Lateral tidal mixing in the Antarctic marginal seas     

Aike Beckmann  Adriene F. Pereira 《Ocean Dynamics》2003,53(1):21-26

Tidal mixing plays an important role in the modification of dense water masses around the Antarctic continent. In addition to the vertical (diapycnal) mixing in the near-bottom layers, lateral mixing can also be of relevance in some areas. A numerical tide simulation shows that lateral tidal mixing is not uniformly distributed along the shelf break. In particular, strong mixing occurs all along the Ross Sea and Southern Weddell Sea shelf breaks, while other regions (e.g., the western Weddell Sea) are relatively quiet. The latter regions correspond surprisingly well to areas where indications for cross-shelf exchange of dense water masses have been found. The results suggest that lateral tidal mixing may account for the relatively small contribution of Ross Sea dense water masses to Antarctic Bottom Water.  相似文献   

A Study of Oil Biodegradation in the Black Sea Water     

Tarkhova  E. P.  Koval'chuk  Yu. L.  Poltarukha  O. P. 《Water Resources》2003,30(1):92-97

A laboratory study was conducted to examine oil biodegradation in the presence of a fouling organism community. It is shown that the majority of fouling species exhibit relatively weak tolerance to oil. Oil degradation in seawater is shown to proceed quicker and more completely in the presence of the fouling organism community than it does without such organisms. The population of specific bacterial groups is shown first to grow and next decrease as a result of accumulation in water of toxic products of their vital activity. Oil biodegradation is found to cause substantial changes in the water hydrochemical characteristics in experimental vessels.  相似文献   

Fishery Water Releases to the Lower Pool of the Volgograd Hydroelectric Power Plant     

Ratkovich  D. Ya.  Vyruchalkina  T. Yu.  Solomonova  I. V. 《Water Resources》2003,30(4):387-403

Conditions of fish reproduction in the Volga–Caspian Basin depending on the hydrological regime in the Volga lower reaches, transformed by water withdrawals and regulatory impact of reservoirs are considered.  相似文献   

Petrogenesis of the Ulsan carbonate rocks from the south-eastern Kyongsang Basin, South Korea   总被引：1，自引：0，他引：1  

Kyounghee Yang  Jin-Yeon Hwang  Sung-Hyo Yun 《Island Arc》2003,12(4):411-422

Abstract The petrogenesis of the Ulsan carbonate rocks in the Mesozoic Kyongsang Basin of South Korea, which have previously been interpreted as limestone of Paleozoic age, is reconsidered in the present study. Within the Kyongsang Basin, a small volume of carbonate rocks, containing a magnetite deposit and spatially associated ultramafic rocks, is surrounded by sedimentary, volcanic and granitic rocks of the Mesozoic age. The simple cross‐cutting relationships and other outcrop features of the area indicate that the carbonate rocks are an intrusive phase and younger than the other surrounding Mesozoic rocks. The Ulsan carbonates have low concentrations of rare earth elements (REE) and trace elements with the carbon and oxygen isotope values in the range of δ¹³C_PDB = 2.4 to 4.0‰ and δ¹⁸O_SMOW = 17.0 to 19.5‰. Outcrop evidence and geochemical signatures indicate that the Ulsan carbonates were formed from crustal carbonate melts, which were generated by the melting/fluxing of crustal carbonate materials, caused by the emplacement‐related processes of alkaline A‐type granitic rocks. Compared to typical mantle‐derived carbonatites associated with silica‐undersaturated, strongly peralkaline systems, the relatively small size and geochemical characteristics of the Ulsan carbonates reflect carbonatite genesis in a silica‐saturated, weakly alkali intrusive system. Major deep‐seated tectonic fractures formed by the collapse of the cauldron or the rift system associated with the opening of the East Sea (Japan Sea) might have facilitated the ascent of the crustal carbonate melts.  相似文献   

西昆仑北缘新元古代片麻状花岗岩锆石SHRIMP年龄及其意义   总被引：19，自引：0，他引：19  

张传林  杨淳  沈加林  王爱国  赵宇  董永观  郭坤一 《地质论评》2003,49(3):239-244

在西昆仑北缘早前寒武纪变质地层中,笔者等识别出大量不同时代的片麻状花岗岩,其中包括新元古代片麻状花岗岩。获得最新的新元古代片麻状花岗岩的单颗粒锆石SHRIMP年龄为815±57Ma,片麻状花岗岩的岩石学特征反映它们形成于裂解构造背景,结合对区域上新元古代地层及中元古代末期构造事件的研究,笔者认为新元古代片麻状花岗岩反映了古塔里木板块作为Rodinia超大陆一员发生裂解的时间,这对研究古塔里木板块在Rodinia超大陆中的位置及中国Rodinia超大陆裂解的研究提供了重要的地质依据。  相似文献   

0．7Ma以来的念青唐古拉山脉隆升过程——来自冰川剥蚀作用的证据   总被引：1，自引：0，他引：1  

朱大岗赵希涛  孟宪刚吴中海邵兆刚  冯向阳杨朝斌 王建平 《地质论评》2003,49(6):630-637

通过对念青唐古拉山冰碛地层划分及冰碛物同位素测年，发现最早一期冰碛物形成于0．7～0．6MaBP，指示自中更新世以来念青唐古拉山脉开始隆升，主峰地区发生了大规模的冰川剥蚀作用，形成了大面积分布的冰碛高平台；0．2～0．14MaBP念青唐古拉山又快速隆升，并堆积了刚刚伸出各大沟谷口的高侧碛；0．07～0．03MaBP念青唐古拉山再次小规模隆起，形成各大沟谷内的侧碛和终碛垄；0．01Ma BP还有小规模冰川活动。念青唐古拉山主峰地区的冰川剥蚀作用反映出的山脉隆升过程，可较好地与青藏高原的隆起过程相对比，它应是青藏高原隆升的响应。  相似文献   

SHRIMP U-Pb zircon age,geochemistry and Nd isotope of the Guandaoshan pluton in SW Sichuan: Petrogenesis and tectonic significance     

Li Xianhua  Li Zhengxiang  Zhou Hanwen  Liu Ying  Liang Xirong  Li Wuxian 《中国科学D辑(英文版)》2003,46(1):73-83

SHRIMP U-Pb zircon age, geochemical and Nd isotopic data are reported for the Neo-proterozoic Guandaoshan pluton in the Yanbian region, SW Sichuan. This pluton is of typical I-type granite and emplaced at (857 ± 13) Ma. Geochemical and Nd isotopic characters suggest that the pluton was generated by partial melting of pre-existing, young (late Mesoproterozoic to early Neo-proterozoic) low-K tholeiitic protolith within an intraplate anorogenic setting. The Guandaoshan pluton probably records the earliest magmatism induced by the proposed ca. 860–750 Ma mantle superplume beneath the supercontinent Rodinia.  相似文献   

Strong earthquake activity all over the world and strong moderate earthquake activity within and near China (Dec., 2002 – Jan., 2003)     

Chen Pei:shan 《地震科学（英文版）》2003,16(3):356-357

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Calibration of an oscillating nozzle‐type rainfall simulator     

Bofu Yu  Cyril A. A. Ciesiolka  Paul Langford 《地球表面变化过程与地形》2003,28(13):1483-1490

Nozzle‐type rainfall simulators are commonly used in hydrologic and soil erosion research. Simulated rainfall intensity, originating from the nozzle, increases as the distance between the point of measurement and the source is decreased. Hence, rainfall measured using rain gauges would systematically overestimate the rainfall received at the ground level. A simple model was developed to adjust rainfall measured anywhere under the simulator to plot‐wide average rainfall at the ground level. Nozzle height, plot width, gauge diameter and height, and gauge location are required to compute this adjustment factor. Results from 15 runs at different rain intensities and durations, and with different rain gauge layouts, showed that a simple average of measured rain would overestimate the plot‐wide rain by about 20 per cent. Using the adjustment factor to convert measured rainfall for individual gauges before averaging improved the estimate of plot‐wide rainfall considerably. For the 15 runs considered, overall discrepancy between actual and measured rain is reduced to less than 1 per cent with a standard error of 0·97 mm. This model can be easily tested in the ?eld by comparing rainfall depths of different sized gauges. With the adjustment factor they should all give very similar values. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

陕西省地下水水质监测发展探析   总被引：1，自引：0，他引：1  

鱼晓利 《地下水》2003,25(1):11-12,25

本文针对陕西省地下水水质监测控制范围局限于农灌区，监测项目单一的现状，通过分析研究，提出水质监测的发展思路，剖析实现新思路的相关条件。  相似文献