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921.
林以安  Martin  J.M  Thomas  A.J 《海洋与湖沼》1996,27(2):145-150
于1986年1月,采取大体积取样,Co-APDC螯合并沉淀富集分离,银片上自沉积和a-计算分析,研究长江口区可溶态210Pb的来源,分布和逗留时间。结果表明,全区平均放射性比度为7.5dpm/m^3,从河向海纵向分布呈口内段和近外海两端高,而低谷出现在中间的口门外最大浊度及稀释带高生产力区。210Pb明显因悬浮颗粒物的吸附絮凝沉降和浮游生物的吸收利用被清除。经探析,该区210Pb主要来源是大气气溶  相似文献   
922.
The present study examines the impact of exposure to oil-derived products on the behaviour and physiology of the Australian 11-armed asteroid Coscinasterias muricata. Asteroids were exposed to dilutions of water-accommodated fraction (WAF) of Bass Strait stabilised crude oil, dispersed oil or burnt oil (n = 8) for 4 days whereby, prey-localisation behaviour was examined immediately after exposure, and following 2, 7, and 14 days depuration in clean seawater. The prey-localisation behaviour of asteroids exposed to WAF and dispersed oil was significantly affected though recovery was apparent following 7 and 14 days depuration, respectively. In contrast, there was no significant change in the prey-localisation behaviour of asteroids exposed to burnt oil. Behavioural impacts were correlated with the total petroleum hydrocarbon concentrations (C6-C36) in each exposure solution, WAF (1.8 mg l(-1)), dispersed oil (3.5 mg l(-1)) and burnt oil (1.14 mg l(-1), respectively. The total microsomal cytochrome P450 content was significantly lower (P(Dunnett test) < 0.01) in asteroids exposed to dispersed oil than in any other asteroids, whilst asteroid alkaline phosphatase activity was not significantly affected (P(ANOVA) = 0.11). This study further documents the deleterious impact of dispersed oil to marine organisms and supports further research in the area of in situ burning as a less damaging oil spill response measure towards benthic macro-invertebrates.  相似文献   
923.
Effect of an exotic prey on the feeding pattern of a predatory snail   总被引:2,自引:0,他引:2  
The mussel Brachidontes pharaonis, which invaded the Mediterranean from the Red Sea about 120 years ago, has recently become abundant in many midlittoral and some infralittoral rocky habitats along the Israeli rocky shore. We investigated the influence of B. pharaonis, as a novel prey, on the foraging patterns of the large whelk Stramonita haemastoma in the field, and examined food preferences in the laboratory. S. haemastoma has shifted from indigenous species to feeding on the novel mussel when abundant. The whelk prefers to prey upon the invasive mussel over all indigenous species offered (e.g. barnacles and mussels), probably due to its larger size. In the midlittoral zone, the foraging activity of S. haemastoma is considerably low even where refuges are readily available (incisioned-rocks) and food density is high (mainly B. pharaonis). Higher proportions of whelks are actively foraging in the infralittoral zone but usually on smaller prey, mostly barnacles. We suggest that this differential foraging activity in the two zones is related to the degree of exposure to wave action. The midlittoral is inherently more exposed to wave action than the infralittoral, where sea conditions are more benign and the whelks may enjoy longer activity periods.  相似文献   
924.
From 1995 to 2000 biological effects were studied in liver of flounder (Platichtysflesus L.) from the German Bight. During the study period deleterious consequences of acute discharges of DDT and PCBs in early spring 1996 and after 1998 due to remobilization of contaminants from riverbed deepening of the River Elbe became evident. As core biomarker which reflects toxically induced liver pathologies and integrates effects of various classes of pollutants we measured the integrity of lysosomal membranes in individual flounder liver. During the study period, twice statistically significant disturbances of lysosomal function was detected in fish from the River Elbe: in summer 1996 and in spring 1999. Yet, the detrimental contaminant effects were not only restricted to individuals from the Elbe but expanded to those flounder inhabiting formerly less polluted reference areas. In contrast to flounder of the Elbe, their ability to recover from the lysosomal disorders were limited. While in autumn 2000 Elbe individuals showed clear signs of recovery, those fish caught in areas more distant to the source of toxicant input still maintained significantly decreased lysosomal membrane integrity. It can be speculated that fish populations which are not continuously exposed to chronic anthropogenic stress may have a lower potential or need a longer period to recover from the effects of pollution.  相似文献   
925.
世界海洋石油污染物的地理分布及其消亡规律的研究   总被引:1,自引:0,他引:1  
大西洋及其所属海域主航道承担了大量石油及其产品的运输任务,也是石油污染物最为集中的地方,然而在公海也聚集着大量石油污染物,太平洋属于污染较轻的,但日本周围,东海,南海和北美沿岸海面上的也常被石油薄膜或团块充斥,只在赤道及南太平洋是很少有石油污染物的领域。大洋环流,信风流是石油污染扩散的重要角色,北大西洋暖流可以把大量的石油污染物携带到遥运的挪威,巴伦支海,乃至整个北冰洋,使之成为举世瞩目的(石油)  相似文献   
926.
Heath  J.  Mills  Robert  J.  Martinez  Sandra  Story  Patricia  A.  Sobecky  周洋 《海洋地质》2007,(2):10-27
为了更好的了解微生物活动在墨西哥湾水合物生态系统中的作用和贡献,我们对固态气水合物中的微生物,尤其在原位水合物环境下生理上比较活跃的微生物组合特征进行了研究。本次研究首先从含沉积物水合物层(SEH)和水合物层内部(IH)提取RNA和DNA,然后对RNA和DNA源的16SrRNA克隆文库进行系统发育学分析,从而确定细菌和古菌的群落组成。克隆分析所用的水合物样品是由水下载入深潜器上的Johnson Sea Link水合物取样器在墨西哥湾北部大陆坡一个有明显水合物活动特征的裸露的隆丘上获得的(水深:550m)。较早时的地球化学分析表明,微生物群落在SHE层中的新陈代谢能力要比在珊层中的新陈代谢能力强(B.N.Orcutt,A.Boetius,S.K.Lugo,I.R.Macdonald,V.A.Samarkin,and S.Joye,Chem.Geol.205:239—251)。RNA和DNA源的克隆文库系统发育学分析表明,SHE层的克隆文库的多样性要比在珊层中的大。从微生物群落新陈代谢活动部分所获得的克隆大多数与推测的硫酸盐还原细菌和厌氧氧化甲烷古菌密切相关。在RNA和DNA源的克隆文库中也发现一些先前未经人工隔离培养的新的细菌和古菌种群。本次研究是首次对赋存在墨西哥湾水合物丘的SHE层和珊层微生物群落新陈代谢活动进行分子系统发育学分析。  相似文献   
927.
在几乎所有的海底都有适合于天然气水合物的温度和压力,但是热力学平衡提出了形成水合物需要另一个涉及到溶解气浓度的条件。通过一种模拟退火算法--这种算法使得甲烷气体与海水混合物的自由能最小-我们量化了水合物的热力学条件。平衡相用一个压力、温度和盐度的函数来描述各稳定相的成分。我们发现溶解气的浓度(溶解度)随着温度的增加而迅速下降。在海水中,气体溶解度在特定的盐度时也是降低的。由于低溶解度会减少形成水合物所需要的气体量,所以海水中的盐实际上促进了水合物的形成。盐度的变化(常常引起水合物形成情况的变化)增加了一个热力学自由度,这就形成了一个三相区,此区域中水合物、海水和自由气体在恒压下的一个温度范围内共存。我们把该计算用于确定海底稳定相的分布。气体溶解度的计算结果表明水合物可以直接由海底的溶解气结晶而成。气体沿着平衡浓度梯度的扩散表明气体被连续不断地由水合物层运送到所覆盖的海水中。为了在海底沉积的过程中保持水合物,需要有一个持续的甲烷气源以弥补扩散所引起的损失。通过简单的近海沉积的物理条件模型就可以估算水合物的生长和消耗。  相似文献   
928.
太平洋南莱恩群岛和北科克群岛海域广泛分布锰结核。锰结核丰度变化从0.17公斤/米~2到31.2公斤/米~2,其中大于20公斤/米~2、15—10公斤/米~2和10—5公斤/米~2的站位分别为3.4%、13.8%和24%。锰结核大小从1厘米以下到10厘米,但多数直径在2—6厘米之间。锰结核的丰度变化与中结核(2—6厘米)的含量呈正比。结核分布和水深有关,以5000~5400米深度最为富集。在南纬5~9°的南部区多数丰度超过10公斤/米~2。控制南莱恩群岛和北科克群岛海域锰结核丰度变化的主要因素是沉积速率、碳酸盐补偿深度和浊流。  相似文献   
929.
The Pagasitikos gulf ecosystem is studied through the analysis of experimental field data acquired during several monitoring projects and the application of a complex biogeochemical model. The gulf was separated into three different parts (internal, top central-external, bottom central-external) according to the patterns exhibited by the key ecosystem indicators. Unlike other semi-enclosed gulfs Pagasitikos can be characterised as meso-oligotrophic undergoing periods of P or N limitation. Although the signal of nutrient inputs is not very clear in the field data, their importance is assessed through simulation. Increased phosphate concentrations either due to mixing or due to anthropogenic activities can result in phytoplanktonic blooms with significant contribution by diatoms. The effect of hydrodynamic patterns on primary production has been demonstrated through ecosystem modeling indicating that due to long stratification periods, all nutrients released through the benthic regeneration are trapped in the deeper layers, developing a microbial food web. However when the thermocline erodes nutrients find their way up in the upper layers of the euphotic zone and the system turns into more classical type with primary producers growing significantly faster.  相似文献   
930.
1996年5月31日~6月9日,笔者随“鲁辽渔业交流考察团”赴台进行了渔业交流和实地考察,对台湾渔业概况有了初步了解,现就所见所闻作如下介绍: 台湾除了本岛外,还有大大小小100多个附属岛屿,海岸线总长1600公里。台湾浅海广阔,海底平缓倾斜,是良好的近海底栖渔场,特别是寒流和暖流交汇的台湾海峡,既有寒水性的浮游生物,又有暖水性的浮游生物,还有大量从大陆随江河而来的营养盐类,使海水更加肥  相似文献   
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