Showing papers by "Swiss Federal Institute of Aquatic Science and Technology published in 1983"
TL;DR: In this article, six different conversion processes are identified in the degradation of particulate organic material (biopolymers) to methane, and the kinetic data are applied to the design of an anaerobic digester for raw domestic sludge.
1,038 citations
TL;DR: Aromatic hydrocarbon fractions isolated from sediments polluted with crude oil, from sampling stations in and around Sullom Voe, Shetland Islands, were found to exhibit, as the major feature in their gas chromatograms, an unresolved complex mixture or "hump" as discussed by the authors.
115 citations
TL;DR: In this article, the ozone reaction rate with free aqueous chlorine when present as hypochlorite ion (OCl−) with a second order rate constant of 120 ± 15 M−1 s−1 at 20°C.
103 citations
66 citations
TL;DR: In this paper, the acidification of lakes, streams and soils is influenced by hydrology, biota, geology and weathering rates, and it is essential to distinguish between free H+ acidity and the H+ reservoir (base neutralizing capacity).
Abstract: The occurrence of acid precipitation in regions of the northern hemisphere results from the anthropogenic disturbance of cycles that couple land, water and atmosphere. The oxidation of C, S and N resulting mostly from fossil fuel burning rivals oxidation processes induced by photosynthesis; the acidity of rain is a consequence of these redox processes in the atmosphere and in the rain. In evaluating the impact of aqueous acidity upon the environment and vice versa, it is essential to distinguish between free H+ acidity and the H+ reservoir (base-neutralizing capacity). The acidification of lakes, streams and soils is influenced by hydrology, biota, geology and weathering rates.
50 citations
01 Mar 1983
TL;DR: In this paper, the analysis of data from moored instrument systems (atmospheric boundary layer, lake temperature distribution, bottom currents) was correlated to the long-term development of vertical mixing as seen from profiles of natural isotopes (radon-222, tritium and helium-3) and chemical species.
Abstract: In Lake Baldegg, Switzerland (surface area 5.3 km2, maximum depth 66 m) the analysis of data from moored instrument systems (atmospheric boundary layer, lake temperature distribution, bottom currents) was correlated to the long-term development of vertical mixing as seen from profiles of natural isotopes (radon-222, tritium and helium-3) and chemical species. The investigation shows: 1. Vertical mixing coefficients below 25 m are small. Consequently the vertical concentration distribution of sediment emanating species in the deep hypolimnion is controlled by the bottom topography. 2. Renewal of deep hypolimnic water is significant even during stratification. 3. Weakly damped internal waves characterize the internal dynamics during stratification. 4. Horizontal bottom currents play an important role in the hypolimnion mixing and can be correlated to internal waves during stratification.
50 citations
TL;DR: In this article, the authors encourage chemists to participate in the solution of ecotoxicological problems: chemodynamical concepts permit the estimation-on the basis of physical-chemical generalizations and with the help of compound-specific data-of the fate, the distribution, the potential for bioaccumulation in the food chain, and the approximate residence time of pollutants (and thus the attainable residual concentrations) in the environment and therefore to predict the relative risk of different pollutants.
Abstract: The development of cultural and technical civilization has been marked with increasing interference in hydrogeochemical cycles and the production of a growing number of chemicals; this is accompanied by a growing concern on the potential adverse effects of chemicals on biological systems. Assessment of the potential toxicological and ecological effects of pollutants is of central importance. We are of the opinion that this cannot be accomplished by merely evaluating the harmfulness of a substance on the basis of toxicity tests with individual organisms and by monitoring analytically the environment for pollutants. We would like to encourage chemists to participate in the solution of ecotoxicological problems: chemodynamical concepts permit the estimation-on the basis of physical-chemical generalizations and with the help of compound-specific data-of the fate, the distribution, the potential for bioaccumulation in the food chain, and the approximate residence time of pollutants (and thus the attainable residual concentrations) in the environment and therefore to predict the relative risk of different pollutants.
28 citations
01 Dec 1983
TL;DR: In this article, a new set of nets in twin arrangement for quantitative layer-sampling of crustaceans is presented and compared to a volume sampler, as regards capturing characteristics.
Abstract: A new set of nets in twin arrangement for quantitative layer-sampling of crustaceans is presented and compared to a volume sampler, as regards capturing characteristics. Due to a favorable geometry and clearly defined opening of the net, there is no loss due to flight reaction nor water backup.
26 citations
01 Mar 1983
TL;DR: In this paper, the mixing and transport processes in Lake Biel have been studied using the heat and excess Rn-222 as natural tracers, and the mixing parameters were established in terms of coefficients of eddy diffusion in a two-dimensional box model.
Abstract: The mixing and transport processes in Lake Biel have been studied using the heat and excess Rn-222 as natural tracers. The mixing parameters were established in terms of coefficients of eddy diffusion in a two-dimensional box model. To account for observed transient Rn-222 distribution, transport by advection had to be included in the model calculations.
17 citations
01 Mar 1983
TL;DR: In this paper, the authors applied a nonlinear dynamic lake model to predict that the defined water quality goals can only be achieved within the next 15 years if the external phosphorus loading is reduced by at least 50% and simultaneously lake-internal measures, such as hypolimnion areation or hypoline siphoning are carried into effect.
Abstract: Since 1954 average orthophosphate and total phosphorus concentrations have increased twenty and eightfold respectively in Lake Sempach. It is demonstrated that the lake is not in steady state with its phosphorus loading and that the net deposition rate of phosphorus is not linearly related to the phosphorus content of the lake. This implies that linear steady state one-box models are unsuitable to describe the phosphorus balance of this lake. Applying a nonlinear dynamic lake model we predict that the defined water quality goals ([P] ⩽30 mg m−3, [O2 ⩾4 mg m−3]) can only be achieved within the next 15 years if the external phosphorus loading is reduced by at least 50% and simultaneously lake-internal measures, such as hypolimnion areation or hypolimnion siphoning are carried into effect.
14 citations
TL;DR: According to today's practice, it must be assumed that in only 14 years the use of compost will have enriched soils to such an extent that its cadmium content will prohibit the production of food for human consumption.
01 Dec 1983
TL;DR: A device is described which can be used where working equipment has to be instantly activated (i.e. without time delay) under water.
Abstract: A device is described which can be used where working equipment has to be instantly activated (i.e. without time delay) under water. The latch with an adjustable spring, on which the instrument is fastened, can be released by jerking on the supporting cable or by suddenly stopping the lowering motion, thereby instantly activating the working equipment.
01 Dec 1983
TL;DR: In this paper, a simple, transportable powered winch which can be mounted in any boat is described, which is operated by a 200-watt geared electromotor and has a lifting power of 50 kp at a lifting speed of 0.4 m/s.
Abstract: A simple, transportable powered winch which can be mounted in any boat is described. It is operated by a 200-watt geared electromotor. The lifting power at the capstan amounts to 50 kp at a lifting speed of 0.4 m/s. The load can be pivoted into the boat by a small crane integrated in the machinery. For special uses such as rapid hoisting of lighter measuring probes, rewinding of the supporting cable, etc., the capstan can be exchanged for any type of cable drums. The current is provided by a 220-volt transportable electric generator.
01 Mar 1983
TL;DR: The central theme of the meeting was the mutual microscopic study and discussion of problematic blue-greens from natural habitats, that were mostly collected during the three field trips into different areas of central Switzerland.
Abstract: The 8th Symposium of the International Association for Cyanophyte Research IAC was attended by 29 specialists from 11 countries. The 19 oral presentations and discussions centered on the following themes: The basic principles of cyanophyte taxonomy (3 lectures), systematic problems of certain taxonomic groups (5 lectures), morphology (6 lectures) and ecology (5 lectures). The intensive discussions between representatives of the classical (european) taxonomic treatment of cyanophytes (based on morphological and ecological characteristics) and those representing the bacteriological study of ‘cyanobacteria’ were especially valuable. The central theme of the meeting was, however, the mutual microscopic study and discussion of problematic blue-greens from natural habitats, that were mostly collected during the three field trips into different areas of central Switzerland (Grimsel-Gotthard-Nufenen. Klewenalp. Gerzensee).