Effect of chromophoric dissolved organic matter on epilimnetic stratification in lakes     

Sophie Caplanne  Isabelle Laurion 《Aquatic Sciences - Research Across Boundaries》2008,70(2):123-133

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中国都市圈中运量型轻轨交通的发展问题研究   总被引：6，自引：0，他引：6  

袁家冬  于宁 《地理科学》2007,27(1):24-30

从都市圈的空间结构和交通需求的特点分析入手,讨论了中运量型轻轨交通在都市圈公共交通中的地位与作用。结合中国都市圈建设中有关轻轨公共交通发展的问题,指出发展以中运量型轻轨交通为骨干的城市公共交通是中国都市圈交通建设的重要方向,并对中国都市圈以中运量型轻轨交通为骨干的都市圈综合交通体系的规划建设提出了若干建议。  相似文献   

“照亮”地下          下载免费PDF全文

叶英 《地球物理学进展》2009,24(5):1646-1651

本文介绍利用地震角度偏移法实现照亮地下的理论构想,并做了大量的研究工作,说明地震波角度偏移法在地下空间探测中的巨大作用和应用前景.研究中利用仿生学眼睛的功能,阐述了照亮地下的理论和方法技术,特别研究了眼睛的形觉、光觉、色觉、立体觉与地下空间探测的对比关系.最后结合研究的实测结果说明照亮地下理论的可实现性及效果.  相似文献   

津滨轻轨地磁干扰范围的实验研究   总被引：1，自引：0，他引：1  

徐学恭  田山  韩润泉  张明东  胡培元  刘学历  马义山  刘金城 《地震地磁观测与研究》2008,29(6):41-44

在塘沽地震台与津滨轻轨之间及向北延长线建立野外磁测剖面,对轻轨运营期间的磁场干扰变化进行了实测研究,并对实测结果进行了曲线拟合,得出满足规划中的地磁观测网的环境要求——在以津滨轻轨铁路为骚扰源的影响范围,地磁观测网的地磁固定观测台距轻轨铁路的距离应大于24km。  相似文献   

Weathering of granite in Antarctica: I. Light penetration into rock and implications for rock weathering and endolithic communities     

Kevin Hall  Mauro Guglielmin  Andrea Strini 《地球表面变化过程与地形》2008,33(2):295-307

Where rocks are composed of translucent minerals, light penetrates the rock and, in so doing, impacts on the thermal conditions. Where minerals are not translucent all the heat transformation must be at the rock surface, and steep thermal gradients can occur. Where light does penetrate, a component of the incoming radiation is transformed to heat at differing depths within the rock, thereby decreasing the thermal gradient. Equally, light transmissive minerals facilitate endolithic communities, which can also play a role in rock weathering. The attribute of light transmission within rock and the impact this has on the resulting thermal conditions has not been considered within rock weathering studies. An attempt was made to monitor the amount of light penetrating the outer 2 mm of coarse granite under Antarctic summer conditions and to evaluate the thermal impact of this. It was found that the amount of light penetration at this site exceeded modeled or postulated values from biological studies and that it could significantly impact the thermal conditions within the outer shell of the rock. Although the resulting data highlighted a number of flaws in the experimental procedure, sufficient information was generated to provide the first assessment of the range of thermal responses due to light transmissive minerals in rock. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

少量降水对壤中气汞量测量结果的影响     

邹长毅  史长义  张金华 《物探与化探》2000,24(6):451-454

降水是影响壤中气汞测量结果的重要因素之一。大雨或透雨过后,壤中气汞含量急剧降低,甚至使异常消失 ;降水量较小,有时会使壤中气汞含量显著浓集。  相似文献   

太阳射电IV型爆发及伴随现象与白光耀斑的关系     

谢瑞祥  汪敏 《中国天文和天体物理学报》2000,20(1)

通过1991年6月6日共生太阳白光耀斑（WLF）的射电运动IV型爆发及其伴随现象（包括耀斑后环、爆发衰减相的射电脉动、多波段射电辐射和太阳物质抛射等）观测资料的分析,定性地探讨了WLF的起源、加热机制和发射地点的问题．假设了WLF和射电运动IV型射电爆发可能有共同起源的低日冕电子加速区,讨论了WLF的能量传输可能是通过二步加速过程,即来自低日冕的非热电子沉降能量于色球层,产生色球层的压缩波或向下的辐射场进而使上光球层温度增加导致WLF此外,提出WLF可能会伴有耀斑后环和射电精细结构的对应物．  相似文献   

Prospects for detecting light echoes of galactic supernovae by wide-angle polarimetry     

I. A. Maslov 《Astronomy Letters》2000,26(7):428-432

We propose to use a global (wide-angle, of the order of several degrees) distribution of linearly polarized emission over the sky to detect light echoes of historical supernovae exploded in our Galaxy. The echo emission must be polarized tangential to the direction of the supernova explosion site, and its degree of polarization must exhibit a characteristic dependence on angular distance. The near infrared is an optimum spectral range for detection. A spotted structure in the shape of a ring ～5° in diameter and ～3° in width with a total brightness of ～12–13^m in polarized light with a tangential orientation of the electric vector must be currently seen in the direction where Tycho Brahe observed a supernova explosion in 1572. A comparison of the expected intensity of the echo with the intensities of the zodiacal light and the atmosphere shows that it can be detected in principle during long-term observations from space and, under favorable conditions, even from the ground.  相似文献   

River flow control on the phytoplankton dynamics of Chesapeake Bay     

YU Qingyun  WANG You  TANG Xuexi  LI Ming 《中国海洋大学学报(英文版)》2013,12(1):103-114

Recent observations support an emerging paradigm that climate variability dominates nutrient enrichment in costal eco-systems, which can explain seasonal and inter-annual variability of phytoplankton community composition, biomass (Chl-a), and primary production (PP). In this paper, we combined observation and modeling to investigate the regulation of phytoplankton dynamics in Chesapeake Bay. The year we chose is 1996 that has high river runoff and is usually called a ’wet year’. A 3-D physical-biogeochemical model based on ROMS was developed to simulate the seasonal cycle and the regional distributions of phytoplankton biomass and primary production in Chesapeake Bay. Based on the model results, NO3 presents a strong contrast to the river nitrate load during spring and the highest concentration in the bay reaches around 80 mmol Nm-3 . Compared with the normal year, phytoplankton bloom in spring of 1996 appears in lower latitudes with a higher concentration. Quantitative comparison between the modeled and observed seasonal averaged dissolved inorganic nitrogen concentrations shows that the model produces reliable results. The correlation coefficient r2 for all quantities exceeds 0.95, and the skill parameter for the four seasons is all above 0.95.  相似文献   

The adaptation of Arctic phytoplankton to low light and salinity in Kongsfjorden （Spitsbergen）     

CUI Shikai  HE Jianfeng  HE Peimin  ZHANG Fang  LIN Ling  MA Yuxin 《极地研究(英文版)》2012,23(1):19-24

The basic environmental variables and adaptability ofphytoplankton communities to low light and salinity were stud- ied using incubation experiments in Kongsfjorden, a high Arctic fjord of Spitsbergen, in late summer 2006. Chlorophyll a concentrations were steady or decreased slightly in darkness after one day or one week incubation. Chlorophyll a concentrations showed an initial decline when exposed to natural light after one week incubation in darkness, and then increased significantly. In a salinity experiment, the maximal growth rate was observed at a dilution ratio of 10%, however, higher dilution ratios （≥0%） had an obvious negative effect on phytoplankton growth. We suggest that the phytoplankton communities in fjords in late summer are dark- ness adapted, and the inflow of glacial melt water is favorable for phytoplankton growth in the outer fiords where the influence of freshwater is limited.  相似文献