Identifying the relative importance of predation and resources in population dynamics has a long tradition in ecology, while interactions between them have been studied less intensively. In order to disentangle the effects of predation by juvenile fish, algal resource availability and their interactive effects on zooplankton population dynamics, we conducted an enclosure experiment where zooplankton were exposed to a gradient of predation of roach (<I>Rutilus rutilus</I>) at different algal concentrations. We show that zooplankton populations collapse under high predation pressure irrespective of resource availability, confirming that juvenile fish are able to severely reduce zooplankton prey when occurring in high densities. At lower predation pressure, however, the effect of predation depended on algal resource availability since high algal resource supply buffered against predation. Hence, we suggest that interactions between mass-hatching of fish, and the strong fluctuations in algal resources in spring have the potential to regulate zooplankton population dynamics. In a broader perspective, increasing spring temperatures due to global warming will most likely affect the timing of these processes and have consequences for the spring and summer zooplankton dynamics.

Sampling is a key step in the analysis of chemical compounds. It is particularly important in the environmental field, for example for wastewater effluents, wet-weather discharges or streams in which the flows and concentrations vary greatly over time. In contrast to the improvements that have occurred in analytical measurement, developments in the field of sampling are less active. However, sampling errors may exceed by an order of magnitude those related to analytical processes. We proposed an Internet-based application based on a sampling theory to identify and quantify the errors in the process of taking samples. This general theory of sampling, already applied to different areas, helps to answer questions related to the number of samples, their volume, their representativeness, etc. The use of the internet to host this application facilitates use of theoretical tools and raise awareness of the uncertainties related to sampling. An example is presented, which highlights the importance of the sampling step in the quality of analytical results.

Women are often regarded as counting amongst the most vulnerable social groups. Especially in developing countries, women continue to have fewer rights and access to assets than men. As a con-sequence, women have less access to decent work and are overrepresented in informal work that can weaken the benefits earned through employment. However, for many impoverished women informality offers the only opportunity to make ends meet.<br /> Accordingly, in Côte d’Ivoire women are most present in informal employment. In the city of Abidjan some women make a means of living through extracting valuable waste materials from streets, drains and dumps. These so-called waste pickers rely on waste as the basis of their livelihoods. The-reby, waste picking not only enables the making of livelihoods but also compensates for the failures of the public waste services. As many other rapidly urbanizing areas in developing countries, Abidjan faces the challenges of managing its increasing amount of waste.<br /> This master thesis concerns female waste pickers who work on the waste dump of Akouédo in Abid-jan. It aims to deepen the understanding of women’s livelihoods as informal waste pickers and sheds light on their roles, needs and priorities in the thematic area of waste management in developing countries. [...]<br /><br /> Les femmes sont souvent considérées comme le groupe social le plus vulnérable. Surtout dans les pays en développement, les femmes ont moins de droits et d'accès aux biens que les hommes. En conséquence, les femmes ont des difficultés à trouver un travail décent et sont surreprésentées dans le travail informel, qui peut limiter les avantages sociaux gagnés par l'emploi. Ainsi, en Côte d'Ivoire, les femmes sont les plus présentes dans l'emploi informel. Dans la ville d’Abidjan, certaines femmes gagnent leur vie grâce à la collecte des déchets précieux dans les rues, les caniveaux et notamment les décharges. Ainsi, le ramassage de déchet permet non seulement de créer des moyens d’existence mais aussi de compenser les défaillances des services publics de traitement des déchets. Comme d’autres villes dans les pays en développement qui s'urbanisent rapidement, Abidjan est confronté à gérer la quantité croissante des déchets.<br /> Ce travail de master concerne des ramasseuses de déchets qui travaillent à la décharge d'Akouédo à Abidjan. Il a pour objet l’approfondissement de la compréhension des moyens d’existence de ces femmes et le renseignement de leurs rôles, besoins et priorités liés au thème de la gestion des dé-chets aux pays en développement. [...]

The delta smelt (<I>Hypomesus transpacificus</I>) is an endangered pelagic fish species endemic to the Sacramento?San Joaquin estuary (CA, USA), and considered an indicator of ecosystem health. Copper is a contaminant of concern in Californian waterways that may affect the development and survival of this endangered species. The experimental combination of molecular biomarkers with higher level effects may allow for interpretation of responses in a functional context that can be used to predict detrimental outcomes caused by exposure. A delta smelt microarray was developed and applied to screen for candidate molecular biomarkers that may be used in monitoring programs. Functional classifications of microarray responses were used along with quantitative polymerase chain reaction determining effects upon neuromuscular, digestive, and immune responses in Cu-exposed delta smelt. Differences in sensitivity were measured between juveniles and larvae (median lethal concentration?=?25.2 and 80.4?µg/L Cu<SUP>2+</SUP>, respectively). Swimming velocity declined with higher exposure concentrations in a dose-dependent manner (<I>r</I>=-0.911, <I>p</I><0.05), though was not statistically significant to controls. Genes encoding for aspartoacylase, hemopexin, α-actin, and calcium regulation proteins were significantly affected by exposure and were functionally interpreted with measured swimming responses. Effects on digestion were measured by upregulation of chitinase and downregulation of amylase, whereas downregulation of tumor necrosis factor indicated a probable compromised immune system. Results from this study, and many others, support the use of functionally characterized molecular biomarkers to assess effects of contaminants in field scenarios. We thus propose that to attribute environmental relevance to molecular biomarkers, research should concentrate on their application in field studies with the aim of assisting monitoring programs.

A new method was developed for the analysis of natural and synthetic androgenic steroids and their selected metabolites in aquatic environmental matrixes using direct large-volume injection (LVI) high-performance liquid chromatography (HPLC) tandem mass spectrometry (MS/MS). Method accuracy ranged from 87.6 to 108% for analytes with well-matched internal standards. Precision, quantified by relative standard deviation (RSD), was less than 12%. Detection limits for the method ranged from 1.2 to 360 ng/L. The method was demonstrated on a series of 1 h composite wastewater influent samples collected over a day with the purpose of assessing temporal profiles of androgen loads in wastewater. Testosterone, androstenedione, boldenone, and nandrolone were detected in the sample series at concentrations up to 290 ng/L and loads up to 535 mg/h. Boldenone, a synthetic androgen, had a temporal profile that was strongly correlated to testosterone, a natural human androgen, suggesting its source may be endogenous. An analysis of the sample particulate fraction revealed detectable amounts of sorbed testosterone and androstenedione. Androstenedione sorbed to the particulate fraction accounted for an estimated 5 to 7% of the total androstenedione mass.

Vorwort zur Sondernummer "Wasser" der Ciba Hauszeitschrift.

Drains can be installed to reduce saturated soil condi-tions and improve crop growth. This article evaluates the extent to which these systems may cause losses of plant protection products (PPP). To that end, we esti-mated the drained fraction of Swiss arable land using both existing drainage maps and machine learning. Our drainage map suggests that 25% of Swiss agricultural land has a moderate to high potential of being drained. We further evaluated the risk for PPP losses via drainage and the potential of selected mitigation measures based on a conceptual model summarising the relevant scientific literature. Although drainage losses are highly variable, they are strongly influenced by the extent of preferential flow (PF) in soils and are an important transport pathway to surface waters. Most agricultural soils in Switzerland are prone to PF, given their loamy texture, suggesting that PPP losses via tile drains are an important phenomenon in Swit-zerland’s drained arable fields. The most common mitigation measures for drainage are those recommend-ed for runoff, erosion and leaching. However, given the uncertainty of the local PPP losses and driving factors, no site-or PPP-specific measures can currently be proposed to reduce PPP drainage losses. This study also examines the effectiveness of the regulatory model EXPOSIT in predicting total PPP losses and peak concentrations in watercourses. When compared with experimental data from Agroscope at Zurich-Affoltern, our findings suggest that EXPOSIT does not yield the worst-case estimates for Swiss conditions.

Der "International Bodenseetag" vom 2.Dezember 1967, an dem praktisch die ganze Bevölkerung um den Bodensee zur See-Putzete antrat, gestaltete sich zu einer eindrücklichen Willenskundgebung der gesamten Seeanwohner, das Ihre zu tun, um den bedrohten See, von dem in mancher Hinsicht ihre Existenz abhängt, einer Sanierung entgegenzuführen.

Special Issue: Abstracts of the XXIX International Congress of Psychology

A kinetic model of the contact stabilization process has been developed and experimentally verified with the aid of bench-scale activated sludge units treating domestic sewage. The model provides information on the relationship between the design parameters (process loading, temperature, residence time distribution) and process performance (sludge, production, oxygen uptake, COD-removal, organic nitrogen conversion, nitrification and effluent suspended solids). An oxygen equivalence mass balance equation, which is applicable to all activated sludge process modifications is proposed and may be used in the design and operation of these processes.

Under laboratory conditions, the availability of cadmium, lead and copper in an Orthic Luvisol was investigated when applied to the soil at various initial concentrations. The metals were applied separately or concurrently with the other two heavy metal ions in order to bring about competition for the adsorption sites.<br/> The presence of competing metals increased the general availability especially of cadmium in the soil. Lead and copper were to a lesser extent also affected by the competition of other ions.<br/> On the basis of our ion-competition results we developped two models, namely a chemical equilibrium model and a convective—dispersive model. The models, suitable to predict the consequences of regular heavy metal loading (e.g., in the form of sewage sludge), take into consideration the annual precipitation and the relevant physical parameters of the soil. The conclusions reached by both models are essentially the same and imply that the threshold values for heavy metals in the sewage sludge regulation (Switzerland) are too high.

The partition of Cu and Zn between the particulate and dissolved phases has been investigated in the Carnon River and Restronguet Creek, England; a system contaminated by acid mine drainage. It is shown that binding to the surfaces of amorphous Fe oxyhydroxides regulates Cu and Zn concentrations in solution, in both fresh and saline waters. The sorptive process is pH dependent and is in general agreement with laboratory studies of trace metal adsorption on amorphous Fe oxyhydroxides.

Fluvio-glacial gravel deposits make up most of the groundwater reservoir in Switzerland. At the outcrop scale these deposits display a complex pattern of sedimentary structures. A minor part of these deposits is made up of stringer gravels without any fine fraction. The degree of interconnection of these layers and their extent determine the easiest flow path. Deterministic numerical models help visualize the influence of sedimentary structures on groundwater circulation at different scales.

The derailment of a petrol cistern train at Zürich-Affoltern followed by several explosions caused, a damage of about 10 million Swiss Francs to the sewer system. In the following, the paper describes the measures taken after the desaster and it tries to reconstruct the events in the sewer system that took place after the petrol had entered the system. And finally it looks into potential hazards to sewer systems and plants in general and outlines the measures which must be taken.

This paper investigates whether siphon weight limits the elongation of the siphon of deposit-feeding benthic bivalves under natural conditions. Were this to be so, it would imply that foraging and predator avoidance place conflicting demands on these animals, since an increase in the feeding radius on the surface would be associated with a decrease in the burying depth, and vice versa. The paper presents methods with which to measure siphon length and equations to transform siphon weight to siphon length in two benthic bivalves, <I>Scrobicularia plana</I> and <I>Macoma balthica</I>. Relatively heavy siphons are longer, but also thicker, than lightweight ones. We conclude that most individual bivalves stretch their siphons fully while feeding. However, bivalves with heavy siphons keep part of the siphon in reserve within the shell. Siphon cropping therefore results in an immediate reduction in siphon length, unless the siphon is heavy and a reserve is available. The feeding radius of <I>M. balthica</I> and <I>S. plana</I> is a linear function of shell size. <I>S. plana</I> use half of their siphon length to feed on the surface and the other half to bury themselves, but if the siphon weight is below average, the proportion extended over the surface decreases with siphon size. However, among the animals with a short siphon, those with a good body condition take no risks and live as deeply as possible. A comparison between species reveals that the weight of the extended inhalant siphon per cm amounts, on average, to 0.6% of the total body weight.

A simple, one reactor vessel system, called a fill-and-draw system, was developed for the study of enhanced biological phosphate removal under defined conditions. Sludge was grown in a medium with acetate and glucose as sole energy and carbon sources. The sludge was exposed to cycles with three distinct, consecutive periods; first an anaerobic period, then an aerobic period and finally a settlement period. In the period of settlement one third of the liquid was replaced with fresh medium. Sludge grown under this regime became considerably enriched with polyphosphate-accumulating bacteria. The polyphosphate content reached up to 110 mg P/g dry weight. The amount of polyphosphate in the cells during steady state depended on the acetate:glucose ratio, the nitrate and phosphate concentration in the medium. Highest phosphate accumulation was obtained with an acetate:glucose ratio of 9:1. Intracellular polyphosphate was formed during the aerobic period and was anaerobically hydrolysed and released as phosphate into the medium. In the absence of oxygen and in the presence of 2g acetate-COD/l, 80-90% of phosphate was released by sludge containing 100 mg P/g dry weight. In the absence of acetate only 2-19% of the accumulated phosphate was excreted.

The nickel(II) ion in factor F₄₃₀ pentacarboxylic acid, both in the native form and in the 12,13-di-epimer, in solution can be reversibily in a one-electron to the monovalent state by the action of titanium-(III) citrate. The 3d⁹ Ni(I) is quantitatively detected by EPR spectroscopy as a tetragonally distorted octahedral system with the in the d(<I>x</I>²-<I>y</I>²) orbital resulting in an <I>S</I> = ¹/₂ spin with <I>g</I>_∥ = 2.244, <I>g</I>_⊥ = 2.061, (<I>g</I>_∥ = 2.238, <I>g</I>_⊥ = 2.057 for the di-epimer), subject to isotropic superhyperfine interaction from the four in-plane nitrogen ligand with <I>A</I> = 1.0 mT. The UV-visible spectrum of the reduced native F₄₃₀ has peaks (extinction coefficients in mM^-1 cm^-1) at 268 (24.0), 378 (34.7), and 715 nm (2.3), In the reduced di-epimer these values are 265 (23.7), 376 (27.6), and 710 nm (1.6). Complete reduction is achieved only at alkaline pH; the process an apparent p<I>K</I> of 8.9 (native) or 9.4 (di-epimer). The Ni(II)/Ni(I) in <I>F</I>₄₃₀ has a reduction <I>E</I>_m,10.4 = -0.65 (native) or -0.62 V(diepimer). Three-pulse stimulated ESEEM spectroscopy on the reduced complexes reveals a single, near isotropic proton at ≈13 MHz. In ²H₂O solution this line is replaced by a quadrupole-split deuterium resonance around ≈2 MHz, indicating that the Ni(I) in and 12,13-di-epimeric F₄₃₀ is weakly coordinated by water. The absence of a strong axial bond with water would leave the ability of the d(<I>z</I>²) pair for nucleophilic attack on substrate carbon largely intact.