Is Precipitation the Dominant Controlling Factor of High Inorganic Nitrogen Content in the Changjiang River and Its Mouth？   总被引：1，自引：1，他引：0  

沈志良 《中国海洋湖沼学报》2003,21(4):368-376

The main reasons for the high content of inorganic N and its increase by several times in the Changjiang River and its mouth during the last 40 years were analysed in this work. The inorganic N in precipitation in the Changjiang River catchment mainly comes from gaseous loss of fertilizer N, N resulting from the increases of population and livestock, and from high temperature combustions of fossil fuels. N from precipitation is the first N source in the Changjiang River water and the only direct cause of high content of inorganic N in the Changjiang River and its mouth. The lost N in gaseous form and from agriculture non-point sources fertilizer comprised about 60% of annual consumption of fertilizer N in the Changjiang River catchment and were key factors controlling the high content of inorganic N in the Changjiang River mouth. The fate of the N in precipitation and other N sources in the Changjiang River catchment are also discussed in this paper.  相似文献   

FUZZY COMPREHENSIVE EVALUATION OF CONTAINER TRANSPORTATION MODES ALONG THE CHANGJIANG RIVER MAIN LINE AND ITS DELTA AREA   总被引：1，自引：0，他引：1  

ZHANGShi-yu XIAOHan-liang 《中国地理科学(英文版)》2003,13(3):259-261

The Changjiang River (Yangtze) is one of the fastest growth areas of container transportation in Chi-na. Rail, road and water transportation have competed against each other for container transportation in the Chang-jiang River main line and its delta area. It is of significance to assess these different transportation modes scientifi-cally in order to organize container transportation efficiently in this area and make decision for integral plan and construction of transportation system in this area. This paper outlines application of fuzzy comprehensive evaluation to appraise different modes of typical direction of containers. Twelve assessment indexes were decided. Membership functions were formulated. Evaluation results indicated that road transportation was optimal mode in the Changjiang River delta area, however water transportation was the primary way in the Changjiang River main line.  相似文献   

Biogenic silicate accumulation in sediments, Jiaozhou Bay   总被引：1，自引：0，他引：1  

李学刚宋金明  戴纪翠袁华茂李宁  李凤业孙松 《中国海洋湖沼学报》2006,24(3):270-277

1 INTRODUCTION Silicate, or silicic acid (H4SiO4), is a very im- portant nutrient in the ocean. Unlike other major nu- trients such as phosphate and nitrate or ammonium, which are needed by almost all marine plankton, silicate is an essential chemical req…  相似文献   

“气候跃变”对气候要素统计相关的影响     

李存强 《高原气象》1991,10(3):332-336

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Guocheng Pan  D. P. Harris 《Mathematical Geology》1991,23(6):861-886

A new multidimensional scaling (MS) technique, referred to as the Pijk model, is formulated on the basis of associations among triple objects (samples or variables), instead of pairs of objects as used in the usual MS methods, such as factor analysis. The computational scheme provided for this method is the reduction of an original problem to a standard eigenvalue-eigenvector problem. The major goal of the technique is simplification and reduction of data structures and the rescaling of original objects into a new and reduced space, so that patterns and relations of the original objects can be conventiently examined in two-dimensional factor plots. The Pïjk method is illustrated and tested by using a set of geochemical data related to the epithermal gold and silver vein deposits in the Walker Lake quadrangle of Nevada and California. The characteristics of element associations suggested in the Pijk analysis are consistent with field observations. A preliminary comparison between the new method and the ordinary factor analysis also is made on the basis of the same data set. Results are encouraging in that analysis by the Pijk model captures triple-object associations that might be missed by the ordinary factor analysis which considers only pair-variable correlations  相似文献   

Sensitivity analysis of support safety factor for predicting the effects of contributing parameters on roof falls in underground coal mines   总被引：2，自引：0，他引：2  

S.K. Palei  S.K. Das 《International Journal of Coal Geology》2008,75(4):241-247

Roof falls accounted for 18.18% of all fatal accidents in Indian coal mines, contributing about 35.29% of all fatal accidents in below-ground operations in 2005. The support safety factor, always preferred in support planning and design of underground coal mines, may be an important predictor for roof falls. In this paper, geotechnical data were collected from 14 roof fall incident places in an underground coal mine, located in the Eastern India, which has bord and pillar method of workings. The mean value of probabilistic support safety factor for the case study mine was found to be 1.24. However, the probability, of the estimated support safety factor of less than or equal to one, was found to be 0.246. Sensitivity analysis was conducted to analyze the effects of the contributing parameters on support safety factor and the likelihood of the roof fall. The multi-variate regression analysis was carried out for the data generated by Monte Carlo method to correlate the contributing factors to support safety factor. It ranked gallery width as the first parameter to control the support safety factor.  相似文献   

On the Assessment of Failure in Slope Stability Analysis by the Finite Element Method   总被引：3，自引：0，他引：3  

H. Zheng  D. F. Liu  C. G. Li 《Rock Mechanics and Rock Engineering》2008,41(4):629-639

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强降雨条件下土质边坡瞬态稳定性分析   总被引：9，自引：1，他引：8  

吴长富  朱向荣  尹小涛  刘雪梅 《岩土力学》2008,29(2):386-391

基于实际降雨气象资料,设计了单峰降雨和8个不同时间间隔的双峰降雨计算方案,利用非饱和土力学理论,对边坡的瞬态稳定性进行了计算和分析,研究了水分在坡体内的运移对边坡稳定性的时间空间影响效应,同时考察了降雨入渗造成的土性渗透特性的改变。分析发现：一次降雨的影响历时约12 d,降雨后约0.5 d该类土质边坡最危险;不同时间间隔的两次降雨对边坡稳定的影响比单峰降雨的最小安全系数滞后约0.3 d～0.8 d,影响历时基本保持不变;土体物理力学性质、边坡最危险滑动面及其对应的安全系数随水分在坡体内渗透运移而变化。  相似文献   

鲢鱼(Hypophthalmichthys molitrix)摄食强度和节律的实验研究     

王芳  董双林  李德尚  邴旭文 《中国海洋大学学报(自然科学版)》1993,(2)

报道用室内实验方法对鲢鱼摄食强度和摄食节律的研究结果,探讨了影响它们的因子。提出鲢鱼在不同水温、不同花粉密度及不同鱼规格下的摄食量的统计分析。指出:食粒密度和水温与摄食量正相关,而鱼规格与摄食量负相关;食粒密度对摄食量影响最大(P<0.01),其次为水温;水温和食粒密度在影响摄食量的过程中可能有一定的交互作用。鲢鱼摄食强度在室内条件下也具明显的昼夜节律。在食粒规格较小、密度较低且溶氧充足条件下,鲢鱼夜晚非但不停食且出现摄食率次高峰。在本实验条件下,鲢鱼的日摄食节律与水温和光照无关,可能受饵料可得性和自身的生物钟节律等制约。  相似文献   

南黄海灾害地质因素及分区     

陆凯  宋召军 《海洋地质前沿》2005,21(7):9-12

尝试性地将南黄海灾害地质因素分为4大类。同时参考地貌沉积界线和其他因素将南黄海分成4个灾害地质区：即海岸带、苏北浅滩、海州湾和南黄海东部灾害地质区，并时各灾害地质区进行了定性评价，苏北浅滩灾害地质区是研究区内灾害地质环境最不稳定的区域。  相似文献