City Of Zurich Research Articles

Spatial Distribution of Atmospheric PCBs in Zurich, Switzerland: Do Joint Sealants Still Matter?

Passive air samplers were deployed at 23 sites across the city of Zurich, Switzerland to investigate the spatial distribution of polychlorinated biphenyls (PCBs) in air. Concentrations of the six indicator PCBs (iPCBs) in air ranged from 54 to 3160 pg·m(-3) in the two sampling campaigns (spring 2011 and spring 2013). Measurements at two sampling sites were significantly higher than the median in both years, because of the proximity to primary PCB sources. Concentrations at most other stations were in a narrow range, suggesting that atmospheric PCB concentrations in Zurich are mainly caused by a high number of rather small sources. A correlation of iPCB concentrations in air with the number of buildings constructed between 1955 and 1975 in the surrounding areas of the sampling sites was observed. This demonstrates that PCB-containing building materials, such as joint sealants, influence PCB levels in urban air. Additionally, atmospheric iPCB concentrations were measured in the surrounding of a housing complex with PCB-contaminated joint sealants. Using a Gaussian diffusion model, annual iPCB emissions of 110-190 g were calculated for this housing complex. This appreciable amount released by a single building points out that more efforts are required to further eliminate remaining PCB stocks.

Statistical modelling of particle number concentration in Zurich at high spatio-temporal resolution utilizing data from a mobile sensor network

Abstract Highly resolved pollution maps are a valuable resource for many issues related to air quality including exposure modelling and urban planning. We present an approach for their generation based on data from a mobile sensor network and statistical modelling. An extensive record of particle number concentrations (PNCs) spanning more than 1.5 years was compiled by the tram-based OpenSense mobile sensor network in the City of Zurich. The sensor network consists of 10 sensor nodes installed on the roof of trams operating on different services according to their regular operation schedules. We developed a statistical modelling approach based on Generalized Additive models (GAMs) utilizing the PNC data obtained along the tram tracks as well as georeferenced information as predictor variables. Our approach includes a variable selection algorithm to ensure that individual models rely on the optimal set of predictor variables. Our models have high temporal and spatial resolutions of 30 min and 10 m by 10 m, respectively, and allow the spatial prediction of PNC in the municipal area of Zurich. We applied our approach to PNC data from two dedicated time periods: July–Sept. 2013 and Dec. 2013–Feb. 2014. The models strongly rely on traffic related predictor variables (vehicle counts) and, due to the hilly topography of Zurich, on elevation. We assessed the model performance by leave-one-out cross-validation and by comparing PNC predictions to measurements at fixed reference sites and to PNC measurements obtained by pedestrians. Model predictions reproduce well the main features of the PNC field in environment types similar to those passed by individual trams. Model performance is worse at elevated background locations probably due to the weak coverage of similar spots by the tram network. We end the paper by outlining a route finding algorithm which utilizes the highly resolved PNC maps providing the exposure minimal route for cyclists.

Acrylamide in a fried potato dish (rösti) from restaurants in Zurich, Switzerland

ABSTRACTRösti, a fried potato product, is a large contributor to acrylamide exposure locally in Switzerland. A survey of 55 dishes prepared by 51 restaurants in the city of Zurich showed that the average rösti contained 702 µg/kg acrylamide. By analysing the content of reducing sugars in the potatoes used for frying, it is shown that with simple measures, the exposure to acrylamide could easily be reduced by factor 2 or more, while even improving the culinary experience. Though rösti is a typical dish in the German-speaking areas in Switzerland, the result may be of general interest for fried potato products which are popular in large areas of Central Europe.

Communication About Micropollutants in Drinking Water: Effects of the Presentation and Psychological Processes.

This study investigates how people change their risk perception, trust, and behavior as a consequence of being informed about the occurrence of micropollutants in drinking water. Micropollutants are substances present in extremely low concentrations that might be dangerous in higher concentrations. Data were gathered in the city of Zurich, Switzerland in 2013 using a questionnaire in which the information on micropollutants was presented differently to 12 experimental groups. Data of the key constructs were gathered before and after this information, so that causal effects could be quantified by regression analyses. Affective reactions to the information turned out to be the critical mediator of changes in risk perception (operationalized as the perceived change of quality due to pollution), which is an important determinant of changes in behavior and trust. Also, direct effects of affective reactions on behavior and trust were observed. Trust before appraising risks reduces negative affective reactions; however, it also reduces perceived quality (i.e., increases risk perception) and trust after risks are appraised. The different forms of information mainly influenced the participants' affective reactions, but they also influenced perceived quality. The presentation with the least negative effects was a comparison of the intake of the substance by water with intake by food. The experimental design with repeated measurement that considers trust as a determinant and consequence of risk perception uncovered positive and negative effects of trust before appraising risks on changes of risk perception and trust due to appraising risks.

The effects of on‐street parking on the service rate of nearby intersections

SummaryAn on‐street parking maneuver can often start a temporary bottleneck, leading to additional delay endured by the following vehicles. If the maneuver occurs near a signalized intersection, the service rate of the intersection might be reduced. In this paper, a model is built to analyze the effects of parking maneuvers on the intersection service rate. Based on the hydrodynamic theory of traffic flow, the perturbation caused by the parking maneuver is analyzed. Using dimensional analysis, we illustrate the relation between the background conditions, the distance from the parking area to the intersection, and the intersection service rate. Based on this relation, one can compute the service rate reduction caused by existing on‐street parking areas. A minimum distance between the parking area and the intersection to avoid such reduction can be accordingly found. Numerical examples based on empirical data from the city of Zurich, Switzerland, are provided to illustrate the practical applications. Although the analysis is based on streets with a single lane per direction, the findings can provide some insights regarding different situations. We hope such findings can be used as a basis for developing on‐street parking design guidelines. Copyright © 2015 John Wiley & Sons, Ltd.

Short-Chain Chlorinated Paraffins in Zurich, Switzerland--Atmospheric Concentrations and Emissions.

Short-chain chlorinated paraffins (SCCPs) are of concern due to their potential for adverse health effects, bioaccumulation, persistence, and long-range transport. Data on concentrations of SCCPs in urban areas and underlying emissions are still scarce. In this study, we investigated the levels and spatial distribution of SCCPs in air, based on two separate, spatially resolved sampling campaigns in the city of Zurich, Switzerland. SCCP concentrations in air ranged from 1.8 to 17 ng·m(-3) (spring 2011) and 1.1 to 42 ng·m(-3) (spring 2013) with medians of 4.3 and 2.7 ng·m(-3), respectively. Both data sets show that atmospheric SCCP levels in Zurich can vary substantially and may be influenced by a number of localized sources within this urban area. Additionally, continuous measurements of atmospheric concentrations performed at one representative sampling site in the city center from 2011 to 2013 showed strong seasonal variations with high SCCP concentrations in summer and lower levels in winter. A long-term dynamic multimedia environmental fate model was parametrized to simulate the seasonal trends of SCCP concentrations in air and to back-calculate urban emissions. Resulting annual SCCP emissions in the city of Zurich accounted for 218-321 kg, which indicates that large SCCP stocks are present in urban areas of industrialized countries.

Cumulative energy demand in LCA: the energy harvested approach

Environmental life cycle assessment (LCA) is today an important methodology to quantify the life cycle based environmental impacts of products, services or organisations. Since the very first LCA studies, the cumulative energy demand CED (also called ‘primary energy consumption’) has been one of the key indicators being addressed. Despite its popularity, there is no harmonised approach yet and the standards and guidelines define the cumulative energy demand differently. In this paper, an overview of existing and applied life cycle based energy indicators and a unifying approach to establish characterisation factors for the cumulative energy demand indicator are provided. The CED approaches are illustrated in a building’s LCA case study. The five approaches are classified into two main concepts, namely the energy harvested and the energy harvestable concepts. The two concepts differ by the conversion efficiency of the energy collecting facility. A unifying ‘energy harvested’ approach is proposed based on four theses, which ensure consistent accounting among renewable and non renewable energy resources. The indicator proposed is compared to four other CED indicators, differing in the characterisation factors of fossil and biomass resources (upper or lower heating value), the characterisation factor of uranium and the characterisation factors of renewable energy resources (amount harvested or amount harvestable). The comparison of the five approaches is based on the cumulative energy demand of a newly constructed building of the city of Zurich covering the whole life cycle, including manufacturing and construction, replacement and use phase, and end of life. The cumulative energy demand of the life cycle of the building differs between 336 MJ oil-eq/m2a (‘CED uranium low’) and 836 MJ oil-eq/m2a (‘CED energy statistics’). The main differences occur in the use phase. The main reason for the large differences in the results are the different concepts to determine the characterisation factors for renewable and nuclear energy resources. The energy harvested approach ‘CED standard’ is a consistent approach, which quantifies the energy content of all different (renewable and non-renewable) energy resources. The ‘CED standard’ approach and the impact category indicator results computed with this approach reflect the safeguard subject ‘energy resources’ but not (no other) environmental impacts. The energy harvested approach proposed in this paper can readily be implemented in different contexts and applied to various data sets.

Marginal cost congestion pricing based on the network fundamental diagram

Congestion pricing schemes have been traditionally derived based on analytical representations of travel demand and traffic flows, such as in bottleneck models. A major limitation of these models, especially when applied to urban networks, is the inconsistency with traffic dynamics and related phenomena such as hysteresis and the capacity drop. In this study we propose a new method to derive time-varying tolling schemes using the concept of the Network Fundamental Diagram (NFD). The adopted method is based on marginal cost pricing, while it also enables to account realistically for the dynamics of large and heterogeneous traffic networks. We derive two alternative cordon tolls using network-aggregated traffic flow conditions: a step toll that neglects the spatial distribution of traffic by simply associating the marginal costs of any decrease in production within the NFD to the surplus of traffic; and a step toll that explicitly accounts for how network performance is also influenced by the spatial variance in a 3D-NFD. This pricing framework is implemented in the agent-based simulation model MATSim and applied to a case study of the city of Zurich. The tolling schemes are compared with a uniform toll, and they highlight how the inhomogeneous distribution of traffic may compromise the effectiveness of cordon tolls.

Intentional methomyl-poisoning of peregrine falcons (Falco peregrinus) in Switzerland

The present report describes two proven cases of illegal poisoning of peregrine falcons in the city of Zurich, Switzerland. Both animals died in their eyries after capturing and feeding on a methomyl-laced pigeon. Both eyries are surveillanced by cameras, and the death of one falcon was broadcasted live on the Internet. The city game warden had noticed the disappearance of a brooding female from an artificial eyrie in 2009 and had found five dead falcons at plucking posts or artificial eyries between 2009 and 2013. Owing to these reports in combination with reports on the disappearance of at least eight pairs of peregrine falcons from traditionally used nesting sites in north-western Switzerland since the 1980s, the authors presume that there may be a high number of unreported cases of illegal killing of peregrine falcons in Switzerland. They suggest an increased surveillance, and a coordinated collection of data on wildlife crime may aid the prosecution of perpetrators.

Evaluation of trade-offs between two data sources for the accurate estimation of origin–destination matrices

In this paper, we evaluate the trade-offs between loop detector data and floating car data (FCD) for the real-time estimation of origin–destination (OD) matrices in small networks. The proposed methodology is based on a bi-level optimisation using fuzzy logic theory. Here we demonstrate that it provides accurate results with low computational cost, while presenting several advantages over other existing algorithms (especially in terms of data requirements, computational complexity, and quality of adjustment). The methodology is illustrated with three examples covering two different locations in the city of Zurich, Switzerland. Results are used to evaluate the trade-offs between loop detector coverage and the penetration rate of FCD, and to determine minimum values for ensuring a given accuracy level on the estimated OD matrices. In general, the resulting error in OD estimation is affected by the data redundancy in the network.

Evaluating the influence of carsharing stations’ location on potential membership: a Swiss case study

Carsharing as a mode, in any of its different forms, has the peculiarity of being accessible only to members. The research presented in this paper focuses on round-trip-based carsharing, where vehicles are parked at fixed locations, called in this paper stations. Round-trip-based carsharing has been the first successful form of carsharing, and is still the most diffused one in many countries. Several studies looked at the potential of such a system in various countries but the link between spatial distribution of the stations and potential membership has not been done yet. This paper looks at this question while trying to address other limitations of the existing literature on carsharing potential. The research has two parts. In the first part, a binary logistic model of round-trip based carsharing membership in Switzerland is estimated. The model is based on a large RP dataset (the Swiss national travel diaries survey) where information on carsharing membership is collected. This provides a representative and non-biased sample. The model takes into account accessibility to carsharing at local level introducing a dependency between potential membership and actual availability of the service. The model is then run on a synthetic population representing the whole Swiss population—created based on full census data—and then validated against actual membership data of the Swiss carsharing operator Mobility. It is shown that the model estimated is able to reproduce fairly well the spatial distribution of carsharing members in Switzerland. The second part is aimed at showing that the location of stations actually impacts potential membership. To this purpose an approach to solve the problem of the optimal location of carsharing stations is proposed, where the model estimated in the first part is used as objective function of an optimization algorithm. The region surrounding the city of Zurich is taken as case study for this approach. The proposed technique is suitable to find new constellations of stations so that the number of carsharing members is incremented and can also be seen as an innovative instrument which can help in the planning of carsharing station networks.

Two-week NO2 maps for the City of Zurich, Switzerland, derived by statistical modelling utilizing data from a routine passive diffusion sampler network

We developed a method to generate two-week NO2 concentration maps with a high spatial resolution (10 m by 10 m) for the city of Zurich, Switzerland, based on statistical modelling. Our models utilize data from a dense passive diffusion sampler network consisting of 49 sites that measured 14-day mean NO2 concentrations in the year 2008. The regression analysis is based on Generalized Additive Models (GAMs) and a stepwise forward selection algorithm that leads to models relying on a small number of explanatory variables (2–3). The explanatory variables included in the regression analysis are spatially resolved information on traffic and heating systems related NOX and NO2 emissions, respectively, sky view factors, and topography (elevation). Deviance explained of the 26 models ranges from 0.66 to 0.79. 81% of the modelled and 77% of the predicted NO2 concentrations, respectively, deviate less than 25% from the observations.The modelling approach outlined in this paper augments the value of point measurements obtained from urban routine passive diffusion sampler networks by providing spatially resolved concentration fields. The derived maps allow a detailed assessment of NO2 levels in cities and can be used in applications such as public health protection.

Reformed Preaching in the Sixteenth Century: The Use of Lectionaries in Zurich

We know how important preaching was for the Reformers, who centred the service around the sermon. Although the content of sermons has been studied, their form has hardly ever been considered. There were three main models which existed for sixteenth-century preachers: starting from the first verse of the first chapter of a biblical book and commenting on it until its end in lectio continua, using commonplaces (loci communes), or using a lectionary as the Roman Catholic Church did during the Middle Ages. The article focuses on the practice of Zwingli’s successor as the Zurich antistes, Heinrich Bullinger, with an examination of his handwritten drafts. We thus discover that Bullinger preached not only according to the lectio continua, or favoring commonplaces when he wrote the Decades, but he still continued to preach according to the remains of a lectionary which was still current in Zurich, together with some yearly sermons, as well as in particular civil and political circumstances: the feast day of the City of Zurich, battle sermons, or sermons on marriage.

Sex and Secrecy: A Secular Prosecution of Abortion in Fourteenth-Century Zurich

Until now the earliest known evidence in the German-speaking lands of the prosecution of abortion according to Roman-canonical procedure has been dated to the fifteenth century. This article examines a case from 1392 investigated by the municipal council court of the Free Imperial City of Zurich apparently according to these procedural rules. The case focussed upon a single woman named Repplin accused of aborting or killing her child. The article looks closely at the fama reported by witnesses who knew her, a number of whom also claimed to be recent sexual partners of Repplin. Although the case indicates that some individuals might tolerate or overlook the actions of women who terminated pregnancies, the record also suggests how the web of associations in the Middle Ages between sex, secrecy, and the female body might come together with devastating effect for individual women in a judicial context, decreasing their ability to resist negative gossip and to defend themselves.

The sociodemographics of political public deliberation: Measuring deliberative quality in different user groups

AbstractGovernments and local administrations increasingly use the internet to improve citizens’ participation in deliberation processes. However, research studies have pointed out that deliberation outcomes vary due to the participants’ sociodemographic differences. In this paper, we address this debate by quantitatively measuring different sociodemographic participant groups’ deliberation quality. By building an index of the quality of understanding (IQU), we analyze the quality of 1,991 postings on local political issues that participants contributed during the 2011 Zurich City debate. We defined five indicators for deliberation quality: statement of reasons, proposals for solutions, respect, doubts, and reciprocity. The analysis confirms that the sociodemographic composition of the participants is of great importance for self-selected participation and deliberation quantity, but not for the deliberation quality.

Flirting in the field: shifting positionalities and power relations in innocuous sexualisations of research encounters

In the last few decades, an engaged and sophisticated discussion about the production of data and power relations has developed within feminist methodology. Positionality, i.e. the set of relations constituting informants' and researchers' subject positions, has been widely used as an analytical tool to account for the complicated ways in which data are co-constructed in fieldwork. Based on our own experience of fieldwork conducted in the city of Zurich, however, we argue that sexuality is underrepresented in this debate. First, reflexive writing on fieldwork has been reluctant to consider sexuality as a category in the same way, for instance, as gender or race. Second, even apparently innocuous sexualisations have a considerable effect on the constitution of data and are therefore worth including in the analysis. In this article, we examine how flirtation as a part of the participant–researcher relation has re-shaped the research encounters in our respective research projects. We discuss the complex navigations between conflicting rationales that it entailed for us as researchers, depict the minor and major shifts in positionalities that emerge from the flirtation and examine the reasons why we sometimes embraced flirtation and sometimes rejected it. The objective of the article is to further enrich feminist methodological writing, and to suggest to the reader the potential for including various shades of sexual performances, such as apparently harmless flirtation, into our reflections on data collection.

Deriving high-resolution urban air pollution maps using mobile sensor nodes

Up-to-date information on urban air pollution is of great importance for environmental protection agencies to assess air quality and provide advice to the general public in a timely manner. In particular, ultrafine particles (UFPs) are widely spread in urban environments and may have a severe impact on human health. However, the lack of knowledge about the spatio-temporal distribution of UFPs hampers profound evaluation of these effects. In this paper, we analyze one of the largest spatially resolved UFP data set publicly available today containing over 50 million measurements. We collected the measurements throughout more than two years using mobile sensor nodes installed on top of public transport vehicles in the city of Zurich, Switzerland. Based on these data, we develop land-use regression models to create pollution maps with a high spatial resolution of 100 m × 100 m. We compare the accuracy of the derived models across various time scales and observe a rapid drop in accuracy for maps with sub-weekly temporal resolution. To address this problem, we propose a novel modeling approach that incorporates past measurements annotated with metadata into the modeling process. In this way, we achieve a 26% reduction in the root-mean-square error–a standard metric to evaluate the accuracy of air quality models–of pollution maps with semi-daily temporal resolution. We believe that our findings can help epidemiologists to better understand the adverse health effects related to UFPs and serve as a stepping stone towards detailed real-time pollution assessment.

Bibliography and Library

Bibliographies and Libraries have always been bound by a link that makes them complementary: the first one is about the reporting and recording of the books, while the second one is devoted to the collection, organization and storage of the books. The origin of this link traces back to the second half of the sixteenth century, in the city of Zurich. Conrad Gesner, Josias Simler, Conrad Lycosthenes and Johann Jacob Frisius, inspired by their master Huldrych Zwingli, realized some bibliographies - such as the Bibliotheca Universalis , Pandectae and subsequent summaries - that showed a clear awareness of the relationship between libraries and bibliographies. This consciousness is well represented by praefationes of these repertoires.

Assessing habitat connectivity for ground-dwelling animals in an urban environment.

To ensure viable species populations in fragmented landscapes, individuals must be able to move between suitable habitat patches. Despite the increased interest in biodiversity assessment in urban environments, the ecological relevance of habitat connectivity in highly fragmented landscapes remains largely unknown. The first step to understanding the role of habitat connectivity in urban ecology is the challenging task of assessing connectivity in the complex patchwork of contrasting habitats that is found in cities. We developed a data-based framework, minimizing the use of subjective assumptions, to assess habitat connectivity that consists of the following sequential steps: (1) identification of habitat preference based on empirical habitat-use data; (2) derivation of habitat resistance surfaces evaluating various transformation functions; (3) modeling of different connectivity maps with electrical circuit theory (Circuitscape), a method considering all possible pathways across the landscape simultaneously; and (4) identification of the best connectivity map with information-theoretic model selection. We applied this analytical framework to assess habitat connectivity for the European hedgehog Erinaceus europaeus, a model species for ground-dwelling animals, in the city of Zurich, Switzerland, using GPS track points from 40 individuals. The best model revealed spatially explicit connectivity “pinch points,” as well as multiple habitat connections. Cross-validation indicated the general validity of the selected connectivity model. The results show that both habitat connectivity and habitat quality affect the movement of urban hedgehogs (relative importance of the two variables was 19.2% and 80.8%, respectively), and are thus both relevant for predicting urban animal movements. Our study demonstrates that even in the complex habitat patchwork of cities, habitat connectivity plays a major role for ground-dwelling animal movement. Data-based habitat connectivity maps can thus serve as an important tool for city planners to identify habitat corridors and plan appropriate management and conservation measures for urban animals. The analytical framework we describe to model such connectivity maps is generally applicable to different types of habitat-use data and can be adapted to the movement scale of the focal species. It also allows evaluation of the impact of future landscape changes or management scenarios on habitat connectivity in urban landscapes.

A supervised method for object-based 3D building change detection on aerial stereo images

Abstract. There is a great demand for studying the changes of buildings over time. The current trend for building change detection combines the orthophoto and DSM (Digital Surface Models). The pixel-based change detection methods are very sensitive to the quality of the images and DSMs, while the object-based methods are more robust towards these problems. In this paper, we propose a supervised method for building change detection. After a segment-based SVM (Support Vector Machine) classification with features extracted from the orthophoto and DSM, we focus on the detection of the building changes of different periods by measuring their height and texture differences, as well as their shapes. A decision tree analysis is used to assess the probability of change for each building segment and the traffic lighting system is used to indicate the status "change", "non-change" and "uncertain change" for building segments. The proposed method is applied to scanned aerial photos of the city of Zurich in 2002 and 2007, and the results have demonstrated that our method is able to achieve high detection accuracy.