金塔南山河流砾石特征指示的青藏高原东北缘地貌演化

青藏高原的隆升扩展不但塑造了高原及其周边的地貌,影响了气候的变化,而且极大地改造了其周缘的水系格局。其中,河流沉积物最直接地记录了河流演化与水系演变的过程。本研究主要利用河流砾石层的沉积特征分析金塔南山地区水系演化对高原东北缘扩展过程的响应。金塔南山顶面普遍沉积一套磨圆度较好、分选较好的河流砾石层,其砾石岩性主要组分为岩屑砂岩、石英砂岩和硅质岩,在局部地区也存在较多的砾岩和灰岩。祁连山北部主要的7条河流出山口主河道的砾石组分统计结果显示砾石岩性主要组分存在较大差异;河流之间的砾石岩性差异很好的解释了金塔南山顶面砾石岩性组分自东向西的变化。根据对比金塔南山顶面砾石组分和祁连山北部主要的7条河流主河道砾石组分中不同抗风化能力岩性的含量与分布,我们认为金塔南山顶面砾石主要来源于祁连山。对金塔南山顶面砾石ab面的测量发现：东段砾石倾向单一,指示古流向为北;而中西段倾向复杂。总体来说,砾石倾向指示的古水流方向是北向。结合砾石岩性组分与分布以及古流向,认为在金塔南山顶面沉积砾石层时,此处的河流处于摆荡状态且河流之间可能有汇合现象,造成局地砾石ab面指示的古流向与整体流向不一致;而后随着中更新世以来金塔南山的抬升,黑河和北大河下切分别形成正义峡和鸳鸯峡,形成两个相对独立和稳定的水系。     

哀牢山过山气流的气候效应

本文研讨哀牢山脉北段西南季风与东北季风的过山气候效应。     

浙江杭嘉湖平原区土壤中营养元素丰缺状况的评价

根据杭嘉湖平原区区域地球化学调查的结果,对本区土壤中农作物营养元素含量及有效量特征进行了评价研究。研究结果表明,本区土壤中营养元素除Mo、S含量表现缺乏外,其它元素为足量和丰富水平。不同土壤中营养元素有效量水平存在明显差异。在区域分布规律上,营养元素的含量及有效量随成土母质、成土过程和人类耕作等因素的不同而显示其差异特征。评价研究结果为本区农业生产中的合理区划、科学施肥、合理种植、土壤改良等提供了重要的地球化学依据。     

春季季风间期赤道东印度洋浮游植物光合生理特征

Phytoplankton physiologies are dynamic and have sensitive responses to the ambient environment. In this paper,we examine photosynthetic physiologies of phytoplankton communities with Phyto-PAM in the eastern equatorial Indian Ocean during the spring inter-monsoon. Environmental parameters were measured to investigate the coupling between phytoplankton photosynthetic physiologies and their habitats. During the cruise, the water column was highly stratified. The mixed layer extended to about 75 m and was characterized by high temperature(28°C) and low nutrient level. The F_v/F_m values and chlorophyll a(Chl a) concentrations were lower at the surface, as consequences of nutrient depletion and photo-inhibition. Subsurface Chl a maximum(SCM) occurred between 75 and 100 m, and had the highest F_v/F_m values. The formation of SCM was a balance between nutrient availability and light limitation. The SCM may contribute significantly to pelagic food web and primary production in the water column. Phytoplankton in different layers encountered different light, trophic and hydrographic dynamics and evolved distinct photosynthetic characteristics. Despite of co-limitation of nutrient limitation and photo-inhibition, phytoplankton in the surface layer showed their acclimation to high irradiance, had lower light utilization efficiencies(α: 0.061±0.032) and could exploit a wide range of light irradiance. Whereas, phytoplankton in the SCM layers presented the highest light utilization efficiencies(α:0.146±0.48), which guaranteed higher photosynthetic capacities under low light level. These results provide insights into phytoplankton photo-adaption strategies in this less explored region.     

Response spectral amplification ratios from 1- and 2-dimensional nonlinear soil site models

In order to determine the effect of geometry on the ground response of 2-dimensional (2-D) basins filled with soils that can develop nonlinear response, we use three basin models with width/depth ratios 3, 6 and 10. The three basins are subjected to a suite of rock site records with various magnitudes and source distances. We compute response spectral amplification ratios at four locations on the surface of the 2-D basins, and determine the average variation of the amplification ratios with respect to excitation spectra, for peak ground acceleration (PGA) and 3 spectral periods of 0.2, 0.5, 1 s. Similarly, we compute the average response spectral amplification ratios for two 1-dimensional (1-D) nonlinear models, one having the soil profile at the basin centre and the other having a soil profile at half the depth of the basin. From the relationship between the average amplification ratios and excitation spectra, we determine the cross-over point in terms of excitation spectral values that separate the amplification range from the deamplification range. Our results show that the cross-over point varies significantly from one location to another on the ground surface and from one basin to another, in a range of 0.3–1.1g for PGA. The effects of basin geometry are very strong at weak and moderate excitation, but decrease with increasing excitation spectra in a significant portion around the basin centre. Our results provide some justification for using 1-D models for 2-D basins with a width/depth ratio ?6 if the soil site is subjected to strong ground shaking.     

应用北太平洋表层水温及环流场进行海冰预报

渤海及黄海北部处在中纬度地带,每年冬季都有不同程度的结冰现象。以辽东湾结冰时间最长,全部结冰日数平均为100多天,约占全年的三分之一。从全海区看,建国后冰情较重的有1957、1968、1969、1977年的1、2月份,尤其是1969年,渤海海面发生了该海区历史上罕见的冰封,整个海面几乎全部被海冰所覆盖,严重阻碍了海上的航运交通及海上石油开采工作,从而给国民经济带来很大损失。     

青岛冷水团的消亡机理研究

本文基于多年月平均水温资料,分析了青岛冷水团的长消过程,并利用气候态月平均大气数据和数值模拟结果,探讨了青岛冷水团的消亡机理。结果表明,青岛冷水团3月出现,4月成型,5月最盛,6月减弱,7月消失;南黄海6-7月间偏南风的增强和温跃层以下反气旋涡的减弱是青岛冷水团消亡的动力机制,而海面净热通量的下传和水平热量的输入则是青岛冷水团消亡的热力机制。     

Environmental magnetic studies of sediment cores from Gonghai Lake: implications for monsoon evolution in North China during the late glacial and Holocene

Environmental magnetic studies were conducted on a 9.42-m-long sediment core from Gonghai Lake, North China. Radiocarbon dating indicates that the record spans the last 15,000 cal year BP. The principal magnetic mineral in the sediments is pseudo-single domain magnetite of detrital origin with minimal post-depositional alteration. Although the variations in the concentration of detrital magnetic minerals and their grain size throughout the core reflect inputs from both soil erosion and eolian dust, it is shown that their climatic and environmental significance changes with time. In the lowermost part of the core, ~15,000–11,500 cal year BP, the magnetic minerals were supplied mainly by bedrock erosion, soil erosion and dust input when climate ameliorated after the cold and dusty last glacial maximum. The increasing magnetic susceptibility (χ) in this interval may indicate a combination of changes in the lake environment together with catchment-surface stabilization and a decreasing proportion of dust input. In the central part of the core, ~11,500–1,000 cal year BP, the detrital magnetic minerals mainly originated from dust inputs from outside the catchment when the lake catchment was covered by forest, and catchment-derived sediment supply (and thus the lake sediment accumulation rate) were minimal. The generally low concentration of magnetic minerals in this part of the core reflects the highest degree of soil stability and the strongest summer monsoon during the Holocene. In the uppermost part of the core, the last ~1,000 years, detrital magnetic minerals mainly originated from erosion of catchment soils when the vegetation cover was sparse and the sediment accumulation rates were high. Within this part of the core the high magnetic susceptibility reflects strong pedogenesis in the lake catchment, and thus a strong summer monsoon. This scenario is similar to that recorded in loess profiles. Overall, the results document three main stages of summer monsoon history with abrupt shifts from one stage to another: an increasing and variable summer monsoon during the last deglacial, a generally strong summer monsoon in the early and middle Holocene and a weak summer monsoon in the late Holocene. The results also suggest that different interpretational models may need to be applied to lake sediment magnetic mineral assemblages corresponding to different stages of environmental evolution.     

聂尔库组植物化石新材料及其地层意义

聂尔库组分布于辽宁东北部新宾县南杂木一带的苏子河盆地,为一套河湖相砂页岩沉积。该组含有较丰富的动、植物化石,但由于系统采集和研究不够,自建组以来,在地层时代和对比方面迄今仍是众说纷云。作者通过系统采集,共获植物亿石12属13种,化石组合面貌与英国威尔登植物群可以比较;与辽西的海州组、辽北—吉中营城组、黑龙江东部的穆棱组植物组合亦很相似,其时代大体相当于早白垩世尼殴克姆晚期。文中对我国首次发现的属种作了描述。     

中国近海海水中几种微量金属离子的分布研究

中国近海海水中的锌等微量元素，尚未进行过较为广泛而可靠的分布研究。极为零星的资料，还是近几年来在沿岸进行污染调查时，用陈旧的方法测定的。 世界海洋海水中微量元素的含量，不同文献报道的数据，常有一定的差别。这是自然变化，抑方法误差(包括所测形态)，是值得研究的。 本文采用单池示差反向极谱法，比较广泛而可靠地研究了中国近海海水中,锌等微量，元素的离子(和不稳定络合物)的地球化学分布。测定锌、铅、铜、镉时，样品不加任何试剂，因而避免了元素存在形态的转移及被测离子的带入或损失。