Zum Umweltverhalten von Fluortensiden. Teil 3: Reinigung der industriellen Abwässer

Four fluorotensides which are used mainly industrially are investigated with respect to their removability from waters. Since, in general, fluorotensides are difficult to remove or not at all removable biochemically, the effects of chemical or physicochemical treatment processes are tested. As the results represented in pictures and tables show, different modes of behaviour can be recognized with respect to the respective purification effect for the investigated fluorotensides, partly among them. Flocculation with Al- and Fe-salts as well as chlorination and ozonization show only partial effects. But all the investigated fluorotensides can be adsorptively eliminated by means of powder or granular active charcoal and adsorbent resin Wofatit EA₆₀.     

Zum Umweltverhalten von Fluortensiden Teil 1: Prüfung auf Aquatoxizität

Poecilia reticulata PETERS (guppy) and the green alga Monoraphidium griffithii were used for testing of different fluorotensides. After the representation of the methods of investigation and the definition of criteria of toxicity the obtained results of investigation are discussed. In general, the toxicity of the four investigated fluorotensides to algae was lower than to fish. The anionic fluorotenside CF₃—(CF₂)n—CFH—COONa was an exception. In tables and diagrams the results are summarized. Finally, for the condition of the receiving-water biocenosis class “2” the respective still permissible matter concentrations are proposed. They vary between 0.05 and 0.2 mg/1.     

Bed-flow instability of the longshore current

An initially uniform longshore current on a plane erodible beach is considered and a linear stability analysis of the bed-flow system is performed in order to investigate the growth of alongshore periodic topographic features such as transverse or oblique bars. γ, numerical model based on the shallow water equations and a simple sediment transport formula is used. For a wide range of parameters instability is found, leading to the growth of large-scale topographic features (lengthscale of the order of the current width) downflow progressing. The growth rates and the dominant unstable mode depend mainly on R = c_d/β parameter, where c_d is the bottom friction coefficient and β is the beach slope. For a small R, say less than 0.1, instability is very weak, probably negligible. For R between 0.1 and 0.7 instability increases with R, leading typically to a quite simple transverse bars pattern. A further increase in R produces a far more complicated behaviour where complex patterns with downcurrent oriented oblique bars, bumps and holes can be dominant. In this region growth rates may either decrease or increase with R depending on the beach slope and the maximum Froude number of the basic flow, F. Usually, the most complex behaviour is found for gently sloping beaches. The physical mechanism of the instability is found to lie on the disturbances of potential vorticity caused by topographically induced differences in bottom friction. In this sense it is similar to the alternate bars growth in a river rather than the dunes or antidunes occurrence for 1D channel flow. The predictions of the model compare well with the available experimental data. The alongshore wavelength, γ, typically of the order of one to four times the width of the current, is close to four times for the most common values of R. The typical growth time is proportional to γ² and for a wavelength of 100 m can be of the order of one day, depending on the sediment transport rate. The migrational speed is inversely proportional to γ, in accordance to earlier field data reported by Sonu (1969) Collective movement of sediment in littoral environment.     

Hysteresis properties of titanomagnetites: Grain-size and compositional dependence

Sized fractions of x = 0.6, 0.4, 0.2 and 0.0 titanomagnetites were studied with a vibration magnetometer. In the course particles (d > 150 μm), no compositional dependence of hysteresis parameters was found. H_C was less than 50 Oe, H_R/H_C > 4 and J_R/J_S < 10^?2, reflecting multi-domain behaviour. In contrast, fine particles ($\text{d ? 0.1 μ}\text{m}$) revealed systematic grain-size dependence of parameters with coercive force as high as 2,000 Oe in x = 0.6 titanomagnetite. Grain-size dependence studies revealed broad transition sizes for the onset of true multi-domain behaviour depending upon which factor is chosen. In magnetite it varies from 10 to 20 μm. The experimental critical size for single-domain behaviour for magnetite is about 0.1 μm and for x = 0.6 titanomagnetite 1–2 μm.     

Vergleichende aquatoxikologische Ergebnisse mit ausgewählten Wasserschadstoff-Gruppen und repräsentativen Wasserorganismen

Salmo gairdneri, Cyprinus carpio, Poecilia reticulata, Leuciscus idus melanotus, Asellus aquaticus, Ankistrodesmus falcatus and Monoraphidium griffithii were exposed to four growth regulating herbicides, four photosynthesis toxicants, lindane, an anionactive tenside, KCN and Na₃[Cu(CN)₄] in standardized toxicity tests. The biochemical degradability of the substances was tested with activated sludge. In order to test the possible effects in waters there should be used Salmo for the oligosaprobic zone. Poecilia as well as Ankistrodesmus and Monoraphidium provide reliable estimations for β-mesosaprobic waters. With respect to the longer-term permission of plant protection products, besides Salmo there can be recommended also Leuciscus.     

TBT toxicity on the marine microalga Nannochloropsis oculata

Commercial antifouling formulations containing TBT are the major source of organotin contamination in coastal waters. In view of the persisting TBT residues (13 ng Sn l⁻¹) in the coastal waters of South Korea, an attempt has been made to evaluate the growth response and biochemical composition of laboratory-cultured Nannochloropsis oculata to TBT toxicity. It is evident that the persisting concentration level of TBT is high enough to cause adverse effect on the microalgal species. The EC₅₀ (24 h) was found to be at 0.89 nM level of TBT for this marine eustigmatophyte N. oculata. Photosynthetic pigment content was significantly affected. At elevated TBT concentrations of 1.0 nM, especially pronounced changes in biochemical composition was found. TBT tolerance of N. oculata and its growth as well as biochemical responses are discussed.     

Hydrodynamic behaviour of coarse bioclastic sand from shelly cheniers

Cheniers from Mont‐Saint‐Michel bay (France) are coarse shelly sand ridges migrating on the mudflat up to the salt marshes where they accumulate and merge in a littoral barrier. In this macrotidal setting and low wave forcing, the cheniers are rarely submerged. However, they are found to move up to several metres during coincidence of spring tide and wave activity. Their processes of migration, morphology and internal structure (composition of the beddings, grain size, sorting and grain arrangement) are thought to be closely related to the hydrodynamic behaviour of the coarse and shelly sediment. This paper focuses on the hydrodynamic behaviour of bioclastic sand sampled from the cheniers: settling velocities of the shell fragments were measured using a 2 m long sedimentation tube. Thresholds of motion under unidirectional current, velocity and turbulence vertical profiles were characterized in a small recirculating flume using Laser Doppler Anemometry (LDA). The flat‐shaped bioclastic particles feature low settling velocities and reveal a good resistance to the re‐suspension effect of the flow when imbricated in a sediment bed. The shear stress in the bottom boundary layer has been measured in the viscous and log sub‐layers. Nikuradse roughness heights (k_s) for shell debris beds of different sizes have been quantified. It is found that k_s ≈ 2·56d₅₀. This value is close to the ones used for classic rounded sand grains despite their major differences of shape. The dual behaviour of the shell fragments (low settling velocity, good resistance to unidirectional flow) should be considered as a key to understanding how this coarse material is transported across the tidal flat, and finally accumulated as cheniers. Further flume experiments including wave activity and tidal fluctuations are necessary to better quantify these complex processes. Copyright © 2010 John Wiley & Sons, Ltd.     

Accuracy of finite difference representations for the transient response analysis of shells

The frequency versus wave number characteristics of four O(ΔS₂) finite difference formulations for one-dimensional linear shell (ring and axisymmetric) equations are investigated and compared with the exact continuum characteristics. It is found that three of the formulations give virtually identical results. These are half-spacing techniques with equilibrium in terms of displacements or resultants and whole-spacing with equilibrium in terms of displacements. The formulation based on whole-spacing with equilibrium in terms of resultants produces some dramatically different results. These discrepancies partially explain some late time instability problems and critical time step behaviour that have been reported by other investigators.     

Effects of sublethal concentrations of copper and freshwater on behaviour in an estuarine gastropod Polinices sordidus

This study investigated the effects of contamination by copper and freshwater on the behaviour of the estuarine gastropod Polinices sordidus. The burying response was inhibited by both pollutants. In the case of copper, it was suggested that this response after 30 min could reflect toxicity after 96 h, i.e. the 96 h LC₅₀ and the 30 min ED₅₀ were very similar. P. sordidus responded to freshwater at concentrations well below the 96 h LC₅₀, suggesting that this species can detect sublethal concentrations of freshwater. Thus, for salinity, the 30 min ED₅₀ is not a reliable indicator of the 96 h LC₅₀. A linear decline in crawling activity was found in the presence of increasing concentrations of both pollutants. These results for both aspects of behaviour are discussed in the light of results reported earlier for a marine species Polinices incei.     

Characteristics of selenium in marine animals

The biochemical association and chemical form of selenium in the muscle tissues of four marine animals has been examined. Selenium was predominantly associated with soluble proteins (72–80%), and not present as characterizable inorganic selenium species (SeO₃^2?, SeO₄^2?).     

Environmental Effects on the Toxicity of Methyl Mercuric Chloride to Chorella vulgaris.

The effect of different concentrations, viz. 0.01, 0.001 and 0.0001 ppm of methyl mercuric chloride on survival, growth behaviour and chlorophyll content of Chlorella vulgaris has been studied under various environmental conditions. Methyl mercury at 0.01 ppm is 100% toxic to the test alga. At a sublethal (0.001 ppm) dose of CH₃HgCl, Chlorophyll a was more inhibited than Chlorophyll b. Toxicity was found to be very much under the influence of pH as at acid pH growth is highly reduced by a sublethal concentration, whereas the same concentration does not have an inhibitory influence in the alkaline range of pH. Eutrophic waters seem to reduce the heavy metal toxicity in general.     

Effects of heavy metals on the survival and feeding behaviour of the sandy shore scavenging gastropod Nassarius festivus (Powys)

The effects of Cu, Cd, Zn and Cr on the survival and feeding behaviour of the sandy shore scavenging gastropod Nassarius festivus were compared. The 96-h LC₅₀ for Cu, Cd, Zn and Cr were 0.36, 1.52, 1.76 and 36.9 mg l⁻¹, respectively. Four sublethal concentrations of each metal plus a control were prepared and the snails were exposed to experimental solutions for 96 h. Feeding behaviour was studied after the snails were starved for five days. As compared with the control, the number of individuals feeding was significantly reduced by exposure to 0.05 mg l⁻¹ Cu, 0.2 mg l⁻¹ Zn, 0.5 mg l⁻¹ Cd and 5 mg l⁻¹ Cr. The time spent feeding was greater for individuals exposed to greater concentrations of Zn and Cd but no effect was found for Cu and Cr. Chemoreception of food was studied by placing the snails at a fixed distance of 15 cm from the bait. The success rate of reaching the bait was less for individuals exposed to Cr but no effect was found for Zn, Cu or Cd. The time required for an individual to reach the bait decreased as the concentration of Zn increased. In contrast, a longer time was required for individuals exposed to Cr whereas the effect of Cd and Cu was insignificant. The potential of using feeding behaviour and chemoreception in contaminant evaluations is discussed.     

Toxicity of sediment-incorporated drilling fluids

The 24, 96, or 168h LC₅₀s of four used drilling fluids or barite incorporated into sediment were determined in toxicity tests with lancelets (Branchiostoma caribaeum), a benthic chordate. Concurrent to LC₅₀ determinations, EC₅₀s were calculated from the number of lancelets that did not burrow into contaminated sediments. Observations of the burrowing behaviour allowed quantitation of effects after 24h exposures to each of the drilling fluids whereas lancelet mortality was sufficient to calculate 24h LC₅₀s for only one drilling fluid. Drilling fluids were less toxic to lancelets when incorporated into sediments than to mysids (Mysidopsis bahia) or benthic invertebrate communities in water-column exposures.     

The system enstatite-wollastonite at high pressures and temperatures,with emphasis on diopside

High-pressure phase transformations for three intermediate compositions (including diopside) in the system enstatite (MgSiO₃)-wollastonite (CaSiO₃) were investigated in the pressure range 100–300 kbar at about 1000°C in a diamond-anvil press coupled with laser heating. The phase behaviour of the two end components (enstatite and wollastonite) at high pressure has been reported earlier. The results of this study reveal that there is very limited solid solution of diopside (CaMgSi₂O₆) in the various high-pressure phase assemblages of enstatite. At pressures greater than about 200 kbar, diopside and a composition between diopside and wollastonite were found to transform into non-quenchable phases, as does wollastonite. It is thought probable that diopside and wollastonite form solid solutions with the perovskite structure at high pressure, but that on release of pressure it is not possible to preserve the high-pressure modification.     

Effect of reservoir construction on suspended sediment load in a large river system: thresholds and complex response

Dam construction greatly alters the channel boundary of rivers, making the dammed river system a human‐controlled system. Based on hydrometric data in the upper Changjiang River basin, the change in behaviour of sediment transport of some dammed rivers was studied. As a result, some phenomena of threshold and complex response were found. When the coefficient (C_r,a) of actual runoff regulation by reservoirs, defined as the ratio of total capacity of reservoirs to annual runoff input, is smaller than 10%, suspended sediment load at Yichang station, the control station of the Changjiang River, shows a mild decreasing trend. When this coefficient becomes larger than 10%, suspended sediment load decreases sharply. The coefficient of 10% can be regarded as a threshold. The C_r,a of 10% is also a threshold, when the variation of suspended sediment concentration (SSC) with C_r,a at Yichang station is considered. The impacts of reservoir construction can be divided into several stages, including road construction, dam building and closure, water storage and sediment trapping. During these stages, some complex response was identified. At the station below the dam, SSC increases and reaches a maximum, and then declines sharply. This phenomenon was found on the main‐stem and several major tributaries of the upper Changjiang River. In the Minjiang River, where a series of dams were built successively, the response of SSC is more complicated. Copyright © 2010 John Wiley & Sons, Ltd.     

Regional runoff prediction through aggregation of first-order hydrological process knowledge: a case study

Abstract

The dominant processes concept was used to develop a regionally applicable rainfall—runoff model. The first-order runoff processes are identified through a combination of field investigations, physico-geographical analysis of the research area, the Alzette River basin in the Grand-Duchy of Luxembourg, and discharge data series analysis. Lithology appeared to be the major source of discrepancy in hydrological behaviour over the total area. As a result, the hydrological behaviour of each lithological substratum was characterized and conceptualized into a parsimonious model structure. The runoff signals were calibrated against the hourly-recorded discharge series of eight sub-basins, with parameter sensitivity and correlation analysis outlining the need for minor corrections to the model structure. Validation against another set of 10 sub-basins showed good results for the regional parameter set, with an average loss in efficiency (R_eff) of 0.04, compared to the reference model, with a mean R_eff of 0.79. Due to an up-scaling effect, inducing variations in the dominance of particular runoff processes, some anomalies were found in the performance of individual runoff characteristics. In this respect, limiting the application of the model to a certain spatial scale gives a high reliability of the prediction of the dynamics of hourly runoff in ungauged basins within the study area.     

Sulfur geochemistry of hydrothermal waters in Yellowstone National Park, Wyoming, USA. II. Formation and decomposition of thiosulfate and polythionate in Cinder Pool

Cinder Pool is an acid-sulfate-chloride boiling spring in Norris Geyser Basin, Yellowstone National Park. The pool is unique in that its surface is partially covered with mm-size, black, hollow sulfur spherules, while a layer of molten sulfur resides at the bottom of the pool (18 m depth). The sulfur speciation in the pool was determined on four different days over a period of two years. Samples were taken to evaluate changes with depth and to evaluate the importance of the sulfur spherules on sulfur redox chemistry. All analyses were conducted on site using a combination of ion chromatography and colorimetric techniques.Dissolved sulfide (H₂S), thiosulfate (S₂O₃²⁻), polythionates (S_xO₆²⁻), and sulfate were detected. The polythionate concentration was highly variable in time and space. The highest concentrations were found in surficial samples taken from among the sulfur spherules. With depth, the polythionate concentrations dropped off. The maximum observed polythionate concentration was 8 μM. Thiosulfate was rather uniformly distributed throughout the pool and concentrations ranged from 35 to 45 μM. Total dissolved sulfide concentrations varied with time, concentrations ranged from 16 to 48 μM. Sulfate was relatively constant, with concentrations ranging from 1150 to 1300 μM. The sulfur speciation of Cinder Pool is unique in that the thiosulfate and polythionate concentrations are significantly higher than for any other acid-sulfate spring yet sampled in Yellowstone National Park. Complementary laboratory experiments show that thiosulfate is the intermediate sulfoxyanion formed from sulfur hydrolysis under conditions similar to those found in Cinder Pool and that polythionates are formed via the oxidation of thiosulfate by dissolved oxygen. This last reaction is catalyzed by pyrite that occurs as a minor constituent in the sulfur spherules floating on the pool's surface. Polythionate decomposition proceeds via two pathways: (1) a reaction with H₂S, yielding thiosulfate and elemental sulfur; and (2) by disproportionation to sulfate and thiosulfate.This study demonstrates that the presence of a subaqueous molten sulfur pool and sulfur spherules in Cinder Pool is of importance in controlling the pathways of aqueous sulfur redox reactions. Some of the insights gained at Cinder Pool may be relevant to acid crater lakes where sulfur spherules are observed and variations in polythionate concentrations are used to monitor and predict volcanic activity.     

Implications of design philosophies for seismic response of steel moment frames

During a severe earthquake, steel moment resisting frames are expected to experience significant inelastic deformation in their members and joints. This behaviour is dependent upon several design parameters such as member sizes, frame's overstrength, member deformation capacities and the detailing of components. In this study, the influence of such aspects on the inelastic response of frames is investigated. Inelastic static and dynamic analyses were performed on four frames of different designs for a typical six-storey building. The frames were designed and detailed in accordance with current North American code requirements. The computed response of each frame was compared with the behaviour expected by the codes. Recommendations for a design procedure are suggested for improving the structural performance of low-rise steel frames subjected to strong earthquake excitation.     

Creep of crystals: J.P. Poirier,Cambridge University Press, 1985, xii + 260 pp., £27.50, US$ 49.50, ISBN 0-521-26177-5

Fractional crystallization behaviour of a magma ocean extending to lower mantle depths was deduced from estimations of melting relations for the deep mantle and the density relationships between ultrabasic liquid and mantle minerals. The accretional growth of the Earth necessarily involves a molten zone (magma ocean) in the outer layer of the growing Earth. The fractionation by melting during accretion results in primary stratification composed of a molten ultrabasic upper mantle (magma ocean), a perovskite-rich lower mantle, and an iron core. A certain amount of Al₂O₃ and CaO was removed from the magma ocean and retained in the lower mantle due to eclogite fractionation in the early stage of accretion and the perovskite fractionation in the later stage of accretion. Models of the stratification of the upper mantle arising from fractional crystallization of the magma ocean and subsequent convective disturbance were deduced on the basis of estimations of melting relations for the deep mantle and the density relationships between the ultrabasic liquid and mantle minerals. The stratification of the mantle, which is consistent with geophysical constraints is as follows; the upper mantle is composed of two layers, the upper olivine-rich layer and the lower garnet-rich layer with a thickness around 200 km, and the lower mantle with a perovskite-rich composition. In this model, both the 400 and 650 km discontinuities are the chemical boundaries.     

Thermomagnetic analysis of meteorites, 1. C1 chondrites

Samples of all five of the known C1 chondrites have been analyzed thermomagnetically. The only magnetic phase found in four of the chondrites (Alais, Ivuna, Orgueil, Tonk) was magnetite containing less than 6% nickel. The Revelstoke C1 chondrite contains essentially Ni-free Fe₃O₄ as the predominant phase; however, a small amount of a thermally unstable iron compound (presumably FeS) is additionally present. Estimates of the weight percentage of magnetite, based on saturation moments, are: Alais, 5.3 ± 0.4%; Ivuna, 12.2 ± 0.9%; Orgueil, 11.9 ± 0.8%; Revelstoke, 7.2 ± 0.5%; and Tonk, 9.4 ± 0.6%. The first three estimates are based on multiple analyses and are considered to be grossly representative of the meteorites as a whole. The last two estimates are based on single-sample measurements and should be considered only in that context. The magnetite of the Alais sample appears to be somewhat unusual inasmuch as it is inhomogeneously distributed, and its content is only about half that of the average C1 chondrite.