Atmospheric lead fallout over the last century recorded in Gulf of Lions sediments (Mediterranean Sea)     

Miralles J  Véron AJ  Radakovitch O  Deschamps P  Tremblay T  Hamelin B 《Marine pollution bulletin》2006,52(11):1364-1371

Six marine sediment cores from the Gulf of Lions continental slope (700-1700 m water depth) were analyzed for stable lead isotopes and (210)Pb geochronology in order to reconstruct lead atmospheric fallout pattern during the last century. The detrital lead contribution is 25 microg g(-1) and the mean sediment anthropogenic inventory is 110+/-7 microg cm(-2), a little bit higher than atmospheric deposition estimate. Anthropogenic lead accumulation in sediments peaked in early 1970s (1973+/-2) in agreement with lead emissions features. For the period 1986-1997, the sediment signal also reflect the decrease of atmospheric lead described by independent atmospheric fallout investigations. The anthropogenic Pb deposition in the late 1990s was similar to the 1950s deposition, attesting thus of the output of European environmental policies.  相似文献   

Salinity-induced survival strategy of Vibrio cholerae associated with copepods in Cochin backwaters     

Thomas KU  Joseph N  Raveendran O  Nair S 《Marine pollution bulletin》2006,52(11):1425-1430

The occurrence of Vibrio cholerae in water, sediment and copepods was studied over a wide range of salinity using conventional and polymerase chain reaction (PCR) techniques in the Cochin backwaters. V. cholerae occurred either as culturable or non-culturable form in this tropical estuary. During the pre monsoon period when high salinity prevailed (35.5psu) V. cholerae was associated with copepods only in non-culturable form, but with the onset of monsoon when lower salinity prevailed, copepod-associated-V. cholerae reverted back to culturable form. The optimum salinity range for culturability was found to be 15-20psu. This points to the fact that salinity is a major factor that which influences V. cholerae's culturability and its association with copepods in Cochin backwaters.  相似文献   

The use of the marine biotic index AMBI in the assessment of the ecological status of the Obidos lagoon (Portugal)     

Carvalho S  Gaspar MB  Moura A  Vale C  Antunes P  Gil O  da Fonseca LC  Falcão M 《Marine pollution bulletin》2006,52(11):1414-1424

This study reports the longitudinal distribution of sediment properties, including inorganic and organic contaminants, and the structure of the benthic community in Obidos lagoon, a coastal system permanently connected to the sea and with negligible freshwater sources. Sediments from the upper to central lagoon consist of fine particles (91%) and from the lower lagoon of sands (94%). Chemical composition is strongly correlated to the percentage of fine particles. Contamination is relatively low in those sediments suggesting the effect of diffuse sources. The increase in organic matter content from down- to upstream areas was associated with the dominance of opportunistic species, while sensitive and indifferent species to organic enrichment were mainly associated to the clean sandy downstream area. The marine biotic index (AMBI) was suitable for the discrimination of the biological and environmental gradients in the Obidos lagoon and was highly related with the gradient of organic matter content in this system.  相似文献   

A planetary companion orbiting the intermediate-mass G Giant HD 173416     

Yu-Juan Liu Bun＇ei Sato Gang Zhao Hiroyasu Ando 《中国天文和天体物理学报》2009,9(1)

The discovery of a planetary companion to the intermediate-mass late-type giant star HD173416 from precise Doppler surveys of G and K giants at Xingiong station and Okayama Astrophysical Observatory (OAO) is presented in this letter. The planet has a minimum mass of 2.7 MJ an eccentricity of 0.21, a semimajor axis of 1.16 AU and an orbital period of 324 days.  相似文献   

西藏恰功铁矿岩浆演化序列及斑岩出溶流体特征   总被引：6，自引：1，他引：5  

谢玉玲  李应栩  Zhaoshan CHANG  David R. COOKE  Chris G. RYAN  Jamie LAIRD  白劲松  刘云飞  李光明  张丽 《地质学报》2009,83(12):1869-1886

冈底斯成矿带是碰撞造山过程形成的最重要的成矿带,恰功矽卡岩铁(铜)矿床即位于冈底斯成矿带中部.本文在详细的野外地质填图和室内研究基础上确定了恰功铁矿与成矿有关的斑岩体为二长花岗斑岩,锆石的U-Pb定年结果为68.8±2.2 Ma,明显早于冈底斯东部与后碰撞伸展有关的斑岩型矿床和主碰撞期形成的矽卡岩型矿床,其应代表了冈底斯一次尚未被充分认识到的成矿事件.通过对成矿斑岩的岩石学、岩石化学、岩浆出溶流体的包裹体岩相学、显微测温分析及包裹体成分的LRM、LA-ICP-MS和PIXE分析,本文探讨了与该矽卡岩矿床有关的斑岩的岩浆起源、斑岩侵位机制及出溶流体特征.结果表明,成矿斑岩为矿区最早的侵入岩单元,具有壳幔源混源特征,其常量元素组成与冈底斯东部斑岩铜矿带的埃达克质岩相近,但稀土和微量元素组成与东部斑岩明显不同,为地幔物质上涌并诱发角闪岩相下地壳熔融的产物,岩体侵位深度大(>7 km)、剥蚀程度高.早期岩浆出溶的流体为高温、高压、高盐度流体,其中富含Fe、Pb、Zn、Cu等成矿金属,与世界其他斑岩铜矿床相比,相对富铁、铅而贫铜.流体的沸腾作用发生于钾硅化阶段,形成了一套富气、高盐、高固相和气液包裹体组合,不同于早期出溶流体的包裹体组合.从岩浆起源和出溶流体性质可以看出,该斑岩具有形成与斑岩有关的铁铅多金属矿床的成矿潜力,但从该矿区地表出露的蚀变和包裹体测压结果可以看出,该斑岩体目前剥蚀深度较大,对斑岩型矿床保存不利,对该斑岩体及与成矿关系的认识对理解该区内的矿床成因和指导区域找矿具有重要的指示意义.  相似文献   

辽宁寒岭-偏岭平移断裂带特征及其形成动力机制   总被引：1，自引：0，他引：1  

张国仁  江淑娥  杨占兴  李春明  关培彦  韩小平  丁伟  王海鹏 《地学前缘》2004,11(3):183-192

寒岭—偏岭平移断裂带位于辽宁东部 ,是中国东部郯庐断裂东盘的一个次级断裂。它控制着辽东鞍山—本溪地区地质体的分布。通过对平移断裂的展布、形态、伴随构造、牵引构造、位移方向和幅度、平移时间、断层尾端及动力学演化等特征研究 ,认为该断裂主要活动于晚三叠世 ,在晚侏罗世—早白垩世最为活跃 ,伴随岩浆侵入活动、火山喷发及陆相沉积。断裂带长约 1 3 0km ,中段位移最大可达 3 1km ,向东西两端逐渐减少。该断裂活跃时期主要表现为左行平移性质。构造的活动 ,主要与中生代时期欧亚大陆与伊佐奈岐板块、太平洋板块的相互作用有关  相似文献   

塔里木地块上石炭统的古地磁研究   总被引：3，自引：1，他引：2  

翟永建  张正坤  李永安  李强  李燕平  Michael McWilliams  Allan Cox  Robert sharps 《现代地质》1988,2(1):43

本文对塔里木地块西北缘柯坪地区的3条上石炭统康克林组剖面进行了古地磁研究。95个定向岩心样品的逐步热退磁和交变退磁揭示出3个磁性组分,第一个是具有低解阻温度谱或低矫顽力谱在现代地磁场作用下形成的粘滞剩磁A(D=10°;I=56°,α95=4°);第二个是红色石英砂岩的具有反极性的高温组分B(D=217°,I=-43°,λ=56°,Φ=184°E;A25=6°详细研究表明,该分量受附近晚二叠世脉岩侵入的重磁化;第三个是灰岩高矫顽力谱的反极性组分C（D=241°、I=-51°,λ=41°N,Φ=160°E,A（?）=4°）。这一分量通讨倾斜检验,在95%概率水平上明显不同于塔里木地块目前已有的石炭纪以后的古地磁方向,它代表了原生剩磁。研究结果表明:（1）晚石炭世塔里木地块已和哈萨克斯坦地块、苏联西天山地块以及西伯利亚地块发生碰撞:（2）苏联西天山地块相对塔里木地块曾逆时针旋转了70°（欧拉极位置λ=8°N,Φ=69°E）,而塔里木地块则相对西伯利亚地块逆时计旋转了21°（欧拉极位置λ=20°N,Φ=34°E）。从该区已有的晚古生代至早三叠世占地磁数据看,这些地块之间的相对旋转运动发生于早三叠世之后。  相似文献   

油藏产量预测的不确定性     

Lia  O 王桥 《海洋地质译丛》1998,(2):10-24

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闽江口水下三角洲的形成与演变──Ⅰ.水下三角洲形成的环境因子与地貌发育     

陈峰  王海鹏  郑志凤  张培辉  叶燕贻 《台湾海峡》1998,(4)

从分析控制或影响闽江口水下三角洲发育的环境因素入手,探讨了闽江口水下三角洲的地貌特征、成因及演变。结果表明,闽江口水下三角洲属于构造-潮控型三角洲,其地貌特征和成因与典型的潮成三角洲既有共同点,也存在着较大的差异。此外,其近期地貌的发育和演变亦受到人类工程活动的重大影响。这些结论可为闽江口航道综合整治工程提供科学理论依据。本文为其第一部分,主要探讨控制或影响闽江口水下三角洲形成的环境因子与地貌发育。  相似文献   

ANALYSIS ON PECULIARITIES OF "92.8"FLOOD EVENT IN THE LOWER YELLOW RIVER     

WANG Gang  XU Mingquan 《国际泥沙研究》1999,(2)

lCOMPOSITIONOFTHE"92.8"FLOODThreerainstormsoccurredfrom7ththrough13,,,August,1992inShaanxiProvince,diStributingfromnorthtosouthinsequence.Therainfallareacoveredtheregionsofintensivesoilerosion,'wheretheaveragerateoferosionis10,000-15',000ton/kmZ'year.Fig.IshowsisohyetsofrainfallintensityinthecatchmentoftheMiddleYellowRiVerdepictingthedistributionoftherainstormsfrom7thto13,,,August,1992(thehydrologicalBureauYRCC,1992).ThecenterofthefirstrainstormwaslocatedattheYikezhaomengPrefec…  相似文献