Studies have shown that herbicide losses often originate from a limited part of a catchment only. These areas are characterized by fast flow processes. We test the predictability of such critical source areas with the modified hydrological model SMDR. The study area was a small agricultural catchment in Switzerland, where herbicide losses were monitored in previous field studies. Input data needed for SMDR are maps of digital elevation, land use and soil characteristics. The hydrological properties were determined from the soil map using pedotransfer functions. For the sensitivity and uncertainty analysis SMDR was linked with the system analysis software tool UNCSIM. The a priori predicted discharge agreed fairly well with the measured values for spring 2000 (Nash-Sutcliffe 0.8). Analysis of the spatial distribution of contributing areas showed that fields with high predicted runoff losses correspond to the fields with the highest observed herbicide losses. The most sensitive parameters turned out to be the percolation rate into groundwater and the hydraulic conductivity of macropores. This observation is critical because not much information is obtained from soil maps. Discharge data from the catchment had some value in constraining the parameter space of behavioural simulations affecting the spatial predictions of runoff formation.

Biocidal products are widely used in urban areas for material protection. Carbendazim and diuron are representatives for biocides in paints and plaster of facades. Factors influencing release of biocides and their fate in urban sewer systems are not well understood at present time. We therefore investigated several biocides at different scales: facades and roofs, effluent and sludge from wastewater treatment plants and receiving waters (project URBIC). Carbendazim, diuron and mecoprop were often detected in the different compartments. Bitumen sheets for roof waterproofing treated with the root protection agent mecoprop were investigated more specifically. Initial laboratory tests resulted in leaching rates differing by a factor of 100 between different products. The knowledge on leaching processes and occurrence of biocides from material protection products in urban water systems is a prerequisite for efficient implementation of technical measures or at-source controls.<br/><br/> Les biocide sont des produits employés couramment en milieux urbains pour la protection des matériaux. Les facteurs influençant le lessivage de ces substances et leur devenir dans les réseaux d'assainissement sont encore actuellement mal connus. Plusieurs biocides ont été suivis à différentes échelles de travail dans le cadre du projet URBIC, allant de l'étude de toiture et de façade, de la station d'épuration ou du milieu récepteur. Les produits les plus souvent détectés ont été la carbendazim, le diuron et le mecoprop. Des tests de lessivage de membranes bitumeuses, utilisées pour les toitures plates, ont été réalisés. Les taux de mecoprop (produit d'inhibition de la croissance racinaire) varient d'un facteur 100 entre plusieurs produits testés. La connaissance de ces processus de lixiviation et des quantités de biocides utilisés est indispensable pour une protection efficace des milieux récepteurs par le biais de mesures techniques ou de solution de contrôle à la source.

In the context of applied psychology modelling human behaviour is intensively discussed. There are various psychological theories that focus on psychological aspects of decision making and on communication aspects. It is obvious to analyze these questions by the means of modelling and simulation. In this situation, the modeller has two main problems: Firstly, there are lot of very detailed investigations on psychological phenomena but all these theories are quite isolated to each other and do not give an integrated and comprehensive view on the relevant process. Secondly, for formulating the model and for simulating it later on, there is no support on software level.<br/> In this situation an efficient software concept is needed which brings together the very special objectives of the innovative and continuously developing thematic scope and a scalable and payable software architecture to work with. This paper introduces such a software concept. Preconditions for the work are a communication network simulator and a psychological model for a human agent. The network enables the modeller to specify communication networks between the modelled individuals, the agents and executes a simple next-event-simulation mechanism with a discrete time-model. The agent model structures the psychological components and processes participating in decision making.<br/> The main part of the paper analyzes the use cases for the planned software system as initialize the network, initialize an agent, observe trajectories, simulate, analyze results, change parameter values, change agent behaviour, and focuses on the special problems caused by applying these tasks to the field of agent based communication models. On the base of these deliberations an adequate software architecture is proposed. Thereby, the following conflicts had to be solved: <ul><li>Complexity of the model versus design of the user interface.</li> <li>Universal software system versus easily adaptable simulation program.</li> <li>User interface versus highly specialized interventions on behaviour programming level.</li> <li>Object oriented programming paradigm versus (procedural) programming skills of the social scientists.</li></ul> These conflicts concentrate on a cost benefit problem concerning universal system and comfortable user interface on the one hand and on the problem of the access level for the inexperienced user on the other. The decisions made for models following the ATASIS meta model are as follows: The graphical user interface gives support only for simple standard functions. Higher functionality is accessible by the interface of the database system and its query language directly. For the model description level the argumentation is more complex. The solution is realized as follows: <ol><li>Model structure in strong analogy to the psychological theory.</li> <li>Strongly sequential runtime algorithm.</li> <li>Dataflow by message mechanism between the psychological components.</li> <li>Updating the model code by the use of a standard development environment.</li></ol> So far, the conflict between a proper object-oriented design of the modelling and simulation software environment for the ATASIS meta model and the usability by users without deepened programming skills is discussed. For the complete project of model development, this paper tries to motivate <ul><li>A sophisticated balance between user skills and higher concepts of object oriented programming paradigm: We just used the concepts of modularisation but no heritage and no method concepts.</li> <li>The cost benefit calculations for the user interface, which lead to very pragmatic solutions especially for non standard application areas of simulation methodology.</li> <li>The intensive analyse of user demands which leads to smaller and more efficient solutions.</li> <li>The concept of the expert-mode interface for access to model code and data base which leads to an open system architecture with only negligible cut backs in comfort.</li> <li>The acceptance and integration of user skills which has restricting effects concerning programming experiences however very positive effects concerning the use of the database interface including its query language.</li></ul>

In zebrafish, two isoforms of the aromatase gene exist, namely <I>cyp19a1</I> and <I>cyp19a2</I>, expressed predominantly in the gonads and brain, respectively. In this study, we focus on characterizing the specificity of antibodies against the aromatase isoforms, and on (xeno)estrogen-induced changes of individual <I>cyp19a2</I> mRNA concentrations in the brains of adult male zebrafish. Among three polyclonal antibodies studied, the one against CYP19A2 was found to be specific in Western blots and immunohistochemistry. Real-time RT-PCR analyses revealed strong interindividual variation of <I>cyp19a2</I> levels in the brains of adult male zebrafish. After a three-week-exposure to (xeno)estrogens, mean values of <I>cyp19a2</I> mRNA levels tended to increase, with significant induction at 200 ng 17β-estradiol/L, but interindividual variation of <I>cyp19a2</I> expression was maintained.

The expression of the glutathione peroxidase homologous gene <I>Gpxh</I>, known to be specifically induced by the formation of singlet oxygen (<SUP>1</SUP>O<SUB>2</SUB>), was analyzed in cells of <I>Chlamydomonas reinhardtii</I> exposed to environmental conditions causing photoinhibition. Illumination with high light intensities, leading to an increased formation of <SUP>1</SUP>O<SUB>2</SUB> in photosystem II, continuously induced the expression of <I>Gpxh</I> in cell for at least 2 h. Phenolic herbicides like dinoterb, raise the rate of <SUP>1</SUP>O<SUB>2</SUB> formation by increasing the probability of charge recombination in photosystem II via the formation of the primary radical pair and thereby <SUP>3</SUP>P<SUB>680</SUB> formation (Fufezan C et al. 2002, FEBS Letters 532, 407–410). In the presence of dinoterb the light-induced loss of the D1 protein in <I>C. reinhardtii</I> was increased and the high light-induced <I>Gpxh</I> expression was further stimulated. DCMU, a urea-type herbicide, causing reduced <SUP>1</SUP>O<SUB>2</SUB> generation in photosystem II, protected the D1 protein slightly against degradation and downregulated the expression of the <I>Gpxh</I> gene compared to untreated cells exposed to high light intensities. This indicates that the <I>Gpxh</I> expression is induced by <SUP>1</SUP>O<SUB>2</SUB> under environment conditions causing photoinhibition.

The commercially available LIVE/DEAD BacLight kit is enjoying increased popularity among researchers in various fields of microbiology. Its use in combination with flow cytometry brought up new questions about how to interpret LIVE/DEAD staining results. Intermediate states, normally difficult to detect with epifluorescence microscopy, are a common phenomenon when the assay is used in flow cytometry and still lack rationale. It is shown here that the application of propidium iodide in combination with a green fluorescent total nucleic acid stain on UVA-irradiated cells of <em>Escherichia coli, Salmonella enterica</em> serovar Typhimurium, <em>Shigella flexneri</em>, and a community of freshwater bacteria resulted in a clear and distinctive flow cytometric staining pattern. In the gram-negative bacterium <em>E. coli</em> as well as in the two enteric pathogens, the pattern can be related to the presence of intermediate cellular states characterized by the degree of damage afflicted specifically on the bacterial outer membrane. This hypothesis is supported by the fact that EDTA-treated nonirradiated cells exhibit the same staining properties. On the contrary, this pattern was not observed in gram-positive <em>Enterococcus faecalis</em>, which lacks an outer membrane. Our observations add a new aspect to the LIVE/DEAD stain, which so far was believed to be dependent only on cytoplasmic membrane permeability.

Timing divergence events allows us to infer the conditions under which biodiversity has evolved and gain important insights into the mechanisms driving evolution. Cichlid fishes are a model system for studying speciation and adaptive radiation, yet we have lacked reliable timescales for their evolution. Phylogenetic reconstructions are consistent with cichlid origins prior to Gondwanan landmass fragmentation 165-121 million years ago, onsiderably earlier than the first known fossil cichlids (Eocene). We examined the timing of cichlid evolution using a relaxed molecular clock calibrated with geological estimates for the ages of (i) Gondwanan fragmentation and (ii) cichlid fossils. Timescales of cichlid evolution derived from fossil-dated phylogenies of other bony fishes most closely matched those suggested by Gondwanan break-up calibrations, suggesting the Eocene origins and marine dispersal implied by the cichlid fossil record may be due to its incompleteness. Using Gondwanan calibrations, we found accumulation of genetic diversity within the radiating lineages of the African Lakes Malawi, Victoria and Barombi Mbo and Palaeolake Makgadikgadi began around or after the time of lake basin formation. These calibrations also suggest Lake Tanganyika was colonised independently by the major radiating cichlid tribes that then began to accumulate genetic diversity thereafter. These results contrast with the widely accepted theory that diversification into major lineages took place within the Tanganyika basin. Together this evidence suggests that ancient lake habitats have played a key role in generating and maintaining diversity within radiating lineages, but also that lakes may have captured pre-existing cichlid diversity from multiple sources from which adaptive radiations have evolved.

Knowledge about the sensitivity of the test organism is essential for the evaluation of any disinfection method. In this work we show that sensitivity of <em>Escherichia coli</em> MG1655 to three physical stresses (mild heat, UVA light, and sunlight) that are relevant in the disinfection of drinking water with solar radiation is determined by the specific growth rate of the culture. Batch- and chemostat-cultivated cells from cultures with similar specific growth rates showed similar stress sensitivities. Generally, fast-growing cells were more sensitive to the stresses than slow-growing cells. For example, slow-growing chemostat-cultivated cells (<em>D</em> = 0.08 h^–1) and stationary-phase bacteria from batch culture that were exposed to mild heat had very similar <em>T</em>₉₀ (time until 90% of the population is inactivated) values (<em>T</em>_{90, chemostat} = 2.66 h; <em>T</em>_{90, batch} = 2.62 h), whereas <em>T</em>₉₀ for cells growing at a µ of 0.9 h^–1 was 0.2 h. Wepresent evidence that the stress sensitivity of <em>E. coli</em> is correlated with the intracellular level of the alternative sigma factor RpoS. This is also supported by the fact that <em>E. coli rpoS</em> mutant cells were more stress sensitive than the parent strain by factors of 4.9 (mild heat), 5.3 (UVA light), and 4.1 (sunlight). Furthermore, modeling of inactivation curves with GInaFiT revealed that the shape of inactivation curves changed depending on the specific growth rate. Inactivation curves of cells from fast-growing cultures (µ = 1.0 h^–1) that were irradiated with UVA light showed a tailing effect, while for slow-growing cultures (µ = 0.3 h^–1), inactivation curves with shoulders were obtained. Our findings emphasize the need for accurate reporting of specific growth rates and detailed culture conditions in disinfection studies to allow comparison of data from different studies and laboratories and sound interpretation of the data obtained.

Aims: To determine the efficacy of solar disinfection (SODIS) for enteric pathogens and to test applicability of the reciprocity law.<BR/>Methods and Results: Resistance to sunlight at 37°C based on <I>F</I><SUB>99</SUB> values was in the following order: <I>Salmonella</I> Typhimurium > <I>Escherichia coli</I> > <I>Shigella flexneri</I> > <I>Vibrio cholerae</I>. While <I>F</I><SUB>90</SUB> values of <I>Salm. Typhimurium</I> and <I>E. coli</I> were similar, <I>F</I><SUB>99</SUB> values differed by 60% due to different inactivation curve shapes. Efficacy seemed not to be dependent on fluence rate for <I>E. coli</I> stationary cells. Sensitivity to mild heat was observed above a temperature of 45°C for <I>E. coli</I>, <I>Salm.</I> Typhimurium and <I>Sh. flexneri</I>, while <I>V. cholerae</I> was already susceptible above 40°C.<BR/>Conclusions: <I>Salmonella</I> Typhimurium was the most resistant and <I>V. cholerae</I> the least resistant enteric strain. The reciprocity law is applicable for stationary <I>E. coli</I> cells irradiated with sunlight or artificial sunlight.<BR/>Significance and Impact of the Study: <I>Escherichia coli</I> might not be the appropriate indicator bacterium to test the efficacy of SODIS on enteric bacteria and the physiological response to SODIS might be different among enteric bacteria. The applicability of the reciprocity law indicates that fluence rate plays a secondary role in SODIS efficacy. Stating inactivation efficacy with <I>T</I><SUB>90</SUB> or <I>F</I><SUB>90</SUB> values without showing original data is inadequate for SODIS studies.

Adaptive responses of bacteria to physical or chemical stresses in the laboratory or in the environment are of great interest. Here we investigated the ability of <I>Escherichia coli</I> growing in continuous culture to adapt to UVA radiation. It was shown that <I>E. coli</I> indeed expressed an adaptive response to UVA irradiation at an intensity of 50 W/m<SUP>2</SUP>. Cells grown in continuous culture with complex medium (diluted Luria Bertani broth) at dilution rates of 0.7 h<SUP>−1</SUP>, 0.5 h<SUP>−1</SUP> and 0.3 h<SUP>−1</SUP> were able to maintain growth under UVA irradiation after a transient reduction of specific growth rate and recovery. In contrast, slow-growing cells (<I>D</I> = 0.05 h<SUP>−1</SUP>) were unable to induce enough protection capacity to maintain growth under UVA irradiation. We propose that faster growing <I>E. coli</I> cells have a higher adaptive flexibility to UVA light-stress than slow-growing cells. Furthermore it was shown with flow cytometry and viability stains that at a dilution rate of 0.3 h<SUP>−1</SUP> only a small fraction (1%) of the initial cell population survived UVA light-stress. Adapted cells were significantly larger (30%) than unstressed cells and had a lower growth yield. Furthermore, efflux pump activity was diminished in adapted cells. In a second irradiation period (after omitting UVA irradiation for 70 h) adapted cells were able to trigger the adaptive response twice as fast. Additionally, this study shows that continuous cultivation with direct stress application allows reproducible investigation of the physiological and possibly also molecular mechanisms during adaptation of <I>E. coli</I> populations to UVA light.

A 650-yr-long sediment sequence from a crater lake on Tristan da Cunha, South Atlantic, was analysed for its <SUP>10</SUP>Be content. Based on <SUP>14</SUP>C dating, and sedimentary, geochemical, magnetic and palynological records, the period between 900 and 1450 AD appears to have been unusually stable in terms of sedimentation and vegetation and therefore this period was chosen for analysis of the <SUP>10</SUP>Be content. During this period of highly organic sedimentation and closed vegetation, the pattern of <SUP>10</SUP>Be flux variations follows the <SUP>10</SUP>Be fluctuations from the GRIP ice core and estimated <SUP>14</SUP>C production rates well. However, before and after this stable period, variable sedimentation rates have to be accounted for to obtain results that are comparable to the established <SUP>10</SUP>Be/<SUP>14</SUP>C records. Our data show not only the possibility of obtaining detailed enough <SUP>10</SUP>Be flux data from sedimentary sequences to reconstruct past solar forcing but also how sensitive this type of record is to sedimentary and environmental changes. If suitable archives can be found, they have the potential to improve reconstructions of solar activity far back in time.

In this paper, we apply the method of material flow analysis to analyze the consumption and waste mass flows of short-lived goods and we provide first insights into the waste management behavior of households in Santiago de Cuba. The goods analyzed are glass, aluminum, organic material and PET. The necessary data were gathered in personal interviews with 1171 households using a standardized questionnaire. The questionnaire contained questions about socio-demographic variables, such as age, sex, education, income and occupation. The households were asked how many PET bottles, aluminum and glass containers they consume per month and how they dispose of the different kinds of garbage. <BR/>Our investigations show that:<BR/><BR/>(i) Cuba has a high recycling rate closely comparable to that of Switzerland and Germany, which have the highest recycling rates world-wide. The high recycling rate is achieved through a combination of social organization, control and internalized norms. In contrast to other developing countries, where the informal sector plays an important role in recycling activities, in Santiago de Cuba the contribution of the informal sector is marginal.<BR/>(ii) The preferred recycling path, where 50–70% of the waste is disposed of, is Comité de Defensa de la Revolución, Revolution Defense Committee (CDR), a collection entity organized at the neighborhood sector level, which also fulfills social control functions. <BR/>(iii) Recyclable goods could also be sold in the "cases to compra", where for 20 empty bottles, a filled one can be obtained. However, this recycling path is only used for 1.5–5% of the waste fraction. This can be explained by the fact that, in addition to the social control provided by CDR, pushing people to bring their recyclable materials to CDR, there is a problem of reputation: people who collect empty bottles are looked down on.<BR/>(iv) There are virtually no differences in the disposal and recycling pattern between the rich and the poor quartile of the population.

Oxidation of the antimicrobial agent triclosan by aqueous ozone (O<SUB>3</SUB>) was investigated to determine associated reaction kinetics, reaction site(s), and consequent changes in antibacterial activity of triclosan. Specific second-order rate constants, k<SUB>O3</SUB>, were determined for reaction of O<SUB>3</SUB> with each of triclosan's acid-base species. The value of k<SUB>O3</SUB> determined for neutral triclosan was 1.3 (± 0.1) × 10<SUP>3</SUP> M<SUP>- 1</SUP> s<SUP>- 1</SUP>, while that measured for anionic triclosan was 5.1 (± 0.1) × 10<SUP>8</SUP> M<SUP>- 1</SUP> s<SUP>- 1</SUP>. Consequently, triclosan reacts very rapidly with O<SUB>3</SUB> at circumneutral pH (the pH-dependent, apparent second-order rate constant, k<SUB>app, O3</SUB>, is 3.8 × 10<SUP>7</SUP> M<SUP>- 1</SUP> s<SUP>- 1</SUP> at pH 7). The pH-dependence of k<SUB>app, O3</SUB> and comparison of triclosan reactivity toward O<SUB>3</SUB> with that of other phenolic compounds indicates that O<SUB>3</SUB> reacts initially with triclosan at the latter's phenol moiety. k<SUB>O3</SUB> values for neutral and anionic triclosan were successfully related to phenol ring substituent effects via Brown-Okamoto correlation with other substituted phenols, consistent with electrophilic attack of the triclosan phenol ring. Biological assay of O<SUB>3</SUB>-treated triclosan solutions indicates that reaction with O<SUB>3</SUB> yields efficient elimination of triclosan's antibacterial activity. In order to evaluate the applicability of these observations to actual wastewaters, triclosan oxidation was also investigated during ozonation of effluent samples from two conventional wastewater treatment plants. Nearly 100% triclosan depletion was achieved for a 4 mg / L (8.3 × 10<SUP>- 5</SUP> mol / L)O<SUB>3</SUB> dose applied to a wastewater containing 7.5 mg / L of DOC, and ∼ 58 % triclosan depletion for dosage of 6 mg / L (1.3 × 10<SUP>- 4</SUP> mol / L)O<SUB>3</SUB> to a wastewater containing 12.4 mg / L of DOC. At O<SUB>3</SUB> doses greater than 1 mg / L (2.1 × 10<SUP>- 5</SUP> mol / L), hydroxyl radical reactions accounted for < 35 % of observed triclosan losses in these wastewaters, indicating that triclosan oxidation was due primarily to the direct triclosan-O<SUB>3</SUB> reaction. Thus, ozonation appears to present an effective means of eliminating triclosan's antibacterial activity during wastewater treatment.

We present a travel-time based reactive transport model to simulate an in-situ bioremediation experiment for demonstrating enhanced bioreduction of uranium(VI). The model considers aquatic equilibrium chemistry of uranium and other groundwater constituents, uranium sorption and precipitation, and the microbial reduction of nitrate, sulfate and U(VI). Kinetic sorption/desorption of U(VI) is characterized by mass transfer between stagnant micro-pores and mobile flow zones. The model describes the succession of terminal electron accepting processes and the growth and decay of sulfate-reducing bacteria, concurrent with the enzymatic reduction of aqueous U(VI) species. The effective U(VI) reduction rate and sorption site distributions are determined by fitting the model simulation to an in-situ experiment at Oak Ridge, TN. Results show that (1) the presence of nitrate inhibits U(VI) reduction at the site; (2) the fitted effective rate of in-situ U(VI) reduction is much smaller than the values reported for laboratory experiments; (3) U(VI) sorption/desorption, which affects U(VI) bioavailability at the site, is strongly controlled by kinetics; (4) both pH and bicarbonate concentration significantly influence the sorption/desorption of U(VI), which therefore cannot be characterized by empirical isotherms; and (5) calcium-uranyl-carbonate complexes significantly influence the model performance of U(VI) reduction.

Many endocrine-disrupting chemicals act <I>via</I> estrogen receptor (ER) or aryl hydrocarbon receptor (AhR). To investigate the interference between ER and AhR, we studied the effects of 17ß-estradiol (E2) and 2,3,7,8-tetrachlorodibenzo-<I>p</I>-dioxin (TCDD) on the expression of zebra fish <I>cyp19a</I> (zf<I>cyp19a</I>) and <I>cyp19b</I> (zf<I>cyp19b</I>) genes, encoding aromatase P450, an important steroidogenic enzyme. <I>In vivo</I> (mRNA quantification in exposed zebra fish larvae) and <I>in vitro</I> (activity of zf<I>cyp19</I>-luciferase reporter genes in cell cultures in response to chemicals and zebra fish transcription factors) assays were used. None of the treatments affected zf<I>cyp19a</I>, excluding the slight upregulation by E2 observed <I>in vitro</I>. Strong upregulation of zf<I>cyp19b</I> by E2 in both assays was downregulated by TCDD. This effect could be rescued by the addition of an AhR antagonist. Antiestrogenic effect of TCDD on the zf<I>cyp19b</I> expression in the brain was also observed on the protein level, assessed by immunohistochemistry. TCDD alone did not affect zf<I>cyp19b</I> expression <I>in vivo</I> or promoter activity in the presence of zebra fish AhR2 and AhR nuclear translocator 2b (ARNT2b) <I>in vitro</I>. However, in the presence of zebra fish ER, AhR2, and ARNT2b, TCDD led to a slight upregulation of promoter activity, which was eliminated by either an ER or AhR antagonist. Studies with mutated reporter gene constructs indicated that both mechanisms of TCDD action <I>in vitro</I> were independent of dioxin-responsive elements (DREs) predicted in the promoter. This study shows the usefulness of <I>in vivo</I> zebra fish larvae and <I>in vitro</I> zf<I>cyp19b</I> reporter gene assays for evaluation of estrogenic chemical actions, provides data on the functionality of DREs predicted in zf<I>cyp19</I> promoters and shows the effects of cross talk between ER and AhR on zf<I>cyp19b</I> expression. The antiestrogenic effect of TCDD demonstrated raises further concerns about the neuroendocrine effects of AhR ligands.

1. Hybridization between species is a common phenomenon in plants and animals. If parasite prevalence differs for hybrids and parental species (i.e. taxa) there may be considerable consequences for relative hybrid fitness. Some studies have investigated hybrid complexes for infection, and complex-specific differences in parasite prevalence have been detected.<BR/>2. Based on the results of a field study on a hybridizing <I>Daphnia</I> population from a single lake, it has been hypothesized that permanently over- or under-infected hybrids do not exist. The observed field-patterns can only be temporal because taxa, in addition to single genotypes, might be the subject of parasite driven host frequency-dependent selection. Thus, parasites will track any common taxon within a hybrid complex.<BR/>3. In the present study, hybridizing <I>Daphnia</I> populations from 43 lakes were screened for parasite infections to obtain indirect evidence for coevolutionary cycles. It was hypothesized that, due to time lags between the evolution of resistance in host populations and the evolution of the parasite towards tracking of a common host taxon, the same <I>Daphnia</I> taxon will be over-infected in some lakes, while being under-infected in others.<BR/>4. Two of the four parasite species were specialists: their prevalence differed among coexisting <I>Daphnia</I> taxa. The varying infection patterns detected across spatially segregated hybridizing <I>Daphnia</I> populations are consistent with theoretical predictions for coevolutionary cycles. Thus the infection patterns, as observed under natural conditions, are temporal and unstable.<BR/>5. Additionally, the spatial distribution of the four parasite species was analysed with respect to habitat differences. The results show that the presence of a particular parasite on a host taxon was determined not only by the host-specificity of the parasite, but also by host-habitat relations.

The expression of the <I>GPXH</I> gene, coding for a phospholipid hydroperoxide glutathione peroxidase homologous protein, was shown to be strongly induced in <I>Chlamydomonas reinhardtii</I> exposed to photooxidative stress conditions like high light illumination. Here, we show that the response of the <I>GPXH</I> gene to high-light conditions is induced by two independent signals and mechanisms: first, there is a fast but transient transcriptional induction by singlet oxygen formed after charge recombination and energy transfer from the overexcited photosystem II reaction center to molecular oxygen. Second, upon very strong or ongoing photooxidative stress, <I>GPXH</I> upregulation is further stimulated presumably by an mRNA stabilization mechanism as a result of lipid hydroperoxide formation. This could be confirmed by imitating the high-light response of <I>GPXH</I> by exposing cultures of <I>C. reinhardtii</I> to a mixture of the singlet oxygen producing photosensitizer rose bengal and organic hydroperoxides. Furthermore, determination of mRNA decay rates allowed simulating the <I>GPXH</I> responses to various stress conditions with a mathematical model. A preventive effect of singlet oxygen formation on the resistance against photooxidative stress and lipid peroxidation was shown by acclimation experiments. Thus, the consecutive regulation of <I>GPXH</I> expression by an early transcriptional upregulation by a primary (singlet oxygen formation) and a time-dependent stabilization of mRNA levels by a secondary effect (lipid peroxidation) of high light stress might be an efficient mechanism to control the stress response.

The failure of river rehabilitation projects is often reported in the literature. One possible reason for this failure is the insufficient consideration of factors degrading riverine ecosystems at large spatio-temporal scales. A precedent analysis of the evolution and significance of these factors at the watershed level is proposed as a prerequisite for a successful rehabilitation project. Based on a watershed-scale approach, we investigated the current and historical states of the fish assemblage and of relevant abiotic factors in the river Rhone, a seventh-order stream in Switzerland scheduled for large-scale rehabilitation. Recent field data gathered by electrofishing and habitat mapping were analysed by means of a mixed model approach and were qualitatively compared compared to historical information derived from topographic maps and documentary sources.<BR/>The length of the entire active channel has been reduced by 45% (102 km) since 1850, representing a significant diminution in lateral connectivity. Our recent fish survey revealed a depleted species set, with only two of 19 historically documented species found. The density of brown trout was generally low, but positively correlated with the presence of cover. Thus, morphological improvements, e.g. through local river widening, offer extensive potential for the restoration of native fish assemblages, but will probably only be successful in combination with a more natural hydrological regime.

As part of the Swiss Fischnetz project (network for declining fish yields in Switzerland) studies were carried out to investigate the decline in catches of brown trout. Insufficient YOY (young-of-the-year) recruitment of brown trout due to different abiotic and/or biotic factors was hypothesized as a potential cause of this decline. Quantitative assessments of fish ecology parameters and habitat measurements were carried out at 97 river sites over a two-year period. The main objectives of this study were to document the occurrence and abundance of naturally reproduced YOY trout and to develop an understanding of environmental factors responsible for the observed YOY density. A general linear model (GLM) was used to analyse the influence of selected environmental abiotic and biotic parameters on YOY density.<BR/>Successful recruitment of YOY trout was observed in all but three of the sites studied. Abundance was correlated with abiotic and biotic factors, such as river width, slope, altitude, substratum condition, and the occurrence of proliferative kidney disease (PKD). The results highlight the importance of small streams for natural YOY recruitment of brown trout and their function as a source of individuals for downstream river sections.

Predicting the disinfection performance of a full-scale reactor in drinking water treatment is associated with considerable uncertainty. In view of quantitative risk analysis, this study assesses the uncertainty involved in predicting inactivation of <I>Cryptosporidium parvum</I> oocysts for an ozone reactor treating lake water. A micromodel is suggested which quantifies inactivation by stochastic sampling from density distributions of ozone exposure and lethal ozone dose. The ozone exposure distribution is computed with a tank in series model that is derived from tracer data and measurements of flow, ozone concentration and ozone decay. The distribution of lethal ozone doses is computed with a delayed Chick–Watson model which was calibrated by Sivaganesan and Marinas [2005. Development of a <I>Ct</I> equation taking into consideration the effect of Lot variability on the inactivation of <I>Cryptosporidium parvum</I> oocysts with ozone. Water Res. 39(11), 2429–2437] utilizing a large number of inactivation studies. Parameter uncertainty is propagated with Monte Carlo simulation and the probability of attaining given inactivation levels is assessed. Regional sensitivity analysis based on variance decomposition ranks the influence of parameters in determining the variance of the model result. The lethal dose model turns out to be responsible for over 90% of the output variance. The entire analysis is re-run for three exemplary scenarios to assess the robustness of the results in view of changing inputs, differing operational parameters or revised assumptions about the appropriate model. We argue that the suggested micromodel is a versatile approach for characterization of disinfection reactors. The scheme developed for uncertainty assessment is optimal for model diagnostics and effectively supports the management of uncertainty.

We developed a model to predict the impacts of river rehabilitation activities on the local economy. The model is based on the Input–Output analysis technique and was applied to the planned rehabilitation project for the River Thur in northern Switzerland, along the 4 km stretch between the communities of Bürglen and Weinfelden. We estimated changes in local employment and local economic output resulting from government spending on rehabilitation, associated changes in adjacent land use, and increased recreational activity. Accounting for land use changes required a modification of the conventional Input–Output analysis technique which should be of general interest. We accounted for uncertainty in the data and in some of the model assumptions by using a probabilistic formulation and propagating uncertainty through the model equations. As time-consuming local surveys were beyond the scope of this study, we used the Location Quotient non-survey technique to construct the local technical coefficients from national data and local employment data. This implies that the model can be applied quite easily to a different study area in Switzerland as long as local employment data are available. For each CHF 1 million expenditure per year on rehabilitation activities in our study region, we estimate an extra 8 fulltime employment equivalents (standard deviation, <I>σ</I> = 0.4 fte) and an increased output of CHF 1.4 million (<I>σ</I> = CHF 0.05 million). The low uncertainty of these estimates can be partly attributed to the structure of Input–Output analysis and partly to the fact that we estimated changes in the economic output, rather than output itself. In addition to the above impacts, we estimate that increased recreational use of the area will increase output by as much as CHF 0.17 million (<I>σ</I> = CHF 0.12 million) and employment by as much as 1.7 fulltime employment equivalents (<I>σ</I> = 1.3 fte), depending on the specific rehabilitation option selected.

Highly polymorphic colouration patterns are often associated with sexual selection in fish and can be the initial cause of divergence among closely related taxa. Here we use genetic, body colour and geometric morphometric data collected on 118 fish from Lake Matano, Sulawesi, Indonesia to test if colouration is the initial cause of divergence in the radiating <I>Telmatherina</I> genus. Results reveal that all <I>Telmatherina</I> previously described in this system can be categorized into three mitochondrial lineages and that colouration is only weakly associated with early divergence. Clade-specific body shapes, however, likely adapted to microenvironments are key to the initial divergence in this system. Data also show that although colourations were not likely instrumental in seeding divergence in these fish, they appear to have developed in parallel within each clade. Our results are consistent with an emerging pattern repeated in many vertebrate radiations, whereby divergence by colouration or other display traits is preceded by specialization to environmental adaptive peaks.

The conventional analysis of pumping tests by type-curve methods is based on the assumption of a homogeneous aquifer. Applying these techniques to pumping test data from real heterogeneous aquifers leads to estimates of the hydraulic parameters that depend on the choice of the pumping and observation well positions. In this paper, we test whether these values may be viewed as pseudo-local values of transmissivity and storativity, which can be interpolated by kriging. We compare such estimates to those obtained by geostatistical inverse modeling, where heterogeneity is assumed in all stages of estimation. We use drawdown data from multiple pumping tests conducted at the test site in Krauthausen, Germany. The geometric mean values of transmissivity and storativity determined by type-curve analysis are very close to those obtained by geostatistical inversion, but the conventional approach failed to resolve the spatial variability of transmissivity. In contrast, the estimate from geostatistical inversion reveals more structure. This indicates that the estimates of the type-curve approaches can not be treated as pseudo-local values. Concerning storativity, both analysis methods show strong fluctuations. Because the variability of all terms making up the storativity is small, we believe that the estimated variability of storativity is biased. We examine the influence of measurement error on estimating structural parameters of covariance functions in the inversion. We obtain larger correlation lengths and smaller prior variances if we trust the measured data less.

We simulated a meta-population with random dispersal among demes but local mating within demes to investigate conditions under which a dominant female-determining gene W, with no individual selection advantage, can invade and become fixed in females, changing the population from male to female heterogamety. Starting with one mutant W in a single deme, the interaction of sex ratio selection and random genetic drift causes W to be fixed among females more often than a comparable neutral mutation with no influence on sex determination, even when YY males have slightly reduced viability. Meta-population structure and interdeme selection can also favour the fixation of W. The reverse transition from female to male heterogamety can also occur with higher probability than for a comparable neutral mutation. These results help to explain the involvement of sex-determining genes in the evolution of sex chromosomes and in sexual selection and speciation.

Knowing the travel-time distributions from infiltrating rivers to pumping wells is important in the management of alluvial aquifers. Commonly, travel-time distributions are determined by releasing a tracer pulse into the river and measuring the breakthrough curve in the wells. As an alternative, one may measure signals of a time-varying natural tracer in the river and in adjacent wells and infer the travel-time distributions by deconvolution. Traditionally this is done by fitting a parametric function such as the solution of the one-dimensional advection-dispersion equation to the data. By choosing a certain parameterization, it is impossible to determine features of the travel-time distribution that do not follow the general shape of the parameterization, i.e., multiple peaks. We present a method to determine travel-time distributions by nonparametric deconvolution of electric-conductivity time series. Smoothness of the inferred transfer function is achieved by a geostatistical approach, in which the transfer function is assumed as a second-order intrinsic random time variable. Nonnegativity is enforced by the method of Lagrange multipliers. We present an approach to directly compute the best nonnegative estimate and to generate sets of plausible solutions. We show how the smoothness of the transfer function can be estimated from the data. The approach is applied to electric-conductivity measurements taken at River Thur, Switzerland, and five wells in the adjacent aquifer, but the method can also be applied to other time-varying natural tracers such as temperature. At our field site, electric-conductivity fluctuations appear to be an excellent natural tracer. Association.

Under steady-state conditions, the degradation of contaminant plumes introduced continuously into an aquifer is controlled by transverse dispersion when the other reacting compound is provided from ambient groundwater. Given that the reaction is instantaneous and longitudinal dispersion can be neglected, the length of the plume is inversely proportional to the transverse dispersion coefficient. In typical scenarios of natural attenuation, however, the considered reaction is biotic and kinetic. The standard model of bioreactive transport relies on double-Monod kinetics and pseudo first-order biomass decay. Under these conditions, a fraction of the injected mass flux remains beyond the length of the plume determined for the instantaneous reaction. We present an analytical framework to derive the steady-state concentration distributions of the dissolved compounds and the biomass from the concentration distribution of a conservative compound, assuming double-Monod kinetics and two different models describing biomass decay. The first biomass-decay model assumes a constant first-order decay coefficient, while the second assumes that the decay coefficient depends upon the electron-acceptor concentration. We apply the method to the case of a line-injection in two-dimensional uniform flow. In general, the bioreactive concentration distributions are similar to the distributions computed for an instantaneous reaction. The similarity is greater when the biomass decay coefficient is assumed to depend on the electron-acceptor concentration rather than being constant.

Connectivity among demes in a metapopulation depends on both the landscape's and the focal organism's properties (including its mobility and cognitive abilities). Using individual-based simulations, we contrast the consequences of three different cognitive strategies on several measures of metapopulation connectivity. Model animals search suitable habitat patches while dispersing through a model landscape made of cells varying in size, shape, attractiveness and friction. In the blind strategy, the next cell is chosen randomly among the adjacent ones. In the near-sighted strategy, the choice depends on the relative attractiveness of these adjacent cells. In the far-sighted strategy, animals may additionally target suitable patches that appear within their perceptual range.<BR/>Simulations show that the blind strategy provides the best overall connectivity, and results in balanced dispersal. The near-sighted strategy traps animals into corridors that reduce the number of potential targets, thereby fragmenting metapopulations in several local clusters of demes, and inducing sink-source dynamics. This sort of local trapping is somewhat prevented in the far-sighted strategy. The colonization success of strategies depends highly on initial energy reserves: blind does best when energy is high, near-sighted wins at intermediate levels, and far-sighted outcompetes its rivals at low energy reserves.<BR/>We also expect strong effects in terms of metapopulation genetics: the blind strategy generates a migrant-pool mode of dispersal that should erase local structures. By contrast, near- and far-sighted strategies generate a propagule-pool mode of dispersal and source-sink behavior that should boost structures (high genetic variance among- and low variance within local clusters of demes), particularly if metapopulation dynamics is also affected by extinction-colonization processes.<BR/>Our results thus point to important effects of the cognitive ability of dispersers on the connectivity, dynamics and genetics of metapopulations.

A new phytotoxicity bioassay based on chlorophyll fluorescence imaging of algae suspensions in multiwell plates is introduced. Phytotoxicity is quantified via inhibition of photosystem II quantum yield, <I>Y</I>(II), assessed with the saturation pulse method. The basics of this approach as well as the factors enhancing and limiting its performance are outlined. Compared to other established techniques the new system allows exceptionally rapid and accurate measurements of phytotoxicity using pulse-amplitude-modulation (PAM) fluorometry. While instrument related errors are negligibly small, optimal performance depends on appropriate choice of algae and illumination conditions. Illustrative examples for the response of <I>Phaeodactylum tricornutum</I> to diuron are presented. The standard deviation involved in the <I>Y</I>(II) determination of a single well amounts to the equivalent of 44 ng/L diuron. A decisive role is played by the light (measuring light, saturation pulses, actinic light) to which samples are exposed during the bioassay: (1) the inhibitor response is enhanced at high measuring light intensity. (2) Saturation pulses may be considered non-invasive only, if applied at low frequency and as long as physiologically healthy algae cultures are used. (3) Continuous actinic light may be problematic, as it induces complex physiological reactions that limit the performance of the approach; it is not required for assessment of diuron-type inhibitors at high measuring light intensity.

Separating urine from wastewater at the source reduces the costs of extensive wastewater treatment. Recovering the nutrients from urine and reusing them for agricultural purposes adds resource saving to the benefits. Phosphate can be recovered in the form of struvite (magnesium ammonium phosphate). In this paper, the behaviour of pharmaceuticals and heavy metals during the precipitation of struvite in urine is studied.<BR/>When precipitating struvite in urine spiked with hormones and non-ionic, acidic and basic pharmaceuticals, the hormones and pharmaceuticals remain in solution for more than 98%.<BR/>For heavy metals, initial experiments were performed to study metal solubility in urine. Solubility is shown to be affected by the chemical conditions of stored and therefore hydrolysed urine. Thermodynamic modelling reveals low or very low equilibrium solute concentrations for cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), nickel (Ni) and lead (Pb). Experiments confirmed Cd, Cu and Pb carbonate and hydroxide precipitation upon metal addition in stored urine with a reaction half-life of ca. 7 days.<BR/>For all metals considered, the maximum specific metal concentrations per gram phosphate or nitrogen showed to be typically several orders of magnitudes lower in urine than in commercially available fertilizers and manure. Heavy metals in struvite precipitated from normal stored urine could not be detected.<BR/>Phosphate recovery from urine over struvite precipitation is shown to render a product free from most organic micropollutants and containing only a fraction of the already low amounts of heavy metals in urine.

Arsenic contamination of groundwater has been identified in Cambodia, where some 100,000 family-based wells are used for drinking water needs. We conducted a comprehensive groundwater survey in the Mekong River floodplain, comprising an area of 3700 km<SUP>2</SUP> (131 samples, 30 parameters). Seasonal fluctuations were also studied. Arsenic ranged from 1 to 1340 μg L<SUP>-1</SUP> (average 163 μg L<SUP>-1</SUP>), with 48% exceeding 10 μg L<SUP>-1</SUP>. Elevated manganese levels (57% >0.4 mg L<SUP>-1</SUP>) are posing an additional health threat to the 1.2 million people living in this area. With 350 people km<SUP>-2</SUP> potentially exposed to chronic arsenic poisoning, the magnitude is similar to that of Bangladesh (200 km<SUP>-2</SUP>). Elevated arsenic levels are sharply restricted to the Bassac and Mekong River banks and the alluvium braided by these rivers (Kandal Province). Arsenic in this province averaged 233 μg L<SUP>-1</SUP> (median 100 μg L<SUP>-1</SUP>), while concentrations to the west and east of the rivers were <10 μg L<SUP>-1</SUP>. Arsenic release from Holocene sediments between the rivers is most likely caused by reductive dissolution of metal oxides. Regions exhibiting low and elevated arsenic levels are co-incident with the present low relief topography featuring gently increasing elevation to the west and east of a shallow valley - understood as a relict of pre-Holocene topography. The full georeferenced database of groundwater analysis is provided as Supporting Information.

Daily mean lake surface-water temperatures (LSWTs) measured in Swiss Alpine lakes in summer and early autumn 2000 were compared with LSWTs measured simultaneously in Lake Balaton, Hungary, 750 kin to the cast. The Swiss lakes are small (0.0043-0.46 km²), predominantly oligotrophic, and are located in a mountainous environment, some at altitudes &gt; 2,000 m above sea level, whereas Lake Balaton is a large (593 km²), shallow, mesotrophic lake situated in the much lower-lying Carpathian Basin. Despite the large distance separating the two regions and the extreme differences in character between the lakes, the LSWTs in Switzerland and Hungary exhibited a coherent response to synoptic-scale meteorological forcing, expressed in terms of exponentially smoothed air temperature, which can be viewed as a causal forcing variable in its own right and as a proxy for other forcing variables with which it is correlated. The coherent response of LSWT in very dissimilar lakes in two different geographical regions of Europe demonstrates that large-scale climatic forcing on synoptic timescales is much more important for lakes than previously thought. This appears to be particularly true for low-altitude lakes, whereas lakes at higher altitudes exhibit more heterogeneity in their response.

1. Elaborate restoration attempts are underway worldwide to return human-impacted rivers to more natural conditions. Assessing the outcome of river restoration projects is vital for adaptive management, evaluating project efficiency, optimising future programmes and gaining public acceptance. An important reason why assessment is often omitted is lack of appropriate guidelines.<BR/>2. Here we present guidelines for assessing river restoration success. They are based on a total of 49 indicators and 13 specific objectives elaborated for the restoration of low- to mid-order rivers in Switzerland. Most of these objectives relate to ecological attributes of rivers, but socio-economic aspects are also considered.<BR/>3. A strategy is proposed according to which a set of indicators is selected from the total of 49 indicators to ensure that indicators match restoration objectives and measures, and that the required effort for survey and analysis of indicators is appropriate to the project budget.<BR/>4. Indicator values are determined according to methods described in detailed method sheets. Restoration success is evaluated by comparing indicator values before and after restoration measures have been undertaken. To this end, values are first standardised on a dimensionless scale ranging from 0 to 1, then averaged across different indicators for a given project objective, and finally assigned to one of five overall success categories.<BR/>5. To illustrate the application of this scheme, a case study on the Thur River, Switzerland, is presented. Seven indicators were selected to meet a total of five project objectives. The project was successful in achieving 'provision of high recreational value', 'lateral connectivity' and 'vertical connectivity' but failed to meet the objectives 'morphological and hydraulic variability' and 'near natural abundance and diversity of fauna'. Results from this assessment allowed us to identify potential deficits and gaps in the restoration project. To gain information on the sensitivity of the assessment scheme would require a set of complementary indicators for each restoration objective.

We investigated the interactions of dissolved reactive phosphorus (DRP) and dissolved nonreactive phosphorus (DNRP) with suspended and settled aquatic particles. The sorption to minerogenic particles from an alpine catchment collected in rivers, hydropower reservoirs, and a downstream ultraoligotrophic lake was modeled using Langmuir-type isotherms. DRP and DNRP exhibited about equal affinities to particle surfaces. The sorption of dissolved species to surfaces alters the fate of P in water bodies. In spite of the small surface-binding constants, high particle concentrations enhance the sorption of P to surfaces, and, consequently, chemical analysis of DRP can substantially underestimate the potentially bioavailable P. In unpolluted rivers with high content of suspended mineral particles, e. g., triggered by heavy rain events (2 mu g DRP/L, 1.3 g/L suspended particles), P loads solely based on DRP measurements underestimate the true load of potentially bioavailable P by more than a factor of two. Modeling P sorption equilibria with a single type of surface site generates a management tool for water quality in P-limited oligotrophic systems.

The improved integration of disparate knowledge stocks is one of the key promises of transdisciplinary research. This present paper illustrates the multifaceted characteristics of knowledge integration by analysing the experience gained through a major transdisciplinary research project on green certification procedures for hydropower plants. These lessons learned allow a better understanding of the challenge to manage the diversity of interfaces between different actors and different forms of knowledge.

Could urine source separation replace the conventional nutrient elimination on wastewater treatment plants? Divided in nine work packages, the Eawag cross-cutting project Novaquatis pursued this question and highlighted the potential advantages and difficulties of such an enterprise. In many rapidly growing cities, the NoMix technology offers a rapid defense against nutrients in coastal waters, without waiting for the long and tiresome construction of sewers and treatment plants. In order to avoid the urine transport, an important next step will be the rapid development of decentralized process engineering opportunities. Also in Switzerland, the NoMix technology has a future, especially in the case of growing requirements for water pollution control.

The Sun is the most important energy source for the Earth. Since the incoming solar radiation is not equally distributed and peaks at low latitudes the climate system is continuously transporting energy towards the polar regions. Any variability in the Sun-Earth system may ultimately cause a climate change. There are two main variability components that are related to the Sun. The first is due to changes in the orbital parameters of the Earth’s position relative to the Sun induced by the other planets. Their gravitational perturbations induce changes with characteristic time scales in the eccentricity (∼100,000 years), the obliquity (angle between the equator and the orbital plane) (∼40,000 years) and the precession of the Earth's axis (∼20,000 years). The second component is due to variability within the Sun. A variety of observational proxies reflecting different aspects of solar activity show similar features regarding periodic variability, trends and periods of very low solar activity (so-called grand minima) which seem to be positively correlated with the emitted energy from the Sun, the total and the spectral solar irradiance. The length of these records ranges from 25 years (solar irradiance) to 400 years (sunspots). In order to establish a quantitative relationship between solar variability and solar forcing it is necessary to extend the records of solar variability much further back in time and to identify the physical processes linking solar activity and total and spectral solar irradiance. The first step, the extension of solar variability, can be achieved by using cosmogenic radionuclides such as ¹⁰Be in ice cores. After removing the effect of the changing geomagnetic field on the ¹⁰Be production rate, a 9000-year long record of solar modulation was obtained. Comparison with paleoclimatic data provides strong evidence for a causal relationship between solar variability and climate change. It will be the subject of the next step to investigate the underlying physical processes that link solar variability with the total and spectral solar irradiance.

Das Grundwasser ist die wichtigste Trinkwasserressource in der Schweiz. Deshalb besteht grosses Interesse, die Grundwasservorkommen möglichst frei von künstlichen, langlebigen Schadstoffen zu halten. Insbesondere soll eine Beeinträchtigung durch Stoffe wie Arzneimittel oder Pestizide vermieden werden. <br/> Um die Grundwasserbelastung durch diese Stoffe zu ermitteln, wurden in Proben von ausgewählten NAQUA-Messstellen eine Auswahl von Pestiziden und einige ihrer Abbauprodukte sowie eine breite Palette an Arzneimitteln analysiert. Anhand der Messdaten wird ein Überblick über die allgemeine elastungssituation gegeben und die Bedeutung der im Grundwasser noch kaum untersuchten Pestizid-Abbauprodukte und Arzneimittel diskutiert.

The oxidation of N-nitrosodimethylamine (NDMA) precursors during water treatment was investigated using ozone and chlorine dioxide (CIO<SUB>2</SUB>). Second-order rate constants for the reactions of model NDMA precursors (dimethylamine (DMA) and 7 tertiary amines) with ozone (k<SUB>app</SUB> at pH 7 = 2.4 × 10<SUP>-1</SUP> to 2.3 × 10<SUP>9</SUP> M<SUP>-1</SUP> s<SUP>-1</SUP>), CIO<SUP>2</SUP> (k<SUB>app</SUB> at pH 7 = 6.7 × 10 <SUP>-3</SUP> to 3.0 × 10<SUP>7</SUP> M<SUP>-1</SUP> s<SUP>-1</SUP>), and hydroxyl radical (<SUP>̇</SUP>OH) (k<SUB>app</SUB> at pH 7 = 6.2 × 10<SUP>7</SUP> to 1.4 × 10<SUP>10</SUP> M<SUP>-1</SUP> s<SUP>-1</SUP>) were determined, which showed that the selected NDMA precursors, with the exception of dimethylformamide (DMFA) can be completely transformed via their direct reaction with ozone. During ozonation, DMFA may be partially transformed through oxidation by the secondary oxidant <SUP>̇</SUP>OH. CIO<SUB>2</SUB> was also shown to effectively transform most of the precursors, with the exceptions of DMA and DMFA. In the second part of the study, the NDMA formation potentials (NDMA-FP) in synthetic and natural waters were measured with and without pre-oxidation with ozone and CIO<SUB>2</SUB>. A significant reduction in the NDMA-FPs was observed after complete transformation of the model NDMA precursors. Ozonation generally led to more effective reduction of the NDMA-FP than CIO<SUB>2</SUB>. For most of the precursors, the formation of DMA could account for the NDMA-FPs remaining after complete transformation of the model NDMA precursors. In contrast, dimethylethanolamine and dimethyldithio-carbamate yielded other NDMA precursors (not DMA) as their oxidation products. Pre-oxidation by ozone and CIO<SUB>2</SUB> of several natural waters showed behavior similar to that of the oxidation of model NDMA precursors with a reduction of the NDMA-FP by 32-94% for various natural water sources.

Solid-phase microextraction (SPME) coupled to gas chromatography/isotope ratio mass spectrometry was used to determine the δ<SUP>15</SUP>N and δ<SUP>13</SUP>C signatures of selected nitroaromatic contaminants such as the explosive 2,4,6-trinitrotoluene (TNT) for derivation of isotopic enrichment factors of contaminant transformation. Parameters for efficient extraction of nitroaromatic compounds (NACs) and substituted anilines from water samples were evaluated by SPME-GC/MS. δ<SUP>13</SUP>C signatures determined by SPME-GC/IRMS and elemental analyzer IRMS (EA-IRMS) were in good agreement, generally within +/- 0.7%, except for 2,4-dinitrotoluene (2,4-DNT) and TNT, which showed slight deviations (< 1.3%). Limits of detection (LODs) for δ<SUP>13</SUP>C analysis by SPME-GC/IRMS were between 73 and 780 μg L<SUP>-1</SUP> and correlated with the extraction efficiencies of the compounds determined by SPME-GC/MS. Nitrogen isotope measurements by SPME-GC/IRMS were of similar precision (standard deviations < 0.8%) for all NACs except for TNT. δ<SUP>15</SUP>N signatures matched the reference values obtained by EA-IRMS within +/- 1.3% (+2.5% for TNT), but no systematic trend was found for the deviations. LODs of δ<SUP>15</SUP>N measurements ranged from 1.6 to 9.6 mg L<SUP>-1</SUP> for nitrotoluenes, chlorinated NACs and DNTs (22 mg L<SUP>-1</SUP> for TNT). The SPME-GC/IRMS method is well suited for the determination of isotopic enrichment factors of various NAC transformation processes and provides so far unexplored possibilities to elucidate behavior and degradation mechanisms of nitroaromatic contaminants in soils and groundwaters.

Despite the concern raised by the detections of veterinary antibiotics like sulfonamides (SA) in the environment, their fate in soils is still not sufficiently understood. In a previous article, we demonstrated that manure may substantially influence losses of SA via runoff from soils. Here, we report on the effect of manure on SA availability in soil pore water. Three sulfonamides (sulfadimidine, sulfadiazine, sulfathiazole) and two tracers (bromide and Brilliant Blue) were either applied in manure or as aqueous solution on grassland plots. After I and 3 d contact time, the plots were irrigated with deionized water. One day after irrigation, soil cores were taken and profiles of pore water concentrations were determined. The median SA concentrations of the top layer on manured plots varied between 40 and 60 mu g L^-1 and between 10 and 30 mu g L^-1 on the controls. For the conservative tracer Br the mass recovery was about 60 to 75% and much lower for the SA (2 to 14%). Apparent distribution coefficients K_d,app of the SA in the topsoil ranged between 3 and 15 L kg^-1 on the manured plots and between 30 to 35 kg L^-1 on the controls. Below the top layer, the concentration distribution showed a pattern typical for preferential flow. Locally, SA concentrations down to 30- to 50-cm depth were as high as in the top 5 cm with little effect of the two application matrices. In the topmost layer, the data indicate that 10 to 25% of sulfadimidine were transformed to its acetyl-metabolite.

Bergmann's and Rensch's rules describe common large-scale patterns of body size variation, but their underlying causes remain elusive. Bergmann's rule states that organisms are larger at higher latitudes (or in colder climates). Rensch's rule states that male body size varies (or evolutionarily diverges) more than female body size among species, resulting in slopes greater than one when male size is regressed on female size. We use published studies of sex-specific latitudinal body size clines in vertebrates and invertebrates to investigate patterns equivalent to Rensch's rule among populations within species and to evaluate their possible relation to Bergmann's rule. Consistent with previous studies, we found a continuum of Bergmann (larger at higher latitudes: 58 species) and converse Bergmann body size clines (larger at lower latitudes: 40 species). Ignoring latitude, male size was more variable than female size in only 55 of 98 species, suggesting that intraspecific variation in sexual size dimorphism does not generally conform to Rensch's rule. In contrast, in a significant majority of species (66 of 98) male latitudinal body size clines were steeper than those of females. This pattern is consistent with a latitudinal version of Rensch's rule, and suggests that some factor that varies systematically with latitude is responsible for producing Rensch's rule among populations within species. Identifying the underlying mechanisms will require studies quantifying latitudinal variation in sexspecific natural and sexual selection on body size.

Large, uncoated copper and zinc roofs cause environmental problems if their runoff is infiltrated into the underground or discharged into receiving waters. Since source control is not always feasible, barrier systems for efficient copper and zinc removal are recommended in Switzerland. During the last few years, research carried out in order to test the performance of GIH-calcite adsorber filters as a barrier system. Adsorption and mass transport processes were assessed and described in a mathematical model. However, this model is not suitable for practical design, because it does not give explicit access to design parameters such as adsorber diameter and adsorber bed depth. Therefore, for e.g. engineers, an easy to use design guideline for GIH-calcite adsorber systems was developed, mainly based on the mathematical model. The core of this guideline is the design of the depth of the GIH-calcite adsorber layer. The depth is calculated by adding up the GIH depth for sorption equilibrium and the depth for the mass transfer zone (MTZ). Additionally, the arrangement of other adsorber system components such as particle separation and retention volume was considered in the guideline. Investigations of a full-scale adsorber confirm the successful application of this newly developed design guideline for the application of GIH-calcite adsorber systems in practice.

Sulfonamides (SA), ionizable, polar antimicrobial compounds, may reach the environment in substantial amounts by the spreading of manure. The environmental behavior of SA is still difficult to predict. We investigated the influence of the main factors supposed to control SA sorption to organic materials: composition of sorbent, solute chemistry, and contact time. For that purpose, sulfathiazole (STA) sorption to compost, manure, and humic acid after 1 and 14 d was studied under sterile conditions. The experiments demonstrated that sorption was most strongly affected by contact time and pH. Irrespective of sorbent and pH, sorption continued substantially after the fast initial sorption within 1 d. For all sorbents and both contact times, STA sorption exhibited a pronounced pH dependence. Species-specific <I>K</I><SUB>oc</SUB> values decreased in the order <I>K</I><SUB>oc</SUB><SUP>cation</SUP> > <i<K</I><SUB>oc</SUB><SUP>neutral</SUP> > <I>K</I><SUB>oc</SUB><SUP>anion</SUP>. Differences in sorbent composition influenced STA sorption weaker. For the neutral STA species, NMR chemical shift regions assignable to ketonic, carboxylic, and phenolic C as well as aromatic C-H and methoxyl/N-alkyl C seemed to control sorption. For the cations, sorption followed the cation exchange capacities of the sorbents. STA sorption to manure and humic acid increased with higher ionic strength (0.31 M compared to 0.06 M) at pH 7.5.

Struvite (MgNH<SUB>4</SUB>PO<SUB>4</SUB>·6H<SUB>2</SUB>O) precipitation eliminates phosphate efficiently from urine, a small but highly concentrated stream in the total flux of domestic wastewater. Precipitation experiments with hydrolysed urine evaluated the solubility product of struvite. The stored and fully hydrolysed urine had an ionic strength of between 0.33 and 0.56 M and required the estimation of activity coefficients. From our data, we identified the Davies approximation with the two constants <I>A</I>=0.509 and <I>B</I>=0.3 as agreeing best with our laboratory results. The standard solubility product <I>K</I><SUB>s</SUB><SUP>0</SUP>=<I>f</I><SUB>1</SUB>[NH<SUB>4</SUB><SUP>+</SUP>]<I>f</I><SUB>2</SUB>[Mg<SUP>2+</SUP>]<I>f</I><SUB>3</SUB>[PO<SUB>4</SUB><SUP>3−</SUP>] ([ ]=concentration of the species; <I>f</I><I><SUB>x</SUB></I>=corresponding activity coefficient) of struvite in urine was found to be 10<SUP>−13.26±0.057</SUP> at 25 °C and the enthalpy of struvite formation Δ<I>H</I> was 22.6(±1.1) kJ mol<SUP>−1</SUP>. The equilibrium calculations required the following dissolved complexes: [MgCO<SUB>3</SUB>]<SUB>aq</SUB>, [MgHCO<SUB>3</SUB>]<SUP>+</SUP>, [MgPO<SUB>4</SUB>]<SUP>−</SUP>, [NH<SUB>4</SUB>HPO<SUB>4</SUB>]<SUP>−</SUP>, and [NaHPO<SUB>4</SUB>]<SUP>−</SUP> and to a lesser extent [MgSO<SUB>4</SUB>]<SUB>aq</SUB> and [NH<SUB>4</SUB>SO<SUB>4</SUB>]<SUP>−</SUP>. Organic complexes do not seem to influence the solubility product substantially.<br/>For practical purposes, a conditional solubility product <I>K</I><SUB>s</SUB><SUP>cond</SUP>=[Mg<SUB>aq</SUB>]·[NH<SUB>4</SUB><SUP>+</SUP>+NH<SUB>3</SUB>]·[P<SUB>ortho</SUB>]=10<SUP>−7.57</SUP> M<SUP>3</SUP> was derived to calculate struvite solubility in urine at 25 °C, pH=9.0 and ionic strength <I>I</I>=0.4 M directly from measured concentrations.

Distributed hydrological models like SWAT (Soil and Water Assessment Tool) are often highly over-parameterized, making parameter specification and parameter estimation inevitable steps in model calibration. Manual calibration is almost infeasible due to the complexity of large-scale models with many objectives. Therefore we used a multi-site semi-automated inverse modelling routine (SUFI-2) for calibration and uncertainty analysis. Nevertheless, the question of when a model is sufficiently calibrated remains open, and requires a project dependent definition. Due to the non-uniqueness of effective parameter sets, parameter calibration and prediction uncertainty of a model are intimately related.<BR/>We address some calibration and uncertainty issues using SWAT to model a four million km<SUP>2</SUP> area in West Africa, including mainly the basins of the river Niger, Volta and Senegal. This model is a case study in a larger project with the goal of quantifying the amount of global country-based available freshwater. Annual and monthly simulations with the "calibrated" model for West Africa show promising results in respect of the freshwater quantification but also point out the importance of evaluating the conceptual model uncertainty as well as the parameter uncertainty.

Particle fluxes were measured from 2000 to 2001 with 3 integrating open traps (O-traps) and a sequencing trap (S-trap) in the 73-m deep, oligotrophic, high-mountain Estany (Lake) Redó (2240 m a.s.l.) over a period of 558 days. O-traps were deployed at 26, 46, and 66 m water depth to measure overall sedimentation rates, while the S-trap was deployed at 66 m water depth to detect dynamics of seasonal particle fluxes with a resolution of 4 days (during ice break-up, summer, ice formation) to 21 days (during ice cover). Our results show a high degree of seasonal variability in particle dynamics. Total particle fluxes vary from almost zero to more than 600 mg m<SUP>-2</SUP> d<SUP>-1</SUP>. The highest fluxes occur during short time windows after ice-break-up (minerogenic particles), during spring (planktonic biomass), and during fall overturn (chrysophycean cysts). Particle fluxes also differed markedly from year to year in absolute values (2000: 644 mg m<SUP>-2</SUP> d<SUP>-1</SUP>, 2001: 370 mg m<SUP>-2</SUP> d<SUP>-1</SUP>) as well as in average values (2000: 76 mg m<SUP>-2</SUP> d<SUP>-1</SUP>, 2001: 44 mg m<SUP>-2</SUP> d<SUP>-1</SUP>). Annual and seasonal meteorological changes and events have a clear influence on the lake system and on the amount and composition of particles. C/N ratios during April and May increased significantly from 2000 (6-14) to 2001 (>28), reflecting the more intense soil erosion and transport of terrestrial plant remains into the lake caused by heavy precipitation in 2001. Air temperature strongly influences the timing of the occurrence of the main bio-productivity peak. Strong wind events shorten the period of ice cover. Our investigation shows that sediment trap studies lasting more than one limnological cycle are useful in studying the effects of short-term meteorological changes and weather events on high mountain lakes. However, long-term particle flux measurements would be necessary to determine amplitudes of natural seasonal cycles and for the interpretation of the decadal-scale environmental changes occurring in such lakes.

Spatial variations in nekton use are often attributed to differences in the configuration and composition of habitat. We predicted that differences in nekton use among intertidal creeks were related to certain geomorphological characteristics. We measured or derived 28 features at 8 intertidal creeks in the high salinity North Inlet Estuary, South Carolina, USA. Nekton were collected simultaneously from all creeks once each season for 2 yr. Spatial variations in total abundance and biomass were greater than seasonal variations. Differences of 3- to 30-fold in resident and transient taxa densities occurred among creeks on the same date. Relative use (ranks) was similar among seasons and years. In canonical correlation analyses, depth, steepness, flow, and location were primary factors for total nekton and many taxa. Creeks that were shallow, broad, and filled and emptied slowly supported the greatest use. Total nekton use was not related to creek size, amount of edge, or oyster bottom. Grass shrimp <I>Palaemonetes</I> spp., numerically dominant in 83% of the collections, responded most to creek shape. Mummichog <I>Fundulus heteroclitus</I> favored shallow creeks with low flow and low proportions of submerged bottom at low tide. Juvenile spot <I>Leiostomus xanthurus</I> and pinfish <I>Lagodon rhomboides</I> were associated with the same features throughout their seasonal periods of occurrence. Persistent differences in nekton use of adjacent intertidal creeks might be explained by behavioral selection for preferred conditions and reoccupation of selected creeks. Geomorphological variations are significant among sites and must be considered when assessing factors affecting nekton use along salinity and other environmental gradients.

β-Blockers are used to treat high blood pressure as well as patients recovering from heart attacks. In several studies, they were detected in surface water, thus indicating incomplete degradability of these substances in sewage treatment plants (STPs). In this study, we determined the sorption coefficients (K<SUB>D</SUB>) and degradation rates of the four β-blockers sotalol, atenolol, metoprolol and propranolol in sludge from an STP operating with municipal wastewater.<BR/>The sorption coefficients (K<SUB>D</SUB>, standard deviations in brackets) were determined as 0.04(+/-0.035), 0.04(+/-0.033), 0.00(+/-0.023) and 0.32(+/-0.058) L g<SUP>-1</SUP><SUB>COD</SUB>, and the pseudo-first-order degradation rate constants were estimated to be 0.29(+/-0.02), 0.69(+/-0.05), 0.58(+/-0.05) and 0.39(+/-0.07) L d<SUP>-1</SUP> g<SUP>-1</SUP><SUB>COD</SUB> for sotalol, atenolol, metoprolol and propranolol, respectively.<BR/>These values translate into a typical elimination in STPs (sludge concentrations of 4 g<SUB>COD</SUB> L<SUP>-1</SUP> and a hydraulic retention time of 6 h) of 25%, 37%, 44% and 50% for sotalol, propranolol, metoprolol and atenolol, respectively. These results are also confirmed by measurements in two municipal STPs for atenolol, sotalol and propranolol. The estimated eliminations are slightly too high for metoprolol.

We investigated calcium interactions with the surface of individual living cells of the freshwater cyanobacterium <I>Synechococcus leopoliensis</I> PCC 7942 under illumination and calcite supersaturation, with respect to calcium carbonate nucleation on the cell surface. Immobilized living cells were scanned by Atomic Force Microscopy (AFM) with conventional and chemically modified tips which were coated with carboxylic groups, so-called Chemical Force Microscopy (CFM). Calcium adsorption was heterogeneous and altered the surface charge of the cells. This was confirmed by bulk measurements of the zeta-potential at different Ca<SUP>2+</SUP> concentrations and compared to measurements made with other bivalent cations (Mg<SUP>2+</SUP>, Sr<SUP>2+</SUP>, Ba<SUP>2+</SUP>). Zeta-potential increased rapidly (< 2 min) from - 46.9 mV in calcium-free solution to + 0.8 mV in 22 mmol L<SUP>-1</SUP> CaCl<SUB>2</SUB> solution, using a 1.5 mmol L<SUP>-1</SUP> NaHCO<SUB>3</SUB> solution as background electrolyte in both cases. This was followed by the slow ( several hours) formation of nonmineralized protuberances at the cell surface. These changes in the microtopography did not show obvious spatial relationship to surface charge or Ca<SUP>2+</SUP> adsorption. The formation of the protuberances was reversible when Ca<SUP>2+</SUP> was removed from the circumfluent solution. Ca2+ adsorption to the cell surface was faster than calcium-induced changes in the surface microtopography and much faster than calcite nucleation on the cell surface which was observed on a fraction of the cells in previous bulk experiments under similar supersaturation.

In the present study, Zn and Mn competition with Cd uptake was investigated in the freshwater alga <I>Scenedesmus vacuolatus</I>. <I>Scenedesmus vactiolatus</I> was exposed to experimental media with Cd and either Zn or Mn in short-term experiments; long-term experiments were undertaken to investigate the effect of growth on Cd accumulation. Cadmium accumulation in <I>S. vacuolatus</I> could be detected at very low exposure concentrations (free Cd<SUP>2+</SUP> 2 x 10<SUP>-14</SUP> to 1 x 10<SUP>-11</SUP> M), and uptake was proportional to the free-Cd<SUP>2+</SUP> concentration. Zinc was an effective competitive inhibitor of Cd uptake when the Zn<SUP>2</SUP>+ to Cd<SUP>2+</SUP> ratio was greater than 14 in the exposure medium, whereas Mn competed with Cd for uptake above a Mn<SUP>2+</SUP> to Cd<SUP>2+</SUP> ratio of greater than 10,000. Binding constants for Cd and Zn affinity to the transport sites were determined (<I>K</I><SUB>Zn</SUB> and <I>K</I><SUB>Cd</SUB>). Values for <I>K</I><SUB>Zn</SUB> were slightly higher (log <I>K</I> = 9.4-9.8) than values for <I>K</I><SUB>Cd</SUB> (log <I>K</I> = 8.9-9.8). In contrast, Cd seemed not to compete with the Mn-binding sites for uptake over the Mn concentration range from 1 x 10<SUP>-10</SUP> to 1 x 10<SUP>-8</SUP> M. Determined values for the binding constants of Zn and Cd show that a simple model can be applied to predict Cd uptake at known Zn and Cd concentrations. The environmental implications of these results are discussed with respect to potential Cd toxicity for aquatic organisms.