The Influence of the Incubation Temperature on the Body Length and the Yolk Sac Volume of Coregonus albula (L.) Eleutheroembryos

Eggs of Coregonus albula were incubated at temperatures of 1.1, 2.0, 4.9, 6.6, 8.4 and 9.9 °C. The successful hatching is optimum with 61 % at 4.9 °C; incubation time and period of hatching decrease significantly with rising temperature. The length of eleutheroembryos decreases with rising temperature, the yolk sac volume increases. Between the incubation time till hatching and the body length a significantly positive regression exists in the range of 4.9… 8.4 °C, for the yolk sac volume the regression is negative, it is significant in the range of 2.9… 6.6 °C; at the same time a negative regression exists between the yolk sac volume and the body length. Thus, low temperatures cause a delay of hatching, higher temperatures accelerate hatching and at the same time result in a reduced utilization of the yolk reserves. Besides these influences of temperature on the rate of ontogenetic processes, some autoecological consequences of the influence of temperature result, which have to be taken into account in further investigations.     

Zytotoxikologische Untersuchung von Schadstoffen und Wasserblüten mit gefrierkonserviertem Bullensperma (Spermatest)

The method is based on the determination of the number of the nonmotile sperms and/or the lethally damaged sperms with the aid of the fluorescent dye primuline. Incubation takes place at a suspension density of 10.000/mm³… 38.000/mm³, at 40°C or 46 °C for 15… 60 min. During the test with sublimate the loss of motility amounts to 55% at 4 mg/l Hg²⁺, the LC₅₀ is 7.3 mg/l Hg²⁺. Phenyl-mercuric acetate causes the total loss of motility with 20 mg/l, the LC₅₀ is above 168 mg/l (equivalent to 100 mg/l Hg²⁺). The LC₅₀ of sodiumpentadecylmonosulphonate and dodecylpyridinchloride are 11.6 and 15.8 mg/l, resp. Filtrates of blooming of cyanophyceae on Baltic, having been digested by repeated freezing and thawing, with 1.5… 6.4 g/l dry matter showed motility losses of 30… 100 % for Nodularia spumigena, whereas no significant effect was produced by a filtrate of Microcystis aeruginosa with 28.2 g/l dry matter as well as water-blooming of Nodularia spumigena from the Small Jasmund Bodden.     

Zur Konzentrationsabhängigkeit der Sorption von Co(II) an Titanschwamm

The sorption of Co(II) from aqueous solutions on granulated titanium dioxide was investigated in dependence on pH-value (pH = 6 … 10) and solution concentration (c_L = 10^?7 … 10^?2 mol/kg) at 83 °C. The precipitation in the solution occurred at high pH-values and solution concentrations was determined by control experiments without the adsorber. The adsorption isotherms are S-shaped. This can be interpreted as transition from chemisorption at the basic material to surface precipitation.     

Die gaschromatographische Bestimmung von freien flüchtigen Fettsäuren (C2 — C6) im Sickerwasser von Hausmülldeponien

After extensive experiments aimed at determining the free volatile fatty acids (C₂ to C₆) in organically highly polluted percolation water of household refuse dumping places there proved optimum a column packed with 10% Carbowax 20 M on Chromatron N-AW-DMCS after having been conditioned for five days at 270°C and subsequently covered with 10% hard wax. On short retention times the investigated isomeric column pairs are completely separated. Equally favourable results were obtained also for liquid manure and silage extracts. The detection limits lie between 10 and 20 mg/l, the relative standard deviation is 20 … 30% in the range of the lower detection limit and 2 … 3% at 200 mg/l in the upper range. In the investigation of percolation waters with concentrations between 235 and 4300 mg/l reproducibility lies at a mean relative standard deviation of 0.5 … 2.8%. The technique is well suited for routine checking.     

Zum Einfluß von Rückständen von Zink- und Bleiverbindungen im Wasser auf die Assimilation von Fontinalis antipyretica

The carbon-dioxide assimilation of Fontinalis antipyretica is inhibited by 100 mg/1Zn²⁺ or Pb²⁺, without a lethal effect being caused. With increasing time of exposure from one to six days the threshold value of toxicity is lowered and at the same time the net assimilation is reduced within the range of concentration of 0.1 mg/1. In the ecological optimum of the environmental conditions the toxicity is weaker than under other unfavourable environmental conditions at the same time. Therefore, the photoecologically optimum illumination of 1200 lx is an effective bioprotector against phytotoxic lead ion concentrations, so that at 1200 lx also at a comparatively high load a positive photosynthesis balance can be maintained. In the dark, in the first hour after the application of the lead ions dissimilation is a function of concentration, subsequently the respiration differences decrease very much in the range between 0 and 100 mg/1 lead(II)-ions. Stimulating effects could be demonstrated only by 0.01 mg/1 Pb²⁺ and only for the carbondioxide assimilation.     

Efficaciousness of Certain Chemicals to Control Dracunculiasis — A Field Trial

To prevent infection with Dracunculus medinensis, a carrier host, the copepod Cyclops, has to be controlled. After preceding laboratory investigations a field trial with well water and different additions of chlorine and sodium permanganate is carried out. The exposure is performed at an ambient temperature of 25… 40 °C and in bright and dark samples (5… 11 h of sunshine/d) as well as in the well. The residual concentrations of the two chemicals are an exponential function of the time of exposure with half-times between 6 and 23 h for chlorine and 11… 30 h for sodium permanganate. The depletion of the two oxidizing agents under light is faster than in darkness. Dosage should be done in such a way that the LC_90,24h after 24 h of exposure will not be fallen below; in a specific case, this guarantees at the same time that the permissible concentrations for drinking water will not be reached 96 h after addition. For this, initial concentrations of 30 mg 1 Cl₂ or 50 mg/l KMnO_r are necessary. Under these conditions, the Cyclops population had died on the seventh day after the application of chemicals, but after seven weeks it reached the original density again. With one application of chloride or sodium permanganate a week Dracunculiasis can be completely controlled.     

Untersuchungen zum Einfluß limnischer Makrophyten auf die Absterbegeschwindigkeit von Escherichia coli im Wasser

In bioassays in aquaria, the dying of Escherichia coli was accelerated by Glyceria maxima, Schoenoplectus lacustris, Alisma plantago-aquatica as well as Mentha aquatia as compared with check tanks without any plants (initial concentration 15 × 10³ colony-forming units per ml). As expected, by this the antibacterial effect of the limnic macrophytes attains its maximum effectivity within the first days of the period of investigation. The decimal time of reduction is shortened by one third to half, the centimal reduction time is shortened by one fourth to one third. Mean contact times of 7… 11 h are required for the decimation of bacteria by 90 %, and mean contact times of 16… 19 h are necessary for a 99 % reduction of the population. Possibly, the antibacterial effect in mixed stands of different plant species is increased additively or superadditively.     

Origination of <Emphasis Type="Italic">G</Emphasis> conditions in the ionospheric <Emphasis Type="Italic">F</Emphasis> region depending on solar and geomagnetic activity

The dependence of the origination of G conditions in the ionospheric F region on solar and geomagnetic activity has been determined based on numerical simulation of the ionosphere over points 50° N, 105° E and 70° N, 105° E for summer conditions at noon. It has been found that the threshold value of the Kp geomagnetic activity index (Kp _S ), beginning from which a G condition can originate, is minimal for a low solar activity level at relatively high latitudes during the recovery phase of a geomagnetic storm. On average, Kp _S increases with increasing solar activity, but G conditions can originate at high solar activity levels and be absent at moderate ones for certain Kp values, which was apparently predicted for the first time. These properties of the origination of G conditions do not contradict the known results of a G-condition statistical analysis performed based on the data from the global network of ionospheric stations.     

Untersuchungen zum Vorkommen von R+-Bakterien im Flußwasser

With colony numbers of 2 · 10⁴… 3 · 10⁵ and coliform contents of 2 · 10³… 1 · 1 · 10⁴ per ml, in the investigated river section 2.1% of colonies were resistant to tetracycline, 0.3% to chloramphenicol, 7.5% to kanamycin, 5.4% to trimethoprim, 12.7% to ampicillin and 0.14% to gentamycin. For the coliforms the resistances were 5.1% to tetracycline, 2.1% to chloramphenicol, 2.7% to kanamycin and 0.15% to gentamycin. There were isolated 63 different resistance types. Of the resistant Klebsiella strains 75% were resistant to three or more antibiotics. Of the coliform bacteria (Escherichia coli, Klebsiella, Enterobacter, Citrobacter) 31.6… 51.9% of the strains transferred their antibiotics-resistance to Escherichia coli K-12, for the antibiotics-resistant strains of Pseudomonas and Aeromonas a transfer of resistance was not observed at all.     

Daphnia magna as a Model to Assess Heavy Metal Toxicity: Comparative Assessment with Mouse System

The acute static bioassays with heavy metals at 13 ± 1.5 °C in hard water (total hardness = 240 ppm as CaCO₃) were conducted in the laboratory with Daphnia magna. The 48 hr LC values and their 95 per dent confidence limits in ppm of metal were: 0.0038 (0.0027… 0.0053) for Hg; 0.015 (0.009… 0.026) for Ag; 0.1 (0.063… 0.16) for Cu; 0.69 (0.48… 1.0) for Zn; 1.52 (1.01… 2.28) for Co; 1.8 (1.16… 2.70) for Cr; 1.5 (1.07… 2.1) for Cd; 2,63 (1.7… 4.08) for Pb; 7.3 (5.49… 9.71) for Ni and 19.5 (13.45… 28.3) for Sn. At the close of 24 h of exposure Zn and Cd solutions showed milky white precipitation. The order of toxicity of heavy metals in this model was: Hg>Ag>Cu>Zn>Cd>Co>Cr>Pb>Ni>Sn. Comparison of D. magna and mouse LC₅₀ data showed that Daphnia were sensitive at 1/2710, 1/83, 1/123 and 1/5.5, the LC₅₀ values of Hg, Cu and Zn, respectively. Toxicity test with D. magna is simple, requiring less space, time, facilities, acclimatization time and equipment. Furthermore, Daphnia is more functional, reliable and gives reproducible results. Based on this data we believe the Daphnia magna model can be used as a model to study heavy metal toxicity.     

Die Massenentwicklung der Geißelalge Uroglena americana (Alk.) Lemm in Trinkwassertalsperren Thüringens und ihre Bekämpfung

A mass development of Uroglena americana with cellular densities of up to 13.5 · 10⁶ and 86.10⁶ cells/l, was observed in two drinking-water reservoirs. In the first case the development remained confined to the upper 20 m, in the second case there occurred a gradual shift of the maximum to deeper zones from May to July with decreasing cellular densities down to a depth of 35 m. Laboratory experiments for the control of the algae development were performed in order to protect the drinking-water resources from potential impairments of odour and taste. Samples of the storage-reservoir water with 20.10⁶ cells/l of Uroglena were concentrated up to 1.25 … 12.5 mg/l Ca(OH)₂ (pH-values of 7.2 … 9.6) by addition of calcium hydroxide and observed for 39 h. First impairment of the cells of Uroglena is detectable at 5 mg/l Ca(OH)₂ after 15 h, an immediate effect can be observed at 7.5 mg/l Ca(OH)₂ together with increased sedimentation, also Gymnodinium and Cryptomonas having been damaged. Thereupon a successful control of Uroglena by liming up to pH-values above 8.0 is possible. The application of lime to outdoor areas was not necessary, in the final analysis, since the drinking-water quality could be secured by the optimum choice of the intake depth of raw water with a maximum of 4.10³ to 77.10³ cells/l.     

Studies on Primary Productivity and some Hydrochemical Aspects of a Polluted Water-body of the Himalayan Jhelum Valley

The lake without any outlet (11 ha, 55000 m³, z_max 2,25 m) has a weak thermal stratification with maximum surface temperatures of 32.5 °C. The annual variation of temperature and depth of visibility is unimodal, with the maxima or minima in August. Phytoplankton consists mainly of Cyanophyceae. The primary production determined by the light-dark bottle technique (oxygen method) varies in the annual variation between 0.3… 0.5 g m^?2 d^?1 C (winter) and 3.4… 4.6 g m^?2 d^?1 C (summer); as the annual means of 1975 and 1976 there were found 1.9 and 2.4 g m^?2 d^?1 C, resp., gross production at a utilization of 0.42… 2.85% of the radiation energy. The chemism is a well-buffered hydrogen-carbonate water (pH 8.1… 9.0) with 74… 90 mg/1 Na and 20.5… 31.5 mg/1 K and with a good nutrient supply (20… 40 μg/1 PO₄—P and 100… 240 μg/1 NO₃—N) at the same time.     

Winter chemical leaching from deciduous tree branches as a function of branch inclination angle in central Massachusetts

Leaching is an important process in the biogeochemical cycling of nutrients from above‐ground vegetative surfaces to the forest floor. Little is known about winter leaching from deciduous tree species and the influence of branch inclination angle on leachate chemistry. Using a set of field‐based isolated branches harvested from mature crowns of Betula lenta, Carya glabra and Quercus rubra, we tested the null hypothesis that during winter neither branch inclination angle nor branch species would have a detectable influence on differences in leachate chemistry and the quantity of intercepted precipitation from the branch surface. Leachate concentrations were significantly greater from branches inclined at 20° than 5° or 38°. Absolute nutrient inputs were also greatest for branches inclined at 20°. The significantly enriched branchflow and greater total nutrient input from branches inclined at 20° were attributed to increased residence time of intercepted precipitation with the branch surface, the lower probability of branch drip than branches inclined at 5°, and only minimal differences in branchflow quantity compared with branches inclined at 38°. Branchflow was more enriched from all three branch angles during precipitation events of longer duration and lower intensity than shorter, intense events. The leachate quantities of K⁺ and Ca²⁺ differ significantly among species. Carya glabra and Quercus rubra leached more K⁺ than Betula lenta. All three species leached significantly different amounts of Ca²⁺, with Quercus rubra leaching the most and Carya glabra the least. The adaptive geometry of deciduous canopy trees should be considered in relation to the interception of precipitation and aqueous leaching during winter when the canopy is leafless. Copyright © 2002 John Wiley & Sons, Ltd.     

Überleben von Campylobacter jejuni im Wasser

The Campylobacter jejuni survival pattern was investigated in model experiments using drinking water and surface waters differing in organic contamination. Further conditions studied were two different temperature levels (4 °C and 20 °C, resp.) as well as several starting densities of the testing strain. In drinking water, i.e. relatively uncontaminated water, the starting density showed a direct influence on the interval of surviving. The same was noted for temperature, where higher levels (20 °C) resulted in a relative quick inactivation of the investigated agent. Mentioned influences played a similar role in the surface water medium, together with the level of organic contamination: An increase of the value of COD to about 15.4 mg/l O₂ halved the interval of surviving. No relation to the dissolved oxygen tension was found.     

Phyto- and Zooplankton Composition and Some Ecological Observations on a Man-made Lake in Wadi el Majanin,Libya

The small eutrophic man-made lake in Wadi el Majanin, Libya has a well-buffered hydrogen-carbonate (98 … 160 mg/l CaCO₃) system (pH = 7 … 7.8) and a poor Secchi visibility (21 … 35 cm). Conductivity data (272 … 480 μS/cm) fit the water-body in class 2 (‘freshwater’ range) of Beadle. The annual surface water temperature cycle (before noon readings) showed strong seasonal variations from 12 °C in Jan. and Feb. 1986 to 28.5 °C in June, 1987. The lake sustains a good crop of plankton populations. The main phytoplankton were species of Pediastrum, Scenedesmus, Navicula, Amphora, Synedra, Gomphonema, Oscillatoria, Gomphosphaeria and from zooplankton these were Keratella, Polyarthra, Brachionus, Moina, Acanthocyclops and nauplii of copepods. The presence of euglenoids supports the enriched water status of the ecosystem. Planktonic algal flora appeared closer to the eutrophic chlorococcales-diatom type (Hutchinson). Rotifers dominated the zooplankton community. A well established macrophytic vegetation was lacking.     

Gaschromatographische Spurenanalyse von leichtflüchtigen Halogenkohlenwasserstoffen im Wasser mittels FID-Detektion

The substances expelled with a nitrogen flow from the water sample are adsorbed on Tenax GC and then transferred from it into the separation column by heating to 200°. Detection is made by means of a flame ionization detector. The technique is suitable for routine application and in the practice of sanitation and water works with water samples of 0.5 l it allows the detection of < 1 μg/l of individual halogenated hydrocarbons.     

Der Einfluß von Erdölkohlenwasserstoffen auf die Primärproduktion des Donauplanktons

Danube river water samples were saturated with mineral oil, and then the primary production (gross) was determined by means of the light-dark bottle method (oxygen) in situ at depths of 0.1… 1.5 m in comparison with untreated samples. Samples were exposed for half a solar day alternately during the first and second half-days. Investigations carried out between March and October for periods of 14 days showed a mean production of 2.56 g · m^?2d^?1 O₂, which was reduced by 36% due to 12.6 mg/l hydrocarbons. Production decreases with the water depth from 6.2 to 0.9 mg · l^?1d^?1 0₂, whereas the inhibition by hydrocarbons increases from 31 to 41%.     

Einfluß der Temperatur auf die Bildung von Magnetit als Zusatzstoff für die Magnetseparation

Influence of the Temperature on the Formation of Magnetite as an Additive for Magnetic Separation To investigate the influence of the temperature on the formation of magnetite in aqueous solution, experiments were performed in which ferrous hydroxide was precipitated from oxygen-free ferrous sulfate solution (c₀(Fe) = 5 mmol·dm^?3) and subsequently oxidized with synthetic air. The precipitates so obtained are a mixture of solids whose compositions depend on the temperature and on the rate of aeration. Above all, magnetite, goethite, and δ-FeOOH had been formed. Magnetite occurs at temperatures above about 15 °C, goethite above 35 °C, and δ-FeOOH below about 10 °C. Referring to the thermogravimetric plots and to the relationship between the temperature of formation and the pH measured upon completion of the reaction, it is justified to assume that also sulfate is contained in the precipitates. The values of the magnetic moment of the precipitates, which are crucial in magnetic separation, made evident the dependence on the temperature of formation expected on the basis of solid analyses and confirmed the presence of δ-FeOOH at rather low temperatures. At the rates of aeration applied, it was possible to obtain from about 15 °C on solids having magnetic moments which are sufficient for magnetic separation.     

Toxicity of distillery wastes to Puntius sophore (HAM.) and Mystus Vittatus (BLOCH) (Pisces,Cyprinidae, Bagridae) Part 3: Bioassay studies and TLm determination

The toxicity of the distillation wastes with low acidity, high turbidity and high organic load to the two fish species is tested by a laboratory test. The threshold value of toxicity is found at a 4 or 7 per cent dilution of wastewater. The statistical analysis of the survival rates has shown that the survival rates are significantly dependent on concentration and the time of exposure, for Puntius sophore also on temperature within the range of 20…34°C. Mystus vittatus proves to be the significantly more resistant species. The maximum permissible concentration of waste in the water ist calculated, too.     

Ein Beitrag zur Bestimmung von partikulärem organischen Kohlenstoff in Wasserproben

The method after Strickland and Parsons is modified for fresh water as follows: filtration on glass-fibre paper, oxidation with K₂Cr₂O₇ in cone. H₂SO₄ for 2 h at 130 °C, dilution to 2.5 times the volume by aqua dest., centrifuging-off of the turbidity and extinction measurement at 445 nm against the blank value, the sample solution being balanced to the transmission of 100% (extinction = 0). Here, the following calibration line holds for the concentration C and the quantity of oxidation solution Ox: C = E_1cmc · 0.162 · Ox, C in mg filter. The oxidation solution contains 4.8 g K₂Cr₂O₇ as dissolved in 20 ml aqua dest. and made up with conc. H₂SO₄ to 11. With 5 ml of this solution one is able to determine 0.05 … 1 mg C/filter. Calibration is performed with 125 mg/l glucose solution. Comparative investigations have shown a good agreement with elementary-analytically obtained measured values. The occurring errors have been determined mainly by sampling. In the range of very small values we have to take into account a blank value of the filter due to the adsorption of dissolved organic substances on the filter.