Glucose uptake in lake water samples has been determined with short-time ¹⁴C-experiments at different additions of the single heavy metals Cu⁺⁺, Zn⁺⁺, Cd⁺⁺, Pb⁺⁺, Hg⁺⁺ and at different additions of a combination of all metals. The degree of a metal induced inhibition of glucose uptake varied from lake to lake and from season to season, whereby the addition of legally tolerated concentrations of 10 μg Cu/l and 200 μg Zn/l inhibited glucose uptake in most samples significantly, as well as the simultaneous addition of all metals. The legally tolerated limit of 1 μg Hg/l inhibited glucose uptake in Lake Lucerne samples almost completely, showed however no effect in samples of Lake Baldegg.<br /> The equimolar toxicity sequence of heavy metals for heterotrophic microorganisms has been determined as: Hg&gt;Cu&gt;Cd&gt;(Zn, Pb). Glucose uptake of plankton sampled from metal polluted limno-corrals was less inhibited than that of the control plankton, when heavy metals were added to the samples singly or in combination. It is assumed that this effect is due to the natural selection of more resistant plankton species.

Long-term impacts of increased metal loading (Hg, Cu, Cd, Zn and Pb) on phytoplankton communities of large limno-corrals (diameter 12 m, depth 10 m) were studied. Increased metal concentrations initially lowered phytoplankton biomass, as well as species number and photosynthetic activity of phytoplankton. They caused changes in metal speciation and shifts in phytoplankton community structure, favoring less susceptible species. Although adaptation was not sufficient to completely prevent the metal-induced depression of photosynthesis, due to depressed zooplankton grazing, at the end of the experiment even higher phytoplankton densities were observed in the metal-loaded corrals than in the control.

Phytoplankton, periphyton and zooplankton samples, chironomid and <em>Sialis</em> sp. larvae, and fry of trout and bream collected from unpolluted and artificially metal-polluted limno-corrals were analyzed for mercury, copper, cadmium, zinc and lead. The results indicate that these metals are not accumulated through the food chain and suggest that increased metal concentrations in the environment favor the growth of phytoplankton organisms with a low metal sorption capacity.

It was the goal of the interdisciplinary research project MELIMEX to study ecological consequences of increased heavy metal loadings on limnic ecosystems. A detailed description of the limno-corrals (diameter 12 m, depth 10 m water flow through rate 11.5 m³/day) used in this study is presented. Since the physico-chemical environment must have a direct bearing on the results of such an experiment a brief description of Lake Baldegg, in which the experiments were conducted is given and conditions in which limno-corrals differ from natural systems are discussed. Furthermore the major findings of the various MELIMEX studies are briefly summarized.

The tracer-diffusion coefficient of ions in water, <I>D</I><I><SUB>j</SUB></I><SUP>0</SUP>, and in sea water, <I>D</I><I><SUB>j</SUB></I><I><SUP>*</SUP></I>, differ by no more than zero to 8 per cent. When sea water diffuses into a dilute solution of water, in order to maintain the electro-neutrality, the average diffusion coefficients of major cations become greater but of major anions smaller than their respective <I>D</I><I><SUB>j</SUB></I><I><SUP>*</SUP></I> or <I>D</I><I><SUB>j</SUB></I><SUP>0</SUP> values. The tracer diffusion coefficients of ions in deep-sea sediments, <I>D<SUB>j</SUB></I><SUB>,</SUB><SUB>sed.</SUB>, can be related to <I>D</I><I><SUB>j</SUB></I><I><SUP>*</SUP></I> by <I>D<SUB>j</SUB></I><SUB>,</SUB><SUB>sed.</SUB> = <I>Dj* · α/θ²</I>, where <I>θ</I> is the tortuosity of the bulk sediment and <I>α</I> a constant close to one.

Anorganische Industrieschlämme, insbesondere aus der metallbearbeitenden Industrie, dürfen nicht als harmlos bezeichnet werden. Bei deren unkontrollierter Ablagerung im Gelände können wasserlösliche toxische Stoffe, die zum Teil schon in den Schlämmen enthalten sind, zum Teil aber auch im Laufe der Zeit neu gebildet werden, ins Grundwasser gelangen oder unter Umständen in Oberflächengewässer abfließen.<BR/><BR/> Beseitigung der Industrieschlämme bedeutet in jedem Falle Ablagerung im Gelände, und zwar nach den Regeln der „geordneten Deponie". Das letzte Wort bei der Standortwahl für die Deponie hat der Grundwassergeologe.<BR/><BR/> In den meisten Fällen wird man gezwungen sein, die Schlämme vorzubehandeln. Der erste Schritt liegt im Wasserentzug, mindestens bis zur Stichfestigkeit. Diese kann grundsätzlich mit denselben Entwässerungsgeräten, wie sie für die Klärschlammentwässerung üblich sind, erreicht werden. Das abgeschiedene Schlammwasser sollte zur Weiterbehandlung in die Entgiftungs- und Neutralisationsanlage zurückgeführt werden.<BR/><BR/> Eine weitere Möglichkeit der Vorbehandlung, d. h. eine Umwandlung der Schlämme (nach deren Entwässerung) in wasserunlösliche Produkte, liegt in der Versinterung in Spezialöfen bei Temperaturen zwischen 1100 und 1200° C oder in einer Versteinerung der Schlämme mit Hilfe von Zement und Sand. Aus wirtschaftlichen Gründen werden diese beiden Verfahren wohl kaum von sehr großer Bedeutung sein.<BR/><BR/> Die Verbrennung der anorganischen Industrieschlämme in konventionellen Müllöfen mit Temperaturen zwischen 800-1000° C wird nicht empfohlen.<BR/><BR/> Es ist möglich, Industrieschlämme mit Hausmüll zusammen zu kompostieren, resp. den Kompost als Einschlußmittel für die Schlämme zu verwenden, wodurch eine weitgehende „Verdünnung" resultiert, die durch die Verteilung des Kompostes auf eine große Landfläche nochmals potenziert wird.

The strong development of industry, the increase in population, and the ever-increasing prosperity have all created new problems: our environment has become damaged to a dangerous degree by fluid, solid and gaseous pollutions from industry, trade and household.<br /> The cleansing of our waters may be said tobe satisfactory in Switzerland. By the middle of the present decade about 60% of the population and a great part of the industry will be provided with water cleansing works andrefuse disposal centres. But with the building of these works alone, the problem is not solved. Numerous unsolved problems and expensive measures are still before us if we wish to protect our atmosphere, waters and soils from destruction. For example, the question of the removal of the scum from the sewage works is not yet satisfactorily solved in many parts of Switzerland. Not only a surplus of scum but also serious anxiety on the part of the veterinary experts makes the practice of using the scum in the simplest and most economic way as agricultural manure, ever more problematic. Furthermore, the removal of much of the refuse from industry and commerce nowadays causes great difficulties.<br /> The pollution of the atmosphere by gases from house chimneys, from automobile exhausts and from industrial manufactories appears to be less serious in Switzerland, according to the experts, than in rnany other countries. However, we need to rnake every effort to rnaster for the future this undoubtedly threatening danger.<br /> The duty to keep our environrnent clean involves not only the protection of water and air, but also the protection of the land. Water, land and air form our natural environrnent: a unity which we have to protect frorn deteriora tion.

The apparatus described was assembled using relatively inexpensive parts and makes the cultivation of various forms of algae under steady-state conditions and different flowrates (variation under 0.5%) possible. There was no difference in the biodensity in the reactor compared to that in the outflow.

A test procedure for capillary gas chromatographic columns, first published three years ago, is described in further detail, giving practical guidelines based on accumulated experience.

In den vergangenen 3 Jahrzehnten hat sich der Zustand der meisten Seen der Schweiz stark verschlechtert. Die wichtigste und heute nicht mehr bestrittene Ursache ist die zu hohe Belastung der Seen mit Phosphat. Im unbeeinflussten, ursprünglichen Ökosystem steuert Phosphat als der essentielle Pflanzennährstoff, der zuerst aufgebraucht wird, den gesamten Stoffumsatz, die Biomassesynthese und damit auch die Belastung mit eigenen Produkten. Eine steigende derartige Belastung wird im gesamten als Eutrophierung bezeichnet. Dass die Phosphorbelastung der Seen seit dem 2. Weltkrieg tatsächlich gewal- tig angestiegen ist, wird durch die einschlägigen Statistiken und durch Messungen der Phosphorfracht einiger Seezuflüsse (z.B. Schussen, Argen, Alpenrhein) belegt, dann aber auch durch eine grosse Zahl gründlicher Analysen der Seen.

With help of field data from several alpine lakes and results from culture studies [54] an attempt was made to describe the conditions necessary for the occurrence of the blue-green alga <em>Aphanizomenon flos-aquae</em> in a lake. Special attention was paid to temperature, phosphorus, nitrogen and light.

The influence of temperature and light on the growth of <I>Aphanizomenon flos-aquae</I> was studied in batch cultures. To measure the P and N demand the algae were cultured in chemostats. Growth parameters of <I>A. flos-aquae</I> were estimated by fitting model equations which describe the growth rate as a function of the external PO<SUB>4</SUB> concentration or of the cell quota. Under PO<SUB>4</SUB>-limitation, cellular P, N and chlorophyll a content increased with increasing dilution rates. The lack of combined N caused a decrease of the critical dilution rate. No direct correlation between the N<SUB>2</SUB>-fixation and the number of heterocysts could be observed.

The separation number (Trennzahl: TZ) as a measure of separation efficiency has been criticized because of its dependence on temperature, and its replacement by a measure based on the temperature-independent HETP concept has been suggested. We discuss the temperature dependence of TZ, then we show that this dependence, rather than being a weak point of the TZ concept, is directly related to an essential part (selectivity) of the column quality. The fact that this part is missing from all separation efficiency expressions based on HETP makes such expressions have poor suitability, and possibly be misleading, for direct practical extrapolation. Another consequence, which is against the interests of most users, is that most commercial columns, at least in the past, have been manufactured with relatively thick films. Obviously, in order to obtain comparable TZ values more specifications regarding the method of determination are required than for plate numbers. This drawback is overcome by using a standardized test procedure, an essential part of which may be the use of temperature programming.

Mass transfer coefficients and the degree of saturation of the exit gas are important parameters in transferring volatile organic substances from water to the atmosphere. Aeration systems in batch and continuous flow reactors are discussed based on theoretical analysis and experimental data. Three different ranges of the degree of saturation of the exit gas are introduced and their significance for model experiments and technical operations is evaluated. The effect of the aeration system and of surface active agents on the mass transfer coefficient of tetrachloroethylene is studied. Mass transfer coefficients for six nonpolar volatile organic compounds are presented. The stripping efficiencies of different types of gas-liquid contact devices used in water and waste water treatment are assessed.

Laboratory batch and column experiments have been conducted to elucidate the sorption behavior of nonpolar organic compounds (e.g., halogenated alkenes and benzenes) in a river water-groundwater infiltration system. For the low concentrations typical of the environment, sorption equilibria can be described by the equation <I>S</I> = <I>K</I>_p<I>C</I>, where <I>S</I> = concentration in the solid phase, <I>K</I>_p = partition coefficient, and <I>C</I> = concentration in the liquid phase. For a variety of sorbents, it was found that the partition coefficient <I>K</I>_p^Z of a particular compound Z can be estimated from its 1-octanol/water partition coefficient <I>K</I>_OW^Z and from the organic-carbon (OC) content <I>f</I>_OC (fraction organic carbon) of the sorbents if <I>f</I>_OC is greater than 0.001: log <I>K</I>_p^Z = 0.72 log <I>K</I>_OW^Z + log <I>f</I>_OC(s) + 0.49. Sorption was found to be reversible, but sorption kinetics may have an effect on material transport over the range of flow velocities encountered in aquifers. The conclusions of this study are applicable to a wide range of sorption and transport problems including artificial groundwater recharge and leaching of pollutants from landfills.

Settling particles in the Lake Zürich were collected at different depths. Water samples and particles have been analyzed for heavy metals and for organic matter elements. Samples were investigated by transmission electron microscopy, scanning electron microscopy, energy dispersive X ray and X ray. The elemental composition of the settling particles was found to be almost constant. Special remarks are made on iron and phosphate and on manganese. Manganese oxidizing microorganisms were found near the bottom of the lake.

The calculation of the mean y₀, the amplitude A, and the phase t₀ of the periodic regression function y(t)=y₀+(A/2)sin[(t-t₀)2π/T] is shown for the case of known period length T. An error estimation gives valuable information on how to plan efficient research programs. The theory is exemplified using stream temperature measurements. Applicability of the method to other limnological data, such as oxygen content is briefly discussed.

Spricht man von Abfallbewirtschaftung, so ist in diesem Begriff auch die Wiederverwertung von Materie oder Energie enthalten, selten werden aber Beispiele gebracht, die eine sinnvolle Wiederverwertung bei kleinen Abfallbeseitigungsregionen beschreiben.<br /><br />Da bereits in kleinen Deponien (Deponievolumen bis ca. 10⁶ m³ , Müllmengen bis etwa 100 t/d) beträchtliche Gasmengen produziert werden können, wurde bereits früher an einer kleinen Deponie mit einer Pilotanlage [1] versucht, das entstehende Gas sinnvoll zu nutzen. Aufgrund der dabei gewonnenen Erfahrungen wird im folgenden das Thema Gasnutzung bei geordneten Deponien etwas eingehender betrachtet.

The Indigo Method is well known for the measurement of ozone in air and exhaust gases. It has now been adapted for the measurement of ozone and chlorine dioxide in drinking water and in other aqueous solutions. This method is faster and of higher precision than the colorimetric methods which are generally applied in waterworks. In the pH region ≤ 4 one mol ozone discolors 1.0 mol of aqueous sulfonated indigo. The stoechiometric factor stays constant even if concentrations varied in the range from 5 μg/l to 10 mg/l. The absorbance at 600 nm changes by ~ 20 000 when based on an addition of 1 mol/l ozone and a 1 cm cell. Chlorine dioxide is determined at pH > 4. The absorbance changes by ~ 7000-9000 per 1 mol/l of added chlorine dioxide. All calibration curves are linear. Reagents and oxidized reagents are quite stable. Hydrogen peroxide, organic peroxides, chlorite, chlorate, manganous ions and oxidized species in drinking water do not interfere with the determination. Chlorine is masked by malonic acid or glycine when ozone respectively chlorine dioxide are to be determined. Good photometers give a precision of 1.5 % or 2 μg/l. Visual methods have a limit of detection of about 10 μg/l.

La loi suisse sur la protection des eaux offre d'excellentes bases pour une protection étendue et efficace des eaux contre la pollution. Lors des deux dernières décennies, la Confédération, les cantons et les communes ont, à cet effet, fourni des efforts considérables. Après cette période de grands progrès, principalement en ce qui concerne la construction et l'exploitation de stations d'épuration et de canalisations ad hoc, il convient de faire le point et, partiellement, de donner une nouvelle orientation aux efforts.

Persilylated glass capillary columns are the most universal GC columns available. They are relatively easy to prepare, but there is nevertheless a great need for helpful practical instructions. In the recent literature, methods and conditions for the preparation of persilylated columns have been recommended, but these might confuse the individual column maker, since they seem to originate from limited observations rather than from comprehensive investigation. They will hardly help to make column preparation safer. This paper attempts a summarized view of the present experience with persilylation and provides basic information for column makers.

Specific adsorption of organic and inorganic weak acids and of anions on hydrous oxide surfaces and the concomitant influences upon surface charge can be interpreted as ligand exchange reactions at the reactive surface sites. Direct (inner sphere) binding of the ligands to the surface is postulated. The extent of adsorption and its pH dependence can be explained by considering the affinity of the surface sites and those of the ligands. Surface equilibrium constants have been determined experimentally for various surface reactions; they can be used to predict extent of adsorption and resulting surface charge. The adsorption of simple weak acids or their anions is largest around the pH value of pH = pK. The surface complex formation constants show the same trend in stability as the corresponding solute complex formation constants; thus surface coordination equilibrium constants can be estimated from the corresponding complex formation constants in solution.