A study of the cycling of manganese and other elements in a seasonally anoxic lake, Rostherne Mere, U.K.

The vertical distribution of sulphate, dissolved sulphide, alkalinity, pH, total iron and manganese, Fe(II) and Mn(II) and humic substances was monitored for a year in a seasonally anoxic lake, Rostherne Mere, U.K. During summer stratification Mn(II), probably of sediment origin, accumulated in the hypolimnetic bottom waters to a concentration of 50μm. Release occurred in two stages and appeared to be related to the supply of organic material to the sediment. No ferrous iron or dissolved sulphide were detected in the water column, although they were measured in the interstitial waters of the sediment. Ferrous sulphide formation in the sediment controls the iron(II) and dissolved sulphide concentrations and so minimises the concentration gradients at the sediment-water interface. Electron acceptors other than oxygen are capable of oxidising ferrous and sulphide ions in the water column. pH and alkalinity were the only other chemical components to show appreciable variation with depth, reflecting the biological processes of photosynthesis, respiration and decomposition. Iron and humic substances simultaneously increased in the surface waters after a major flood indicating that they are both present in the solution in contact with the soils of the catchment.     

Diagenetic remobilization of manganese, iron, copper and lead in anoxic sediment of a freshwater pond

The diagenetic remobilization of manganese, iron, copper and lead in anoxic sediment of a freshwater pond, T Reservoir, Japan has been examined in an in situ submerged chamber system, through the interstitial water and sediment analyses. Manganese was released continuously from the sediment into the overlying water during the experiment, whereas iron was released from the sediment abruptly after the 2nd day of the experiment. The steep vertical concentration gradients of manganese and iron were observed in the interstitial water. The release of manganese and iron from the sediment is due to the dissolution of ferro-manganese oxides and hydroxides in the surface sediment under anoxic condition. In contrast to manganese and iron, copper and lead were not released from the sediment during the experiment, and their concentrations in the interstitial water were not significantly different from the values of the overlying water. The results show that the diagenetic remobilization of copper and lead in the sediment is negligibly small. It is likely that copper and lead are fixed into the sediment by some process other than the formation of sulfides.     

小型水厂除锰工艺改造实践

针对次坞镇水厂出水锰含量超标问题,对该水厂除锰工艺进行了改造.实践表明,通过向澄清池中投加混凝剂和催化剂,形成催化剂悬浮层,可以增强除锰效果,达到澄清池除锰的目的;改造后出厂水的铁、锰含量分别降低至0.1和0.05 mg/L以下,满足《生活饮用水卫生标准》( GB 5749 - 2006)中的限值要求.     

钢铁中锰含量测定方法的研究

采用高碘酸钠(钾)分光度法,对钢铁中锰含量进行了测定,介绍了实验原理、所用仪器与试剂,并对试液制备、空白值测定、最低检出限测定等实验过程进行了阐述分析,指出利用该方法测定钢铁中锰含量具有操作简便、灵敏度高、精密度好等优点。     

Pilot testing of manganese oxidation in a high-rate sedimentation process for the reprovisioning of the Sha Tin water treatment works, Hong Kong Special Administrative Region

The Sha Tin water treatment works (STWTW), Hong Kong Special Adminstrative Region, was commissioned in 1964 with an initial treatment capacity of 364 million litres per day (MLD). Since then it has undergone three stages of expansion to reach the current nominal capacity of 1227 MLD. The plant is in need of an in situ reprovisioning. The challenge is to complete the reprovisioning while maintaining a minimum output of 900 MLD, with any shutdown to be limited to 8 h generally. With the site already fully utilised, the key to success is to first replace the conventional low‐rate sedimentation process with high‐rate robust processes to free up the much needed space. Among other requirements, the chosen process must also be capable of treating water with variable turbidity and removing spikes of manganese effectively. The project team conducted a 4‐month pilot testing programme with an Actiflo^® high‐rate pilot plant and the key results are described.     

铁锰超标对天然河床潜流水水质影响及处理

研究了铁锰离子超标对天然河床潜流水水质的影响及相应的处理技术,分析了潜流水中铁锰的危害及迁移富集规律,通过对除铁锰技术进行比选,得出接触氧化法是去除潜流水中铁锰的最佳方法,并对其工艺流程作了具体介绍,以期指导实践。     

利用电解锰渣生产加气混凝土的研究

电解锰渣是用硫酸溶液处理碳酸锰矿粉电解生产二氧化锰的工业固体废弃物。针对电解锰渣化学成分、矿物成分、放射性等方面的研究,探寻电解锰渣综合利用途径,促进电解锰渣综合利用工作,达到节能减排的目的。     

锰渣的基本特性及在混凝土中的研究进展

锰渣是锰合金工业最大的工业废渣,随着锰工业的发展,锰渣的有效利用问题显得尤为迫切。介绍了锰渣的来源,我国锰渣的生产、排放现状。重点论述了锰渣的基本特性,锰渣粉对混凝土性能的影响,分析了锰渣在混凝土中应用存在的问题,提出了进一步研究的建议。     

生物滤池地下水除铁除锰过程中漏锰现象研究

针对生物滤池地下水同步除铁除锰过程中的“漏锰”现象进行研究。结果表明,“漏锰”现象是由亚铁离子与锰氧化物的反应引起的;砂样生物活性、溶解氧及浸泡时间等对亚铁离子与锰氧化物的反应影响不大;增加浸泡次数可使“漏锰”现象得到缓解;出水锰浓度与砂样质量和亚铁离子含量均呈二次抛物线关系,底物浓度越大,出水锰含量增大越快;酸性条件可以促进亚铁离子和锰氧化物的反应,碱性条件下“漏锰”现象不易发生。     

Airborne remote sensing for freshwater and estuarine monitoring

A state of the art review of remote sensing hardware and parameters which can be measured by these techniques in the aquatic environment is presented. The list of measurable determinands runs to some 26 items. It can generally be concluded that remote sensing of the aquatic environment is potentially a very useful tool. However satellite data are unlikely to be of major importance in the freshwater field but their wide synoptic coverage make them useful in large scale estuary and coastal work. Of the microwave techniques, only passive radiometry for salinity and oil thickness measurement is likely to be of interest.     

The state of suspended sediment in the freshwater fluvial environment: a method of analysis

Primary particles in rivers are frequently and perhaps characteristically transported as larger flocculated particles. Typically floc size has been determined by destructive, indirect laboratory methods or by laborious microscopic measurements.A unique direct observation digitizing method of floc characteristic analysis was developed and applied to suspended solids from Sixteen-Mile Creek in Southern Ontario. Suspended sediment particles in the creek are strongly flocculated, and the flocs are relatively stable within the realms of the sampling and analytical method.The digitizing method allowed for direct observation of floc structures which is impossible with conventional methods of sediment sizing. The method provides reasonable results with good precision on floc equivalent spherical diameter, surface area, perimeter and circularity. It is limited, however, by its labour intensive nature, possibility of sediment overlap, the individual investigator's criteria and by the photographic and microscopic instruments and techniques used. Other sizing techniques, or the use of the digitizing method by other investigators, may produce different results.     

原水铁锰含量对细菌除铁除锰效能的影响

将从水厂成熟锰砂中分离出来的细菌进行驯化和增殖培养,通过改变原水中铁锰含量来改变细菌生长环境,考察了不同条件下混合细菌对铁锰的去除效果.结果表明:在有Fe2+存在的情况下,铁锰氧化细菌维持着正常的活性,对铁锰始终具有高效而稳定的去除能力;Fe2+的存在与否也影响着Mn2+的氧化速率;原水中锰的存在对细菌除铁影响较小.     

海岛淡水透镜体形成及倒锥演变规律分析

本文采用自制的室内物理模型,对海岛淡水透镜体的演变过程进行了模拟实验。为了避免电导率测定值受自然因素等的影响,实验采用观测孔测得的电导率值与海水电导率值的相对值作为刻画淡水透镜体形状的手段。实验结果表明：降雨强度越大,则降雨入渗量越大、淡水透镜体越厚,透镜体厚度最终稳定在22cm;开采强度越大,透镜体越易被击穿。这一结果不仅为海岛淡水资源的开发利用提供了理论基础,同时为国内外开展相关研究提供参考。     

两级过滤去除地下水中铁锰的试验研究

通过锰砂和硅碳素两级过滤的方式,研究了含锰、含铁及高铁低锰三种水质条件下铁锰的去除效果,进一步探讨了不同水质中铁锰的去除方法。结果表明,对于单独含锰的水质,可仅采用二级硅碳素滤柱去除;对于单独含铁的水质,可仅采用一级锰砂滤柱去除;对于高铁低锰的水质,可通过两级过滤同时去除铁锰。锰砂和硅碳素两级过滤处理含铁锰地下水是可行的,根据不同的水质,可以采用不同的处理方法。     

锰渣水泥混凝土在港航工程中的应用研究

通过利用0、5%、10%、15%、20%、25%、30%的锰渣废弃物矿渣代替同体积水泥配制成的混凝土进行力学性能、干缩性能、抗冲磨性能等方面的试验研究和分析,发现当锰渣废弃物矿渣代替量小于15%时,对混凝土在港航工程的水工建筑物上的应用各方面性能的影响微小,但能降低混凝土的生产成本和具有一定的社会环保价值.为锰渣废弃物矿渣在港航工程的水工建筑物上的应用提供依据.     

农村地下水除锰工艺设计及不同滤料除锰效果

为更好地去除农村地下水中的过量锰,设计高效的除锰处理工艺,掌握不同滤料的除锰能力,在所设计的工艺基础上进行了除锰效果分析实验,分别对比了河南巩义天然锰砂、锦西天然锰砂、活化沸石三种不同性能滤料的除锰效果,得出了一些有价值的结论。     

锰渣废弃物在建筑材料上的应用研究

通过对锰渣废弃物的化学成分、活性指标、矿物组成和颗粒形貌等性能分析,证明锰渣废弃物是一种活性材料,其可作为水泥、水泥混凝土等建筑材料的掺合料.以锰渣废弃物作为掺合料以不同掺量掺入水泥和水泥混凝土中,并对其相关性能指标进行试验测试,从而发现锰渣废弃物掺量对水泥和水泥混凝土性指标能的影响情况,寻找锰渣废弃物的最佳掺量.同时为进一步研究锰渣废弃物在建筑材料上的应用提供参考.     

The diversity and distribution of freshwater macrophytes in the wedian of the mountainous northern Oman

The paper reports the first study of diversity and distribution of freshwater macrophytes in the wedian (plural of wadi = seasonal river) of the northern Al Hajar Mountain range in Oman. Fifteen lentic habitats in the wedian were surveyed. The number of species, their growth forms and abundance were recorded in the studied habitat of each wadi. In all, 41 species belonging to 14 families and 32 genera were collected. Of these 37 species were emergent and four were submergent. Poaceae was the most diverse emergent family with 17 species. Phragmites australis was the most common emergent followed by Typha domingensis. Among submerged macrophytes, Chara vulgaris had higher frequency of occurrence with low abundance followed by Potamogeton distinctus with relatively high abundance. Floristic diversity was estimated using species richness (Margalef’s D), general diversity (Shannon–Wiener H′), evenness (Pielous’s EH), and dominance (Berger–Parker d) indices for each study habitat. Principal component analysis was used to evaluate the variability using four indices. PC1 and PC2 explained 98.18% of the variability. Some habitats in different watersheds exhibited similar species diversity, but some in the same watershed were different. Baseline data on the freshwater macrophytes in northern Oman are provided here.     

液氯应用于地表水厂应急除锰研究

针对水厂原水夏季锰超标带来的出厂水浊度、色度超过滤后水的问题,经对比试验和分析论证采用液氯氧化除锰方案.通过在预氧化接触池投加氯,出厂水中锰从原水的0.1-2.0mg/L降低到0.05 mg/L以下,色度从原水的50-80度降低至5度,工艺简单,易于操作.同时调查分析了水厂锰的来源及变化,并针对水厂设计以及液氯除锰中需...     

The effect of a subsurface barrier on the conservation of freshwater in coastal aquifers

An investigation has been undertaken to study the effect on the water table and the shape of a freshwater/seawater interface produced by an impermeable subsurface barrier partially embedded into an unconfined coastal aquifer. Considerations are restricted to steady flow in an isotropic aquifer. Shape factors describing the distribution of mass density and of the velocity are introduced and their values derived. From the laboratory model study using a vertical plane Hele-Shaw model the velocity shape factor was determined. It was approximately unity for flow without a barrier, and decreased when a barrier was introduced. The barrier depressed the interface considerably and the upconing started with a higher flow rate as compared with the case without a barrier. By introducing the concept of a virtual origin it is shown that the free surface does not approach the seepage face tangentially. This was also confirmed experimentally.