Influence of sea ice and sea surface temperature on the abundance of Antarctic krill in Area 48.2

In this paper we examine the relationship between Antarctic krill catch, sea ice concentration, and sea surface tempera- ture （SST）. Data on the Antarctic krill catch from 2003 to 2010 in CCAMLR Area 48.2 were combined with sea ice and SST data. Results showed that krill fishing in Area 48.2 took place from February to August each year but the catch was concentrated from March to July, with production during this period accounting for about 99.3% of the annual catch. Regression analysis showed that the catch per unit effort （CPUE） was clearly related to sea ice concentration and SST intervals. CPUE was negatively correlated with the area of sea ice among years （R2=0.64）, and the correlation was strongest （R2=0.71） when sea ice concentration was greater than 90%. Over the months the CPUE initially increased, then decreased as the area of sea ice increased. The relationship was strongest （R2=0.88） when the concentration of sea ice was 60%--70%. There was no negative correlation among years between CPUE and the ice-free area when S ST was between -2 ℃ and 3 ℃ （R2=0.21）, but there was a significant negative correlation when SST was between 1 ℃ and 2℃ （R2=0.82）. Over the months, CPUE initially increased then decreased with increasing sea ice-free area, and the relationship was strongest （R2=0.94） when SST was between 0℃and 1 ℃. This study shows that sea ice concentra- tion and SST have significant effects on the abundance of krill in Area 48.2, and the findings have practical significance for the use and conservation of Antarctic krill resources.     

3D裂隙网络随机模拟及其工程应用研究

岩体中存在的大量随机分布的裂隙对岩体的工程性质及稳定性有着极其重要的影响。传统的工程地质研究方法难以客观地描述其空间分布特征。应用概率与统计学的理论 ,通过统计分析得到裂隙的分布规律性 ,采用随机模拟的方法实现与统计分布相适应的裂隙网络是研究随机裂隙宏观特征的有效途径。通过模拟所得的 3D裂隙网络 ,进一步研究了裂隙的连通特征及工程开挖面上的稳定分析与加固措施优化的方法     

基于改性糯米灰浆的3种锚杆锚固性能对比研究

锚固浆液的类型及其与杆体、土体的兼容协调性问题是土遗址锚固领域的研究焦点。由糯米浆为胶凝主材和由黏土、粉煤灰为填充料组成的改性糯米灰浆与木锚杆、玻璃纤维增强塑料锚杆、钢筋锚杆组成了3种锚固系统。通过对3种锚固系统的原位锚固、拉拔试验和界面应力-应变监测,分析比较了3种锚固系统的破坏模式、极限荷载、荷载-位移特征,剖析了杆体-浆体界面应力分布传递规律和界面测点应变对荷载时步的响应程度。在初步分析其锚固机制的基础上,最终得出了此类基于改性糯米灰浆的3种锚固系统的锚固性能的优劣完全取决于杆体-浆体的受力机制、变形和强度特征所决定的力学兼容性的结论。该研究成果为以糯米浆为主材的改性浆液在土遗址锚固领域中的应用提供了依据和参考。     

Cyclone formation and development in the Antarctic Prydz Bay

Using meteorological data of field observation in 1990 - 2000, especially polar orbit high-resolution NOAA satellite cloud maps received from the Antarctic expedition vessel since 1997, the formation and development of the Prydz Bay cyclone are studied in this paper. Some new viewpoints are suggested such as: when surround-polar cyclone enters the Prydz Bay, it can also intensify and develop in summer; cyclone can also develop in the easterlies in this bay. These view points revise old uncom-plete view point that the Prydz Bay is a burial ground of cyclone, and also further consummate formation-development theory of surround-cyclone in the Antarctic westerlies and cyclone in the Antarctic easterlies. In this paper, the mechanism of ice-air-sea interaction in the Prydz Bay is studied, and the physical process of cyclone formation-development is explained. By use of wholly dynamic transportation method, an energy exchange case of a cyclone, which explosively developed after entering the Prydz Bay, is calcu     

Timing of the late-glacial climate reversal in the Southern Hemisphere using high-resolution radiocarbon chronology for Kaipo bog, New Zealand

The pattern of climate change in the Southern Hemisphere during the Younger Dryas (YD) chronozone provides essential constraint on mechanisms of abrupt climate change only if accurate, high-precision chronologies are obtained. A climate reversal reported previously at Kaipo bog, New Zealand, had been dated between 13,600 and 12,600 cal yr B.P. and appeared to asynchronously overlap the YD chron, but the chronology, based on conventionally radiocarbon-dated bulk sediment samples, left the precise timing questionable. We report a new high-resolution AMS ¹⁴C chronology for the Kaipo record that confirms the original chronology and provides further evidence for a mid-latitude Southern Ocean cooling event dated between 13,800 and 12,400 cal yr B.P. (2σ range), roughly equivalent to the Antarctic Cold Reversal.     

南极长城站地区现代环境地球化学特征

本文通过环境背景值、风化壳地球化学、对流层(大气气溶胶)地球化学和人为地球化学异常,初步探讨了南极长城站地区的现代环境地球化学特征。分析表明:环境要素固有的地球化学性质、区域环境条件和自然环境演变之间具有深刻的内在联系。     

基于稳定性同位素的普里兹湾南极大磷虾不同发育阶段食性转变分析

As one of the most common and dominant species in the Southern Ocean, Antarctic krill(Euphausia superba)play a significant role in food web structure and the process of energy flow. The diet of Antarctic krill in the Prydz Bay during austral summer of 2012/2013 was investigated and the ontogenetic shift in krill diet was evaluated using the stable isotope method. The nitrogen stable isotope values(δ~(15) N) of adults((2.78±0.58)‰) were much higher than those of juveniles((1.69±0.70)‰), whereas the carbon stable isotope values(δ~(13) C) of adults(–(28.26±1.08)‰) were slightly lower than those of juveniles(–(27.48±1.35)‰). Particulate organic matter(POM)from 0, 25, and 50 m depth combined(0/25/50 m) represented phytoplankton food items. The results showed that phytoplankton food items in surface water and mesozooplankton were two essential food items for Antarctic krill in the Prydz Bay during summer. POM(0/25/50 m) contributes 56%–69% and 26%–34% to the diet of juvenile and adult krill, respectively, whereas mesozooplankton composes 13%–34% and 58%–71% of the diet of juvenile and adult krill, respectively. Thus, an ontogenetic diet shift from POM(0/25/50 m), which consists mainly of phytoplankton, to a higher trophic level diet containing mesozooplankton, was detected. The capacity for adults to consume more zooplankton food items may minimize their food competition with juveniles, which rely mostly on phytoplankton food items. This suggests "diet shift with ontogeny" which may somehow help krill keep their dietary energy budget balanced and well adapted to the Antarctic marine ecosystem as a dominant species.     

散粒体中锚杆间距的锚固效应研究

采用细观数值模拟方法研究散粒体的锚固效应,基于随机模拟技术生成三维多面体颗粒及其在空间中的分布,在随机散粒体不连续变形模型的基础上将砾石锚固试验进行数值实现,分析加锚散粒体材料的宏观与细观力学性能,研究加锚密度及其与颗粒粒径的关系对散粒体力学性质的影响,并探讨锚杆在散粒体材料中的作用机制。分别建立不同锚杆间距和不同颗粒粒径的数值试样,数值模拟结果表明：散粒体锚固数值试验能够较好地反映不同加锚散粒体结构的变形规律与锚固效应;散粒体材料的宏观特性与其细观组构的演化密切相关;锚杆加固散粒体的作用机制为加锚散粒体内形成压缩区,挤压加固作用提高了散粒体间的接触作用力,散粒体结构的整体性得到加强并能承受一定荷载;不考虑锚杆长度的情况下,当锚杆间距小于3倍的散粒体平均粒径时,锚杆能够有效地加固散粒体形成稳定结构。     

美国南极科研投入的统计分析及其对我国的启示

近些年来南极科研越来越受到世界各国的重视,作为《南极条约》的发起者和南极条约体系的管理者,美国始终站在南极科学研究前沿,对维护其国际南极事务领导地位有着重要意义。1953—2016年美国国家科学基金资助了7 759个南极科研项目,通过统计分析对项目投入进行以下4个方面的分析:南极项目投入、南极科研各学科投入、科研大项目以及合作机构。研究发现:(1)1953年至今,美国国家科学基金会(NSF)对美国南极科研项目的资助力度和重视力度不断增加,促进了美国南极政策的落实和发展;(2)美国各大科学指导机构出台的前瞻性文件对引领美国南极科考发展方向起到重要作用;(3)NSF充分利用各高等院校和研究机构的资源设施,搭建科研支撑平台,与之展开长期南极科研项目合作;(4)NSF重视科研大项目的开展,这些大项目站在南极科学前沿,引领美国南极科研更好地发展;(5)NSF通过学校、社会、媒体多个渠道开展南极教育,增进群众对南极了解并培养科研人员来维护美国在南极的科考领先地位。上述研究发现为中国南极科研政策制定提供了相应的启示。