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Introduction: Inland navigation has seen explosive growth over the past few decades, leading to increasing concerns about its environmental and health impacts. Coastal waters are usually monitored for wastewater contamination by maritime traffic, but little is known about faecal pollution caused by the inland waterways transport in large rivers. The Danube River in Europe is a very popular destination for cruise ship trips. The extent to which the faecal pollution in the Danube is caused by shipping traffic in general and the growing number of cruise ships specifically is still largely unknown. The Danube River Information Service (DoRIS) has been established to track ship traffic and provide data for monitoring in Austria. This database allows the estimation of the faecal pollution potential of ships with a high level of spatial and temporal resolution for the first time.Methodology: An approach was developed to investigate the potential contribution of various ship categories to faecal pollution in the Danube River (Lower Austria) by combining water quality monitoring data with ship traffic data. The ship traffic data was extracted from DoRIS using a Python-based programming language code and sorted into three categories (cruise, passenger, and freight ships). Water quality monitoring was conducted at 11 transects along a 223-kilometre Danube River reach in Lower Austria. In collaboration with local authorities, each river transect was sampled at 5 points across the profile for one year at monthly intervals. The faecal indicator bacterium E. coli along with physio-chemical water quality parameters was analyzed for all samples. Theoretical faecal impact scenarios were developed using data on average daily ship traffic and factors such as ship type, onboard wastewater treatment facilities, onboard passenger capacity, and seasonal fluctuations of cruise tourism. To evaluate the influence of local and regional shipping traffic on the faecal pollution dynamics, a statistical correlation analysis was performed using data from the entire river reach and ship berthing stations.Results: The faecal impact scenario analysis, revealed that the shipping industry had the same degree of maximum pollution potential as treated municipal wastewater. In case of improper onboard wastewater treatment, faecal pollution can be substantial. According to water quality monitoring, 94% of the samples had low to moderate faecal pollution, while none were classified as high. As a result, no significant increase in E. coli concentrations was detected throughout the 223 km long river stretch. However, at one of the 11 river transects, significant variations in the E. coli concentration were detected. After conducting a correlation analysis using statistical parameters for the whole river reach, we found no significant correlation between E. coli concentrations and any of the investigated ship counting metrics or ship types. Nonetheless, E. coli concentration was found to be significantly higher at one of the cruise ship berthing stations.Acknowledgement: The research was funded by Amt der Niederösterreichischen Landesregierung, Abteilung Wasserwirtschaft (WA2) and the GFF Niederösterreich mbH (LS19-016 Future Danube). We would like to thank collaboration partners from the government of Lower Austria and the Austrian shipping inspectorate.

Per- and Polyfluoroalkyl Substances (PFAS) are chemicals used for many domestic and industrial purposes related to their physicochemical properties. However, those same properties make them mobile and persistent in the environment, and on top of that, they are toxic and can affect human health in the short and long term, as they are bio-accumulative. Many processes govern the transport of PFAS in the surface waters and groundwater, e.g., sorption, biodegradation, co-transport, and transformation. Monitoring PFAS at different locations can help understand these processes and provide datasets to calibrate and validate reactive transport models simulating PFAS fate and transport. This study compares PFAS presence and distribution in river water and groundwater at two Danube river sites. One site is characterized by a steady water level in the river and natural flow from the river to the groundwater, with a clogging layer at the aquifer-river interface. In contrast, the other site has a more dynamic water level in the river, several pumping wells affecting water infiltration rates, and lacks a clogging layer.Samples were collected monthly for 12 months at the static study site and 8 months at the dynamic study site. Targeted analysis for 32 PFAS compounds has been carried out using liquid chromatography mass spectrometry (LCMS). The concentrations of the compounds were generally less than 20 ng/l, and most of the compounds were lower than the limit of quantification/detection. The results show that 3H-perfluoro-3-[(3-methoxypropoxy) propanic acid] (ADONA) had the highest concentration at the two sites, both in the river and groundwater. The longer chain PFAS exhibited a slight reduction in concentration from the river towards groundwater due to, most likely, sorption, while the shorter chain did not. The 6:2 FTS precursor was detected in the river but not in the groundwater. For some substances, the concentrations were higher in the groundwater compared to the river, indicating either background water influence, a transformation of PFAS, different transport routes (e.g., accumulation over time), or longer flow paths. Longer chain lengths, greater than 9 carbon atoms, were never detected above the limit of quantification in the river and groundwater. More PFAS compounds were detected at the dynamic study site than at the static one, even though, it is located further downstream, indicating nearby PFAS sources or/and influents along the river course. It is worth mentioning that large wastewater treatment plants are discharging their effluent downstream of the static site, in addition to sewer overflows from large cities in between. The PFAS concentrations in the river and groundwater during one high-flow event showed little difference compared to the ones during basic monthly monitoring at both study sites, however, another high flow event is needed to confirm this observation.

Streams can carry and spread numerous pathogen species, either free floating or attached to the surface of fine particles. These pathogens can pose serious threats to human health in places where untreated water is directly consumed or by contact with the water when using for recreation, washing or irrigation purposes. The most important sources of pathogens to streams in urbanized catchments are wastewater treatment plants that continuously release wastewater effluent, which is still infectious. Moreover, untreated wastewater is also discharged to streams through combined sewer overflows during heavy rain events, resulting in the release of high loads of pathogens. Once pathogens are introduced to a stream from these sources, their fate is controlled not only by transport in surface water but also by exchange with streambed sediments. Within streambeds, pathogens are subject to a complex array of processes that include seepage transport, sorption to sediment surface, and decay, with some pathogens being eventually released back to surface water. Recently, a model for stream transport of pathogens has been developed that is based on the Continuous Time Random Walk (CTRW) framework. This model describes the stream corridor as the interaction of a mobile and immobile zones, and a few applications to pathogen transport have been discussed in the literature. This contribution will present an application of this model approach to predict the fate of pathogens in an urban stream in Vienna. The model application will be tailored to work with the uncertainty that typically affects the information that is available in these situations. Thus, stochastic boundary conditions will be applied to consider the variability of pathogen loads to the stream, and model parameters will be calibrated on available concentrations of C. perfringens spores (used as conservative microbial tracer for municipal sewage) and the human genetic fecal marker HF183/BacR287, and eventually validated based on concentrations of the reference pathogens Cryptosporidium and Giardia, observed at the catchment outlet.

Riverbank filtration systems are important drinking water resources. Aquifers of riverbank filtration systems are subjected to considerable dynamics concerning the quantity and quality of the infiltrating water. The microbiological quality is mainly jeopardized by faecal contamination of the main river. Besides, water quality can be impacted by growth of natural water-borne bacteria due to the input of nutrients resulting in the proliferation of opportunistic pathogens, impairment of odour and taste or bio-corrosion. The occurrence of such phenomena indicates a biological instability. For highly dynamic riverbank filtration systems, it is thus of high relevance to assess the biological stability of the groundwater resource.In the present study, we applied a holistic, two-tiered concept of in situ and predictive methods to assess the biostability of the aquifer in a bank filtration system of the Danube River. We applied traditional cultivation-based and selected cultivation-independent methods—including cultivation on yeast extract and R2A agar, determination of total cell counts via fluorescence microscopy and flow cytometry, leucine incorporation and 16S rRNA gene amplicon sequencing—at critical control points along the infiltration path from the river to the abstraction well.The concentration of organic nutrients and the hydrological variability were the main controlling factors driving the biological stability of the groundwater body. Wells situated at greater distance displayed significantly lower dissolved organic carbon concentrations and a dampened hydrological influence in comparison to the well situated next to the river. Apparent discrepancies between the methods used indicated a different indicator function of the cultivation-based and cultivation-independent approaches. For complex systems, we thus recommend this new holistic concept for assessing biostability by combining in situ as well as predictive parameters and using cultivation-based and cultivation-independent methods.

Groundwater contamination and transport of viruses and bacteria in aquifers are a major concern worldwide. To ascertain the ability of these aquifers to remove pathogens, tracer tests with microbial surrogates are carried out. These tests are laborious and may require special permits, and therefore, column tests are often done instead. Unfortunately, results from column tests tend to grossly overestimate removal rates when compared to the field scale, which can lead to an underestimation of groundwater contamination risks. Scale is an important consideration when examining pathogen transport through porous media, as pathogen removal is rarely a linear process. In this study, field tests were carried out with endospores of Bacillus subtilis and coliphage phiX174 over a distance of 25 m in an alluvial gravel aquifer near Vienna, Austria. The sandy gravel material from the field site was also used in column tests with the same tracers. Both attachment-detachment and colloid filtration theory were used to model these tests, as well as log-removal rates per meter. The results show that the spatial removal rate (log/m) is approximately 2 orders of magnitude higher on the column scale, when compared to the field. A comparison with the literature showed a correlation between the heterogeneity of the porous media and the difference in removal rates between the column and field scale.

In a biomimetic approach the feasibility of liquid flow actuation by vibrating protruding structures excited via guided acoustic waves is investigated. Inspired by periodically beating cilia the loop part of a punched metallic hook-and-loop tape with tilted protruding loops was used as a waveguide for plate waves in water. Such waves were excited in the frequency range of 110 Hz to 220 Hz by directly coupling the tape to a loudspeaker membrane. A flow generated in the tilt direction of the loops with velocities up to 60 mm·s−1 was visualized by ink droplets deposited on the tape. The phenomenon persisted, when the protruding length of the loops was reduced by decreasing the protrusion angle. However, after closing the punch holes near the loops with sticking tape streaming could not be observed any longer. The same happened with open punch holes when the ink was replaced by glycerol. Low-frequency acoustic streaming around vibrating sharp edges is proposed as an explanation for the observed phenomena. Applications are expected with respect to the modification of flow profiles and the enhancement of transport processes along and across liquid-solid boundaries.

The climate-induced increase in precipitation extremes leads to more frequent combined sewer overflows (CSOs) from wastewater treatment plants into urban rivers, which are often used for recreation. This study simultaneously investigates the changes in precipitation extremes, CSO frequency and volume, the resulting fecal microbial loads to streams, and the human infection risks during recreational use.Our model approach consists of four steps. First, a disaggregation model is used to increase the temporal resolution of the 22 climate scenarios used to cope with the dynamics of urban hydrological processes. Then, continuous simulations are performed using an urban hydrological model (SWMM) for the C20 period (1971-2000), the near-term future (2021-2050), and the long-term future (2071-2100). We simulated the microbial load of the combined sewer discharge with the fecal indicators E. coli, C. perfringens, a human-associated genetic fecal marker HF183/BacR287, and the pathogens Giardia and Cryptosporidium spp. To determine the dilution in the stream, rainfall-runoff modeling is performed using a conceptual semi-distributed hydrological model in the third step for the urban catchment towards the point of CSO discharge. In the final step, a quantitative microbial risk assessment (QMRA) is performed to quantify the potential human infection risks during recreational use.A hypothetical urban drainage system serves as the study area, which was adapted to the local conditions of a subarea of the city of Vienna including a receiving river. For the precipitation extremes, average increases in precipitation of 13 % for the near future and 19 % for the long-term future are determined over the 22 climate scenarios and 5 rainfall stations considered (extreme event durations 5 min to 24 h, recurrence intervals 0.33 yrs to 10 yrs).The increase in precipitation extremes results in a higher number of CSOs for both the near- and long-term future. The simulated discharge of the receiving river is often still unaffected by the rainfall event at the time of discharge due to the concentration-time of the catchment, resulting in no direct relationship between discharge and CSO. A realistic estimate of the microbial load discharges during extreme rainfall events is possible for the first time based on the simultaneous continuous hydrological and urban hydrological models in this study.The resulting concentrations of E. coli, C. perfringens, HF183/BacR287, Giardia, and Cryptosporidium spp. in the receiving water as well as the potential infection risks are analyzed separately on a seasonal and annual basis. For both pathogens, infection risks in the distant future are found to increase in all seasons, with lower increases in the winter months (December-February) than in the rest of the year. The highest risk of infection is found in autumn (September-November).

To minimize the risk of waterborne disease outbreaks, drinking water wells should have a sufficiently large setback distance from potential sources of contamination, e.g. a nearby river. The aim of this study was to provide insight in regards to microbial contamination of groundwater under different hydraulic gradients, which can vary over time due to changes in river stage, season or pumping rate. The effects of these changes, and how they affect removal parameters, are not completely understood. In this study, field tracer tests were carried out in Vienna, Austria to evaluate the ability of subsurface media to attenuate Bacillus subtilis spores, used as a surrogate for Cryptosporidium and Campylobacter. The hydraulic gradient between injection and extraction was controlled by changing the pumping rate (1, 5 or 10 l/s) of a pumping well at the test site. Attachment and detachment rates were determined using a HYDRUS-3D model and setback distances were calculated based on the 60-day travel time, as well as a quantitative microbial risk assessment (QMRA) approach. It was shown that scale must be taken into consideration when determining removal rate (λ), which is crucial for the calculation of setback distances, and that the effect of flow rate becomes more important at lower removal rates.

We developed an innovative approach to estimate the extent of fecal pollution sources for urban river catchments. The methodology consists of 1) catchment surveys complemented by literature data where needed for probabilistic estimates of daily produced fecal indicator (FIBs, E. coli, enterococci) and zoonotic reference pathogen numbers (Campylobacter, Cryptosporidium and Giardia) excreted by human and animal sources in a river catchment, 2) generating a hypothesis about the dominant sources of fecal pollution and selecting a source targeted monitoring design, and 3) verifying the results by comparing measured concentrations of chemical tracers, C. perfringens, and host-associated genetic microbial source tracking (MST) markers in the river, and by multi-parametric correlation analysis. We tested the approach at a study area in Vienna, Austria. The daily produced microbial particle numbers according to the probabilistic estimates indicated that, for the dry weather scenario, the discharge of treated wastewater (WWTP) was the primary contributor to fecal pollution. For the wet weather scenario, 80-99 % of the daily produced FIBs and pathogens resulted from combined sewer overflows (CSOs) according to the probabilistic estimates. When testing our hypothesis in the river, the measured concentrations of the human genetic fecal marker were log10 4 higher than for selected animal genetic fecal markers. Our analyses showed for the first-time statistical relationships between C. perfringens and a human genetic fecal marker (i.e. HF183/BacR287) with the reference pathogen Giardia in river water (Spearman rank correlation: 0.78-0.83, p

Groundwater contamination and transport of viruses and bacteria in aquifers are a major concern worldwide. To ascertain the ability of these aquifers to remove pathogens, tracer tests with microbial surrogates are carried out. These tests are laborious and may require special permits, and therefore, column tests are often done instead. Unfortunately, results from column tests tend to grossly overestimate removal rates when compared to the field scale, which can lead to an underestimation of groundwater contamination risks. Scale is an important consideration when examining pathogen transport through porous media, as pathogen removal is rarely a linear process. In this study, field tests were carried out with endospores of Bacillus subtilis and coliphage phiX174 over a distance of 25 m in an alluvial gravel aquifer near Vienna, Austria. The sandy gravel material from the field site was also used in column tests with the same tracers. Both attachment-detachment and colloid filtration theory were used to model these tests, as well as log-removal rates per meter. The results show that the spatial removal rate (log/m) is approximately 2 orders of magnitude higher on the column scale, when compared to the field. A comparison with the literature showed a correlation between the heterogeneity of the porous media and the difference in removal rates between the column and field scale., Tracer tests at different scales showed that preferential flow is an important factor affecting upscaling of microbial transport.

Cryptosporidium and Giardia are waterborne protozoa that cause intestinal infections in a wide range of warm-blooded animals. Human infections vary from asymptomatic to life-threatening in immunocompromised people, and can cause growth retardation in children. The aim of our study was to assess the prevalence and diversity of Cryptosporidium and Giardia in urban surface water and in brown rats trapped in the center of Vienna, Austria, using molecular methods, and to subsequently identify their source and potential transmission pathways. Out of 15 water samples taken from a side arm of the River Danube, Cryptosporidium and Giardia (oo)cysts were detected in 60% and 73% of them, with concentrations ranging between 0.3–4 oocysts/L and 0.6–96 cysts/L, respectively. Cryptosporidium and Giardia were identified in 13 and 16 out of 50 rats, respectively. Eimeria, a parasite of high veterinary importance, was also identified in seven rats. Parasite co-ocurrence was detected in nine rats. Rat-associated genotypes did not match those found in water, but matched Giardia previously isolated from patients with diarrhea in Austria, bringing up a potential role of rats as sources or reservoirs of zoonotic pathogenic Giardia. Following a One Health approach, molecular typing across potential animal and environmental reservoirs and human cases gives an insight into environmental transmission pathways and therefore helps design efficient surveillance strategies and relevant outbreak responses.

Upscaling groundwater transport from the column scale to the field scale is relevant because field tests with various tracers are often too expensive or not permissible, due to public health or environmental concerns. Therefore, when testing chemical or pathogenic tracers, work is often done using small scale columns in the laboratory and results are extrapolated to the field. Several studies compare tracer transport in small-scale columns to tests in the field, but there is yet to be a study that compares groundwater transport using a meso-scale as well. Within a framework of upscaling, three scales are considered: small laboratory columns (0.1 m scale), a large intact core (1 m scale), and a real-world gravel aquifer (10 m scale). The small column is filled with gravel material taken from boreholes at the field site, which is close to Vienna, Austria. The meso-scale consists of an undisturbed gravel column, which was taken from a gravel pit near Neuhofen an der Ybbs, Austria. It was found that scale effects observed may be due to heterogeneity at the macropore scale versus preferential flowpaths at the meso-scale and field scale. Additionally, differences may be observed due to the small columns being repacked with aquifer material and the large column and field site being “undisturbed”. The meso-scale column allows us to gain insight into the upscaling processes by incorporating an in-between step when comparing groundwater transport at the column to the field scale.

Background: Rivers are important sources for drinking water supply, however, they are often impacted by wastewater discharges from wastewater treatment plants (WWTP) and combined sewer overflows (CSO). Reduction of the faecal pollution burden is possible through enhanced wastewater treatment or prevention of CSOs. Few methodological efforts have been made so far to investigate how these measures would affect the long-term treatment requirements for microbiologically safe drinking water supply under future changes.Objectives: This study aimed to apply a new integrative approach to decipher the interplay between the effects of future changes and wastewater management measures on the required treatment of river water to produce safe drinking water. We investigated scenarios of climate change and population growth, in combination with different wastewater management scenarios (i.e., no upgrades and upgrades at WWTPs, CSOs, and both). To the best of our knowledge, this is the first study to investigate this interplay. We focussed on the viral index pathogens norovirus and enterovirus and made a cross-comparison with a bacterial and a protozoan reference pathogen (Campylobacter and Cryptosporidium).Methods: We significantly extended QMRAcatch (v1.0 Python), a probabilistic-deterministic model that combines virus fate and transport modelling in the river with quantitative microbial risk assessment (QMRA). To investigate the impact of climatic changes, we used a conceptual semi-distributed hydrological model and regional climate model outputs to simulate river discharges for the period 2035 – 2049. We assumed that population growth leads to a corresponding increase in WWTP discharges. QMRAcatch was successfully calibrated and validated based on a four-year dataset of a human-associated genetic MST marker and enterovirus. The study site was the Danube in Vienna, Austria.Results: In the reference scenario, approx. 98% of the enterovirus and norovirus loads at the study site (median: 1010 and 1013 N/d) originated from WWTP effluent, while the remainder was via CSO events. The required log reduction value (LRV) to produce safe drinking water was 6.3 and 8.4 log10 for enterovirus and norovirus. Future changes in population size, river flows and CSO events did not affect these treatment requirements, and neither did the prevention of CSOs. In contrast, in the scenario of enhanced wastewater treatment, which showed lower LRVs by 2.0 and 1.3 log10, climate-change-driven increases in CSO events had a considerable impact on the treatment requirements, as they affected the main pollution source. Preventing CSOs and installing enhanced treatment at the WWTPs together had the most significant positive effect with a reduction of LRVs by 3.9 and 3.8 log10 compared to the reference scenario.Conclusions: The integrative modelling approach was successfully realised. The simultaneous consideration of source apportionment and concentrations of the reference pathogens were found crucial to understand the interplay among the effects of climate change, population growth and pollution control measures. The approach was demonstrated for a study site representing a large river impacted by WWTP and CSO discharges, but is applicable at other sites to support long term water safety planning.

Groundwater contamination and subsequent transport of viruses and bacteria are a major concern in aquifers worldwide. To ascertain the ability of these aquifers to remove pathogens, tracer tests with microbial indicators are carried out. But because these tests are laborious and require special permission, column tests are often done instead. Unfortunately, results from column tests tend to grossly overestimate removal rates λ when compared to the field scale, which can lead to underestimations of groundwater contamination risks. Scale is an important consideration when examining pathogen transport through porous media, as pathogen removal rarely happens by linear processes. Field tests were carried out with Bacillus subtilis endospores and phiX174 coliphages over a distance of 25 m in an alluvial gravel aquifer in Vienna, Austria. The sandy gravel material from the field site was also used in column tests with the same tracers. Both attachment-detachment and Colloid Filtration Theory were used to model these tests. The results show a big difference in removal between the two scales. A comparison with the literature showed a correlation between the heterogeneity (or preferential flow) of the porous media and the difference in removal rates between the column and field scale.

An ultrasound sensor system based on the transmission-mode approach is developed to enable the monitoring and sensing of cryogenic liquids and gases—especially gaseous bubbles and gas-liquid interfaces in liquid nitrogen (LN2). Common sensors do not meet requirements of cryogenic and microgravity-environments. Therefore, a special encapsulation design for the optimization of the electrical connection and the mechanical coupling of the ultrasound sensors is needed. The ultrasound system is qualified in LN2 and is able to measure bubbles (size and location) and fill levels with a high spatial resolution in a submillimetre range and a sampling rate of more than 500 Hz.

We present a versatile and very low-power traveling SAW microfluidic sorting device able to displace and separate particles of different diameter in aqueous suspension; the travelling wave propagates through the fluid bulk and diffuses via a Schröder diffuser, adapted from its typical use in concert hall acoustics to be the smallest such diffuser to be suitable for microfluidics. The effective operating power range is two to three orders of magnitude less than current SAW devices, uniquely eliminating the need for amplifiers, and by using traveling waves to impart forces directly upon suspended microparticles, they can be separated by size.

In this paper, a new wireless measuring method for colorless liquid level measurement was presented, based on latest CLC100 liquid level sensor and Powercast wireless sensor development kit. The wireless system is divided into two parts, level measurement and data transmission part as well as data receiving and display part. First part included the capacitive liquid level sensor CLC100 and the wireless senor board. CLC100 sensor was used for liquid level measurement. Wireless sensor kit from Powercast Corporation included one wireless sensor board, which was used for signal transmission. A built-in PIC microcontroller was embedded in the transmission module, for the purpose of processing and data transmitting. Due to CLC100 sensor’s output voltage exceeding the sensor board’s input limitation, a voltage convertor was designed to connect the sensor and the wireless sensor board. The final results were voltages corresponding to the liquid level, and were processed by an independent PIC development board, and then sent to PC’s hyper terminal via serial-port by this PIC microcontroller. Experiments showed that this wireless sensor node prototype worked well.

Characterization of surface water - groundwater interaction in riverbank filtration (RBF) systems is of decisive importance to drinking water utilities due to the increasing microbial and chemical contamination of surface waters. These interactions are commonly assessed by monitoring changes in chemical water quality, but this might not be indicative for microbial contamination. The hydrological dynamics of the infiltrating river can influence these interactions, but seasonal temperature fluctuations and the supply of oxygen and nutrients from the surface water can also play a role. In order to understand the interaction between surface water and groundwater in a highly dynamic RBF system of a large river, bacterial abundance, biomass and carbon production as well as standard chemical parameters were analyzed during a 20 month period under different hydrological conditions. In the investigated RBF system, groundwater table changes exhibited striking dynamics even though flow velocities were rather low under regular discharge conditions. Bacterial abundance, biomass, and bacterial carbon production decreased significantly from the river towards the drinking water abstraction well. The cell size distribution changed from a higher proportion of large cells in the river, towards a higher proportion of small cells in the groundwater. Although biomass and bacterial abundance were correlated to water temperatures and several other chemical parameters in the river, such correlations were not present in the groundwater. In contrast, the dynamics of the bacterial groundwater community was predominantly governed by the hydrogeological dynamics. Especially during flood events, large riverine bacteria infiltrated further into the aquifer compared to average discharge conditions. With such information at hand, drinking water utilities are able to improve their water abstraction strategies and react quicker to changing hydrological conditions in the RBF system.

The University of Shanghai for Science and Technology (USST), the Coburg University of Applied Sciences and Arts (CUASA) and the OTH Regensburg, University of Applied Sciences (OTHR) established an English taught international cooperative bachelor program in the area of Engineering Physics/Optoelectronics. Students from China study their first four semesters at USST. They continue their studies in Germany for the last three semesters, including an internship and a bachelor thesis, graduating with a Chinese and a German bachelor degree. Students from Germany study their third and fourth semester at USST to gain international experience. While the first cohort of Chinese students is currently in Germany, the second cohort of German students is in Shanghai. Up to now the feedback regarding this study program is completely positive, thus it is planned to develop it further.

Guided acoustic waves, such as Lamb waves, are widely applied for material characterization, sensing of liquids and the generation of streaming in liquids. There are numerical simulation tools for the prediction of their propagation near a solid-liquid boundary but a demand for complementary measurement techniques for the validation of the simulation results remains. In this contribution it is demonstrated that light refractive vibrometry is a suitable approach for the visualization of the interaction of guided acoustic waves with liquids. For this purpose Lamb waves were excited by piezoelectric transducers on copper plates partially immersed in water. There the fundamental symmetric and antisymmetric modes are converted to compressional waves and quasi-Scholte plate waves below a frequency-thickness product of 1 MHz mm. From the vibrometry scans the wavelengths, radiation angles and pressure amplitudes of the involved modes could be determined and thus theoretical predictions of the attenuation of the Lamb modes and the energy distribution of quasi-Scholte plate waves between the solid substrate and the liquid environment could be confirmed.

In this paper, a new acoustic sensor principle for coating detection within liquid-filled tubes and containers based on mode conversion of leaky Lamb waves is introduced. Leaky Lamb waves are excited and detected by single-phase transducers, which are attached on the outer side of a tube or container. By transmission time and amplitude measurements, coating formation within the liquid-filled tube and container is detected non-invasively. This new sensor principle is subdivided into the separate considerations of Lamb wave excitation, mode conversion and inverse mode conversion. The Lamb wave excitation by a single-phase transducer is visualized by scanning laser Doppler vibrometer imaging. The mode conversion process of leaky Lamb waves is measured by membrane hydrophone measurements and Schlieren visualization; afterwards, the measured emission angles are compared with the theoretical one. The inverse mode conversion process of pressure waves back to leaky Lamb waves is visualized by Schlieren images. By merging the results of Lamb wave excitation, mode conversion and inverse mode conversion, the new sensor concept is explained. Theoretical considerations and measurement results of adhesive tape coating inside a liquid-filled plastic tube and a liquid-filled stainless steel container verify the new acoustic sensor principle. Finally the measuring sensitivity and the technical realization are discussed.

An acoustic waveguide sensor consisting of two identical parallel plates on which surface acoustic waves are propagating allows the measurement of proportion of liquid properties taking advantage of the mode conversion of SAW via the measurement of the transmission time and amplitude of short wave pulses [1] . A favourable realization of such a sensor consists of thin plates of non-piezoelectric material with a thickness in the order of the acoustic wavelength for example glass plates of about 1 mm thickness at excitation frequency of 1 MHz on which Lamb waves are excited and detected by means of piezoelectric interdigital transducers attached at the rear surfaces [2] . Due to the dispersion of Lamb waves for a given material and excitation frequency, their propagation velocity depends on the thickness of the plates. Correspondingly for the lowest order symmetric and asymmetric modes of Lamb waves the Rayleigh angle at which mode conversion occurs and the acoustic velocity difference to the liquid will be different and will change in different ways with changes of properties of the liquids. This allows a novel access to the investigation of such liquids with enhanced sensitivity.

The transport of human adenovirus, nanoparticles, and PRD1 and MS2 bacteriophages was tested in fine granular limestone aquifer material taken from a borehole at a managed aquifer recharge site in Adelaide, South Australia. Comparison of transport and removal of virus surrogates with the pathogenic virus is necessary to understand the differences between the virus and surrogate. Because experiments using pathogenic viruses cannot be done in the field, laboratory tests using flow-through soil columns were used. Results show that PRD1 is the most appropriate surrogate for adenovirus in an aquifer dominated by calcite material but not under high ionic strength or high pH conditions. It was also found that straining due to size and the charge of the colloid were not dominant removal mechanisms in this system. Implications of this study indicate that a certain surrogate may not represent a specific pathogen solely based on similar size, morphology, and/or surface charge. Moreover, if a particular surrogate is representative of a pathogen in one aquifer system, it may not be the most appropriate surrogate in another porous media system. This was apparent in the inferior performance of MS2 as a surrogate, which is commonly used in virus transport studies.

To understand how fish density and food availability affect habitat selection and growth of juvenile coho salmon (Oncorhynchus kisutch), we manipulated fish density (2–12 fish·m–2) and natural invertebrate drift (0.047–0.99 mg·m–3) in 12 experimental stream channels constructed in a side-channel of Chapman Creek, British Columbia. Increased food resulted in increased growth of both dominant and subdominant fish and a shift to higher average focal velocities (from 6.5 to 8.4 cm·s–1) with maximum growth in the range of 10–12 cm·s–1. Increased food appears to permit juvenile coho to exploit higher velocity microhabitats that might otherwise be bioenergetically unsuitable at lower food levels. Increased fish density resulted in lower growth of subdominant but not of dominant fish and a general displacement of fish to both higher and lower focal velocities. The shapes of habitat suitability curves were sensitive to food abundance, implying that differences in food availability may affect transferability of habitat suitability curves between streams of different productivity. While habitat suitability curves captured the change in extent of available habitat following prey enrichment, actual increases in growth rate with enrichment (i.e., changes in habitat quality) were poorly represented by habitat suitability values and better represented by bioenergetic model predictions.

In the Eastern Alps, the Dachstein massif with a height of almost 3000 m is an ideal location for investigating the effects of changes in altitude on the human body. Within a few minutes, a cable car facilitates an ascent from 1702 to 2700 m above sea level, where the partial pressure of oxygen is about 550 mmHg (as compared to 760 mmHg at sea level). In this study, 10 healthy subjects performed a reaction time task at 990 m and 2700 m in altitude. The subjects were instructed to perform a right hand index finger movement as fast as possible after a green light flashed (repeated 50 times). The corresponding electrocardiogram (ECG) and the electroencephalogram (EEG) were recorded. From the ECG heart rate and heart rate variability measures in the time and frequency domain were calculated. An event-related desynchronization/synchronization (ERD/ERS) analysis was performed with the EEG data. Finally, the EEG activity and the ECG parameters were correlated. The study showed that with the fast ascent to 2700 m the heart rate increased and the heart rate variability measures decreased. The correlation analysis indicated a close relationship between the EEG activity and the heart rate and heart rate variability. Furthermore it was shown for the first time that the beta ERS in the 14-18 Hz frequency range (post-movement beta ERS) was significantly reduced at high altitude. Very interesting also is the loss of correlation between EEG activity and cardiovascular measures during finger movement at high altitude. The suppressed post-movement beta ERS at the altitude of 2700 m may be interpreted as results of an increased cortical excitability level when compared with the reference altitude at 990 m above sea level.

Determination of the heterotrophic plate count (HPC) is commonly used as a surrogate to assess the general microbial water quality in drinking water. For routine monitoring applications, the HPC is investigated in a quantitative way. However, qualitative data about the HPC bacterial community composition and/or population dynamics are required for particular situations. In order to provide fast and efficient qualitative approaches, molecular biological DNA profiling techniques seem to be suitable tools for the analysis of the total HPC community composition. In this work a DNA profiling technique is presented, which was recently demonstrated by our group to have potential for the rapid qualitative comparison and differentiation of HPC communities from raw and drinking water. The presented approach consists of a polymerase chain reaction (PCR)-based denaturing gradient gel electrophoresis (DGGE) for the generation of 16S-rDNA amplicon fingerprints from whole HPC community DNA extracts. In the context of this proceeding, the methodical background is presented and possible scientific merits as well as potential water management applications are discussed. Selected examples of (i) the demonstration of selective growth of HPC populations on different media and the comparison to the total in situ drinking water eubacterial community, (ii) the screening for HPC community variations at different locations of a drinking water distribution system, and (iii) the influence assessment on groundwater HPC communities by an infiltrating treated sewage effluent (bacterial source tracking) are given.

The kinetics of electrochemical reactions is controlled by diffusion processes of charge carriers across a boundary layer between the electrode and the electrolyte, which result in a shielding of the electric field inside the electrolyte and a concentration gradient across this boundary layer. In accumulators the diffusion rate determines the rather long time needed for charging, which is a major drawback for electric mobility. This diffusion boundary can be removed by acoustic streaming in the electrolyte induced by surface acoustic waves propagating of the electrode, which results in an increase of the charging current and thus in a reduction of the time needed for charging. For a quantitative study of the influence of acoustic streaming on the charge transport an electropolishing cell with vertically oriented copper electrodes and diluted H 3 PO 4 -Propanol electrolytes were used. Lamb waves with various excitation frequencies were exited on the anode with different piezoelectric transducers, which induced acoustic streaming in the overlaying electrolytic liquid. An increase of the polishing current of up to approximately 100 % has been obtained with such a set-up.

With an acoustic levitator small particles can be aggregated near the nodes of a standing pressure field. Furthermore it is possible to atomize liquids on a vibrating surface. We used a combination of both mechanisms and atomized several liquids simultaneously, consecutively and emulsified in the ultrasonic field. Using a high-speed camera we observed the coagulation of the spray droplets into single large levitated droplets resolved in space and time. In case of subsequent atomization of two components the spray droplets of the second component were deposited on the surface of the previously coagulated droplet of the first component without mixing.

Microliter droplet can be propelled on a non-piezoelectric substrate, on which antisymmetrical zero order Lamb waves with 1 MHz center frequency are propagating. Different droplet volume has different ratio of absorbed power, which is described by droplet propulsion distance/electrical input power. Moreover, with increasing droplet volume (10μl, 20μl, 50μl), the excitation frequency (1.03 MHz, 1.04 MHz, 1.06 MHz) must be slightly increased, for the optimization of the propulsion process.

The emission of sound waves resulting from mode conversion of Lamb waves propagating on thin glass plates submerged into water was investigated by a PVDF membrane hydrophone. The antisymmetrical zero order Lamb wave mode was excited by a piezoelectric single phase transducer operated at a frequency of 1 MHz. With the hydrophone the emission pressure distribution of the emitted sound waves in the liquid was recorded and the phase velocities of the Lamb waves were calculated from the direction of the emitted sound waves, i. e. the Lamb angles. Due to the dispersion of Lamb waves the velocity changes with the plate thickness. The measured phase velocities coincide well with the calculated values using the global matrix method for plate thicknesses between 0.5 and 4 mm.

The persistence and seasonal cycling of dissolved cesium radio-muclides in the waterbody of a small and shallow pre-alpine lake was attributed to their mobilization due to ion exchange with ammonium ions and their inability to irreversibly fix on clay particles in the sediments and in the soil of the swampy watershed of the lake. A model of cesium radionuclide cycling between sediment and waterbody is proposed, which is based on ammonium production and cesium release in the sediment due to microbial decomposition of organic matter. This hypothesis is corroborated by results of field measurements of temperature profiles and the depth distribution of the cesium radionuclide inventory in the sediment and of laboratory experiments with respect to the enhancement of cesium radionuclide release from sediment samples by increasing the metabolic activity of microorganisms in the sediment. (orig.)

An ultrasonic transmission sensor system based on piezoelectric transducers is described, which allows the measurement of the concentration of gases in binary mixtures of known constituents. Results of test measurements on CO 2 air, He-air and ArSF 6 mixtures are presented; for CO 2 air mixtures deviations of less than 2% between theoretically calculated and measured values are obtained over the whole range of concentrations. Possible sources of error are discussed and estimates of their relative importance are given; at ambient conditions the influence of variations in total pressure and moisture is found to be negligibly small. A compilation of pairings of gas species of technical importance is given, for which the universality of application of this sensor principle is restricted by ambiguities in the relationship between the velocity of sound and gas concentration.

A combination of detection and propulsion of droplets on glass substrates at macroscopic dimensions has been accomplished via mode conversion of 1 MHz Lamb waves excited and detected by piezoelectric interdigital transducers (IDT) attached to the substrates forming a delay line configuration. Experimental results with respect to water, oil and glycerin droplets with liquid volumes between 8 and 160 µl on hydrophobic and hydrophilic glass surfaces are reported. In order to switch from sensing to actuating the excitation voltage of the IDT has been increased from 20 Vpp to 300 Vpp and the operation mode has been changed from burst to continuous excitation. Applications of this approach are envisaged at mirrors, windows and other optical components whose function may be affected adversely by the presence of liquid droplets.

Das Schloss, das wir vorgefunden haben, war innen teilweise stark verbaut mit Wohnungen wie in einem Gemeindebau. Vieles musste raurnlich bereinigt werden. Heute sieht es wieder nach einem Biedermeierschloss aus, von denen wir in dieser Komplettheit kaum noch welche besitzen. Die Grundsubstanz geht bis auf das Mittelalter zuruck, die Schablonenmalerei, die wir mit den

The mode conversion of acoustic surface waves contacted by liquid droplets has been utilized for the propulsion of nanoliter droplets with respect to lab-on-a-chip applications. In this case, however, piezoelectric substrates equipped with interdigital transducers on the surface on which the droplets are moving have been used for the excitation of surface acoustic waves. Our approach is aiming at the acceleration of comparatively large droplets such as raindrops on non-piezoelectric substrates, e. g. glass plates. Following this approach, we have excited Lamb waves on glass plates by piezoelectric interdigital transducers attached at the rear side of the substrate, which are not in contact with the liquid. A propulsive action on water droplets of µl size has been observed, which could be improved by hydrophobic surface coatings. With continuous wave excitation at a frequency of 1 MHz and an amplitude of 200 V pp an acceleration of about 1 m/s2 has been achieved so far with water droplets of 10 µl on a 1 mm thick glass plate. This concept allows numerous technical applications, including two-dimensional droplet relocation or “intelligent” droplet removal from glass panels in combination with droplet detection via a Lamb wave transmission line established by a second interdigital transducer.

Heterotrophic plate count using ISO 6222 agar (HPC) vs. in situ bacterial (DF) community structure from corresponding samples of a drinking water distribution system were investigated by 16S rRNA gene-based polymerase chain reaction denaturing gradient gel electrophoresis (PCR DGGE) profiling. The investigation regime covered 10 different sampling locations and 2 points in time (t1, t2). In order to ensure accurate and reproducible 16S rRNA gene profile analysis, rigorous methodical evaluation and standardisation procedures were undertaken (DGGE optimisation, replication of PCR, multiple-lane standardisation, representative sampling volume determination, application of multiple similarity coefficients). The reproducibility level of the profile analysis was determined to be > 90% similarity. Two completely different communities were revealed from HPC vs. DF as indicated by DGGE analysis and sequencing. HPC populations could be identified as ubiquitously occurring cultivable copiotrophic microbes, whilst most DF sequences could be allocated to sequences from microorganisms found in oligotrophic aquatic environments. Spatial- and temporal-based 16S rRNA gene amplicon profile analysis from recovered communities further revealed contrasting results. As proven by Jackknife simulations, DF profiles remarkably corresponded to sampling time, whereas HPC profiles revealed spatial associations within the distribution system. Recovered data demonstrate that cultivation based HPC vs. direct cell-based investigations can result in completely different results if used for monitoring purposes in distribution systems.

The acoustic wave propagation in bearings filled with lubricants and driven by pulsed excitation of surface acoustic waves has been investigated with respect to the presence and the distribution of different lubricants. Experimental setups, which are based on the mode conversion between surface acoustic waves and compression waves at the interface between a solid substrate of the bearing and a lubricant are described. The results of preliminary measurements at linear friction bearings, rotation ball bearings and axial cylinder roller bearings are presented.