Showing papers by "Swiss Federal Institute of Aquatic Science and Technology published in 1989"
TL;DR: In this article, experimental measurements and mathematical modeling demonstrate that coagulation in lakes can be sufficiently rapid and extensive to affect suspended particle concentrations and sedimenting fluxes significantly, and that the process dominates particle removal in Lake Ziirich and sub-stantially influences particle concentrations in the water column of Lake Sempach.
Abstract: Rest&s of experimental measurements and mathematical modeling demonstrate that coagulation in lakes can be sufficiently rapid and extensive to affect suspended particle concentrations and sedimenting fluxes significantly. The process dominates particle removal in Lake Ziirich and sub- stantially influences particle concentrations in the water column of Lake Sempach. Natural coagulation in lakes is a process that is strongly influenced by solution chemistry. Calcium ions act as destabilizing agents and enhance natural coagulation while dissolved natural organic matter stabilizes particles and retards coagulation. Since solution chemistry varies widely among lakes, natural coagulation rates are expected to differ among lacustrine systems. Field observations of Lakes Zurich and Sempach support this view. Although primary productivity in Lake Zurich is considerably lower than in Lake Sempach, higher sedimenting fluxes are observed in Lake Zurich. The waters of Lake Zurich are low in dissolved organic carbon, permitting rapid coagulation in the epilimnion of the lake and producing correspondingly rapid sedimentation rates. Colloidal stability can be a factor in eutrophication.
176 citations
96 citations
TL;DR: The mean heat budget of Lake Aegeri, Switzerland, is 950 MJ·m−2, comparable to that of neighbouring lakes as mentioned in this paper. And the annual variation in the net heat flux can be adequately described using a six-term heat balance equation based on 12 years of monthly mean meteorological and surface temperature data.
Abstract: The mean heat budget of Lake Aegeri, Switzerland, is 950 MJ·m−2, comparable to that of neighbouring lakes. The annual variation in the net heat flux can be adequately described using a six-term heat balance equation based on 12 years of monthly mean meteorological and surface temperature data. Although the magnitude of the net heat flux is dominated by the radiative terms of the equation, the one-month backward shift of the net flux and total heat content extrema from the solstices and equinoxes respectively is due to the phase shift of the non-radiative with respect to the radiative terms. A linear approximation was used to express the net heat flux in terms of a heat exchange coefficient and an equilibrium temperature. The former varies from 17 to 28 W·m−2·K−1 in the course of a year; fluctuations in the latter are found to depend mainly on fluctuations in cloud cover and relative humidity, whilst the effect of fluctuations in air temperature and wind speed is slight.
53 citations
TL;DR: In this article, the activities of two short-lived natural radionuclides,234Th and7Be, were measured in Lake Geneva water, suspended solids and sediments, in order to obtain their removal residence times in the lake.
42 citations
TL;DR: In this paper, the authors used a Grignard reaction and gas chromatography with flame photometric detection (GC-FPD) to detect organotins in municipal wastewater and sewage sludge.
33 citations
TL;DR: In this paper, the authors report results of a field program conducted over the period February-May, 1988, when observations were obtained from weekly CTD transects and from three thermistor string/current meter moorings deployed for two months, one near each sill and the third at the southern end of Urnersee near Fluelen.
Abstract: Despite their close proximity and similar dimensions (∼ 200m deep × 10km long × 2km wide) the two eastern basins of Lake Lucerne, Gersauersee and Urnersee, exhibit considerable differences in their internal behaviour, particularly during late winter and spring. The two lakes are separated by a small intermediate basin (∼ 120m deep × 4km long × 1km wide) with sills of approximately 90m depth at each end. We report results of a field program conducted over the period February—May, 1988, when observations were obtained from weekly CTD transects and from three thermistor string/current meter moorings deployed for two months, one near each sill and the third at the southern end of Urnersee near Fluelen. During the observation period the stratification, relative surface to bottom density difference, Δρ/ρ, was 12 × 10−6 in Gersauersee and 4 × 10−6 in Urnersee. Following wind events a large amplitude internal seiche in Gersauersee (vertical excursions of ∼50m and period ∼60 hours) effectively pumpe...
24 citations
TL;DR: In this article, the first detailed sedimentological facies analyses of a Lower Beaufort (Upper Permian) Gondwana sequence from Mt. Chombe are presented.
24 citations
TL;DR: In this paper, Henze et al. describe the biological degradation of NTA and adsorption of the NTA onto activated sludge based on literature studies and experiments undertaken at the Glatt wastewater treatment plant (waste water discharge: Q = 55 - 60 000 m 3 /d, 110 000 inhabitants).
23 citations
TL;DR: In this article, trace levels of PCDD and PCDF were detected in fog samples collected in Dubendorf, Switzerland, where the more chlorinated, less toxic isomers predominated.
10 citations
TL;DR: There was no significant difference in the abundance and size distribution of the principal zooplankton taxa between the 1986 and 1987 samples and the effects of a sudden cooling of the surface water layer on the survival of cold-bred whitefish larvae are discussed.
Abstract: Whitefish larvae (Coregonus sp.) were caught at regular intervals in 1986 and 1987 in oligotrophic Lake Sarnen, and in 1987 in eutrophic Lake Hallwil.
9 citations
TL;DR: In this paper, the historical chemical record contained in sludge-only landfills can reflect the use and disposal of many types of chemical species, such as PCBs and Cd.
TL;DR: Parkin et al. as discussed by the authors presented a paper on the CIC Workshop, Tiibingen 1988, which was later published as a book "CIC Workshop 1988: A Review of CIC Proceedings".
Abstract: Received January 24, 1989 1. Parkin, S. S. P., et al. : Phys. Rev. Lett. 61, 750 (1988) 2. Martin, C., et al.: C. R. Acad. Sci. Paris 307, Ser. ii, 27 (1988) 3. Busing, W. R., Levy, H. A.: Acta Cryst. 10, 180 (1957) 4. Flack, H. D.: ibid. A30, 569 (1974) 5. Burzlaff, H., Rothammel, W.: Proc. 3. CIC Workshop, Tiibingen 1988. Berlin: Springer (in press) 6. Takahashi, T., et al.: Nature 334, 691 (1988)
TL;DR: In this paper, a multidisciplinary field experiment to study wet deposition processes by means of detailed case studies is presented with the help of a video, which combines measurements of radar meteorology, cloud physics, aerosol physics, as well as of inorganic and organic chemistry.
TL;DR: In this paper, the periphyton communities in 13 Swiss streams and rivers were investigated from January 1980 to September 1981 and the NH4-N concentration in these waters varied between 0.015 and 1.0 mg/l.
Abstract: Since sewage treatment plants are most effective in Switzerland, the micro-benthic communities in receiving running waters have changed considerably. From January 1980 to September 1981 the periphyton communities in 13 Swiss streams and rivers were monthly investigated. The NH4-N concentration in these waters varied between 0.015 and 1.0 mg/l. Four typical communities of microorganisms were found: In unpolluted running waters mainly small vagile ciliates were abundant; in slightly polluted waters peritricha (in the presence of bacteria) were found; in moderatly polluted waters peritricha in combination of few hymenostomata and Sphaerotilus could grow when bacteria and some degredable organic material where present; in polluted waters the well-known Spaerotilus-community (after Liebmann) could be found. The microscopic as well as the macroscopic aspect should be considered to qualify the degree of pollution in streams and rivers.
TL;DR: A review of the development of a chemical kinetics and photochemical data base for use in atmospheric modeling is given in this paper, with a focus on ozone depletion in the stratosphere.
TL;DR: The cycle saisonnier de developpement du Cestode Proteocephalidae (Proteocephalus) du Lac Leman, parasite du coregone du lac Leman comprend une phase de maturite sexuelle des individus allant de juin a septembre, suivie par une disparition des parasites adultes en hiver.
Abstract: Le cycle saisonnier de developpement du Cestode Proteocephalidae du genre Proteocephalus, parasite du coregone du lac Leman comprend une phase de maturite sexuelle des individus allant de juin a septembre, suivie par une disparition des parasites adultes en hiver.Les tentatives de reconstitution du cycle parasitaire au laboratoire ont montre l’importance de la densite des hotes intermediaires (Cyclops vicinus Ulianine, 1875) pour la reussite des infestations ainsi que de parametres comme la maturite des œufs et la temperature de l’eau.L’infestation artificielle de coregones 0+ prouve que la realisation du cycle complet de ce parasite est possible au laboratoire. Les differentes phases de ce cycle sont decrites. Le proteocephale des coregones du lac Leman semble pouvoir etre un bon marqueur biologique du flux trophique entre le zooplancton et les poissons de cette espece en hiver et au printemps.