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481.
Hanneke J. M. Meijer Arike Gill Perry G. B. de Louw Lars W. Van Den Hoek Ostende Julian P. Hume Kenneth F. Rijsdijk 《Die Naturwissenschaften》2012,99(3):177-184
Since 2005, excavations at Mare aux Songes, Mauritius, have revealed the presence of a very rich, ∼4,200-year-old fossil bone
bed including dodo (Raphus cucullatus) bones and bone fragments. The recently excavated dodo assemblage comprises at least 17 individuals and is characterised
by the presence of small and fragile skeletal elements, a dominance of leg elements and an absence of juveniles. The hydrology
of the area suggests that dodos, like many other species, were probably lured to Mare aux Songes by the presence of freshwater
during times of drought. The most likely scenario for the origin of the fossil deposit is that animals became trapped in the
sediment in repeated miring events, which would favour the conservation of hindlimbs. Such a scenario is fully in accordance
with the taphonomic characteristics of the bone assemblage. 相似文献
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基于非本地物种的毒性数据推导出的水质基准一直存在争议,质疑者提出应有针对不同生物区系的水质基准。而这个问题在中国尤为突出。本文作者搜集了38种污染物对本地物种和非本地物种的毒性数据,比较了这些生物的HC5和物种敏感度分布,结果显示,基于非本地物种推导的水质基准有74%的确定性可以有效保护中国的水生态系统。如果采用评价因子(AF=5)来校正基准,那么可以获得90%的确定性。
精选自Xiaowei Jin, Zijian Wang, Yeyao Wang, Yibing Lv, Kaifeng Rao, Wei Jin, John P. Giesy and Kenneth M. Y. Leung. Do water quality criteria based on nonnative species provide appropriate protection for native species? Environmental Toxicology and Chemistry: Volume 34, Issue 8, pages 1744–1750, August 2015. DOI: 10.1002/etc.2985
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.2985/full 相似文献
485.
Erik Stenvall Sandra Tostar Antal Boldizar Mark R.StJ. Foreman Kenneth Möller 《Waste management (New York, N.Y.)》2013,33(4):915-922
The compositions of three WEEE plastic batches of different origin were investigated using infrared spectroscopy, and the metal content was determined with inductively coupled plasma. The composition analysis of the plastics was based mainly on 14 samples collected from a real waste stream, and showed that the major constituents were high impact polystyrene (42 wt%), acrylonitrile–butadiene–styrene copolymer (38 wt%) and polypropylene (10 wt%). Their respective standard deviations were 21.4%, 16.5% and 60.7%, indicating a considerable variation even within a single batch. The level of metal particle contamination was found to be low in all samples, whereas wood contamination and rubber contamination were found to be about 1 wt% each in most samples. In the metal content analysis, iron was detected at levels up to 700 ppm in the recyclable waste plastics fraction, which is of concern due to its potential to catalyse redox reactions during melt processing and thus accelerate the degradation of plastics during recycling. Toxic metals were found only at very low concentrations, with the exception of lead and cadmium which could be detected at 200 ppm and 70 ppm levels, respectively, but these values are below the current threshold limits of 1000 ppm and 100 ppm set by the Restriction of Hazardous Substances directive. 相似文献
486.
A multi-regional integrated energy systems model is developed to assess the economic impact of hydrogen fuel cell, hydrogen internal combustion, and battery electric technologies on the economy of New Zealand. Base case results suggest that a hydrogen fuel dominant vehicle fleet offers economic savings over a conventional fleet but requires the largest sequestration capacity as 75% of hydrogen fuel production is derived from fossil fuel. When the oil price is varied from US$120 to US$240 per barrel in 2030, and the carbon tax varied from US$30 to US$90 per tonne of CO2 equivalent, the change in savings ranges from ?65% to +25%. 相似文献
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Advancements in fetal diagnostic imaging have increased prenatal diagnosis of many fetal anomalies. The purpose of this chapter is to review the etiology and natural history of prenatally diagnosed cystic lung lesions, including congenital cystic adenomatoid malformations (CCAM), pulmonary sequestrations (PSs), hybrid lesions, and bronchogenic cysts, and then discuss current concepts in the management and outcome of these lesions. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
490.
Shaocai Yu Rohit Mathur Daiwen Kang Kenneth Schere Daniel Tong 《Atmospheric environment (Oxford, England : 1994)》2009,43(2):355-363
The integrated process rates (IPRs) estimated by the Eta–CMAQ model at grid cells along the trajectory of the air mass transport path were analyzed to quantitatively investigate the relative importance of physical and chemical processes for O3 formation and evolution over the northeastern U.S. during the 2004 International Consortium for Atmospheric Research on Transport and Transformation (ICARTT) period. The Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model is used to determine the back trajectory of air masses reaching the northeast by linking a downwind receptor to upwind source areas. The process analysis is applied to a high O3 episode occurring on July 22, 2004 at three selected sites in the northeastern U.S. The process analysis at the location of the site shows that during the daytime, the O3 concentrations in the surface layer are mainly enhanced by the vertical diffusion of O3-rich air from aloft, followed by horizontal advection (HADV) and chemical production (CHEM), whereas dry deposition (DDEP) and vertical advection (ZADV) mainly deplete O3 concentrations at the sites of Valley Central (VC), NY and Castle Spring (CS), NH. By integrating the effects of each process over the depth of the daytime planetary boundary layer (PBL), it was found that at the VC site, CHEM and HADV contributed about 53% and 41%, respectively, to O3 levels within the PBL. This confirms the significance of regional transport of O3 from the industrialized areas into the Northeast. On the other hand, the process analysis results for O3 formation in moving air masses indicate that on July 22, large chemical production of O3 along the transport path over the polluted urban regions leads to significant increase in O3 in the air mass reaching the VC site, whereas the low chemical production of O3 along the transport path over the low emission regions leads to the low O3 concentration at the site of Belleayre Mountain (BM), NY. The dramatic buildup of O3 concentration from 50 ppb to 102 ppb in the air masses before reaching the VC site after 12:00 EST on 7/22 indicates the significant impact of pollution from the northeastern urban corridor at this site. On the basis of the results at the CS site, it was found that high NOx emissions along the transport path led to large chemical production of O3 in the air mass reaching the CS site on July 22. In contrast, the low chemical production of O3 associated with low emission (relatively clean conditions) along the transport path over the northern portions of the domain is responsible for the low O3 concentration at the CS site on July 26. 相似文献