东南太平洋复活节岛西部幼年海底火山的地质状况     

陈秀澄 《海洋地质前沿》1996,(1)

东南太平洋复活节岛西部幼年海底火山的地质状况在２６°１５＇Ｓ，１１１°Ｗ附近复活节小板块和复活节岛之间发现了很可能与复活节热点有关的海底火山。带有深海拖曳式摄影观测的流体扫描条带测绘和取样揭示出有新鲜的熔岩流被限制在两个不同的区域，即以前众所周知的阿...  相似文献   

沙奈奇湾汞的通量研究     

陆贤崑  K. W. 约翰逊  F. A. 惠特尼  黄志成 《海洋学报》1987,9(2):188-194

用近岸沉积物捕集器测定了沙奈奇湾5站位不同深度的汞、沉积颗粒物和有机碳通量。通量值与生产力有一致的季节变化,而且比太平洋值高约1—2个数量级。与水柱中汞浓度值结合,计算出汞在沉积物-水间的分配系数(155级)和汞的停留时间(2.4年)。  相似文献   

三万五千年以来的海平面     

约翰D?米里曼  K?O埃默里 《海洋科学》1979,3(4):59-60

美国大西洋陆架35,000年来的海平面曲线,是建立在80多个放射性碳年代的基础上,其中15个年代是老于15,000年代的。测年的材料包括浅水软体动物、鲕状岩、珊瑚藻、海滩岩和盐沼泥炭。30,000—35,000年前的海平面,曾经是接近于现在的海平面的。随后冰川发育,16,000年前海平面降低到负130米左右。全新世海侵可能开始于约14,000年前,并迅速地延续到约7,000年前。世界大多数大陆架的年代和这条曲线相一致,说明这条曲线大致是这个时期海平面升降的曲线。  相似文献   

地中海下淹没洞穴堆积物中的贻贝记录了全新世海平面的上升:放射性碳测年的证据     

FabrizioAntonioli  陈秀澄 《海洋地质前沿》1997,(5)

淹没的洞穴堆积物的放射性测年是再现相对海平面过去变化的一种方法（Richards等，1994；Lundberg和Ford，1994）．这种方法的缺点是，它仅提供一个过去海平面的上限：这些年龄指的是海平面上升到洞穴堆积物层位前的时间．此外，洞穴堆积物的增长可能在海水俺没之前就已停止、我们通过测定包结在俺没洞穴堆积物上的海洋有机质的年龄论述了一些问题．这样的测年得到了一条意大利蒂勒尼安海中心区域晚更新世和全新世的海平面曲线（Alessio等，1992）．新方法学部分解决了洞穴珊瑚状层序欠佳的问题．上述洞穴堆积物在海平面研究中的应用可以…  相似文献   

有限域模式中对流参数化方案的比较     

K.栗原  M.上野  N.三浦  佟明远 《海洋预报》1988,(Z1)

一、引 言 对流是强降水现象的最重要影响因子之一,如雷暴、梅雨季节中的强烈降水等等。对有限域模式而言,如此强烈降水的生成已经是个难题,因此,我们应当清楚,怎样一个对流参数化方案在模式中工作,和使用不同方案时什么差别会出现。 我们调查研究,在梅雨季节个例中具有大尺度对流方案的湿调整方案和郭氏方案两者之间的差别。同时,我们也调查研究,当使用湿调整方案时小网格尺度的效果。 二、模式和原始数据 象参数化方案一样,方案被纳入业务,在日本气象厅被应用到模拟方案。我们使用原始有限域模式,模式有:(a )水平网格尺度63.5公里和55×55网格,(b)水平网格尺度25.4公里和111×111网格,两个模式在铅直方面有13层。原始资料由业务客观分析方案提供(d=254公里)。产品为从初始条件1983年7月22日00世界时的24小时。  相似文献   

Exposure of grass shrimp to sediments receiving highway runoff: Effects on reproduction and DNA     

Lee RF  Maruya KA  Bulski K 《Marine environmental research》2004,58(2-5):713-717

A grass shrimp bioassay was carried out on sediments from three estuarine stations which were different distances from a highway storm drain. Total polycyclic aromatic hydrocarbon (PAH) concentrations were 29, 1.5 and 0.1 μg/g sediment at stations A (next to drain), B (100 m from drain) and C (500 m from drain), respectively. Lower embryo production and embryo hatching rates and a higher level of DNA strand breaks (comet assay) were observed in grass shrimp exposed to stations A and B sediments. There appeared to be an association between reproduction abnormalities and increased DNA strand breaks as a result of grass shrimp exposure to estuarine sediments receiving highway runoff.  相似文献   

克里米亚大陆边缘（黑海）存在大量澈同海底的深部流体     

M.K.Ivanov 《海洋地质》2001,(4):69-79

俄罗斯R／V Gelendzhik号在1996年夏天进行的ANAXIPROBE/TTR-6航次调查中，在位于黑海Sorokin海槽内的克里米亚大陆边缘下部发现了一具有大量流向海底的深部流体新区域。该研究区海底底及浅部沉积物内普遍发现的声速常现象反映了气体的存在。底质取样证明了沉积物中存在极高的气体含量，而气体水合物的存在及其它的一些特征则通常与气体的逸出有关。这些特征包括了具体有较碳同位素组分的自生碳酸盐及细菌簇，地球化学资料表明该气体在某种程度上是热成因的。  相似文献   

Assessment of hormonal activity of UV filters in tadpoles of frog Xenopus laevis at environmental concentrations     

Kunz PY  Galicia HF  Fent K 《Marine environmental research》2004,58(2-5):431-435

Residues of UV filters used as ultraviolet absorbers in sunscreens, cosmetics and in light protection have been found in surface water and fish. Recently some of them were shown bearing estrogenic activity, however, very little is known about possible adverse effects to aquatic life. Here we investigate whether two UV filters, 4-methylbenzylidene camphor (4-MBC) and 3-benzylidene camphor (3-BC), interfere with the thyroid and sex hormone system during frog metamorphosis. Xenopus laevis tadpoles were exposed to 1, 5 and 50 μg/L of 4-MBC and 3-BC, respectively, for 35 days (NF stage 52–66). The rate of metamorphosis was not affected, and no obvious differences in body and tail length compared to controls were observed. Neither 4-MBC, nor 3-BC led to effects on the sex ratio or gross gonad morphology of X. laevis at stage 66. Our results indicate that these UV filters do not negatively affect the thyroid system and sex ratio of frogs at environmental concentrations.  相似文献   

Phenomena caused by seismic and geocryological processes across linear infrastructure, South Yakutia, Russia     

L. Gagarin  A. Melnikov  V. Ogonerov  I. Khristophorov  K. Bazhin 《寒旱区科学》2017,9(4):352-362

High seismic activity, difficult permafrost and hydrogeological conditions of South Yakutia (Russia) complicate building and exploitation of engineering construction and require additional detailed and complex research. These conditions are evident within two sites. The first site is located in the middle reach of the Duray River, where it is crossed by the highway Lena. The second site is located on the right side of the Chulmakan River Valley, 400 meters to the east of the ESPO oil pipeline route. Seismic events, occurring four years ago, led to landslides in the mentioned sites. Formation of joint fissures on slopes assisted drainage of aquifers of free water exchange zone. It is worth noting that at the Duray River site, 59 cm of active soil slumping movement towards the roadbed has occurred within two summer months. Such a process is complicated by cryogenic disintegration of rocks in the base of the landslide body due to groundwater discharge and icing formation in winter.  相似文献   

Rural homes and urban dwellings? Gender,migration and the importance of tenure in Gaborone,Botswana     

Datta K 《International journal of population geography : IJPG》1995,1(2):183-195

"The issue of return migration has been widely debated in African migration literature in view of strong rural-urban ties and urban growth based largely on in-migration. On the basis of fieldwork in Botswana, it is argued that there are important gender differences in terms of the commitment to rural and urban areas. It has been postulated in past studies that the decision to remain in towns depends in part upon urban tenure and it is argued that home owners are more likely than tenants to be permanent urban dwellers. Again, there are important gender differences and women appear to be more committed to the urban dwelling than men."  相似文献