CRETACEOUS AND TERTIARY BOUNDARY IN THE TINGRI REGION OF SOUTHERN TIBET

CRETACEOUS AND TERTIARY BOUNDARY IN THE TINGRI REGION OF SOUTHERN TIBETtheNNSFProject(49872 0 0 3)andtheNationalProject (G19980 40 80 0 )ofChina     

北美五大湖区晚更新世劳伦泰德冰盖演化年代学综述及石英光释光测年的初步尝试

北美五大湖区的安大略湖北岸Don Valley Brickyard、Scarborough Bluffs、Bowmanville Bluffs剖面共同构成了北美东北部最长也是最厚的陆地第四纪沉积记录, 较完整地记录了晚更新世劳伦泰德冰盖(the Laurentide Ice Sheet)的演化. 晚更新世劳伦泰德冰盖演化的重建有赖于这些经典剖面中重要沉积地层单元的准确年代学控制. 传统的地层年代学主要是依靠少量¹⁴C年代, 将主要的混杂堆积单元(diamicton)解释为气候变冷环境下的冰川扩张, 并与指示全球冰量变化的深海氧同位素曲线一一比对建立起来的. 这样建立起来的年代学存在很大的不确定性. 20世纪80-90年代的少量热释光年代也不相吻合, 最近的13个长石红外释光定年则只集中于Bowmanville Bluffs的一个分层, 并未建立整个剖面的地层年代学, 使这些经典沉积剖面的年代学一直没有得到系统的建立. 应用石英光释光SAR-SGC法测试了Bowmanville Bluffs剖面Glaciofluvial Sand单元的2个冰水沉积样品, 年代结果分别为(41.6±3.8) ka、(48.1±4.4) ka, 分析表明这一年代结果偏老, 石英颗粒可能晒褪不完全. 由于大测片无法识别晒褪不完全的颗粒, 因此, 测试更多的剖面序列的光释光年代并尝试采用粗颗粒小测片或单颗粒技术解决样品颗粒晒褪不完全的问题将是必要的.     

有关森林天然火灾的低层风和温度廓线

1.引言对负责森林火险天气预报人员来说,查看一下简单的气象图表,并确定气象条件是否有利于星星之火发展到不可控制的大火那将是非常必要的。由于近地面天气状况是受制于高层天气过程的,而火灾又是一种三度空间现象,与大气的铅直剖面关系密切。风和温度随高度变化影响大气对流的强弱,也影响林火的发生和发展。近年来,人们一直在探讨这些因素对森林天然火灾的影响。 1954年,拜厄姆(Byram)提出了在“点燃”林火的上空是某些特殊的风廓线。其要点之一是在火场的上空,风力由近地面的最大值一直到大约2400米附近的高度,而后随高度递减。他认为这样有利于火场上空对流柱的发展,由此能增强在地面火势的强度。     

MANAGEMENT AND SUBSURFACE EFFECTS ON RUNOFF AND SEDIMENT YIELD FROM SMALL WATERSHEDS

lINTR0DUCTIONSoiler0si0ncanbeaseriousproblemonsl0pinguplands0fthes0uthemUnitedStatesthatareintensivelycr0pped.Conservati0nprovisionsofthel985U.S.FarmBillmandateddevelopmentofaconservati0nplanonhighlyer0diblelands.Researchwasinitiatedinl9870na28-haareaattheA-E.Nels0nFarrninn0rthernMississippit0determineiftheconservati0nprovisionscouldbeachievedwhileprofitablygr0wingrowcropsincludingcott0n(GosSyPiumhirsutumL.),soybean(GlyciDemax(L.)Merr.),sorghum(SOrghumbicolor(L.)Moench),c0rn(Zeam…     

Environmental transformation of the Bilbao estuary,N. Spain: microfaunal and geochemical proxies in the recent sedimentary record

The distribution and abundance of benthic foraminifera and a range of elements have been analysed in six long cores (up to 10 m long) from the Bilbao estuary, N. Spain, to document environmental transformation of this estuarine ecosystem and to determine sediment contamination levels. Three different environmental zones could be distinguished in the recent sedimentary record based on its microfaunal and geochemical contents. Initially, a pre-industrial zone containing very abundant and diverse foraminiferal assemblages together with baseline metal levels. Secondly, an older industrial zone exhibiting co-existence of abundant and diverse foraminiferal assemblages with high concentrations of metals. Finally, a younger industrial zone with extreme concentrations of metals and barren of indigenous foraminifera. This environmental transformation has been caused by the discharge of untreated domestic and industrial effluents during the last 150 years. The occurrence of foraminifera in the two industrial zones and along the estuary is not related to defined levels of metals, and this seems to confirm oxygen limitation as the key factor to explain complete estuarine defaunation during deposition of the younger industrial zone (period 1950-2000). Effectiveness of current regeneration schemes could be assessed using microfaunal and geochemical proxies as environmental quality indicators.     

3C273的光学光变周期

收录了类星体3C273约110年的光学资料，并在此基础上讨论了光变周期性.当用两种不同方法(Jurkevich方法及DCF(离散相关系数)法)分析时，发现光变曲线中存在周期为2.0年、(13.65±0.20)及(22.5±2.0)年的周期性.同时也讨论了这种周期的可能机制.     

苏门答腊地震的速度和大小：现在我们对去年巨大地震的特征有了更清晰的认识

我们的地震学分析结果表明，2004年12月26日的苏门答腊一安达曼毁灭性地震比最初报告结果大2．5倍，其震级仅次于1960年智利地震。该地震沿1200km长的断层滑动缓慢释放其能量，产生的长破裂引发了随后的海啸。既然整个破裂区已经滑动，由印度板块向缅甸小板块下俯冲所积累的应变也被释放，因此在该部分板块边界上暂时没有产生类似海啸的危险，虽然南段大地震的威胁依然存在。     

TECTONIC EVOLUTION OF THE YANGTZE PASSIVE MARGIN AND SONGPAN GARZ? FOLD BELT, CHINA

TECTONIC EVOLUTION OF THE YANGTZE PASSIVE MARGIN AND SONGPAN GARZ? FOLD BELT, CHINA     

Sex-specific biochemical and histological differences in gonads of sea urchins (Psammechinus miliaris) and their response to phenanthrene exposure

Female and male individuals of the same species often differ with respect to their susceptibility to toxicant stress. In the present study, sea urchins (Psammechinus miliaris) of both sexes were exposed to high (150 μg L?1) and environmentally relevant (5 μg L?1) concentrations of phenanthrene over 10 days. While food intake was significantly decreased following exposure to 150 μg L?1 phenanthrene, histological indices (lipofuscin accumulation, fibrosis, oocyte atresia), energetic status (energy charge, sum adenylates, AMP/ATP ratio) as well as ascorbate levels in the gonads showed either little or no effect upon phenanthrene exposure. However, most parameters (vitamin C, energy charge, sum adenylates, AMP/ATP ratio, ATP and ADP concentrations, lipofuscin content, fibrosis) significantly differed between male and female animals. This study illustrates the difficulties to identify toxic injury in reproductive tissue as it may be superimposed by gametogenesis and spawning of gametes.     

Variations of antioxidant efficiency and presence of endosymbiotic diatoms in the Antarctic porifera Haliclona dancoi

The role of endosymbiotic diatoms as pro-oxidant stressors in porifera has been investigated in the Antarctic sponge Haliclona dancoi in which the presence of diatoms is influenced by marked seasonal variations during the austral summer. Both chlorophaeopigments and frustules were absent in sponge tissues sampled in early November at the beginning of the summer and increased from the mid of December with slightly shifted temporal trends. The efficiency of antioxidant defenses in the sponge showed a marked response to symbionts with clearly enhanced values corresponding to the peak of diatoms.