Suchergebnisse

AbstractThe Laboratory Biological Activity Reaction Test (LAB-BART) is an easy-to-use assay that utilizes metabolic capabilities to process an array of substrates to semi-quantitatively assess the presence of potentially adverse bacteria in a groundwater sample. Here, we evaluated LAB-BART for the assessment of groundwater samples obtained under real-life conditions from two riverbank filtration (RBF) sites in Austria. Samples were taken monthly for an overall experimental period of six months and analyzed following the manufacturer's recommendations for measuring iron-related, sulfate-reducing, slime-forming and denitrifying bacteria. Additional measurements were done for analyzing chemical water composition, as well as bacterial community structure to evaluate the suitability of LAB-BART by identifying relevant bacteria. Results imply that while LAB-BART could not give detailed information on bacterial concentrations, it might be able to indicate hydrologically induced changes in biogeochemical processes in a subsurface system, thus allowing operators to determine an adequate response to a potential influx of undesired bacteria. Despite its limitations, LAB-BART might therefore be a valuable tool for monitoring purposes due to its ease of use, but more research is necessary to determine its accuracy in measuring bacterial activity.

AbstractRiverbank 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.

AbstractThe alluvial backwater areas of the Danube are valuable ecological habitats containing important drinking water resources. Due to the river regulation and the construction of power plants, the river water levels and natural dynamics of the backwater areas continuously decline, threatening their typical characteristics. The aim of this study was to evaluate how an increased connectivity of the backwater branch located in a nature-protected riverine floodplain (enabled by diverting river water into the backwater system via a weir) affects the microbiological quality of groundwater resources. The defined quality criterion was that the diversion measures must not lead to an increased detection frequency of faecal indicators in groundwater. The microbiological water quality of the Danube, its backwater branch and the groundwater was analysed from 2010 to 2013. E. coli was selected as bacterial indicator for recent faecal pollution. C. perfringens (spores) was analysed as indicator for persistent faecal pollution and potentially occurring pathogenic protozoa. We simulated the microbial transport from the Danube and the backwater river into groundwater using a 3‑D unsaturated-saturated groundwater model coupled with 2‑D hydrodynamic flow simulations. Scenarios for no diversion measures were compared with scenarios for an additional discharge of 3, 20 and 80 m3/s from the Danube River into the backwater branch. While the additional discharge of 20 and 80 m3/s of Danube water into the floodplain strongly improved the ecological status according to ecological habitat models, the hydraulic transport simulations showed that this would result in a deterioration of the microbiological quality of groundwater resources. The presented approach shows how hydraulic transport modelling and microbiological analyses can be combined to support decision-making.

ZusammenfassungZiel dieses Artikels ist es, einen Überblick über Konzentrationen von PFAS in unterschiedlichen (Umwelt‑)Medien im oberen Donaueinzugsgebiet zu erhalten und daraus erste semiquantitative Schlüsse auf potenziell relevante Herkunftsbereiche zu ziehen. Im Zuge des EU-Projekts PROMISCES wurden 32 PFAS-Einzelsubstanzen in unterschiedlichen Donauzubringern, Donau, Donauuferfiltrat, Kläranlagenzu- und -abläufen, Deponiesickerwasser und durch solches beeinflusstes Grundwasser, Oberflächenabfluss und atmosphärischer Deposition analysiert. Darüber hinaus wurden PFAS-Daten aus anderen Projekten und Monitoringprogrammen genutzt. Ergebnisse weisen zum einen auf die geringe Wirksamkeit von Barrieren wie Kläranlagen und Uferfiltration gegen eine PFAS-Belastung von Wasserressourcen hin. So konnte dort für eine Reihe von Einzelparametern kein relevanter Rückhalt festgestellt werden. In Hinblick auf die Herkunftsbereiche von PFAS weisen die Ergebnisse auf eine relevante Bedeutung der Emissionen aus dem Bereich des Chemieparks Gendorf an der Alz für die Belastung der Donau mit Carbonsäuren, aber vor allem mit ADONA hin. Darüber hinaus können Siedlungsbereiche als relevante Herkunftsbereiche angesehen werden. Kläranlagenabläufe spielen eine Rolle, können die Gewässerbelastungen alleine aber nicht erklären. Andere (diffuse) Einträge dürften zudem eine wichtige Rolle spielen. Hohe Konzentrationen von PFAS in Sickerwässern von Altlasten aus Hausmülldeponien weisen auf eine potenzielle Relevanz zumindest auf der Ebene regionaler Einzugsgebietsebene hin. Ähnliches gilt für erhöhte Grundwasserkonzentrationen aufgrund anderer regionaler Hotspot-Belastungen, wie sie auch von Brielmann et al. (2023, in diesem Heft) diskutiert werden. In weiterer Folge sollen im Rahmen des PROMISCES-Projekts die hier dargestellten Ergebnisse für eine Emissionsmodellierung von PFAS im Donaueinzugsgebiet bis Budapest genutzt werden, um verstärkt quantitative Aussagen über die Rolle unterschiedlicher Eintragspfade auf die Belastung der Fließgewässer im Donaueinzugsgebiet oberhalb von Budapest machen zu können.

AbstractPFAS are a class of synthetic chemicals used for many industrial and domestic purposes. However, once released in the environment, they are persistent, mobile and toxic. One of the most important transport routes to drinking water is through riverbank filtration. Although this is usually an effective strategy for removing many organic compounds, its effectiveness in removing PFAS is still unknown. The aim of this study is to investigate the occurrence, as well as the spatial distribution of PFAS at riverbank filtration sites and compare these to two pharmaceuticals and various chemical parameters. A one-year sampling campaign was carried out at four transects with different characteristics along the Danube river. Samples were analysed using Liquid Chromatography Mass Spectrometry.Results show that most of the detected PFAS compounds had concentrations lower than 10 ng/l. NaADONA had the highest concentration at all the sites, indicating the presence of an emission source upstream of the monitored sites. For most compounds, there was no concentration reduction between the river and groundwater, implying that no removal processes take place. This was further confirmed with statistical tests, which showed no significant differences between river- and groundwater concentrations. Two sites in Budapest showed higher concentrations of PFOA, PFOS, and GenX in the background water compared to the river, indicating an inland source of these compounds. The current situation imposes no problems for drinking water as the measured concentrations are lower than the legal limit set by the EU Drinking Water Directive. However, any future legal or industrial changes could create problems since results suggest that these compounds are not removed during riverbank filtration.

AbstractRecent developments in water resource monitoring have increased the demand for the reliable identification of faecal pollution sources, also defined as microbial (faecal) source tracking (MST). Standardized faecal indicator bacteria (SFIB) enumeration does not directly support MST, as SFIB occur in animal and human sources. The aim of this study was to rigorously evaluate the applicability of host-associated faecal genetic MST markers detected by quantitative PCR (qPCR) at representative Austrian water resources (ground-, surface-, raw and treated wastewater, n = 196 samples) with high importance for the water management sector. Groundwater covered a gradient of non- (i.e., deep wells) to surface influenced resources (i.e., karst and shallow wells). In addition, single faecal excreta from humans as well as representative livestock and wildlife species were collected to evaluate the faecal source-specificity and -sensitivity of the MST assays. Genetic MST marker resistance against UV irradiation was evaluated in on-site ground and wastewater treatment installations. Bacteroides-based human- (HF183II, BacHum), ruminant- (BacR), and pig-associated (Pig2Bac) MST marker qPCR quantification was performed in concert with cultivation of E. coli, intestinal enterococci, and Clostridium perfringens (SFIB diagnostics). The selected MST makers revealed high faecal source identification capacity for the Austrian water compartments and quantitatively reflected the selected faecal pollution gradient. The study also demonstrated that SFIB data can efficiently be combined with MST data to solve previously unanswered questions in water safety monitoring and management (e.g., support pollution source-targeted catchment protection, hazard assessment, and health risk management). Further research and development needs are discussed to exploit the full power of MST technology. In conclusion, this study illustrates the capacity of molecular faecal pollution diagnostics to revolutionize water quality testing in the decades to come.