Assessment of marine pollution in Daya Bay, South China： Nutrients, heavy metals and persistent organic pollutants     

《中国地球化学学报》2006,25(B08):166-166

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Effect of particles on the photodegradation of PAHs in natural waters-A case study for the Yellow River     

Xinghui XIA 《中国地球化学学报》2006,25(B08):263-263

Photodegradation of chrysene, benzo （a） pyrene and benzo （g, h, i） perylene in natural water of the Yellow River was studied using simulation sunlight. The effects of particulates on the photodegradation were explored. Several results arose from this study. （1） The photodegradation of PAHs can be fitted with first-order kinetics when no particulate exists in water system, and the first-order constant increases with decreasing of initial concentration of PAHs. The photodegradation rates of the three PAHs are related to their molecule absorption spectrum. （2） The existence of loess exerts two kinds of effects on the photodegradation of PAHs, including the inner filter effects and the photosensitizing effects of humic substance in loess. These two contrary effects lead to the difference of net effects among different contents of loess. When the loess contents are 0.1 and 5.0 g/L, the existence of loess stimulates the photodegradation of chrysene, benzo （a） pyrene. When the loess content is 5.0 g/L, the existence of loess stimulates the photodegradation of benzo （g, h, i） perylene. In addition, the photodegradation of PAHs can be fitted with the second-order kinetics when there is loess in the water system. （3） The soluble humic substances in loess can accelerate the photodegradation of PAHs while the in soluble part cannot. （4） Since the soluble humic substances in the suspended solids of the river have been dissolved in water,  相似文献   

大别山东部花岗岩类的稀土元素地球化学及其地质意义   总被引：1，自引：0，他引：1  

胡雄星  马东升 《矿产与地质》2002,16(6):321-326

在研究大别山东部主要花岗岩体的稀土元素地球化学特征、稀土元素配分型式的基础上 ,探讨了花岗岩体的物质来源、成岩模式及其构造意义。研究表明 :(1)大别山东部出露的主要花岗岩类岩体的物质来源基本相同 ,且源区具有古岛弧的特征 ;(2 )各岩体的成岩模式呈现以分离结晶作用为主的特征 ;(3)花岗质岩浆上侵的构造环境与中国东部燕山期构造转折的大背景有关。伸展拉张过程造成的地幔上涌不但是花岗岩类形成的构造条件 ,也对超高压变质岩的快速折返有重要影响。  相似文献   

MODELING THE FATE AND TRANSPORT OF HYDROPHOBIC ORGANIC COMPOUNDS IN AN UNSTEADY RIVER-ESTUARINE SYSTEM     

Su-Chin CHEN  Jan-Tai KUO 《国际泥沙研究》2002,17(3)

1 INTRODUCTION Extensive literature (Brown et al., 1985; Sawhney et al., 1981; Bierman and Swain, 1982; Connolly, 1980; Lopez-Avila and Hites, 1980; O扖onnor, 1988) described lots of sorbed pollutants or toxic substances in bed sediments of rivers, even after the effluent was halted for a long time. This is particularly true for hydrophobic organic compounds that can be sorbed on the particles and accumulated in the river bed sediments (Karickhoff et al., 1979). Pollution events of…  相似文献   

数字化射线照相技术对轻物质的判断     

韩裕生  罗娅  丁厚本  邵立康  廖南  朱平安 《CT理论与应用研究》2002,11(1):10-12

本文介绍了数字化射线照相技术对轻物质进行判断的方法。经实践证明，该方法是合理和有效的，可大大增强对轻物质的识别能力，是一种非常可行的识别技术。  相似文献   

平原河网区域来水组成原理   总被引：1，自引：0，他引：1  

朱琰  陈方  程文辉 《水文》2003,23(2):21-24

对于一般树状分布河网，上一级河道总是汇入至下一级河道，位于河道下游断面的流量总是由其上游汇集而至。但对于平原河网地区，特别是人工控制建筑物众多，又受潮汐影响的地区(如太湖流域)，河网错综复杂，水流方向不定，要跟踪某个断面的水流去向，或某个河段的水体、断面流量是从哪里汇集而来的，非常困难。但这样的问题在生产实践中往往对其很感兴趣。例如从常熟枢纽引长江水流进入望虞河后，流向何处?河网各断面流量中或各河段水体中常熟枢纽引江水量占多少比重?对这些问题的研究可以估计常熟枢纽引江的效果和影响范围。因此，平原河网区域来水组成方法在生产实践中具有重要意义。重点介绍了平原河网区域来水组成原理及其在太湖流域的应用。  相似文献   

射线透射图像中轻物质自动识别算法的研究     

邵立康  易素君  韩裕生  秦晓燕  丁厚本  沈建华  许小明 《CT理论与应用研究》2003,12(4):1-4

目的：针对射线透射图像中轻物质的自动识别存在的难点问题进行研究。方法：提出了基于轮廓特征和灰度特征的识别算法，结果：详细地阐述了利用识别算法进行识别的过程；结论：给出了识别算法的实验结果。  相似文献   

岩盐及芒硝中各种化合物质量分数的计算     

孙周易  唐淑云 《矿物岩石》1996,16(1):101-103

本文以等物质的量的反应规则建立了岩盐、芒硝中各种化合物的质量分数的计算公式。这些公式既符合法定计量单位的要求，又方便计算。  相似文献   

Fresh and saline groundwater interaction in coastal aquifers: Is our technology ready for the problems ahead?     

V. E. A. Post 《Hydrogeology Journal》2005,13(1):120-123

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Salinisation des nappes côtières : cas de la nappe nord du Sahel de Sfax,Tunisie     

Rouaida Trabelsi  Moncef Zaïri  Habib Smida  Hamed Ben Dhia 《Comptes Rendus Geoscience》2005,337(5):515-524

The intensive agricultural and economic activities induce the increase of the risk of groundwater quality degradation through high groundwater pumping rates. The salinization and contamination are the main sources of this pollution, especially in coastal aquifers. The explanation of the origin of salinity for the shallow aquifer of Northern Sahel of Sfax was analysed by a chemical study of the groundwater main compounds. The partitioning of groundwaters into homogenous groups is undertaken by graphical techniques, including a Stiff pattern diagram, an expanded Durov diagram and several binary diagrams. The study indicates the presence of various salinization processes. In the recharge area, salinization is the result of dissolution/precipitation of the aquifer formation material (group I). The irrigation water return and the intensive pumping have been identified as major sources of salinization in the south by direct cation exchange and mixing reactions (groups II and III). The anomaly of high groundwater salinity observed near the Hazeg zone was explained by the presence of a seawater intrusion in this area. This hypothesis is related to the high chloride concentration, to the presence of inverse cation exchange reactions (group IV), and to the piezometric level inferior to sea level. To cite this article: R. Trabelsi et al., C. R. Geoscience 337 (2005).  相似文献