Centennial blooming of anoxygenic phototrophic bacteria in Qinghai Lake linked to solar and monsoon activities during the last 18,000 years

The productivity of anoxygenic phototrophic bacteria (APB) can be inferred in the sediments of Qinghai Lake from the changing abundance of bacteriophaeophytin a (Bph-a). Using diffuse reflectance spectroscopy (DRS), we identified Bph-a in Qinghai Lake sediments from the late glacial period through the Holocene with a resolution of one sample every 30–50 years. The Bph-a profile of Qinghai Lake demonstrates that in the last 18,000 years APB were only present between 4.2 and 14 ka BP, a period of high rainfall and high summer solar insolation. All the APB blooming events correspond to times of enhanced freshwater influx as revealed by percent redness, an indicator of the input of iron oxide minerals. Our data suggest that solar insolation sets the stage for APB blooms, which are then promoted by increased summer monsoon rainfall and nutrients resulting in the development of a chemocline in the lake. The blooming of APB in Qinghai Lake appears as discrete centennial-scale APB events likely linked to solar activities. Our results suggest the presence of solar-induced, century-long, intense summer monsoon episodes in the middle and early Holocene and the late glacial period.     

Catchment-based imperviousness metrics impacts on floods in Niushou River basin,Nanjing City,East China

Concerns regarding urbanization impacts on floods gradually moved from end-of-pipe solutions, based on open channel hydraulics improvement, to imperviousness ratio limiting and then to land use control and to integrated planning at local and large scale levels. The Niushou River basin is one of the fastest urbanizing areas in Nanjing City, East China, however, the high urban land percentage has leaded to series of flooding events. The paper aims to reveal the impact of imperviousness ratio, patterns and drainage system on flooding areas based on the unit of catchment and Storm Water Management Model (SWMM). The following conclusions were reached. 1) The ratio or spatial characteristics of the impervious surface affected the runoff volumes and associated floods areas. Despite the well-established drainage system, the high imperviousness ratio, particularly clustered pattern in locations such as hydrological sensitive zones aggravated the flooding tension across the basin. 2) The poor drainage hydraulic efficiency in local areas, and the lack of integral processes of infiltration, yield, storage and discharge in local catchment and larger basin are also significant factors. 3) The Niushou River basin development should improve the drainage transformations from a single local, short-term drainage process into integral, elastic processes of infiltration, yield, storage, and discharge.     

峰峰煤田断裂地震识别技术及其发育规律分析

正煤矿开采过程中,断层构造是影响矿业发展的重要问题之一。如果不了解地下结构和断层的发育情况,可能会造成巨大的经济损失,甚至会导致透水等事故的发生。因此,寻找煤层中的小断层对煤矿开采具有重要意义。峰峰煤田断裂构造非常发育,本文通过地震勘探对小断层进行识别,并分析分析该地区断层发育规律,为今后该井田的煤炭勘探提供参考。     

真菌-玄武岩相互作用过程中真菌属种差异对元素释放行为的影响

真菌在矿物、岩石风化和元素溶解过程中发挥着重要作用。土壤中分布和生长着多种真菌,这些不同真菌在矿物和岩石风化,以及元素溶解过程中发挥的作用可能存在显著差异。为限定此差异,本研究从玄武岩风化土壤中分离获取了4种真菌(Aspergillus pesudofelis、Aspergillus viridinutans、Aspergillus undagawae和Aspergillus clavatus),设计批式溶解实验,探究了实验室条件下(28℃、30天内)4种真菌对玄武岩的风化作用,主要通过分析元素(包括Mg、Al、Si、Ca、Ti、Mn、Fe、Ni和Sr)的溶解速率和机制揭示不同属种真菌造成的玄武岩风化差异,并选取其中两种典型真菌所在的体系进行分析。实验结果显示不同属种真菌对玄武岩的风化和元素溶解的作用确实存在显著差异:1)与无机对照组相比,真菌A.pseudofelis的生长使得溶液pH值发生显著变化,元素的线性释放速率(Ril)显著升高;2)不同种真菌对体系pH值和Ril的影响差别巨大,且并非所有真菌均能加快玄武岩风化,如经过30天反应,含真菌A.pseudofelis体系溶液pH值上升了2.1,元素Mg的线性释放速率是无机对照组的22.5倍;而含真菌A.viridinutans体系溶液pH值仅上升了0.1,Mg的线性释放速率与无机对照组近似相等;3)Mg、Al、Ca、Ti元素的线性释放速率Ril最大值均出现在溶液最低pH值条件下,表明这4种元素的释放行为很大程度上受控于质子交换作用,而Fe和Ni的释放则由真菌代谢的草酸主导。由此可知,不同种真菌对有机酸代谢水平的差异影响了玄武岩中元素的释放行为。这也可能表明,在岩石早期风化过程中,具有较强有机酸(如草酸)代谢能力的真菌在Fe和Mg等生命必需元素的释放过程中起着重要作用。     

用卫星遥感技术进行化肥市场预测的可行性探析

利用卫星遥感技术，准确掌握一定地域范围的土壤湿润程度（即土壤墒情）、农作物长势、农作物的播种面积，再结合一定时期的降雨量和气象预报信息，比较准确的预测出市场化肥需求量，用来帮助化肥厂家制定出科学的生产和销售方案，尽可能的利用现有资源产生最大的经济效益。     

论花岗质岩浆多重侵位及其多重成矿模型

我国许多斑岩型和斑岩-矽卡岩型矿床具有“多位一体”特征,在区域上可构成矿床系列,在矿区则构戒矿床体系。本文强调这种多重成矿模型的普遍意义,提出花岗质岩浆的源岩、侵位和矿化的多重性是形成复杂多样的金属矿床的重要原因之一。重视和加强多重成矿模型研究,对于开拓找矿思路是十分有益的。     

Geological Setting of the Porphyry Copper Deposit Series of China

In accordance with the terms global minerogenic series, regional metallogenic series and ore depositsystem which are put forward here, metallogenic environments at different levels are discussed for theporphyry copper deposit series in China. It is considered that the porphyry copper deposits in China arecontrolled not only by the boundaries of convergent plates but, more importantly, by the boundaries ofintraplate divergent mobile belts and those between continental blocks. Besides, the emplacement ofhypabyssal and supper-hypabyssal calc-alkaline magmas and the temporal-spatial distribution of China'sporphyry copper deposits are governed by the superimposition of fracture systems of the pre-Alpine base-ments. Meso-Cenozoic cover and continental-margin new-born crust. Such a superimposition has also re-sulted in the polycyclicity of the mineralization.     

Impact–entrainment relationship in a saltating cloud

The problem of impact–entrainment relationship is one of the central issues in understanding saltation, a primary aeolian transport mode. By using particle dynamic analyser measurement technology the movement of saltating particles at the very near‐surface level (1 mm above the bed) was detected. The impacting and entrained particles in the same impact–entrainment process were identified and the speeds, angle with respect to the horizontal, and energy of the impacting and entrained sand cloud were analysed. It was revealed that both the speed and angle of impacting and entrained particles vary widely. The probability distribution of the speed of impacting and entrained particles in the saltating cloud is best described by a Weibull distribution function. The mean impact speed is generally greater than the mean lift‐off speed except for the 0·1–0·2 mm sand whose entrainment is significantly influenced by air drag. Both the impact and lift‐off angles range from 0° to 180°. The mean lift‐off angles range from 39° to 94° while the mean impact angles range from 40° to 78°, much greater than those previously reported. The greater mean lift‐off and especially the mean impact angles are attributed to mid‐air collisions at the very low height, which are difficult to detect by conventional high‐speed photography and are generally ignored in the existing theoretical simulation models. The proportion of backward‐impacting particles also evidences the mid‐air collisions. The impact energy is generally greater than the entrainment energy except for the 0·1–0·2 mm sand. There exists a reasonably good correlation of the mean speed, angle and energy between the impacting and entrained cloud in the impact–entrainment process. The results presented in this paper deserve to be considered in modelling saltation. Copyright © 2002 John Wiley & Sons, Ltd.     

极隙区纬度太阳活动高年背景电离层特征

本文利用 EISCAT-Svalbard 雷达1999年3月至2003年2月期间观测数据,对太阳活动高年前后极区电离层 F 区电子密度随高度和地方时的二维分布进行统计分析,研究极隙/极盖区背景电离层特征,并与 IRI-2001模式预测结果进行比较。分析结果表明,在 ESR 雷达所在纬度,不存在“冬季异常”现象;但首次发现,此处电离层冬季日变化存在磁午夜前主极大。另外,无论在什么季节,白天时段 ESR 雷达上空电子密度都在磁正午附近有一极大值。与 IRI 模式的比较表明,模式预测的 F 区电子密度与 ESR 实测结果存在较大偏差,在500km 高度以上的顶部电离层和冬季,差别尤其明显。简要讨论了软粒子沉降对造成电子密度日变化磁正午极大的作用和冬季磁午夜前主极大的形成机理。     

A wind tunnel investigation of the influences of fetch length on the flux profile of a sand cloud blowing over a gravel surface

Wind tunnel tests were conducted to examine the fetch effect of a gravel surface on the ?ux pro?le of the sand cloud blowing over it using typical dune sand. The results suggest that the ?ux pro?le of blown sand over a gravel surface differs from that over a sandy surface and is characterized by a peak ?ux at a height above the surface while that over a sandy surface decreases exponentially with height. The ?ux pro?le of a sand cloud over a gravel surface can be expressed by a Gaussian peak function: q = a + b exp (?0·5((h ? c)/d)²), where q is the sand transport rate at height h, and a, b, c and d are regression coef?cients. The signi?cance of the coef?cients in the function could be de?ned in accordance with the fetch length of the gravel surface and wind velocity. Coef?cient c represents the peak ?ux height and increases with both wind velocity and fetch length, implying that the peak ?ux height is related to the bounce height of the particles in the blowing sand cloud. Coef?cient d shows a tendency to increase with both wind velocity and fetch length. The sum of a and b, representing the peak ?ux, increases with wind velocity but decreases with fetch length. The average saltation height derived from the cumulative percentage curve shows a tendency to increase with both the fetch length and wind velocity. For any fetch length of a gravel surface the sand transport equation is expressed as Q = C(1 ? U_t/U)(ρ/g)U³, where Q is the sand transport rate, U is the wind velocity, U_t is the threshold velocity measured at the same height as U, g is the gravitational acceleration, ρ is the air density, C is a proportionality coef?cient that decreases with the fetch length of the gravel surface. At a given wind velocity, the sand transport rate over a gravel surface is only 52–68 per cent of that over a sandy surface. The ?ux rate in true creep over a gravel surface increases with wind velocity but decreases with the fetch length, whereas the creep proportion (the ratio of creep ?ux to the sand transport rate) decreases with both the wind velocity and fetch length. Two‐variable (including fetch length and wind velocity) equations were developed to predict the peak ?ux height, average saltation height and transport rate. Copyright © 2004 John Wiley & Sons, Ltd.