Swiss Lakes Research Articles

Eisbedeckung und hypolimnische Sauerstoffanreicherung im Greifensee von 1950 bis 1980

Hypolimnetic oxygen in the highly eutrophic Swiss lake Greifensee (area 8 km2, maximum depth 33 m) was almost entirely depleted during summer stratification. We found a strong empirical relation between wind action across the lake surface and hypolimnetic reoxygenation in the cold half year. Long periods of ice cover severely limited anemogenic reoxygenation.

Adsorption of dissolved organics in lake water by aluminum oxide. Effect of molecular weight

Dissolved organic compounds in a Swiss lake were fractionated into three molecular size classes by gel exclusion chromatography, and adsorption of each fraction on colloidal alumina was studied as a function of pH. Organic compounds with molecular weight (mr) greater than 1000 formed strong complexes with the alumina surface, but low molecular weight compounds were weakly adsorbed. Electrophoretic mobility measurements indicated that alumina particles suspended in the original lake water were highly negatively charged because of adsorbed organic matter. Most of the adsorbed organic compounds were in the mr range 1000 < mr < 3000. Adsorption of these compounds during the treatment of drinking water by alum coagulation may be responsible for the preferential removal of trihalomethane precursors. Adsorption may also influence the molecular-weight distribution of dissolved organic material in lakes.

On the use of carotenoid stratigraphy in lake sediments for detecting past developments of phytoplankton

A method is described on one‐ dimensional chromatography with four sequential development steps for the separation of carotenoids in plankton and in lake sediments. Quantitative measurements of various carotenoids in cores of sediments from Swiss lakes allow the composition and development of the phytoplankton over the past 150–500 years to be worked out and also show the changing trophic condition of the lakes. an example from lake zürich shows how the change from oligotrophy to eutrophy, as documented by limnological studies, is reflected in the composition and changing concentration of specific carotenoids.

History of Natural Fibers

Abstract Nature, as though aware of the importance of textiles, has long provided an abundance of fibers—plant, animal, and mineral—of different dimensions and properties. Beginning in prehistory, the natural fibers have served man's textile needs for thousands of years. The Swiss Lake Dwellers in 8000 BC cultivated flax and wove linen into fabrics. By 3000 to 2000 BC, the use of fibers was well developed, and the weaving of cotton was well established in India and Pakistan. Improvements in machines for spinning, weaving, etc., beginning in the 1700s, revolutionized the processing of fibers. Eli Whitney's invention of the cotton gin in 1793 helped cotton become king of the fibers. In recent decades the textile industry was revolutionized again by many technological developments, including the creation of synthetic and modification of natural fibers. Today the world and United States fiber markets are dominated by the natural and man-made fibers, respectively. In spite of gains by the man-made fibers, both...

The Use off GAC Filtration to Ensure Quality in Drinking Water From Surface Sources

To ensure that the quality of drinking water derived from Swiss lake water is not inferior to that of well or groundwater, GAC filtration is indispensable, and, at a cost of one eighth of the total treatment costs, its use is also economically feasible.

MELIMEX, an experimental heavy metal pollution study: Chemical speciation and biological availability of copper in lake water

The chemical speciation of dissolved copper was investigated in waters from the limno-corrals of the MELIMEX project and compared with speciation data from other Swiss lakes. Copper is complexed primarily by organic ligands having molecular sizes between 104 and 103 daltons. The mean concentration of the ligands is approximately 5×10−7 mole/mg DOC. The conditional stability constants (pH=8.8) are about 1011. An increased metal load did not induce an increase of binding ligands. A comparison of calculated Cu2+ concentration with corresponding copper contents in the biomass leads to the conclusion that organic ligands and pH are the most important factors in deciding the biological availability of copper. However the sorption capacity of the biomass depends as well on the variety of plankton species.

PEAS: today's number one vegetable

The popularity of garden peas, now easily our most widely favoured green vegetable, is nothing new in the history of human food. Pea seeds were the regular food of many races of prehistoric man, wherever the wild plants grew naturally in the Middle East, Ethiopia and Mid‐Asia. The remains of such seeds have been found in many prehistoric sites, including the Swiss lake dwellings of the Bronze Age dating back some 5,000 years.

Schwermetalle (Hg, Cd, Cu, Pb, Zn) in Lebern und Muskulatur des Flussbarsches (Perca fluviatilis) aus Bielersee und Walensee

Liver and muscle tissue from fish caught between 1973 and 1975 in two Swiss lakes, namely the Lake of Biel and the Walensee, were analyzed for the heavy metals Hg, Cd, Cu, Pb and Zn. The research project was carried out within the framework of an international OECD programme. The mean of the heavy metal concentrations in mg/kg undried material lay within the following ranges: Open image in new window The comparison of metal concentrations in fish originating from the two lakes revealed for the Lake of Biel higher Hg values throughout and higher Cu and Zn values in the livers, whereas for the Walensee the Cd values were found to be higher in the livers. The Pb concentrations did not differ significantly. With regard to the examined organs (livers and muscles) the comparison showed higher Hg concentrations in the muscles than in the livers. The Cd, Cu, Pb and Zn concentrations, however, were found to be higher in the livers.

A dynamic lake model for trophic state prediction

Primary production per unit lake area, ΣP, is selected as a measure of the trophic state of a lake. The relationship between phosphorus loading and ΣP is simulated by means of a dynamic, one-dimensional vertical diffusion model for phosphate [OP] and particulate phosphorus [PP]. ΣP is described by a non-linear function of [OP] and [PP] which takes into account Michaelis Menten saturation and self shadowing by algae. Included in the model are lake morphometry, hydraulic loading, respiration rate, sedimentation, vertical eddy diffusion, depth of thermocline, and exchange of phosphorus at the sediment—water interface. Application of the model to two Swiss lakes, Alpnachersee and Greifensee, as well as to Lake Washington (U.S.A.) shows a good agreement between observation and calculation of the phosphorus variation as a function of time and depth. The calibrated model is used to predict the effectiveness of different eutrophication control measures, such as reduction of phosphorus loading, discharge of hypolimnic water, aeration of the hypolimnion, and destratification. For Greifensee (mean residence time of water 1.2 years) it is shown that a reduction in P-loading to 20% of its present value is needed to achieve permanent aerobic conditions throughout the lake. Other measures result only in minor improvements. For Lake Washington, the model simulates well the observed recovery of the lake after sewage diversion between 1963 and 1967.

Primary production, mineralization, and sedimentation in the euphotic zone of two Swiss lakes

Phosphorus and nitrogen concentrations, phytoplankton, bacteria, detritus, primary production, and sedimentation have been investigated over a year in two Swiss lakes of different trophic state. Inflow and outflow of the lakes were calculated, as well as the eddy diffusion of P and N from the metalimnion into the epilimnion, and from these data a balance of the epilimnetic phosphorus and nitrogen cycle was drawn up. Different methods of calculation all suggested a high intensity of the internal nutrient cycle in the epilimnion. By means of autolysis, destruction, and excretion, about 35–75% of the nitrogen and 55–85% of the phosphorus needed for the measured primary production can thus be regenerated.

Energy relations of density‐current flows: an experimental investigation*

ABSTRACTThree series of density‐current experiments were performed in a 5.76 m flume. In the first series, the flume was horizontal, and in the second and third, it was inclined with a positive slope and negative slope, respectively. Energy relations during successive stages of density‐current movement were computed from observed data, which showed an appreciable frictional energy dissipation. The computed friction factors of our experimental density‐flows were compared to the friction factors for pipe flows (Moody diagram), and while the calculated friction factor increases with increasing Reynold's number within the range of our experiments (Re 2 × 103−2 × 104), it is concluded that with increasing Reynold's number above about 5 × 104 the friction factor decreases. For natural turbidity currents, the Moody diagram gives a reasonable estimate of the friction factor between the current and sediment bed. The value of the friction factor for the interface between the current and overlying water was found to be about 0.2 times the friction factor for the current and flume. However, due to errors inherent in measuring the depth of the current, a value of 0.4 would be more reasonable for density‐currents in our range of Reynold's number. Friction tends to decrease the value of the dimensionless coefficient in Keulegan's law of saline front and to decrease the thickness of the flow. In contrast, the presence of a slope in the direction of flow tends to compensate the effect of friction. The angle θc that provides the potential energy to exactly offset the energy losses incurred during movement by the density‐currents in our experiments has a calculated value of 31′. An empirical formula φ= 0.935θ—0·57 relating friction, in terms of the hydraulic gradient φ, to the slope angle θ was obtained. Since the thickness of the current can be computed from the relationship between φ and θ, we estimated the thickness of naturally occurring density‐currents in Swiss lakes. The results suggest the applicability of our experimental results to small turbidity currents in nature. Our analysis further indicates that large turbidity currents have a small φ and can be expected to flow very long distances on a flat abyssal plain.

Palynological and oxygen isotope investigations on Late‐Glacial sediment cores from Swiss lakes

Results from detailed pollen and 18O/16O studies on two sediment profiles from small Swiss lakes are reported. 18O/16O records in lacustrine carbonate contain paleoclimatic information because they reflect mainly the isotope ratio in rain and snow which is correlated to temperature. Several transitions between different climatic periods determined palyno‐logically are also indicated by marked changes in the isotope ratios in both profiles, namely the transitions Oldest Dryas ‐ Bøiling and Allerød ‐ Younger Dryas ‐ Preboreal. 18o/16O was 2 to 3 %0 lower during Younger Dryas than during the adjacent periods, corresponding to a temperature drop of a few degrees Centigrade according to a tentative estimate.

Improving the production and nutritional quality of food legumes.

Man has been using some legumes as important sources of food ever since the invention of agriculture, probably about 8000 to 10,000 years ago. For example, remains of peas, Fisum sativum, have been found in the Swiss lake dwellings of the Bronze Age (1), and the plant was cultivated by the Greeks and Romans. The broad bean, Vicia faba, probably native to northern Africa and the Near East, has been under domestication for at least 4000 years and probably longer. It was well known to the ancient Egyptians and to the Greeks. Records 5000 years old mention cultivation of the soybean, Glycine max, in eastern Asia, possibly its native habitat, but there is no record of its first domestication, which must have occurred long before.KeywordsCommon BeanBroad BeanRockefeller FoundationField BeanFood LegumeThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Brienzersee, Thunersee, and Bielersee: Effects of Exploitation and Eutrophication on the Salmonid Communities

These three lakes of the Aare Valley in Switzerland have been subjected to increasingly intense fisheries exploitation in recent decades. Fishing intensities have been roughly comparable in the three lakes in any particular year. Attempts at introducing non-native species have been made in all lakes but none of the attempts have had appreciable effect. Nutrient loading, due to domestic wastes predominantly, has been much greater with the downstream Bielersee than the upper two lakes, and somewhat greater in the Thunersee than the highest lake, Brienzersee. But even the latter is now showing symptoms of nutrient stress, in that populations of indicator phytoplankters have recently erupted.Ecological effects ascribed to the fishery include a marked reduction in stocks of Arctic char due to angling and pelagic coregonines due to commercial gillnetting. The latter taxa have recently shown pronounced fluctuations in year-class abundance. An energetic hatchery program has mitigated exploitation effects to some extent.Total stocks of fishes have increased due to eutrophication with initial increases in all fish taxa, except perhaps Arctic char. The cyprinids, percids, and esocids have increased in the Bielersee to a far greater extent than the salmonids with a result that the latter are now contributing smaller proportions of the catches. The cyprinids have little economic value and their burgeoning stocks are creating ecological and economic problems in the Bielersee as well as many other Swiss lakes. The cyprinids apparently cannot be effectively controlled by piscivores such as esocids, even where the latter are assisted by a hatchery program.

Levels of mercury in the sediments of some Swiss lakes including Lake Geneva and the Rhone river

Les sediments recoltes dans les lacs de Bienne, Brienz, Joux, Tuma, Saoseo, Bodan, Leman et dans le Rhone ont ete analyses pour determiner leur teneur en Hg/total. A l'exception du lac de Brienz tous les lacs presentent une contamination mercurielle due soit a la pollution atmospherique soit a des sources industrielles ou urbaines. La teneur en mercure provenant de l'environnement geologique a ete estimee comme etant au maximum de 200 ppb. Les lacs de Tuma et de Saoseo situes sur le versant sud des Alpes sont probablement pollues par les emissions dans l'atmosphere des complexes industriels de l'Italie du Nord, les vents predominants venant de l'ouest et du sud-ouest. Le profil du Rhone montre des concentrations en mercure dans les canaux X, Y et Z et dans un affluent, la Drance, qui sont les sources industrielles de la contamination par le mercure du Rhone et du Leman. La repetition des campagnes d'echantillonnage entre 1964 et 1971 montre un apport important de mercure d'origine industrielle entre 1965 et 1967 et des cette date un accroissement regulier des teneurs jusqu'en 1971.

Some Physico-Chemical Investigations of Stratification in Abbot's Pool, Somerset: The Temperature Cycle

In the study of any biological system, the effect of changing temperature is of paramount importance. It has an obvious effect on the physiology and growth of organisms, and also affects the environment, of particular importance in limnological studies. This is not simply a question of warming and cooling of the water mass but in addition the rate of heat transfer, and the subsequent stratification of temperature, are affected. The first records of changes in temperature with depth were made by de Saussure (1779, 1796) in a Swiss lake. Since then knowledge of thermal characteristics of lakes has been confined mostly to larger bodies of water. Intensive algal and limnological work has been carried out on Abbot's Pool, Somerset, since 1962, and depth temperature studies were instituted in spring 1966 (Moss 1967, 1969). Although the pool is shallow, it stratified thermally during the summer and, to some extent, during the winter. Temperature investigations have been continued for a further 18 months in an attempt to analyse the purely physical conditions in the pool during the year, and to determine the extent to which such a small body of water, some 100 x 40 m and 3 5-4 m deep, could behave as a 'model lake'. Details of Abbot's Pool are given by Eaton (1967), and Moss (1967, 1969).

Un exemple de collaboration internationale en hydrologie

Summary Forecasts of the discharge of the Rhine at Basel have been studied in Zurich since 1954. In this programme have cooperated hydro-power companies of Switzerland, Germany and France, French shipping-firms, and the Dutch water management authorities. For the Netherlands the forecast of the summer yield of the Rhine is of great concern, since it is the main resource of fresh water. The studies have resulted in: — since 1955, annual forecasts of the yield from snowmelt for periods of one to eight months beginning with March, and monthly and bi-monthly forecasts in winter — since 1960, forecasts issued 2 to 5 times per week for the next three days, from October to March. The forecast method is the least squares multiple regression, based on the observations of more than 50 years. For the short term forecasts, the significant predictors are discharge and rainfall, eventually the snow cover percentage on the Swiss midland plateau. The largest errors of forecast were encountered in thawing conditions. Meteorological forecasts are provided by the Swiss Meteorological Institute. For the long range forecasts, the alpine snow pack (in practice represented by the cumulative winter precipitations) and the levels of the Swiss lakes play an important role. The forecasts are used by the hydro-power plants in their operation programmes for maintenance planning, and for proper timing of construction work. In the future, the probability graduation of these forecasts will also be introduced in the optimisation of power production according to the methods of operations research.

Determination of the Age of Swiss Lake Dwellings as an Example of Dendrochronologically-Calibrated Radiocarbon Dating

Comparison of the radiocarbon content of a series of samples of dendrochronologically dated bristlecone pine wood with that from trees for which a so-called floating tree-ring chronology has been established makes it possible to determine an empirical age for this floating tree-ring series based upon the age of the wood used for comparison. For the case of the Swiss Lake Dwellers, the difference between conventional radiocarbon dates and the age values determined in this manner amounts to about 800 years. The age of the floating chronology was determined within a standard error of less than 40 years. The measurements indicate that the dwellings were constructed during the 38th century B. C.

Regional Groups in the Michelsberg Culture: A Study in the Middle Neolithic of West Central Europe

In order to discuss the origin of the Michelsberg culture, a question which has been the subject of much debate during the last five years, a closer definition of the culture is first necessary. This paper begins by reviewing the theories as to origins which have been offered during the last half century, a detailed description of the elements making up the various subdivisions of the culture is then attempted, together with some observations on the internal chronology of the material; and in conclusion a return is made to the question of origin.We owe to Schumacher the first identification of the culture by name, though it was Reinecke's contribution two years later which proposed its attachment to a ‘western’ neolithic family in an article written, as usual, with an insight years ahead of its time. Schumacher had thought that the culture was a late phase of Bandkeramik (Danubian I) influenced by Schnurkeramik (Corded Ware).Later, Reinecke modified his views somewhat and noted the close connection between the material of the Swiss lake dwelling cultures and the mesolithic of Scandinavia and, in two short papers, laid the basis for the second of the principal theories as to origins. It is interesting that the same man was responsible for two major trends in archaeological thought on the question.

Das kombinierte Ramm-Kolben-Lot, ein leichtes Bohrgerät zur vereinfachten Gewinnung mehrere Meter langer, ungestörter Sedimentprofile

In this writing a drilling ring is described representing a combination of a rammer and a piston sampler. The total weight of this drilling ring is only about 25kg. It is easy to transport and to dismantle. For sampling it is set to work by a hand rope capstan mounted over two gondolas. Its application is independent of the depths found in Swiss lakes. It is especially used to obtain drill cores up to 3 m in length for the purpose of investigating the historical development of lakes.