共查询到19条相似文献,搜索用时 93 毫秒
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对南极普里兹湾NP93-2和NP95-1两柱样沉积硅藻进行了定量分析。两柱样分别可划分出3个和7个硅藻组合带。前者的优势种是Nitzschiacurta和Thalasiosiraantarctica,次优势种是N.kerguelensis和N.ritscheri;后者常见的优势种有N.kerguelensis,N.curta,Denticulopsisspp.和T.lentiginosa,常见的次优势种有Eucampiabablaustium,T.antarctica和T.gracilis。利用N.curta/N.kerguelensis比值并结合14C测年数据,可将15000年以来南极气候的变化划分出8个古气候带,其中完好地记录了Heinrich1事件、波令-阿德罗暖期、新仙女木冰期、全新世低温期等重大的气候变化事件,而南极的全新世低温期是首次报道。 相似文献
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《南极海洋生物资源养护公约》框架下的海洋保护区建设备受国际社会关注。2009年,南极海洋生物资源养护委员会建立了第一个海洋保护区,但2012年以来,罗斯海海洋保护区提案以及东南极海洋保护区代表体系提案却一直没有进展,其中涉及了南极条约体系解读与海洋保护区定义等法律争论、保护区建设与地缘政治控制以及排斥其他国家渔业活动等政治争论。研究表明,虽然委员会有权建立海洋保护区,以实现养护南极生物资源的目标,但两个提案一定程度上超越了委员会的职责范围;且这两个提案一定程度上都与提案国的南极领土主权以及渔业活动相关联,无法排除其他国家的政治关切;提案每年变化,也体现了政治妥协。因此,为真正实现按公约养护南极生物资源的目标,应切实解决相关的法律与政治关切,提高程序的透明度,扩大参与度,并认真实施对已建立的海洋保护区的研究与监测。 相似文献
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南大洋海域因其特殊的地理位置、极端的气候环境和丰富的资源,具有重要的科学和经济意义。当今世界各国力争国家权益,积极参与南极海洋保护区设立的国际事务,然而我国虽对此持续关注,但相关研究甚少,在南极海洋保护区设立的适宜性评价指标和区划方法研究方面几近空白。在此背景下,通过对现有各国南极海洋保护区的提案分析,尝试构建南极海洋保护区设立的适宜性评价的多级指标体系,并基于我国南极科学考察数据,运用层次分析法和加权叠加分析,对普里兹湾海洋保护区设立的适宜性进行案例研究,以期为我国南极海洋保护区的设立和相关研究提供参考。 相似文献
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本文报道南极海洋冷水环境中的低分子挥发性脂肪酸的一种测定方法 ,阐述高压液相色谱法对海洋环境中 C1- C5年低分子挥发性脂肪酸的含量测定具有较好的适用性 ,说明该方法具有正确、灵敏、操作简单、快速及需要样品量少等特点。本方法的最低检测限在 0 .1 μg/ml以下 ,个别酸如丙烯酸可达 0 .0 0 1μg/ml以下。南极戴维斯站附近沿海 ,1 989年 1月 3日 6 0 m水柱体样品测定结果丙烯酸为 0 .0 0 4 - 0 .0 4 2 μg/ml,其他酸是 0 .1 - 1 .0 μg/ml,说明了该方法完全可满足实际海水样品的分析。 相似文献
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Changes in the importance of lotic and littoral diatoms in a high arctic lake over the last 191 years 总被引:1,自引:0,他引:1
Both habitat preferences and community associations for some of the most prominent pennate taxa in our profile were established using samples from the modern lake and its watershed. Habitat preferences were used to establish a simple indicator for the relative contribution of lotic communities in this lake (Lotic Index) and indicator taxa for both littoral (Achnanthes spp. and Cymbella spp.) and lotic (Hannaea arcus and Meridion circulare) communities. When profiled, the Lotic Index showed a clear positive relationship to sedimentation rate as recorded in the varves, while profiles of littoral indicator taxa show the opposite trends. It seems likely that the patterns we observed in the Lotic Index are related to changes in runoff. Apparently, there was a period of declining runoff beginning ca. two centuries ago and ending in the late 1800's. This was followed by increasing runoff lasting until the middle of the 20th century. A brief minimum occurred in ca. 1970 followed by a recovery by ca. 1980.A strong positive relationship was also found between the dates of major turbidites, exceptionally thick varves and the concentration of valves in the sediment. It is possible that many of the thicker varves in the profiles contain littoral material transported to the site of deposition by turbid interflows and underflows. For this reason, the concentration of valves in the sediment in our cores appears to be a proxy for sediment deposition from turbidity currents.This is the sixth in a series of papers published in this issue on the Taconite Inlet Lakes project. These papers were collected by Dr R. S. Bradley. 相似文献
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南极磷虾资源量大且营养丰富,是人类赖以生存的后备蛋白库,如何高效利用其资源已经成为当今科技的重点和难点。通过陆上实验,设定温度在120℃的恒定干燥条件下,对其进行热风干燥,来模拟船载南极海域条件下,南极磷虾的干燥曲线和干燥速率曲线。结果显示,在恒定干燥条件下,其干燥速率是0.497g·cm~(-2)·min~(-1),临界含水率为0.56 g水·g干物料~(-1);恒定干燥时间约占全部时间的三分之一。当低于临界含水率时,物料就进入了降速干燥阶段。此外,南极磷虾的干燥速率还与干燥温度和物料的烘干表面积有关;提高干燥温度和表面积都可加快干燥速率,这对于南极磷虾粉的设备设计、实际生产都有着重要的参考和指导意义。 相似文献
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Transport of moisture-bearing air to the Antarctic is one of the important factors that control the mass balance of the ice sheet. Here, we investigate the distribution of air-parcel transport using a backward trajectory analysis over the entire Antarctic ice sheet, based on whether the air parcel was located inside or outside of Antarctica at 5 days before arrival. At this time, we considered the air from outside Antarctica to be moisture rich. Oceanic air was found to dominate in West Antarctica throughout the year, whereas air from inland was more prominently distributed around East Antarctica, especially in summer. In East Antarctica, there was a significant seasonal variation: air from inland dominated in summer, while air of oceanic origin dominated in winter. The distribution of air parcels that came from oceanic/inland sources was similar to the accumulation map (based on satellite data), which indicates that oceanic air parcels could be a substitute for moisture transport to the Antarctic. To determine the future impacts of climate change (e.g., sea level rise), more precise predictions of the variations in the surface mass balance will be required. Our results contribute towards the improved understanding of the spatial distributions of accumulation and aerosols found in Antarctic snow and ice cores. 相似文献
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Sedimentation patterns of diatoms in Lake Holzmaar, Germany - (on the transfer of climate signals to biogenic silica oxygen isotope proxies) 总被引:2,自引:0,他引:2
The seasonal sedimentation pattern of diatom valves in Lake Holzmaar was investigated during 1995 by deploying sediment traps at three different lake depths. According to the sedimentation pattern, the major reproduction zone of diatoms was restricted to the upper 6 m of the water body. The population growth started late in April and blooms of Cyclotella cf. comensis Grun., which dominates the plankton diatoms, and Fragilaria crotonensis Kitton were collected in traps during June and September, and July, respectively. During summer, the seasonal sedimentation pattern of each taxon, as collected in the upper traps, was reflected in the concentrations in the lowest trap. However, in May and from September onwards, the community composition in the lowest trap and augmented trapping rates suggest both sediment focusing and resuspension of bottom sediments.The temperature signals as recorded by 18O values of diatom valves should, therefore, reflect integrated temperatures between 0 and 6 m depth. However, temperatures during summer and autumn are expected to be accentuated in the sedimentary record since the isotopic signal is weighted by both the number and the weight-mass of the valves. During summer, the transfer of these signals by the sedimenting diatoms retains the information pattern recorded, while in spring and autumn/winter additional influxes caused by resuspension may somewhat alter those temperature informations. The proxy signals finally stored in the sediments, may, therefore, not precisely represent the successive temperatures currently recorded during 1995 within mid-lake. 相似文献