Identification of Anomalous Aluminium Contents in Surface and Ground Water in the Alba Territory (NW Italy)

Aluminium was determined in surface and ground waters in the Alba region of NW Italy to provide information on natural and anthropogenic sources of contamination. Determinations were made by a spectrophotometric method based on the aluminium-pyrocatechol complex. The total aluminium content of waters was determined as well as the toxic form of monomeric aluminium, obtained from samples that had been passed through 0.20 μm cellulose filters to remove colloidal and particulate material. Results were correlated with mortality data associated with Alzheimer's disease. There appeared to be a correlation between mortality data and areas having the highest aluminium content of water.     

南极普里兹湾及其邻近海域浮游植物粒度分级生物量和初级生产力

本文报道了 1 990 /1 991年夏季在南极普里兹湾及其毗连海域对浮游植物细胞丰度 ,优势种类组成 ,粒度分级生物量和初级生产力和颗粒有机碳浓度的分布及其与环境因子关系的研究。结果表明 ,调查海区具有显著的空间区域化特征 ,普里兹湾及其毗连陆架由于水体较为稳定 ,有利于浮游植物和冰藻的生长 ,其生物量、生产力和颗粒有机碳均较高 ;在普里兹湾北部毗连南印度洋的近南极大陆海域 ,由于水团沿陆坡的扭曲运动和上升流的出现 ,致使西冰架和谢克尔顿冰架之间的北部区域浮游植物生物量 ,生产力和颗粒有机碳均较高。由于浮游植物的大量繁殖 ,使该二区域营养盐浓度降低 ,溶解氧增加。在调查海区的东西两侧则相反。粒度分级结果表明 ,微型 (<2 0 μm)和微微型 (<2 .0 μm)浮游生物在浮游植物群落生物量和生产力中占有重要比重 ,它们对总生物量和总生产力的平均贡献分别为 5 3 %和 6 9%。     

地震谣传平息后的思考

从对福建省沿海地区“9·26”地震谣言的来因分析、传播过程及平息效果,引发的几点思考。     

A quantitative evaluation of pyrite weathering

Namurian sediments at Mam Tor, Derbyshire are cut by a major landslide and a geological fault. Both channel oxygenated waters into fragmented pyritic shales. Pyrite is rapidly oxidized to sulphuric acid, 1.5 g being destroyed by each litre of water passing through the fault-crush. More than 99 per cent of the acid, however, is immediately consumed in clay-mineral transformation and carbonate dissolution reactions. The typical acid-sulphate ‘ochre’ springs thus retain less than 1 per cent of the acid generated in the crush zone. These very rapid and large scale chemical transformations probably contribute to the slide's continuing activity.     

Primary production and decomposition in the coastal zone of the northern part of the Aral Sea near the delta of the Syr Dar'ya

Data are given on the concentration of suspended organic carbon and chlorophylla in seston, the quantity of organic carbon in bottom sediments, and other environmental characteristics. The results of experiments determining daily quantitites of total and net primary production and aerobic decomposition in plantonic and bottom communities are discussed.     

二类水体水色遥感的主要进展与发展前景

Ⅱ类水体水色遥感是海洋水色遥感的难点和热点。针对Ⅱ类水体的光谱特性和海洋现象的特点，综述了水色卫星传感器在光谱波段配置、辐射探测性能和时空分辨率等方面的设计要求与技术进步。从水色遥感资料反演的两大关键技术——大气校正和生物光学算法两个方面，概述了Ⅱ类水体水色反演算法的研究现状和发展方向。根据我国近海的水体特点，提出了我国水色遥感研究需要解决的关键问题。     

Thermomineral waters of Ca-chloride composition: review of diagnostics and of brine evolution

 Ca-chloride waters are defined as those in which Q=rCa/r(SO₄+HCO₃)>1, rNa/rCl<0.80, rMg/rCa<0.5 and wCl/wBr<286 (r=meq l^–1 and w=mg l^–1). Throughout the last 50 years, different models for the formation of such waters have been suggested. These models include: (1) filtration through semipermeable membranes under conditions of highly compacted argillaceous sediments, (2) deaquation of seawater by evaporation and/or by freezing followed by dolomitization, (3) hydrolysis of plagioclase and biotites in igneous metamorphic rock masses, (4) radiolytic modification of residual metamorphic fluids, and (5) dissolution of chalks followed by ion exchange on smectites. The better understanding of processes and of natural environments leading to the evolution and natural occurrence of such brines, is imperative for the prospection and further sustained exploitation of such waters. Received: 11 October 1996 · Accepted: 24 February 1997     

Characterizing Colloidal Material in Natural Waters

Sampling has inherent uncertainties when applied tothe sub-micron fraction of natural waters.Processes of aggregation, biological activity andchemical transformation potentially effect changesimmediately after a sample is taken from the waterbody and there is no suitable method of samplestabilization. The size distribution and associatedphysical and chemical parameters of colloids in theaquatic environment can be effectively stable overshort periods of time (about two days under idealconditions, but frequently much shorter timeintervals). To achieve accurate representations of thesize distribution and associated colloidalcharacteristics in situ techniques are required,although adequate approximations may be obtained undersome circumstances if separation is done immediatelyafter sampling. This paper reviews the currentlyavailable strategies for separation and analysis ofcolloids from natural waters (primarily filtration andcentrifugation) and discusses their uses andlimitations, as well as potential uses of promisingtechniques (voltammetry, gels, field-flowfractionation, SPLITT). For small colloids, thetechniques of voltammetry, dialysis, DET and DGT maybe used to obtain in situ information. Forlarger colloids it is more difficult to performmeasurements in situ and a combination of rapidfractionation procedures, including filtration,field-flow fractionation and SPLITT, may still berequired.     

Survival of crucian carp,Carassius carassius,exposed to a high low-molecular weight inorganic aluminium challenge

Crucian carp were exposed to three combinations of pH and inorganic aluminium concentrations for 25 days. Mortality, plasma chloride and haematocrit, and gill aluminium content were investigated. No mortality was observed in any of the three exposures. Crucian carp survived acidic Al-rich water (pH 5.17) with a high concentration of low-molecular weight inorganic Al species (242 µgl^–1) for 25 days. These fish had lowered plasma chloride levels and high amounts of aluminium on their gills compared to fish exposed to acidic Al-poor water (pH 5.16 and 12 µgl^–1 Al_i) and control water (pH 6.29 and 4 µgl^–1 Al_i). Haematocrit was the same in all three exposures. Because aluminium was not acutely toxic to the anoxia tolerant crucian carp, the present results give support to the hypothesis that Al polymerization with subsequent hypoxia is of high importance for the mechanism of acute Al toxicity to fish.     

The hydrochemistry of the inland waters of Argentina: a review

The major ion chemistry of 639 aquatic localities in Argentina is presented and discussed. Salinities range from quite fresh (<3 g L^–1) to highly saline (>300 g L^–1); a variety of ion dominances occur but NaCl predominates in highly saline waters. The principal mechanisms controlling water chemistry are rock dominance and evaporation; atmospheric contributions are less important.