Emission line redshift distribution of QSOs

This paper is the second one of a series of papers on the redshift distribution of QSOs. In this paper, we shall study the influence of the selection effect in the identification of emission lines on the redshift distribution of QSOs more thoroughly than the previous paper (Zhouet al., 1983). If we assume that the QSO's redshift is cosmological, adopt the standard model, and consider the selection effect due to the redshift identification, the limiting apparent magnitude in the observation and the evolutionary effect of QSOs, we can compute the emission line redshift distribution for the so-called optically selected QSOs discovered by objective prism, grating prism technique alone, the QSOs discovered by positional methods or by colour technique and for whole QSOs, respectively (see Figures 6, 11, 12). The results of computation agree with the observations very well, especially for optically selected QSOs; the computational distribution has almost the same shape with the observational one. For this kind of the QSOs the computational distribution may give the positions and heights of all these observed peaks. The correlation coefficient between the calculated and observed distributions is larger than 0.95. It shows that (a) the peaks and dips in the redshift distribution of QSOs are mainly caused by the selection effect in the redshift identification, and (b) the redshift of QSOs is cosmological.     

Distinct climate change synchronous with Heinrich event one, recorded by stable oxygen and carbon isotopic compositions in stalagmites from China

Uranium-series dating of oxygen and carbon isotope records for stalagmite SJ3 collected in Songjia Cave, central China, shows significant variation in past climate and environment during the period 20-10 ka. Stalagmite SJ3 is located more than 1000 km inland of the coastal Hulu Cave in East China and more than 700 km north of the Dongge Cave in Southwest China and, despite minor differences, displays a clear first-order similarity with the Hulu and Dongge records. The coldest climatic phase since the Last Glacial Maximum, which is associated with the Heinrich Event 1 in the North Atlantic region, was clearly recorded in SJ3 between 17.6 and 14.5 ka, in good agreement in timing, duration and extent with the records from Hulu and Dongge caves and the Greenland ice core. The results indicate that there have been synchronous and significant climatic changes across monsoonal China and strong teleconnections between the North Atlantic and East Asia regions during the period 20-10 ka. This is much different from the Holocene Optimum which shows a time shift of more than several thousands years from southeast coastal to inland China. It is likely that temperature change at northern high latitudes during glacial periods exerts stronger influence on the Asian summer monsoon relative to insolation and appears to be capable of perturbing large-scale atmospheric/oceanic circulation patterns in the Northern Hemisphere and thus monsoonal rainfall and paleovegetation in East Asia. Climatic signals in the North Atlantic region propagate rapidly to East Asia during glacial periods by influencing the winter land-sea temperature contrast in the East Asian monsoon region.     

Occurrence and evolution of the Xiaotangshan hot spring in Beijing, China

Thermal groundwater occurs in bedrock aquifers consisting of the dolomite of the Wumishan Group of the Jixianin System and the Cambrian carbonate in the Xiaotangshan geothermal field near the northern margin of the North China Plain, China. The hot water in the geothermal field of basin-type discharges partly in the form of the Xiaotangshan hot spring under natural conditions. The hot water has TDS of less than 600 mg/L and is of Na·Ca-HCO₃ type. The geothermal water receives recharge from precipitation in the mountain area with elevation of about 500 m above sea level to the north of the spring. Thermal groundwater flows slowly south and southeast through a deep circulation with a residence time of 224 years estimated with the Ra–Rn method. The Xiaotangshan hot spring dried up in the middle of the 1980s owing to the increasing withdrawal of the hot water in the geothermal field in the past decades. The water level of the geothermal system still falls continually at an annual average rate of about 2 m, although water temperature changes very little, indicating that the recharge of such a geothermal system of basin-type is limited. Over-exploitation has a dramatic impact on the geothermal system, and reduction in exploitation and reinjection are required for the sustainable usage of the hot water.     

Application of MODFLOW and geographic information system to groundwater flow simulation in North China Plain, China

MODFLOW is a groundwater modeling program. It can be compiled and remedied according to the practical applications. Because of its structure and fixed data format, MODFLOW can be integrated with Geographic Information Systems (GIS) technology for water resource management. The North China Plain (NCP), which is the politic, economic and cultural center of China, is facing with water resources shortage and water pollution. Groundwater is the main water resource for industrial, agricultural and domestic usage. It is necessary to evaluate the groundwater resources of the NCP as an entire aquifer system. With the development of computer and internet information technology it is also necessary to integrate the groundwater model with the GIS technology. Because the geological and hydrogeological data in the NCP was mainly in MAPGIS format, the powerful function of GIS of disposing of and analyzing spatial data and computer languages such as Visual C and Visual Basic were used to define the relationship between the original data and model data. After analyzing the geological and hydrogeological conditions of the NCP, the groundwater flow numerical simulation modeling was constructed with MODFLOW. On the basis of GIS, a dynamic evaluation system for groundwater resources under the internet circumstance was completed. During the process of constructing the groundwater model, a water budget was analyzed, which showed a negative budget in the NCP. The simulation period was from 1 January 2002 to 31 December 2003. During this period, the total recharge of the groundwater system was 49,374 × 10⁶ m³ and the total discharge was 56,530 × 10⁶ m³ the budget deficit was −7,156 × 10⁶ m³. In this integrated system, the original data including graphs and attribution data could be stored in the database. When the process of evaluating and predicting groundwater flow was started, these data were transformed into files that the core program of MODFLOW could read. The calculated water level and drawdown could be displayed and reviewed online.     

Origin of Fe-Ti Oxide Ores in Mafic Intrusions: Evidence from the Panzhihua Intrusion, SW China

Economic concentrations of Fe–Ti oxides occur as massive,conformable lenses or layers in the lower part of the Panzhihuaintrusion, Emeishan Large Igneous Province, SW China. Mineralchemistry, textures and QUILF equilibria indicate that oxidesin rocks of the intrusion were subjected to extensive subsolidusre-equilibration and exsolution. The primary oxide, reconstructedfrom compositions of titanomagnetite in the ores and associatedintergrowths, is an aluminous titanomagnetite (Usp₄₀) with 40wt % FeO, 34 wt % Fe₂O₃, 16·5 wt % TiO₂, 5·3 wt% Al₂O₃, 3·5 wt % MgO and 0·5 wt % MnO. This compositionis similar to the bulk composition of the oxide ore, as inferredfrom whole-rock data. This similarity strongly suggests thatthe ores formed from accumulation of titanomagnetite crystals,not from immiscible oxide melt as proposed in earlier studies.The occurrence of oxide ores in the lower parts of the Panzhihuaintrusion is best explained by settling and sorting of densetitanomagnetite in the ferrogabbroic parental magma. This magmamust have crystallized Fe–Ti oxides relatively early andabundantly, and is likely to have been enriched in Fe and Tibut poor in SiO₂. These features are consistent with fractionationof mantle-derived melts under relatively high pressures (10kbar), followed by emplacement of the residual magma at 5 kbar.This study provides definitive field and geochemical evidencethat Fe–Ti oxide ores can form by accumulation in ferrogabbro.We suggest that many other massive Fe–Ti oxide depositsmay have formed in a similar fashion and that high concentrationsof phosphorus or carbon, or periodic fluctuation of fO₂ in themagma, are of secondary importance in ore formation. KEY WORDS: ELIP; Fe–Ti oxide ore; layered intrusion; Panzhihua; QUILF     

The state of land subsidence and prediction approaches due to groundwater withdrawal in China

This article gives a general introduction to land subsidence with the prediction approaches due to withdrawal of groundwater in three subsided/subsiding regions in China: the deltaic plain of Yangtse River (YRDP), North China Plain (NCP), and Fenwei Plain (FP). On YRDP, Shanghai is the typical subsided/subsiding city; on NCP Tianjin is the typical subsided/subsiding city, and on FP Taiyuan is the typical subsided/subsiding city. The subsided area with subsidence over 200 mm on YRDP is about 10,000 km² and the maximum subsided value reached 2.9 m at Shanghai; on NCP the subsided area reached 60,000 km² with the maximum subsidence of 3.9 m at Tianjing; on FP the subsided area is relatively smaller than that on the other two plains and is about 1,135 km² with maximum subsidence of 3.7 m at Taiyuan city. In order to protect the civil and industrial facilities, it is necessary to predict the future development of land subsidence based on present state. Many researchers proposed several approaches to predict the land subsidence due to groundwater withdrawal according to different geological conditions and groundwater withdrawal practice. This article classifies these approaches into five categories: (i) statistical methods; (ii) 1D numerical method; (iii) quasi-3D seepage model; (iv) 3D seepage model; (v) fully coupled 3D model. In China, the former four categories are presently employed in the prediction practice and their merits and demerits are discussed. According to the prediction practice, 3D seepage model is the best method presently.     

厦门湾沉积物中有害有毒甲藻休眠孢囊及塔玛亚历山大藻的潜在危害

本工作通过分析厦门湾表层沉积物中的甲藻休眠孢囊，发现了1种有毒塔玛亚历山大藻(Alexandrium tamarense)休眠孢囊，及两种有害甲藻休眠孢囊：锥状斯氏藻(Scrippsiella trochoidea)、具刺膝沟藻(Gonyaulax spinifera)．对塔玛亚历山大藻进行了培养。并初步研究了该藻的毒性及贝类对其毒素的积累．研究结果表明，厦门海域沉积物中的塔玛亚历山犬藻是有毒的．它的较适宜生长环境条件是：水温20～25℃．盐度为25～30，光照度为3000～50001x．塔玛亚历山大藻在每年的4月26日至6月10日、10月11日至11月20日可能会形成有害藻华，危害厦门海域的海洋生物并可能威胁到人类的健康和生命安全．     

南海大鹏湾夜光藻种群在其生态群落中的地位和功能

分析了１９９１年上半年南海大鹏湾盐田水域夜光菏和浮游动、植物之间的种群动态关系，结果表明，在春季高峰期３月至５月初，调查海域共出现１２个夜光藻和浮游动、植物高峰。其中，以发生４次赤潮的夜光藻种群占主导地位，其次是枝角类的鸟啄尖头蚤，其最高数量高达９６２３８ｉｎｄ／ｍ＾３。相比之下，在夜光藻和枝角类岛啄尖头捕食压力的影响下，浮游植物的春季高峰并不显著。调查结果表明夜光藻的过度繁殖，不但对产浮游性卵的     

Studies on the distribution and antibacterial properties of Streptomyces in the intertidal zone of Southern Fujian

The oceans have rich resources of microbes. In recent years, searching for antibiotic of new structure and special biological activity from marine microbes has received great attention. This paper reports the results of the studies on the distribution and the antibacterial properties of Streptomyces in the intertidal zone of Southern Fujian. These studies have important significance to further investigate     

Application of Monte-Carlo statistical experiments in design of ocean engineering——Estimating the parameters, models and probabilities

Recently, some results have been acquired with the Monte- Carlo statistical experiments in the design of ocean en gineering. The results show that Monte-Carlo statistical experiments can be widely used in estimating the parameters of wave statistical distributions, checking the probability model of the long- term wave extreme value distribution under a typhoon condition and calculating the failure probability of the ocean platforms.