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991.
992.
利用天然蛭石处理造纸黑液 总被引:7,自引:0,他引:7
实验使用未经膨化处理的天然蛭石,添加微量铁质添加剂处理草浆黑液,然后将其沉渣烧制陶瓷制品。微量铁质添加剂使得天然蛭石对造纸黑液中COD的去除率由原来的30%提高到50%以上;利用沉渣烧制陶瓷制品的烧成温度宽,制品的强度高,孔隙率大。 相似文献
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Insect larvae increase in size with several orders of magnitude throughout development making them more conspicuous to visually
hunting predators. This change in predation pressure is likely to impose selection on larval anti-predator behaviour and since
the risk of detection is likely to decrease in darkness, the night may offer safer foraging opportunities to large individuals.
However, forsaking day foraging reduces development rate and could be extra costly if prey are subjected to seasonal time
stress. Here we test if size-dependent risk and time constraints on feeding affect the foraging–predation risk trade-off expressed
by the use of the diurnal–nocturnal period. We exposed larvae of one seasonal and one non-seasonal butterfly to different
levels of seasonal time stress and time for diurnal–nocturnal feeding by rearing them in two photoperiods. In both species,
diurnal foraging ceased at large sizes while nocturnal foraging remained constant or increased, thus larvae showed ontogenetic
shifts in behaviour. Short night lengths forced small individuals to take higher risks and forage more during daytime, postponing
the shift to strict night foraging to later on in development. In the non-seasonal species, seasonal time stress had a small
effect on development and the diurnal–nocturnal foraging mode. In contrast, in the seasonal species, time for pupation and
the timing of the foraging shift were strongly affected. We argue that a large part of the observed variation in larval diurnal–nocturnal
activity and resulting growth rates is explained by changes in the cost/benefit ratio of foraging mediated by size-dependent
predation and time stress. 相似文献
996.
Rates of Movement of Threatened Bird Species between IUCN Red List Categories and toward Extinction 总被引:1,自引:0,他引:1
M. de L. BROOKE‡‡ S.H.M. BUTCHART† S.T. GARNETT‡ G.M. CROWLEY‡§ N.B. MANTILLA-BENIERS†† A.J. STATTERSFIELD† 《Conservation biology》2008,22(2):417-427
Abstract: In recent centuries bird species have been deteriorating in status and becoming extinct at a rate that may be 2–3 orders of magnitude higher than in prehuman times. We examined extinction rates of bird species designated critically endangered in 1994 and the rate at which species have moved through the IUCN (World Conservation Union) Red List categories of extinction risk globally for the period 1988–2004 and regionally in Australia from 1750 to 2000. For Australia we drew on historical accounts of the extent and condition of species habitats, spread of invasive species, and changes in sighting frequencies. These data sets permitted comparison of observed rates of movement through the IUCN Red List categories with novel predictions based on the IUCN Red List criterion E, which relates to explicit extinction probabilities determined, for example, by population viability analysis. The comparison also tested whether species listed on the basis of other criteria face a similar probability of moving to a higher threat category as those listed under criterion E. For the rate at which species moved from vulnerable to endangered, there was a good match between observations and predictions, both worldwide and in Australia. Nevertheless, species have become extinct at a rate that, although historically high, is 2 (Australia) to 10 (globally) times lower than predicted. Although the extinction probability associated with the critically endangered category may be too high, the shortfall in realized extinctions can also be attributed to the beneficial impact of conservation intervention. These efforts may have reduced the number of global extinctions from 19 to 3 and substantially slowed the extinction trajectory of 33 additional critically endangered species. Our results suggest that current conservation action benefits species on the brink of extinction, but is less targeted at or has less effect on moderately threatened species. 相似文献
997.
温度对奶牛粪便温室气体排放的影响 总被引:3,自引:0,他引:3
采用封闭罐-气相色谱法对4种不同温度处理下奶牛粪便温室气体排放速率进行测定.结果表明,温度是影响奶牛粪便温室气体排放的主要因子,温度较低时奶牛粪便温室气体排放速率低,而且随着奶牛粪便处理温度升高而增大.在5、15、25和35℃4个处理中,奶牛粪便CO2排放速率两两之间差异显著;CH4排放速率除了5和15℃处理差异不显著之外,其他两两处理之间差异显著;35℃处理时N2O排放速率与其他温度的排放速率差异均显著,其他两两处理之间差异不显著. 相似文献
998.
阿特拉津对铜绿微囊藻和四尾栅藻生长的影响 总被引:2,自引:0,他引:2
在实验室内利用MA培养液培养,通过测定藻生长量和叶绿素a含量,研究不同浓度下的阿特拉津对铜绿微囊藻(Microcystis aeruginosa)和四尾栅藻(Scenedesmus quadricauda)生长的影响,并以藻细胞数表示的最大比生长率为指标,评价2种藻对阿特拉津的敏感性.结果表明,在0.001~5.000 mg·L-1质量浓度范围内,阿特拉津对铜绿微囊藻和四尾栅藻的生长表现出低浓度刺激、高浓度抑制的效应,且阿特拉津对四尾栅藻的刺激效应明显大于铜绿微囊藻. 相似文献
999.
蒽的不完全臭氧氧化及中间产物特性分析 总被引:1,自引:1,他引:0
对蒽进行了臭氧不完全氧化实验研究,利用HPLC、UV、TOC监测了臭氧氧化过程中发生的变化.结果表明,蒽被臭氧降解时有中间产物生成,臭氧可以与中间产物继续作用,但是难以使之矿化.另外,氧化体系中水溶性有机物的TOC变化及其对活性污泥OUR的影响结果表明,臭氧氧化改善了蒽的可生化降解性.因此,臭氧氧化与生物降解组合技术,有望成为处理废水中蒽的经济有效方法. 相似文献
1000.