Mechanism of Suspended Kaolinite Particle Clogging in Porous Media During Managed Aquifer Recharge     

Xueyan Ye  Ruijuan Cui  Xinqiang Du  Sijia Ma  Jingtong Zhao  Ying Lu  Yuyu Wan 《Ground water》2019,57(5):764-771

Managed aquifer recharge is an effective strategy for urban stormwater management. Chemical ions are normally retained in stormwater and groundwater and may accelerate clogging during the recharge process. However, the effect of water chemistry on physical clogging has not previously been investigated. In this study, we investigated the hydrogeochemical mechanism of saturated porous media clogging in a series of column experiments. The column was packed with river sand and added suspensions of kaolinite particles. Calcium chloride and sodium chloride are used as representative ions to study chemical effects. We found that an increase in ionic strength resulted in retention of kaolinite solids in the column, with a breakthrough peak of C/C₀ value of 1 to 0.2. The corresponding hydraulic conductivity decreased with increased solids clogging. Divalent cations were also found to have a greater influence on kaolinite particle clogging than monovalent cations. The enhanced hydrochemical-related clogging was caused by kaolinite solids flocculating and increasing the deposition rate coefficient by 1 to 2 times in high ionic strength conditions. Three clogging mechanisms of kaolinite solids are proposed: surface filtration, inner blocking, and attachment. This study further deepens the understanding of the mechanisms of solids clogging during aquifer recharge and demonstrates the significance of ionic strength on recharge clogging risk assessments.  相似文献   

Climate and extrema of ocean waves in the East China Sea     

Hailun He  Jinbao Song  Yefei Bai  Yao Xu  Juanjuan Wang  Fan Bi 《中国科学:地球科学(英文版)》2018,61(7):980-994

Wave climate plays an important role in the air-sea interaction over marginal seas. Extreme wave height provides fundamental information for various ocean engineering practices, such as hazard mitigation, coastal structure design, and risk assessment. In this paper, we implement a third generation wave model and conduct a high-resolution wave hindcast over the East China Sea to reconstruct a 15-year wave field from 1988 to 2002 for derivation of monthly mean wave parameters and analysis of extreme wave conditions. The numerical results of the wave field are validated through comparison with satellite altimetry measurements, low-resolution reanalysis, and the ocean wave buoy record. The monthly averaged wave height and wave period show seasonal variation and refined spatial patterns of surface waves in the East China Sea. The climatological significant wave height and mean wave period decrease from the open ocean in the southeast toward the continental area in the northwest, with the pattern generally following the bathymetry. Extreme analysis on the significant wave height at the buoy station indicates the hindcast data underestimate the extreme values relative to the observations. The spatial pattern of extreme wave height shows single peak emerges at the southwest of Ryukyu Island although a wind forcing with multi-core structure at the extreme is applied.  相似文献   

蓝藻光合氮同化的特征与分子调控机理研究进展     

杨小龙  刘莉华  毕永红  王洵  董薇  邓自发  王寿兵 《湖泊科学》2023,35(3):766-779

水华蓝藻的生物学特性及其竞争优势、蓝藻水华的形成与维持机制等科学问题,一直是国内外研究的热点。氮素是诱发蓝藻水华暴发的重要营养盐,蓝藻对氮素的同化与其光合作用密切偶联。然而,水体中氮素存在多种形态,不同形态氮素对蓝藻生长和水华发生的影响具有显著差异。因此,了解蓝藻光合作用特征及其同化不同形态氮素的机制和策略,对深入理解蓝藻水华的发生机理具有重要意义。本文在蓝藻的光能捕获与激发能转移、光合电子传递、碳浓缩机制及CO₂同化等光合作用过程及其特征综述的基础上,对蓝藻摄取、同化5种主要氮素形态(NO₃^-、NO₂^-、NH₄⁺、尿素和N₂)的分子机制及其特征进行了解读,总结了蓝藻细胞光合碳、氮同化的耦合关系及调控机制;并指出了该领域的未来发展方向,以推动该方向的深入研究。  相似文献   

用常规探空资料估算C_n²和ε垂直变化初探     

戴铁丕  潘闻天  朱素芳  毕志刚 《大气科学学报》1997,20(2):251-258

用南京、射阳的常规探空资料建立了估算折射率结构常数C_n²和湍能耗散率ε垂直变化理论模式。结果表明:用该理论模式计算的ε值与用天气脉冲多普勒雷达探测的速度谱宽σ_r²再估算得到的ε值有较好的一致性。  相似文献   

仿射坐标系下的因子分析—仿射因子分析     

毕葵森 《江苏地质》1996,20(1):32-40

传统的因子分析以正交坐标系为其基础坐标系,因而存在某种固有缺陷。文中提出以仿射坐标系为因子分析的基础坐标系,并进而给出了仿射因子分析的方法。新方法不仅消除了原方法所存在的缺陷,同时还实现了样品和变量空间的统一。  相似文献   

黔西南部分地区龙潭组碎屑物组成及其物源背景研究     

陈景河  徐碧良  葛广福  王军荣  林俊英  林菊连 《贵州地质》2011,28(1):9-17

对黔西南、桂西北金异常的钻孔、平硐及有限的地表露头岩石样品的大量光薄片岩相矿相学研究,并进行了岩石化学、微量元素、稀土元素及W(Th)/W(U)等6个元素对的研究证实,龙潭组"大厂层"之上的主体岩性的主要物质(＞50%)为玄武质的火山碎屑物,元素对的比值证明物源采自幔源为主,微量元素对比与峨眉山玄武岩基本相同.其岩性应...  相似文献   

鱼雷仿真试验中脱靶量的计算方法研究          下载免费PDF全文

吴碧  王毅刚  林龙 《数字海洋与水下攻防》2019,2(4):76-79

针对鱼雷仿真试验中脱靶量用点目标计算存在较大误差的情况，通过应用近似的方法建立潜艇和水面舰艇的表面模型，并给出了针对不同表面模型计算脱靶量的方法，用以修正原计算方法的误差。对 2 种计算方法进行了仿真验证，仿真数据表明：与应用点目标计算的脱靶量相比较，给出的方法计算的脱靶量更接近于真实的鱼雷自导导引精度。  相似文献   

简析基层国土所财务管理问题          下载免费PDF全文

张述宽  宋志团  毕翠红 《山东国土资源》2009,25(4)

国土资源系统辖属基层国土所具有数量多、人员多、支出多的特点，随着市场经济体制的逐步建立，特别是2000年开始财政管理制度的重大改革，面临着财务管理中一系列深层次矛盾的解决和多方面利益关系的调整，目前基层国土所的财务管理还存在一些问题有待解决。  相似文献   

有边界条件的忆阻元件模型及其性质          下载免费PDF全文

张旭  周玉泽  闭强  杨兴华  俎云霄 《海洋学报》2010,32(9):6673-6680

对第四类基本电路元件——忆阻元件的基本特性进行了研究,分别建立了无边界条件和有边界条件的忆阻元件的积分形式的数学模型.对有边界条件的数学模型进行了仿真,分析了有边界条件下电源频率和掺杂比、初始掺杂宽度等模型参数对电流、电压电流关系、磁链电荷关系等元件特性的影响,得出了相关的结论.  相似文献