Shallow-Water Gasohydrothermal Vents of Ushishir Volcano and the Ecosystem of Kraternaya Bight (The Kurile Islands)   总被引：2，自引：0，他引：2  

V. G. Tarasov    M. V. Propp    L. N. Propp    A. V. Zhirmunsky    B. B. Namsakakv    V. M. Gorlenko  D. A. Starynin 《Marine Ecology》1990,11(1):1-23

Abstract. A marine ecosystem in the crater of the Ushishir Volcano (Kraternaya Bight, Yankich Island, the Kuriles) showing gasothcrmal activity was studied for hydrographical, hydrochemical, and biological characteristics. Maximal changes in chemical and biological characteristics were observed in the surface water layer of 0–5 m. This layer had higher water temperature, was saturated with volcanogcnic carbon dioxide (up to 2000 10^-6 torr), ovcrsaturatcd with oxygen (up to 200 %), and contained high concentrations of chlorophyll a. Hydrogen sulfide was found in the surface water layer and at a depth of 15 m in the area of maximal effect of volcanic effluents.
The planktonic community is characterized by high rates of production and destruction of organic matter only in the 0–5 m layer. Daily vertical migrations of the ciliatc Mesodinium rubrum were observed, which caused "red tides".
Bacterial, algobacterial, and diatom mats developed on the bottom of the bight in the zone of gasohydrothermal vents and in areas of volcanic water seeping. The rate of organic matter production in algobacterial mats reached 33.4g C-rrr²-d^-l, chcmolithotrophy predominating. Bottom settlements had high population density and great animal biomass, which reached 10 kg m^-2 in gasohydrothermal fields. They obtain sufficient energy from primary production of microphy-tobenthos, algobacterial, and bacterial mats. Bcnthic species dominant in the bight were not found off the Ushishir Islands.
Some species of macrobenthos inhabiting the Kraternaya Bight differ markedly in size and biomass from the same species found beyond the bight.  相似文献   

Factors influencing the oxidation,reduction, methylation and demethylation of mercury species in coastal waters     

Lindsay Whalin  Eun-Hee Kim  Robert Mason 《Marine Chemistry》2007

The objective of this study was to examine the redox reactions and other transformations of mercury (Hg) species in surface waters, and the factors determining the rates of these reactions. For the redox studies completed at the Chesapeake Biological Laboratory (CBL), two isotopes (¹⁹⁹Hg^II and ²⁰²Hg⁰) were added into different types of filtered water (fresh to seawater) to examine the oxidation and reduction reactions. Further studies of both the redox reactions and methylation/demethylation reactions of Hg were conducted with unfiltered water on board research vessels during cruises in May and July 2005 on the Chesapeake Bay and shelf. While CH₃¹⁹⁹Hg^II was added to allow the examination of demethylation, ²⁰¹Hg^II was used to examine both reduction and methylation, and ²⁰²Hg⁰ was used to examine oxidation. Overall, the results showed that both Hg oxidation and reduction were simultaneously occurring and were photochemically mediated in the waters investigated. In contrast to the previously assumed “unreactive” nature of Hg⁰, the studies found that the magnitude of the rate constant for Hg⁰ oxidation was greater than that for reduction, indicating its importance in estuarine and coastal waters. In addition, both experiments at CBL and on board ship showed that Hg^II reduction was similar in magnitude, suggesting that biotic processes were relatively unimportant. While no measurable methylation occurred during the incubation period during the on board studies, concentration of CH₃¹⁹⁹Hg^II decreased over the time during the experiments. It appeared that the demethylation processes were not dominantly photochemically driven, but could be microbially mediated. Further studies are needed in order to help better understand Hg redox and transformations in natural water systems.  相似文献   

东太湖茭草区网围养鱼模式试验研究   总被引：5，自引：0，他引：5  

吴庆龙 《海洋湖沼通报》1997,(1):38-42

根据东太湖茭草区资源及环境特点,开展网围养鱼模式试验,结果表明：（1）经济效益明显,产投比1．2—1．5；（2）有良好生态效应,防治湖泊沼泽化和茭草区水质恶化；（3）社会效益显著,解决湖区剩余劳动力和城市居民吃鱼难的问题；（4）利于湖泊资源管理和保护。  相似文献   

南沙群岛海域水体漫衰减系数Kd(490)的特性研究   总被引：6，自引：1，他引：6  

张清凌  陈楚群  施平 《热带海洋学报》2003,22(1):9-16

对南沙群岛海区水体Kd(490）的特性进行了深入分析和探讨,研究结果表明：Kd（490）的垂直分布与同步测量的海水叶绿素a浓度的垂直分布有很强的相关性;Kd（490）的垂直分布反映出该区域海水存在较强的分层现象,研究中还发现上行辐亮度漫衰减系数KL（490）与Kd（490）垂直变化趋势相当一致,但是以二者达到最大值的深度为界,上层水体的KL（490）值稍大于Kd(490）值,在这一深度以下则相反。  相似文献   

Modeling erosion of sedimentary coasts in the western Russian Arctic     

I. O. Leont'yev   《Coastal Engineering》2003,47(4):413-429

Morphodynamic modeling is employed in the present work to predict the long-term evolution (over the next 100 years) of typical sedimentary coasts in the western Russian Arctic. The studied objects are the coasts of Varandey (the Barents Sea), Baydaratskaya Bay and Harasavey (the Kara Sea). The model developed takes into account both the short-term processes (storm events) and long-term factors (for example, changes in sea level, inter-annual variations in gross sediment flux, lack or excess of sediment supply). Predicted and observed morphological changes in coastal profiles are shown to agree well for time scales ranging from weeks to decades. It is revealed that under given environmental conditions, the morphological evolution is strongly influenced by storm surges and associated wind-driven circulation. The water level gradient created by a surge generates a seaward flow at the bed. This outflow is shown to be an important destructive mechanism contributing to the erosion and recession of Arctic coasts. The rate of change is found to depend on both the exposure of the coast (relative to the direction of dominant winds) and its height above the sea. The open coast of Varandey is expected to retreat as much as 300–500 m over 100 years, while recession of the less exposed coasts of Baydaratskaya Bay would not exceed about 100 m/century. If long-term sediment losses are insignificant, the rate of erosion decays with time and the morphodynamic system may tend toward equilibrium. It is concluded that the expected relative sea-level rise (up to 1 m over the nearest 100 years) is non-crucial to the future coastal evolution if an erosion activity is already high enough.  相似文献   

北方地区秋季日本对虾室内高密度精养的试验   总被引：2，自引：0，他引：2  

林琼武  单保党  刘立东  黄加祺 《台湾海峡》2001,20(4):510-514

为充分利用每年的8月以后直到翌年3月份都处于休闲状态的育苗场设施资源，笔者于1999年8月在河北黄骅进行日本对虾室内高密度精养的试验。在水温23－28℃、盐度28－32下，8月27日放苗，11月24日收成，养殖时间87d，单位水体产量平均为0．818kg/m^3，平均存活率为50．1％，旬生长率平均为0．75cm，成虾体长平均8cm，饵料系数为2．51，投入与产出比为2．5，平均单位水体创利63．83元／m^3，其结果说明本养殖模式不仅是可行的，而且具有利用率和效益高、实用性强的优点。本文还就相关问题进行了讨论。  相似文献   

Circulations east of Taiwan and in East China Sea and east of Ryukyu Islands during early summer 1985     

Yuan Yaochu  Cho-teng Liu  Pan Ziqin  Shi-pei Zheng 《海洋学报(英文版)》1996,15(4):423-435

Ｃｉｒｃｕｌａｔｉｏｎｓ　ｅａｓｔ　ｏｆ　Ｔａｉｗａｎ　ａｎｄ　ｉｎ　Ｅａｓｔ　Ｃｈｉｎａ　Ｓｅａ　ａｎｄ　ｅａｓｔ　ｏｆ　Ｒｙｕｋｙｕ　Ｉｓｌａｎｄｓ　ｄｕｒｉｎｇ　ｅａｒｌｙ　ｓｕｍｍｅｒ　１９８５ＹｕａｎＹａｏｃｈｕ；Ｃｈｏ－ｔｅｎｇＬｉｕ；Ｐ...  相似文献   

福建晚更新世海侵问题探讨   总被引：1，自引：0，他引：1  

曾从盛 《热带海洋学报》1993,(1)

福建沿海在晚更新世大约距今90—80ka、70—60ka、44—39ka和34—20ka期间分别发生过4次海侵。最末一次海侵(距今34—20Ka)期间有过明显的海面下降波动,时间大约在距今28ka前后。  相似文献   

Numerical study of the influence of Kuroshio Current on the thermocline in the sea area around Taiwan Island     

张文静  沙文钰 《海洋预报》2001,18(Z1):17-24

1 INTsoDUcrIONTemperature is one of the most impoFtant essential factors of ocean, and its verticalstructure, especially the phenomenon ofthermocline, is concerned by military and manufacturepractices at all times. There are two classes of research methods for thermocIine, statisticmethod and numerical method. In recent years, more attention has been paid to the latterwhich becomes the primary development direction. Since Munk et al (1948) pot forward1-D model of thermocline at steady sta…  相似文献   

海底浅层介质切变波的初步研究   总被引：2，自引：0，他引：2  

卢博  李赶先  黄韶健 《热带海洋学报》2004,23(4):11-18

初步分析了中国沿海海底浅层介质切变波的传播特性,讨论了多种海底浅层介质切变波与压缩波、物理力学性质之间的关系,并与Hamilton和Chen等人的结果进行了比较。认为海底浅层介质存在切变模量,切变波可以被测量出来,切变波速为50—600m·s-1,测量频率在50—200kHz之间,用波速比可以评价海底浅层介质的应力 应变性质。研究工作有助于描述和评价中国沿海海底浅层介质声学物理性状,并为最终建立中国沿海海底地声模型提供依据。  相似文献