Heinrich事件时北大西洋深水环流消失

深部大洋温盐环流主要受控于北大西洋深层水的供给量。目前,输送到北大西洋高纬度区域的亚热带温盐水是由北大西洋环流携带的。当其向北运移时,海水冷却并下沉,形成全球深部大洋传送系统。更新世时,高纬度区域海水的盐度和温度均发生了急剧变化。冰期时,由于大气环流...     

印度西南海岸Kannur区红树林沉积物的水动力反应

对Ｋａｎｎｕｒ红树林的地表和岩心沉积物的粒度特征和统计参数做过研究。向陆地带、中间过渡带和浅水剖面的砂、泥含量几乎为常量。地表沉积物平均粒度变化范围在１．８３和５．５６之间,岩心沉积物的变化范围在２．３和５．５６之间。沉积物普遍分选差至极差、...     

以哈维氏弧菌(Vibrio harveyi)为重点的鱼类细菌病原的诊断与控制(英文)

作者对鱼类细菌病原的诊断与控制作了较全面的综述。细菌病原诊断技术包括酶联免疫吸附技术（ＥＬＩＳＡ）及蛋白印迹法（Ｗｅｓｔｅｒｎｂｌｏｔｉｎｇ）。细菌病原控制技术包括化学疗剂的应用,有益微生物的应用,营养添加剂,β－葡萄糖苷增强免疫抗病力,及免疫保护作用等。     

青藏高原东缘虎牙断裂带南北段运动方式差异性机理：来自数值模拟的约束

虎牙断裂带作为青藏高原物质东向扩展的前缘断裂之一,其运动方式和强震活动类型表现出显著的南北差异.研究虎牙断裂带运动方式的差异性机理,对于认识地震发生机制与高原东向扩展模式有着重要意义.本文构建包含虎牙断裂带的三维黏弹性有限元模型,研究介质流变性差异与断层几何形态对区域地壳变形及断层三维滑动速率的影响.数值实验结果表明,在青藏高原物质东向挤出的动力学背景下,在虎牙断裂带南段,中下地壳介质流变性横向差异控制着断层以逆冲性质为主的运动,且随着中下地壳断层两侧流变性差异的增大,断层西侧物质的水平运动更易发生向垂向运动的转换.在断层两侧流变强度差1～2个数量级时,断层倾向滑动速率与走向滑动速率的比值达3.3～4.0,表现出显著的逆冲运动,与松潘—平武强震所反映的断层运动特征基本一致.相反,在断裂带北段,考虑断层两侧中下地壳较小的流变性差异时,断层即表现出明显的逆冲运动,这与九寨沟M_S7.0等强震反映的断层以走滑性质为主的运动明显不符,表明虎牙断裂带北段可能不存在中下地壳介质流变性的横向差异,断层以走滑为主的运动方式主要受断裂带几何展布控制.研究结果为认识青藏高原东缘同一构造...     

中朝克拉通东部上地幔精细圈层结构：来自朝鲜核爆源深地震测深剖面的约束

晚中生代以来,中朝克拉通经历了一系列强烈构造和岩浆事件,岩石圈性质发生显著变化.为此,中朝克拉通“破坏”一词被提出,但破坏形态主要来自地表地质、地球化学、地壳结构和上地幔较大尺度的地震学成像等的约束.因较大能量的人工震源方法较难在人口密集的华北地区实施,基于深地震测深剖面对整个上地幔精细圈层结构的探究仍限于较少地区.为此,我们根据中国地震台网和部分流动台站记录的2017年9月3日朝鲜地下核试验地震数据,利用宽角反射/折射成像方法,揭示了中朝克拉通东部及邻区5个不同方位剖面的高垂向分辨率一维地壳和上地幔P波速度结构.结果显示,中朝克拉通东部及周边地区平均地壳厚度为29～30 km,全地壳平均速度在6.10～6.17 km·s^-1之间,远低于全球大陆地壳平均值,表明该区下地壳很薄甚至缺失,且在地壳底部可能存在因局部拆沉而形成的强水平各向异性.该区80 km左右深度可观测岩石圈正速度梯度内部间断面,推测其可能是由尖晶石到石榴石相变引起.在约220 km深度,我们探测到通常存在于稳定克拉通下方的Lehmann间断面,揭示中朝克拉通东部还部分保留类似稳定克拉通的圈层结构.介...     

加拿大内陆水的保护

Contrary to general international perception, Canada does not have an unlimited supply of freshwater. However, because Canada has a small population, it does have a generous water allocation on a per capita basis. Nor is Canada immune from water quality problems:its cold continental climate, urbanization and industrial activities all contribute to water quality concerns and deterioration. Generally, the authority to manage water in Canada is held by the country''s provincial governments. The Great Lakes basin is the world''s largest freshwater ecosystem and is located in Canada''s industrial heartland. Water issues, starting with phosphorus in the 1960''s, created international headlines. In the 1970''s toxics became the predominant issue and this led to the Great Lakes Water Quality Agreement which established the ecosystem approach to water quality management. This approach is now the standard approach to water quality management and has been successfully applied to a number of other lake and river ecosystems in Canada. While there have been improvements in the water quality of the Great Lakes much remains to be done on toxic elimination and the large contaminant stores in the sediments. Atmospheric deposition has become a significant source of chemicals from outside the basin The Canadian prairies, the agricultural heartland of Canada, is one major ecozone that has not been selected to have current and potential water quality problems examined by a federal government program. Both the quantity and quality of water in this region are potentially significant factors limiting economic diversification and sustainable development in this vast and ecologically disturbed region.     

香港一富营养河港内的底泥耗氧和营养盐释放

Tolo Harbour has received massive discharges of municipal sewage, agricultural wastes and cottage industrial effluents, via three river systems, in the past two decades before the mid Eighties. The Harbour is almost land locked and poorly flushed. The soft sediment acted as a sink for nutrients and organic pollutants. After a decade of efforts in establishing and enforcing water pollution control legislations and upgrading wastewater treatment facilities, the sediments have turned into sources of nutrients and exert a measurable oxygen demand upon the overlying waters. In vitro measurements showed that the sediments oxygen demand (SOD) was between 17.6 and 54.3 mgo₂ · m^-2 · h^-1. The maximum rates of release of ortho-phosphate phosphorus and ammonia nitrogen were 15.0 and 206.0 mg · m^-2 · h^-1, respectively.     

晚第四纪中亚高山湖泊的演化

中亚晚第四纪商山湖泊的演化受到复杂的气候波动釤响,主要由水汽的变化、湖盆冰川作用和径流与 流址的变化而引起的。冷干条件伴随右融水补给的减少和湖退;暖湿条件引起了冰川的后退,增加了融水补给,引起湖进。分布于不同海抜高度的天山和帕米尔竑原地区的湖泊,普遍处于较干旱的环境中,通过对湖盆地貌学、冰川和湖泊沉积物的分布和成份的研究、以及对湖泊沉积物的孢粉分析和埋藏植物碎屑的^l4C年代测定,可以里违晚贝新世以来益山湖泊的演化阶段和中亚高山区的古地理环堍。22000-17000a B.P.,天山查特尔库尔湖和帕米尔喀拉湖为外流淡水湖,面积超过目前的2-3倍。湖泊沉积物中孢粉以干草原植被为主,反映气候较暖湿。16000-11000a B.P.,冻川活动达到极盛,气候寒冷、干燥,湖泊干涸、消失。孢粉频率低,以旱生植物花粉为主。10000-8000a B.P.,温度、湿度提中湿植物和蒿属相对藜科增加,开始湖进。查特尔库尔湖水位较今高12m,面积超过现今3倍;8000—4000a B.P.,天山和东帕米尔的湖盆气侯相对暖湿。4000—3500a B.P.,气候变干,旱生植物花粉增加。3000a B.P.以来以气候干旱化为特征,植被以高山干草原和草原-荒漠为主。1500a B.P.以来气候更趋干早,干旱植物花粉增加,湖水位下降,一直持续至今。据历史和考古资料,公元14-16世纪天山气候暖干化,发生湖退;17—18世纪天山和帕米尔湿度增加,出现湖进。目前该地区湖水位普遍处于下降时期,仅若干冰融水补给湖泊有湖进的迹象。     

Vertical seismic absorber utilizing inertance and negative stiffness implemented with gas springs

A novel implementation of negative stiffness elements(NSEs) is proposed, utilizing industrial grade nitrogen gas springs as pre-stressed stiffness elements in a configuration with lever arms. This NSE is combined with an inerter to form a stiff dynamic absorber(SDA) for vertical seismic protection of structures with base isolation. The SDA is optimized to minimize vertical accelerations while ensuring static structural integrity, excellent damping performance and containment of relative displace...