results in a deadweight loss per liter of fuel conserved that is greater than that caused by the diesel fuel tax. This reflects both the high pre-existing tax on petrol fuel and the high own-price elasticities of fuel demand in India. A tax on diesel cars that results in the same diesel market share as the large diesel fuel tax actually has a negative deadweight loss per liter of fuel conserved. The welfare effects of all three policy instruments are positive, once the external benefits of reducing fuel consumption are added to the excess burden of taxation. 相似文献