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31.
We used fresh and brackish water shrimp (Desmoscaris trispinosa and Palaemonetes africanus), in sediment bioassays to assess the toxicity of an industrial detergent containing high levels of anionic surfactant (linear alkylbenzene sulphonate (LAS)). The Organization for Economic Cooperation and Development (OECD), # 218 direct sediment toxicity assessment was employed. The organisms were exposed to different concentrations (31.25, 62.5, 125,250 and 500 mg/kg) of the chemical (Neatex) in replicate treatments. Percentage mortality was measured as the ecological endpoint. Mean mortality and estimated lethal concentration LCso values varied with species type, concentration and exposure duration. The statistical variation in the observed mean mortality of the test organisms in the chemical and the control treatment shows that mortality may be induced by the effect of the chemicals. The lethal concentration (LCso) was significantly different at levels ofp 〈 0.05 for the fresh and brackish water experiments. Consequently, assessment of water and sediment quality as a result of chemical pollutants was necessary for protecting some of the more sensitive benthic invertebrates representing the major proportion of the diet of many species in the Niger Delta ecological zone. 相似文献
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TWO SUITES OF OPHIOLITE RECOGNIZED IN THE MAQEN AREA, NORTHEASTERN TIBETAN PLATEAU1 JiangCF ,YangJS ,FengBG ,etal.OpeningandClosingTectonicsofKunlunMountains.Beijing :GeologicalPublishingHouse (inChinese) ,1992 .
2 XuZQ ,YangJS ,LiHB ,etal.TheA’nyemaqenSutureBeltandtheDynamicsinSubductionandCollision .TheStudyoftheOphioliteandGeodynamics[M ].(inChinese) .1996 .185~ 189.
3 YangJS ,XuZQ .TheA’nyemaqenOphioliteBeltEastKunlunMts.,NWChi… 相似文献
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<正>The forewing of a termite from Early Miocene lake sediments in Otago,southern New Zealand is figured and described.It exhibits the generic characters of the damp-wood termite Stolotermes Hagen,but differs from forewings of the known species in size and venation pattern and is described as Stolotermes kupe sp.nov.S.kupe represents the first confident record of fossil Stolotermitidae and extends the fossil record of the family back to the Early Miocene.It also is the first direct evidence of fossil Isoptera from New Zealand,though silicified termite faecal pellets,referable to Kalotermes brauni,have been previously described.S.kupe indicates that Stolotermitidae has been present in the Australasian region since at least the Early Miocene. 相似文献
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In this paper, the effect of pulse-type motions caused by forward directivity that can release huge amounts of energy in a short time period is studied on a telecommunication tower. Since telecommunication towers have longer periods, they are not as affected by seismic forces. Nevertheless, near source earthquakes characterized by high velocity and velocity pulses can change the behavior of these structures. For this reason, a telecommunication tower located near active faults was selected in this study. Considering the probable earthquake magnitude at the site and the distance of the tower from adjacent faults, nine simulated pulses and three near-fault earthquake records with forward directivity are selected and applied to a 3D fi nite element model of the tower. The results of nonlinear dynamic analysis, i.e., displacements and damage in the tower, indicate that the maximum displacement and drift ratio of the tower under the pulses are obviously affected by the ratio of the structure period to pulse period. When this ratio is decreased and close to 1.0, the maximum displacement and drift ratio are sharply increased and cause large displacements in the tower. 相似文献
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建立哈萨克斯坦共和国地震学数据库是CASIN国际项目的一部分,应由中亚各国来共同完成。项目主要目的旨在建立地震学数据库,以作为今后减小哈萨克斯坦共和国地震危险性的工作基础。哈萨克斯坦共和国地震学数据库由下列子系统构成:1)文件输入子系统;2)信息检索和提交子系统;3)信息元数据存储子系统;4)档案库运行控制子系统;5)信息安全子系统。哈萨克斯坦共和国地震学数据库有以下功能:1)永久存储综合信息并上报和收集(记录)其他资料;2)存储数据和资料计算;3)电子文档的长期存储和管理;4)规定序号进行信息查询和文件的联机保证;5)信息统计和… 相似文献
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中国西南天山山前的晚新生代构造与地震活动 总被引:40,自引:0,他引:40
天山是研究现今陆内造山作用及过程、陆内变形、陆内强震及其预测等大陆动力学问题的理想实验场。西南天山和塔里木之间的新生代褶皱-逆断裂带基本上由一南冲弧形推覆构造系统和一向北反冲的构造系统组成,由北而南主要由以下4个运动学单元组成:(1)新生代复活的喀拉铁热克山-天山南脉古生代造山带,其快速变形和抬升可能起始于23-26Ma前,持续至13-16Ma前。(2)向南逆冲的西南天山前陆薄皮主冲断带,包括木兹杜克弧形薄皮推覆体和依柯冲断带,前者代表了向南薄皮逆掩的天山型岩系,地表主要表现为一系列的飞来峰群,在14Ma前曾有过大规模活动,最小缩短量约为20-35km,最小缩短速率为1.4-2.8mm/a;后者代表了向南叠瓦状薄皮逆冲推覆的前陆古生代基底(塔里木地台型沉积岩系)卷入构造,其西段在距今14Ma时曾有过强烈活动。两者共同组成了一复杂的双重构造;新生代地层也卷入变形。(3)喀什-阿图什弧形反冲褶皱-逆断裂带,由3排向北(天山)反冲的左阶雁列展布的第四纪地表滑脱褶皱组成,仅在大山口以西发育。该构造带形成于距今约1.4Ma以后。依什拉克喀拉乌尔断裂以南,博古孜河剖面的最小缩短速率约为5.8mm/a,翁库尔剖面的最小缩短速率约为8.6mm/a。(4)塔里木克拉通下盘块体,向北西方向缓倾,内部变形较小。里木块体西北存在明显的不均匀性,其学问基底高角度逆断裂和走滑断裂控制了盆地新生代沉积的厚度,导致西南天山前陆冲断带的地形地貌、地层、构造变形样式、变形时间以及变形缩短量沿走向的巨大差异性。迈丹-喀拉铁克断裂和阿图什断裂带均为岩石圈规模断裂,研究区的中强地震主要发生在这两条断裂带以及它们之间的西南天山前陆冲断带上。 相似文献
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