Effects of an Artificial Breakwater on the Distributions of Planktonic Microbial Communities

The summer distributions of planktonic microbial communities (heterotrophic and phtosynthetic bacteria, phtosynthetic and heterotrophic nanoflagellates, ciliate plankton, and microphytoplankton) were compared between inner and outer areas of Lake Sihwa, divided by an artificial breakwater, located on the western coast of Korea, in September 2003. The semienclosed, inner area was characterized by hyposaline surface water (<17 psu), and by low concentrations of dissolved oxygen (avg. 0.4 mg L¹) and high concentrations of inorganic nutrients (nitrogenous nutrients >36 μM, phosphate <4 μM) in the bottom layer. Higher densities of heterotrophic bacteria and nanoflagellates also occurred in the inner area than did in the outer area, while microphytoplankton (mainly diatoms) occurred abundantly in the outer area. A tiny tintinnid ciliate, Tintinnopsis nana, bloomed into more than 10⁶ cells L¹ at the surface layer of the inner area, while its abundance was much lower (10³-10⁴ cells L¹) in the outer area of the breakwater. Ciliate abundance was highly correlated with heterotrophic bacteria (r = 0.886, p < 0.001) and heterotrophic flagellates (r = 0.962, p < 0.001), indicating that rich food availability may have led to theT. nana bloom. These results suggest that the breakwater causes the eutrophic environment in artificial lakes with limited flushing of enriched water and develops into abundant bacteria, nanoflagellates, and ciliates.     

开合旋构造体系及其形成机制探讨:兼论板块构造的动力学机制

开合构造总体上可以表述为:地球膨胀为开,收缩为合;垂向上地球物质离心(地心)运动为开,向心运动为合;水平方向上地球物质相背运动为开,相向运动为合。从驱动机制角度,我们把以热力(热能)为主体驱动的上浮物质运动定义为开;将重力(势能)为主体驱动的下沉物质运动定义为合。因此,开与合是一个高度综合的概念,具有广阔的内涵,开合运动是联系一切地质运动和地质科学的纽带。开合运动具有同步统一性,即垂向的开在水平方向也表现为开;垂向开得强烈,水平方向同样开得强烈,反之亦然。地球刚形成时诸多开合构造是无序的,地球的旋转运动统领地球上所有物质、能量、运动和大大小小的各种开合构造于旋转运动中,并将它们调剂到有序状态。简言之开合构造体系是开合旋运动长期作用下形成的不同时期、不同层次、不同级别的开合旋回组成的动态平衡构造体系。本文总结了地球开合旋构造体系物质组成、结构构造特征和规律,建立了开合旋复杂构造体系简要模型。提出平衡体系的形成机制是开合旋运动遵循地球重力均衡准则、最小内能原理(结晶化)、几何淘汰生长(垂直地心生长)和物质均匀化四条自然演化规律,其中重力均衡准则是主导的。由于地质事件(构造运动)在破坏开合旋平衡体系的同时,经常直接或间接向体系内输入新能量,往往使新的旋回比老旋回的结构构造更符合地质演化的自然规律,于是使地球显得更强大而有活力。这一次又一次的地质事件(构造运动)是开合旋构造体系螺旋式向前发展的动因。本文最后用开合构造观点探讨了地球的形成和演化,分析了板块构造运动的动力学过程。     

汇流计算中若干问题的述评

本文概述了坡面汇流与河道汇流计算中的简化模型,重点讨论了流域汇流计算问题,笔者认为,坡面汇流与河道汇流计算方法相对成熟,以系统分析理论为基础的汇流计算数学模型的研究重点似可转向参数的合理定量与地区综合,以及区间汇流与局部汇流计算方面:汇流非线性现象很复杂,要充分注意非线性向线性转化的条件;地貌单位线正在得到迅速的发展,可能成为解决短缺水文资料地区水文计算与进行小河站网规划的又一途泾;今后汇流计算研究应更多地重视干旱与半干旱地区.     

Interdecadal change in North Korean winter mean rainfall

In the present study, it was found that there was a significant climate regime shift in 1993 from average rainfall amounts in winter (December of a year and January and February of the next year) in North Korea over the last 30 years (1982–2011). This significant climate regime shift in 1993 also appeared in empirical orthogonal function analysis conducted using the winter mean rainfall amounts observed at 26 weather observation stations in North Korea. The reason why winter mean rainfall amounts in North Korea were smaller during the period of 1994–2011 than during the period of 1982–1994 was that anomalous anticyclone was reinforced in regions near Lake Baikal while anomalous cyclone was reinforced on the sea on the east of Japan so that the winter pressure system pattern (west high-east low pattern) appeared and thus anomalous cold and dry northerlies were reinforced in most East Asian regions including North Korea. To figure out the reason why anomalous anticyclone was reinforced further in the East Asian continent in winters during the period of 1994–2011, differences in water equivalent of accumulated snow depths between the two periods were analyzed. As a result, more snow was observed in most East Asian regions during the period of 1994–2011. Therefore, anomalous anticyclone could be further reinforced in the East Asian continent because surface air temperature dropped further due to snow-albedo effect. The surface air temperature cooling deepened further in the East Asian continent during the period of 1994–2011 due to snow-albedo effect was identified through differences in sensible heat net flux between the two periods.     

Black carbon and polycyclic aromatic hydrocarbons (PAHs) in surface sediments of China’s marginal seas

This study investigates the distribution of black carbon (BC) and its correlation with total polycyclic aromatic hydrocarbons (ΣPAH) in the surface sediments of China’s marginal seas. BC content ranges from <0.10 to 2.45 mg/g dw (grams dry weight) in the sediments studied, and varied among the different coastal regions. The Bohai Bay sediments had the highest BC contents (average 2.18 mg/g dw), which comprises a significant fraction (27%–41%) of the total organic carbon (TOC) preserved in the sediments. In ...     

Characteristics of Spatial and Temporal Variations of Monthly Mean Surface Air Temperature over Qinghai-Tibet Plateau

1 Introduction The Qinghai-Tibet Plateau, known as the highest plateau with the most complex topography in the world, covers an area of more than 200km2, with a mean elevation of more than 4000m a.s.l. (Ye and Gao, 1979). Surrounded by the Earth’s highest mountains, such as the Himalayas, Pamir, Kunlun Mountains, the plateau plays a significant role in climate change in China even in the world, thus attracted great attention of researchers. Up to now, many achievements have been gained by…     

An explanation for 13 consecutive day activities of Mrk 421

It is surprising to find an instance of migration in the peak positions of synchrotron spectral energy distribution components during the activity epochs of Markarian 421(Mrk 421),accompanying an orphan flare at the X-ray and GeV-TeVγ-ray bands.A geometric interpretation and standard shock or stochastic acceleration models of blazar emission have difficulty reproducing these observed behaviors.The present paper introduces a linear acceleration by integrating the reconnection electric field into the particle transport model for the observed behaviors of Mrk 421.We note that strong evidence for evolution in characteristic of multi-wavelength spectral energy distribution including shifting the peak frequency,accompanying an orphan flare at the X-ray and GeV-TeVγ-ray bands provides an important electrostatic acceleration diagnostic in a blazar jet.Assuming suitable model parameters,we apply the results of the simulation to the 13-day flaring event in March 2010 of Mrk 421,concentrating on the evolution of multiwavelength spectral energy distribution characteristic by shifting the peak frequency.It is clear that the ratio of the electric field and magnetic field strength plays an important role in temporal evolution of the peak frequency of synchrotron spectral energy distribution component.We suggest it is reasonable that the electrostatic acceleration is responsible for the evolution of multi-wavelength spectral energy distribution characteristic by shifting the peak frequency.Based on the model results,we assert that the peak frequency of the synchrotron spectral energy distribution component may signify a temporary characteristic of blazars,rather than a permanent one.     

From brightening to dimming in sunshine duration over the eastern and central Tibetan Plateau (1961–2005)

The Tibetan Plateau (TP) with an average elevation of over 4,000 m asl is the highest and most extensive highland in the world. We used monthly mean sunshine duration from the Chinese Meteorological Administration to examine the spatial and temporal variability of sunshine duration at 71 stations with elevations above 2,000 m asl in the eastern and central TP during the 1961–2005 period. The temporal evolution of the mean annual sunshine duration series shows a significant increase from 1961 to 1982 at a rate of 49.8 h/decade, followed by a decrease from 1983 to 2005 at a rate of ?65.1 h/decade, with an overall significant decrease at a rate of ?20.6 h/decade during the whole 1961–2005 period, which is mainly due to the summer and spring seasons. This confirms the evidence that sunshine duration in the TP ranges from brightening to dimming in accordance with sunshine duration trends in the rest of China. The surface solar radiation downwards from ERA-40 reanalysis data in the same region confirms the brightening/dimming phenomenon shown by the sunshine duration before/after the 1980s. Otherwise, additional climatic variables such as low cloud amount, total cloud amount, precipitation, relative humidity and water vapor pressure, in most cases, exhibit significant negative correlation with sunshine duration in the TP on an annual and seasonal basis before and after 1982, respectively. The trends of these variables suggest that changes in some of them might be related to the brightening and dimming detected with the use of sunshine duration measurements over the TP. We also hypothesize that the impact of anthropogenic aerosols upon the climatic variables analyzed cannot be rejected, especially in the significant increase in low cloud cover since approximately 1980.     

五河杂岩的变质岩石学及P-T条件分析钻孔的研究

五河杂岩是华北克拉通东部陆块东南缘最重要的岩石单元。然而,直至今日,人们对于该组杂岩一直缺乏足够的研究,特别是对于其形成的变质条件分歧较大。本文通过对蒙城南ZK02钻孔中五河杂岩的构成和地质特征详细研究表明五河杂岩分为上、下两段。上段主要为一套由云母片岩、大理岩和花岗片麻岩组成的变质表壳岩系,下段为一套基性变质岩,主要岩性为斜长角闪岩、角闪岩、石榴斜长角闪岩和少量的混合岩。同时,针对下段特征岩石（石榴斜长角闪岩）,进行了较为详细的岩相学和矿物化学分析,并应用不同的温压计进行P-T条件评价和比较,结合岩相学限定和前人的研究成果,认为五河杂岩的主体普遍经历了高压角闪岩相变质作用,其温压范围为：T=671 ℃～700 ℃和P=0.82～0.95 GPa,地温梯度约为25～28 ℃/km,与典型陆壳地温梯度类似。与同邻区主要岩石单元的变质级别相比,五河杂岩应当形成于板内变质环境,并不具备造山带变质特征。     

黑河出山径流量年际变化特征和趋势研究

根据有关水文气象台站的观测数据,利用定级分类,滑动平均和波谱分析等方法,对黑河出山径流（莺落峡水文站）年际变化特征进行了分析研究,发现黑河出出径流的多年变化具有持续性,周期性和丰枯水变化较平稳,波幅不大等特性,并在此基础上对其未来变化的趋势进行了预测和分析。