Arsenic — a Review. Part II: Oxidation of Arsenic and its Removal in Water Treatment     

Monique Bissen  Fritz H. Frimmel 《洁净——土壤、空气、水》2003,31(2):97-107

In natural waters arsenic normally occurs in the oxidation states +III (arsenite) and +V (arsenate). The removal of As(III) is more difficult than the removal of As(V). Therefore, As(III) has to be oxidized to As(V) prior to its removal. The oxidation in the presence of air or pure oxygen is slow. The oxidation rate can be increased by ozone, chlorine, hypochlorite, chlorine dioxide, or H₂O₂. The oxidation of As(III) is also possible in the presence of manganese oxide coated sands or by advanced oxidation processes. Arsenic can be removed from waters by coprecipitation with Fe(OH)₃, MnO₂ or during water softening. Fixed‐bed filters have successfully been applied for the removal of arsenic.The effectiveness of arsenic removal was tested in the presence of adsorbents such as FeOOH, activated alumina, ferruginous manganese ore, granular activated carbon, or natural zeolites. Other removal technologies are anion exchange, electrocoagulation, and membrane filtration by ultrafiltration, nanofiltration or reverse osmosis.  相似文献   

AEIC：Present and Future Program     

Sunarjo 《中国地震研究》2002,16(3):293-297

The establishment of the ASEAN Earthquake Information Center(AEIC) was endorsed by the 40th Meeting of the Committee on Science and Technology held in October 2000,at the request of the ASEAN Sub-Committee on Meteorology and Geophysics(SCMG) to obtain the ASEAN Standing Committee‘s (ASC) approval to officially use the name“ASEAN Earthquake Infor mation Center(AEIC)“,As part of AEIC activities,the SCMG implemented a project on the ASEAN Seismic Network for Rapid Exchange of Strong Earthquake Data(ASNE RESED).The project was implemented by the ASCMG with funding support from the Government of Japan through the Japan ASEAN Co-operation Promotion Program(JACPP).The aim of the project is to facilitate the rapid exchange of data and information on earthquakes with magnitudes greater than 5.5 on the Richter scale,and to link all of the ASEAN National Seismological Centers through the Internet to disseminate earthquake information.For the future program,we propose a seismic data exchange between the National Seismological Centers in ASEAN countries as well as world seismological centers using the facilities in the AEIC,The plan is basically to develop and update the software and hardware in the NSC and AEIC for data communication.To refresh our knowledge in seismology and data communication,we arrange the training sessions for both topics.  相似文献   

碱性花岗岩的动力学氧同位素交换和流体流动几何学：交换机制和平流冷却   总被引：2，自引：1，他引：2  

刘伟  李新俊等 《岩石学报》2002,18(3):331-339

新疆北部乌仑古塔斯嘎克碱性花岗岩体分为主体相和北部边缘相。条纹长石广泛发育出溶；石英与碱性长石复杂交生。条纹长石的出溶衍生出压应力，造成石英的变形。大部分钠铁闪石是由霓辉石交代形成的。在δ^18O石英-δ^18O条纹长石和δ^18O石英-δ^18O钠铁闪石协变图上，应用耦合的质量传输和动力学限制的同位素交换模型对样品进行了模拟。相对交换速率常数和3个矿物的显微组构特征共同指示，表面反应即溶解-再沉淀和管道扩散是氧同位素交换的主要机制。大气降水从塔斯嘎克碱性花岗岩的北部边缘相住主体相发生了平流渗透。北部边缘相样品的较陡的斜率、以及石英和条纹长石较低的^18O亏损程度，被解释为是由于与同位素组成未演化的短路径大气降水在相对较短的时限内发生氧同位素交换造成的。但是，与同位素组成演化了的长路径大气降水在相对较长的时限内的相互作用，导致了主体样品的较缓的斜率以及石英和条纹长石的较高程度的^18O亏损。对于一个侵入岩体的冷却来说，平流冷却与传导冷却一样重要。  相似文献   

CAD图形快速坐标转换方法实现     

彭良勇  李晓丹 《测绘与空间地理信息》2020,(4):199-201

坐标转换是测绘地理信息数据处理中最常见的问题之一。2018年国土资源部门全面使用2000国家大地坐标系的要求,更增加了图形数据坐标转换的需求。本文首先介绍了用Python编程实现四参数的快速解算方法,然后实现了用Python直接读写DXF文件坐标值实现坐标转换和在AutoCAD VBA环境下进行CAD图形坐标转换的快捷方法,并比较了两种方法的效率和优缺点。本文实现的坐标转换方法编程简单,使用方便,对于地理信息工作者和规划、国土等基层业务管理部门等具有很强的实用性。  相似文献   

庆云县地热回灌存在问题浅析          下载免费PDF全文

朱利民  宋伟华  白通  战静华  张航星 《山东国土资源》2019,35(11)

如何实现地热资源合理开发、高效利用,实现地热资源采灌均衡可持续开发利用模式已成为地热资源开发利用地区重点研究内容。该文根据庆云县某典型小区(以下简称小区A)一个采暖季的开采、回灌监测数据,总结了水温、开采量、回灌量、水位及回灌率变化情况。通过数据分析及调查可知,庆云县回灌工程普遍存在地热尾水温度偏高、热利用效率偏低、地热尾水直接回灌引起管道腐蚀影响供暖效果等问题。针对地板辐射和暖气片采暖两种模式提出了换热技术和增加热泵机组的改进措施建议,既可提高热利用效率,又可保证供暖效果避免设备腐蚀,对庆云县地热供暖工程的升级改造具有一定的指导意义。  相似文献   

A numerical model study of barotropic subtidal water exchange between estuary and subestuaries (tributaries) in the Chesapeake Bay during northeaster events   总被引：3，自引：0，他引：3  

Wenping Gong  Jian Shen  Kyoung-Ho Cho  Harry V. Wang 《Ocean Modelling》2009,26(3-4):170-189

Northeasters are storms that affect the Chesapeake Bay area more frequently, last for longer periods and impact larger areas than hurricanes. Their impacts on storm surge development and the water exchange between estuary and subestuaries (tributaries) in the Bay vary from one event to another. In this study, three different northeaster events were selected based on their tracks when passing through the Chesapeake Bay area. An unstructured grid finite volume model ELCIRC was utilized to examine the response of the water level of the Chesapeake Bay to three selected northeasters, and the barotropic subtidal water exchanges between the tributaries and the estuary in the Bay. Model sensitivity tests were conducted to examine various effects induced by, for example, tide–surge interaction, open boundary condition, river inflow, wetting-and-drying of the low-lying land area and the usage of 2-D or 3-D mode. The results show that excluding tide–surge interaction did not deteriorate the model performance in the lower Bay but it increased the model inaccuracy in the upper Bay and in the tributaries; using radiation boundary condition decreased the sea level variation in the Bay without appropriately specifying incoming wave; excluding wetting-and-drying of low-lying land area reduced the volume flux by approximately 5%; and using 3-D mode generally increased the water level variation in the Bay. The model predicted storm surges well for three northeaster events. Further diagnostic experiments show that the relative importance of the local and remote winds in generating storm surges in the Bay varied with different northeasters. The inverse barometeric effect played an important role in inducing storm surges for two selected northeasters. The interaction between the tributaries and the Bay proper is considerable. The impacts of the remote wind and Bay wind can be much larger than that of the tributary wind and, thus, control the hydrodynamics and mass transport in the tributaries. The Bay wind and tributary wind effects are largely affected by the wind direction and wind phase, and geographic locations of the tributaries in the Bay. The tributary wind can be dominant over the remote wind and Bay wind effects when the local wind stress and barometric pressure changes are large.  相似文献   

Spatial Modeling of Geotechnical Information Using GML   总被引：1，自引：0，他引：1  

Jean-Pierre Bardet  Amir Zand 《Transactions in GIS》2009,13(1):125-165

Geotechnical data characterizes the geometry and physical properties of soil deposits, which are determined from field observations, in-situ and laboratory tests, and engineering analyses. Until now, geotechnical information was mainly described and exchanged as relational data, which occasionally included spatial characteristics. Hereafter, the spatial features of geotechnical data are investigated by invoking the geotechnical data model of the Association of Geotechnical and Geoenvironmental Specialists (AGS), which is widely used in the United Kingdom to exchange geotechnical data in engineering practice. The basic geometric objects in AGS geotechnical data are first identified. These geometric objects are mapped to basic geometric features of the Geography Markup Language (GML). AGS data can therefore be fully rendered using GML-conformant schemas, which make geotechnical data readily importable into GML-aware applications. The data can be also imported to mainstream GIS applications using Extensible Markup Language (XML) transformations. This article demonstrates the rendition of AGS data format to a GML-conformant schema and illustrates the implementation of the new format through a few geotechnical examples.  相似文献   

台湾以北黑潮水与陆架水的混合与交换     

万邦君  郭炳火 《海洋科学进展》1992,(4)

本文根据日本气象厅在台湾以北获得的调查资料及近几年国家海洋局在该海域获得的调查资料,结合卫星图片,分析了夏季和冬季台湾以北海域陆架水与黑潮水的混合与交换过程以及涡旋在水交换过程中所起的作用。结果表明,夏季陆架水从表层向外海方向扩展,与黑潮水进行混合与交换;在陆架底部,黑潮次表层水涌升陆架后与陆架底层水进行混合。冬季由于黑潮表层水大举入侵陆架,低温的陆架水只能沿陆架向南流动,并在台湾西北部转向东沿台湾北岸向东流动,该海域存在的涡旋就象一个旋转泵,在陆架水与黑潮水的混合与交换过程中起了重要的作用。最后,文中还对陆架水与黑潮水的交换量进行了估算。  相似文献   

克拉玛依台与和丰台台址背景噪声对比分析     

刘富安 《内陆地震》2011,(4):379-384

通过对2010年8月初克拉玛依台与和丰台仪器对调前后台址背景噪声的计算和对比,得出,克拉玛依台仪器对调后短周期台址背景噪声RMS由24.7 Counts减小到16.2Counts,远震初动波形比没换仪器前更容易辨认.这次对调仪器有助于克拉玛依台观测质量的提高.  相似文献   

Dispersion Potential of Selected Iowa Lake Sediments as Influenced by Dissolved and Solid‐phase Constituents     

Bogadi T. Mathangwane  Mark A. Chappell  Jutta R. V. Pils  Leticia S. Sonon  Vasilos P. Evangelou 《洁净——土壤、空气、水》2008,36(2):201-208

Critics charge that agricultural managers routinely overdose their fields with chemical N and P to levels that exceed the soil's capacity to adsorb these materials, creating a situation that promotes hypoxia in Iowa lakes. Soil colloidal particles, capable of forming complexes with inorganic and organic N and P, control the equilibrium concentration of dissolved nutrients in lake waters. However, it should be realized that adsorbed nutrients also exhibit strong influences on the potential of sediments to undergo dispersion, a condition that may directly impact nutrient bioavailability. Thus, direct links may exist between adsorbed nutrient compositions and flocculation/dispersion properties of lake colloidal material. This paper presents work involving four Iowa lakes undertaken to determine relationships between ion composition and the dispersion potential of sediments. Surface waters and lake‐bottom grab samples were collected at three separate collection times from August to October. Samples were characterized for dissolved and adsorbed cations. Dispersion potential of each water sample was characterized by relating the total suspended solids concentration to the absorbance at 560 nm. It was found that sediment dispersion was easily predictable by a simple yet significant linear correlation with the concentration ratio of Na (CR_Na = [Na]/[Ca]^–1/2) in solution. This correlation was further improved by including Na concentration, CR_K, electrical conductivity, temperature, and solution P concentrations into the model. Nonlinear inter‐dependences were found between TSS and cation exchange capacity (CEC), and adsorbed Na, K, P, and heavy metals. Our analysis suggests that solution/solid phase constituents influenced the dispersion behavior of sediments through subtle manipulations of the excess surface charge.  相似文献