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101.
原生高碘地下水在我国有广泛分布,为查明不同区域地下水碘赋存机理的异同,通过选取我国大同盆地以及华北平原为代表性区域,完成区域地下水样品系统性采集及水化学、碘形态测试工作,对区域地下水水环境及其演化特征完成详细刻画.结果表明:大同盆地地下水总碘含量为2.86~1 286 μg/L,华北平原地下水总碘含量为2.40~1 106 μg/L,分别约有50.0%及49.5%地下水碘含量超过(GB19380- 2016)《水源性高碘地区和高碘病区的划定》中界定的100 μg/L国家标准.地下水水环境特征表明,在大同盆地,第四纪河湖相沉积所形成的,富含有机质、偏碱性、还原性、Na-HCO3型水环境,利于赋存于固相介质上的碘以碘离子的形式进入地下水中,沿地下水流向,富集于盆地中心排泄区;在华北平原,由第四纪6次海侵形成的冲湖积、海积松散沉积物中富含Na、Cl、I等元素,其偏碱性、还原性、Na-Cl型水环境及低水力坡度的平缓地形利于赋存在固相介质上的碘以碘离子的形式进入地下水,沿地下水流向富集于沿海排泄区.控制两个地区高碘地下水形成的相同因素是偏碱性及偏还原的地下水环境,且该环境下碘的主要赋存形态均为碘离子,但大同盆地高碘地下水形成主要受富有机质环境影响,而华北平原高碘地下水形成的主要受富碘的海相沉积控制.   相似文献   
102.
张弛  王本德  李伟 《水文》2007,27(2):74-77,85
数据挖掘作为知识发现过程中的重要步骤,是从大型数据库中提取未知的、有价值的和可操作性的关系、模式和趋势用于决策支持的过程。我国目前在防洪领域存在着大量水文数据,如何充分有效地利用各种智能算法对这些数据进行分析与挖掘,以形成相应的水文预报模型进行准确的水文预报是防洪决策支持系统完善和发展的重要方面。本文首先全面地介绍数据挖掘的功能分类及以数据挖掘为基础的水文预报体系,然后对数据挖掘技术在水文预报中的应用进行了探讨和研究。  相似文献   
103.
本文以红外细分波段新疆铁木尔特航带为例,依据不同地质体各自的光谱特征,运用主成分分析、多种信息复合等技术与综合分析方法,使该地段的矿化特征提取收到了良好效果。 本航带的矿化特征信息在图像处理结果中表现为黄色异常色调。它反映了当地多金属成矿带中二氧化硅含量低、全铁含量较高的岩矿矿化特征。团块状黄色异常色调表示出地表出露的铁帽、磁铁矿化和矽卡岩化的分布状况。野外验证表明,黄色调的分布地域与实地的地表矿化范围相吻合。 遥感特征信息提取的综合分析方法包括信息基本特征分析、图像处理、后验分析和机理解释等四个相互联系的步骤。研究表明,只有经过综合分析,才能揭示出特征信息的内在规律性,使特征信息具有较好的实用价值。  相似文献   
104.
对蚌埠地震台测震数据中的干扰信号进行分析,并对其进行滤波处理,结果表明,根据干扰源特性分别设计相应的滤波器,能够解决台站测震数据受到的干扰,达到了预期的效果。  相似文献   
105.
The status of a fishery is often defined as the probability of fishing mortality rate exceeding a perilous level for long‐term sustainability. Lobster stock assessments are often subject to large uncertainty in input data and high levels of natural variability in lobster life history processes, which calls for incorporating uncertainty associated with both indicator and management reference points in an evaluation of biological risk of overfishing. Using a Monte Carlo simulation approach, we evaluated the impacts of uncertainty in modelling on the determination of the status of the Taitung spiny lobster (Panulirus penicillatus) fishery (Taiwan), which has not been quantitatively determined despite its commercial importance. The commonly used biological reference points derived from the per recruit model (F 0.1 the fishing mortality rate where the slope of the curve of yield‐per‐recruit model is 10% of the maximum slope and F 4Q%, the fishing mortality rate that reduces the expected egg production for a cohort of female lobsters to 40% of that produced in the absence of a fishery of the egg‐per‐recruit model) were influenced by uncertainties associated with lobster life history and fishery parameters. A large uncertainty in the current fishing mortality rate (F cnr) and estimates of biological reference points (F BRPs) increased the uncertainty in determining the risk of overexploitation throughout the confidence levels of the stochastic decision‐making framework. This simulation study suggests that the target reference point of F 40% is less sensitive to the input parameters’ uncertainty than F 0.1 We suggest a further evaluation of other F‐based references points and development of biomass‐based reference points before final selection and implementation for the management of the Taitung lobster fishery.  相似文献   
106.
The response of phytoplankton assemblage structure to terrestrial nutrient inputs was examined for the Gulf of Kalloni in the Northern Aegean Sea, a productive semi-enclosed coastal marine ecosystem. The study was focused on a typical annual cycle, and emphasis was placed on the comparative analysis between blooms developing after significant nutrient inputs from the watershed, and naturally occurring blooms. Baseline information was collected on a monthly basis from a network of stations located in the oligotrophic open sea and the interior and more productive part of the embayment. Intensive sampling was also carried out along a gradient in the vicinity of a river which was the most important source of freshwater and nutrient input for the Gulf. Phytoplankton assemblage structure was analyzed from 188 samples using diversity indices (Shannon and Average Taxonomic Distinctness), multivariate plotting methods (NMDS), multivariate statistics (PERMANOVA), and canonical correspondence analysis (CCA). Three characteristic assemblages were recognized: (1) an autumn assemblage developed under nutrient depleted conditions, having low diversity due to the dominance of two small diatoms, (2) a winter bloom of the potentially toxic species Pseudo-nitzschia calliantha occurring immediately after a nutrient peak and characterized by very low diversity, and (3) a naturally occurring early summer bloom of centric diatoms with relatively high diversity. The results of the study support the view that moderate nutrient inputs may have a beneficial effect on the functioning of coastal ecosystems, stimulating the taxonomic diversity through the growth of different taxonomic groups and taxa. On the other hand, a sudden pulse of high nutrient concentrations may greatly affect the natural succession of organisms, have a negative effect on the diversity through the dominance of a single species, and can increase the possibility of a harmful algal bloom development.  相似文献   
107.
区域精密水准测量在地震监测中发挥了重要的作用,但是由于其作业范围广、观测周期长,容易受外界复杂多变的环境因素影响。目前对环境因素的影响分析大多是定性描述,缺乏实验观测数据的支撑。针对这一问题,选取大约2000km区域精密水准观测数据,结合观测环境资料,统计分析不同环境因素对观测成果的影响程度,并提出了相应的改进措施。  相似文献   
108.
109.
The research on diagenesis of clastic-rock reservoir is developing rapidly in recent ten years. Thus, it is of great significance in academic and scientific exploration to summarize the domestic and international research progress and the key issues of frontier research on diagenesis. The research progress, main achievement and recognition in diagenesis of clastic-rock reservoirs in recent years is discussed, and the hot issues or developing trend of diagenesis in the future is probed in this paper, on the basis of summarizing the previous research results and understanding, combined with the typical research examples at home and abroad. It is believed that great progress was obtained in provenance and parent rock constraints on sandstone types and their diagenetic evolution pathways, impact of fluid-rock interaction and its product on diagenesis, influence of thermodynamics and overpressure background on diagenesis and pore development, the timing sequence between hydrocarbon accumulation and filling process and the sandstone reservoir becoming low permeability-densification. At present, diagenetic research is developing in direction of the spatial and temporal dynamics and quantitative evolution mechanistic and diagenetic system controlled by the basin fluid dynamics, thermal dynamic processes, combining the micro-scale diagenesis research with the basin macroscopic background such as sedimentation from the source to the basin, burial history, hydrocarbon maturity and charge into reservoirs, tectonic evolution and fluid activity, and fluid and rock interaction.The aim of this paper is to induce the academic peers and experts in diagenesis and the related research fields to come forward with their valuable contributions, to cooperate and work together and joint efforts on the research exquisite, profundity and breadth of diagenesis, and application of the most advanced analytical measurement techniques and methods, as well as integration and infiltration of multidisciplinary, in order to promote the course of the clastic-rock reservoir diagenetic research in China.  相似文献   
110.
A probabilistic precipitation forecasting model using generalized additive models (GAMs) and Bayesian model averaging (BMA) was proposed in this paper.GAMs were used to fit the spatial-temporal precipi...  相似文献   
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