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91.
Herbert L. Windom Suchada Silpipat Aurapin Chanpongsang Ralph G. Smith Manuwadi Hungspreugs 《Estuarine, Coastal and Shelf Science》1984,19(2):133-142
Sediment cores and grab samples were collected in the Upper Gulf of Thailand to determine sedimentation rates and to determine if metal concentrations reflect anthropogenic inputs.Accumulation rates of sediments in the Upper Gulf measured using the 210Pb method, appear to vary from ca. 4 to 11 mm yr?1. Sediment budgets suggest that little of the sediment delivered to the Upper Gulf by the major rivers is ultimately transported to the Lower Gulf. Metal concentrations in Upper Gulf sediments appear to be dominantly controlled by natural inputs. 相似文献
92.
A study of dissolved chromium in the St. Lawrence estuary and Gulf of St. Lawrence has been carried out. A chromium concentration of 0·7 μg l?1 was found in the St. Lawrence River. In the turbidity maximum of the upper estuary, chromium is removed from solution onto fine-grained resuspended sediments and internally produced organic-rich floccules. A simple flux calculation shows that these processes remove ~50% of the total dissolved chromium input of the river. At salinities greater than 5‰ dissolved chromium mixes conservatively. 相似文献
93.
Adam Ružčka 《Astrophysics and Space Science》2003,284(2):519-522
A simple sticky-particle numerical model has been developed in order to check whether extended structures of gas created due
to the dynamical evolution of the Galaxy and the Magellanic Clouds system can be explained as remnants of a tidal interaction.
Influence of dissipative nature of gaseous medium has been taken into account. The most remarkable features are: the Magellanic
Stream, the common HI envelope surrounding both the LMC and SMC and the bridge extended between the Clouds. In contrast to
previous works of Murai and Fujimoto (1980), Gardiner et al. (1994) and H and Rohlfs (1994) no presumptions were done on the
actual galactocentric velocities of the Magellanic Clouds. The mean values of the LMC and SMC velocity vectors obtained from
the Hipparcos proper motion measurements (Kroupa and Bastian, 1997) were used in order to verify whether they allow to reproduce
the observed HI distribution. Numerical simulations showed that tidal forces are really significant for the evolution of extended
structures such as the Magellanic Stream but this approach becomes unsufficient for the internal regions of galaxies where
self-gravity and dissipative properties of the gas cannot be neglected. More precise proper motion measurements are urgently
needed.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
94.
Charles W. Slaughter 《国际泥沙研究》2000,(2)
lINTRODUCTIONRangeandforestlandsofnorthwesternNorthAmericahavebeenutilizedforres0urceextracti0nandproductionsinceinitialhuman0ccupationofthecontinent.Intensive"managed"utilizati0nofec0systemsforspecificbenefitsincludingcattle,sheep,t1sh,w00dandagriculturalpr0ductshasbeenong0ingfornearly0ne-and-haIfcenturies.Intensiveresourceproducti0nhasto0oftenbeenacc0mpaniedbyunwanted"sideeffects"includingacceleratederosion,s0illossandsedimentdeliveredoffsitetod0wnstreamlocati0ns,estuariesandoceanicsin… 相似文献
95.
以高分辨率层序地层学理论为指导,以野外露头、钻井岩心、测井及地震资料的综合研究为基础,研究了黄骅坳陷新近系馆陶组Ⅲ段的高分辨率层序地层特征,识别出1个长期、两个中期和若干个短期基准面旋回层序。其中短期、中期旋回都可分为向上“变深”非对称型和向上“变深”复“变浅”对称型两类。深入探讨了不同结构类型和充填样式的各级次基准面旋回层序对储层的控制作用,认为储集砂体主要发育于长期及中期基准面旋回上升的早期。 相似文献
96.
I. M. Korrat H. M. Hussein I. Marzouk E. M. Ibrahim R. Abdel-Fattah N. Hurukawa 《Acta Geophysica》2006,54(1):33-49
Seismicity in the northernmost part of the Red Sea has been studied using data from Hurghada Seismological Network in addition
to readings from the existing neighbouring networks. Relocated events in addition to data from national centers are used to
obtain a complete and true picture for the seismicity of the area. The spatial distribution of earthquakes defines three earthquake
zones in the Gulf of Aqaba and three zones at the entrance of the Gulf of Suez and southern tip of Sinai Peninsula. The thermal
activity and the triple junction nature control the activity in this area. The activity defines also an active trend extending
from the southern tip of Sinai Peninsula to the median zone of the Red Sea. The seismicity of this trend is probably related
to the active spreading zone associated with the opening of the Red Sea. The b-values are derived for the entrance areas of the two gulfs and for Gulf of Aqaba. Values of b are 1.35 for the triple junction region, 1.13 for the activity before the 22 November 1995 Gulf of Aqaba mainshock and 1.25
for the aftershocks of this event. 相似文献
97.
98.
99.
A large number of studies have documented the structural and sedimentary architecture of the Corinth Gulf, especially the major E–W trending normal faults important in accommodating the main extensional strain and associated growth of the Gilbert fan deltas. However, the role of several N–S oriented structures that crop out at the surface and are detectable at depth by seismic reflection and gravity surveys are not clearly understood. Based on new geological data, collected near Xylokastro, we describe the N–S oriented tectonic activity of this area. The mapped inland faults correspond to off-shore structures identified in re-interpreted seismic lines and appear to have acted as a major transfer zone during the opening of the Corinth Gulf. Reconstruction of the paleo-topography based on sedimentary facies and the environment of clay mineral formation suggest these transfer zones played an important role in controlling both local structural relief and depositional conditions of the Gilbert fan deltas. 相似文献
100.
利用NCEP/NCAR再分析资料,对1949年以来7个进入北部湾后强度突然增强的热带气旋(TC)环流背景特征及物理量场特征进行分析,结果表明,有利TC进入北部湾后强度增强的环流背景是:(1)西太平洋副热带高压稳定加强西伸,(2)热带辐合带北抬至华南沿海活动,(3)西南季风爆发处于活跃期,(4)东风波西移叠加,(5)有适度的弱冷空气侵入;对物理量场的合成分析表明,TC进入北部湾前和进入北部湾后,环流中心附近500hPa涡度变化极小,200hPa高空散度增大,500hPa垂直上升速度增大,850hPa中南半岛水汽输送量增大。 相似文献