A novel microbial risk analysis of groundwater as part of the Dutch guideline document for Quantitative Microbial Risk Assessment (QMRA) of drinking water consumption encompasses 1) vulnerability assessment of groundwater production sites, 2) calculating the protection zone against microbial contamination to remain below an infection risk of 1/10,000 persons/year, 3)  assessment of contamination sources within the protection zone, and 4) QMRA for identified contamination sources. Protection zones are based on a standard virus contamination scenario and may be computed using a required minimal travel time, a hydrological model that includes a first order decay term for virus inactivation and attachment, or the computational tool QMRAwell. QMRAwell is designed for unconfined and (semi)confined sandy aquifers with a forced groundwater gradient due to pumping. QMRAwell can also be used to conduct  QMRA.

How to cite: Schijven, J., van den Berg, H., and Rutjes, S.: Protection of groundwater against microbial contamination, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11053, https://doi.org/10.5194/egusphere-egu23-11053, 2023.

Climate change-associated wildfires are increasing in frequency and severity, causing increasingly variable or deteriorated water quality, and challenging in-plant treatment processes beyond design and operational response capacities, to the point of service disruptions. Recent work has shown that the wildfire impacts on drinking water treatability can extend far downstream and be long-lasting. Notably, very little information regarding the impacts of severe wildfire on groundwater supplies is currently available.

Wildfire transforms fuels (i.e. biomass, soil organic matter). Pyrogenic carbonaceous material formed after wildfire includes particulate ash and biochar, which often contains toxic polyaromatic hydrocarbons, dioxins and furans, as well as some heavy metals. These mobile materials may be incorporated into soil profiles (change the soil properties, e.g., hydrophobicity, pH), redistributed, or removed from a burned site by wind and water erosion to source water. While surface water treatment technologies may have some capacity to remove these contaminants from surface water, the subsurface fate and mobility of these toxic particles has not been documented and is not understood. Moreover, the implications of potential changes in dissolved organic carbon on pathogen transport in these systems has not been documented. Because groundwater-based drinking water supplies do not typically require treatment beyond disinfection, it is possible that contaminated particles could enter drinking water wells after wildfire. Moreover, NOM-associated changes in water quality may increase the risk of pathogen transport through the subsurface.

Here, the impacts of wildfire on the transport E. coli and Cryptosporidium parvum oocysts in various porous media environments (e.g., particle properties, solution chemistry, organic matter character) were evaluated. Column tests were conducted using laboratory prepared wildfire ash-impacted water and wildfire impacted surface water collected after the 2017 Kenow Wildfire in Waterton, Alberta, Canada. These investigation demonstrate that under certain conditions potential post-fire shifts in water quality can substantially enhance particle/microbe transport in porous media, thereby underscoring the need to evaluate microbial risks to groundwater supplies after severe wildfire.

How to cite: Emelko, M., Chowdhury, O., Sun, X., Kennington, A., Schmidt, P., Silins, U., and Stone, M.: Wildfire Threats to Groundwater Supplies: Implications for Pathogen and Particulate Contaminant Transport in Porous Media, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10824, https://doi.org/10.5194/egusphere-egu23-10824, 2023.

Contaminants of emerging concern (CECs) can threaten aquatic ecosystems and human health. Both rural and urban areas are main sources of CECs to the environment. In rural areas, veterinary pharmaceuticals (VPs) are used to prevent diseases and protect the health of farm animals. The excrements of medicated animals are spread as manure to agricultural lands, where, after rainfall, VPs can be mobilized and reach surface waters through runoff. In urban areas, pharmaceuticals excreted by humans are collected in sewage systems and are only partially removed in wastewater treatment plants (WWTPs). Eventually, pharmaceuticals can reach surface waters through discharge of WWTP effluent. Currently, most of the predictive models only consider one source type, e.g. WWTPs or agricultural land. This limits their prediction performance since many CECs are being emitted by multiple source types. Therefore, the aim of this study is to integrate urban and rural sources of CECs in one regional water quality assessment.

Here, we predicted the concentration of CECs in the Eem river basin, the Netherlands, given land-use data combined with hydrological modeling. This allows for integrated evaluation of rural and urban emissions. These emissions were predicted with models developed within the context of the SUSPECt project (https://cec-partnership.nl/web/index.php/projects/suspect). CECs exposures were predicted with the Dutch National Water Quality Model where WWTPs emissions were included as point sources and rural emissions as diffuse sources. The temporal resolution of the model hydrology is seasonal. This is key to analyze the temporal variation of concentration due to manuring of agricultural lands which mainly occurs in Spring.

Predicted concentrations were successfully compared to measured concentrations taken in the SUSPECt project and from the database of the KIWK project (www.kennisimpulswaterkwaliteit.nl) for 6 compounds: carbamazepine and fipronil (only urban sources) and trimethoprim, sulfamethoxazole, permethrin and dexamethasone (urban and rural sources).

How to cite: Bregoli, F., Posthuma, L., Rakonjac, N., Zillien, C., Vermeiren, P., Roex, E., van der Zee, S., Meijers, E., and Ragas, A.: Regional Scale Modelling of Pharmaceutical Pollution in Rivers by Integrating Rural and Urban Sources, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5660, https://doi.org/10.5194/egusphere-egu23-5660, 2023.

Induced bank filtration is a known method for sustainable drinking water production in regions with limited groundwater resources. However, this method is at risk from surface water contaminations, e.g., by pathogens. Numerical models simulating pathogen fate in groundwater are typically too complex to be used as standard tools by waterworks managers or environmental agencies. To mitigate this problem, we present a methodology for the construction of easy-to-use reduced order models as surrogates for complex numerical reactive transport models for pathogens and pathogen indicators in induced bank filtration.

First, a streamlined one-dimensional numerical model was set up for the reactive transport of pathogens and pathogen indicators in induced bank filtration. Processes in the model include advection-dispersion, inactivation, attachment to and detachment from the sediment as well as straining and the presence of a clogging layer. Model parameters are divided into two groups: Group A includes site specific parameters for which values are typically available (with limited uncertainty) for management- and engineer-level users (e.g., grain size, distance of extraction well to the river); Group B includes process parameters which are typically affected by high uncertainty (e.g., inactivation and detachment coefficients).

We rely on an extensive dataset for coliforms and somatic coliphages collected over a 16-month period at an active induced bank filtration site. Stochastic inversion is used to assess uncertainty for model parameters of Group B (constrained on the dataset), while those of Group A are set to the values of the specific site. Principal component analysis (PCA) is applied to reduce the dimensionality of model parameter space and correlation amongst the uncertain parameters of Group B. A surrogate model is then constructed through generalized polynomial chaos expansion (gPCE). In this, the value range of Group A parameters is based on typical scenarios for induced bank filtration sites, while the range of the PCA-reduced Group B parameters is set to the uncertainty identified in the stochastic inversion.

The surrogate model allows to evaluate, at significantly reduced computational cost, the removal of coliforms and somatic coliphages in induced bank filtration based on user-defined values for parameters of Group A, but also including the uncertainty stemming from parameters of Group B. The surrogate model estimates for removal are in good agreement with observed removals for coliforms and somatic coliphages at the monitored site and with other (albeit limited) datasets from induced bank filtration sites found in the published literature. At this stage, the obtained surrogate model can be considered as a prototype. The assessment of its full potential requires additional extensive validation against other field sites. In general, surrogate models together with the overall methodological framework we propose, can be seen as a promising tool to assist informed decisions about pathogen transport at induced bank filtration sites.

How to cite: Knabe, D., Dell'Oca, A., Guadagnini, A., Riva, M., and Engelhardt, I.: Estimating Pathogen Removal in Bank Filtration – A Methodology for the Construction of Surrogate Models to Assist Decision Making, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7060, https://doi.org/10.5194/egusphere-egu23-7060, 2023.

Anthropogenic activities in a watershed may pose human health risks due to faecal contamination of surface waters. Thus, socioeconomic development is important when predicting future microbial water quality. Moreover, climate change alters meteorological conditions, thereby affecting flow regimes as well as fate and transport of microorganisms. In this study, possible risks due to socioeconomic development and climate change were assessed for the drinking water source Lake Vomb in Sweden by means of water quality modelling. The hydrological model ArcSWAT and the hydrodynamic model MIKE 3 FM were used to simulate fate and transport of two microorganisms, i.e., Cryptosporidium and E. coli, from the watershed to the water intake. The hydrological model and the hydrodynamic model were calibrated and validated using observed data on water flow and water temperature, respectively. The water quality in the watershed and in the lake was simulated for a baseline scenario and for future scenarios in the second half of this century. The future scenarios were formulated based on Representative Concentration Pathways (RCPs) and Shared Socioeconomic Pathways (SSPs). The modelling results illustrated the effects of climate changes and of socioeconomic development. The results were also interpreted in the context of infection risks to drinking water consumers using quantitative microbial risk assessment. This study clearly illustrates that socioeconomic development is important to include when investigating future microbial water quality.

How to cite: Sokolova, E., Begion, V., Islam, M. M. M., and Bondelind, M.: Fate and transport modelling of microbial water quality: impacts of climate change and socioeconomic development, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14533, https://doi.org/10.5194/egusphere-egu23-14533, 2023.

The presence of waterborne enteric viruses in lake recreational water sites is not desired, as they may have a negative impact on human health. However, their concentrations, fate and transport in lakes remain poor understood. To date, the health risks posed by enteric viruses in surface water was typically assessed via monitoring of fecal indicators, such as E. coli, whereas a direct assessment of fate and transport of waterborne viruses is less common. In this study, we propose a coupled water quality and quantitative microbial risk assessment (QMRA) model to study the transport, fate and infection risk of four common enteric viruses, using Lake Geneva as a study site. The measured virus load in raw sewage entering the lake was characterized, fitted with different distributions and then used as the source term in the water quality simulations. A Eulerian transport model was employed to model virus transport while considering spatially and temporally varying inactivation of viruses. Eventually, the probability of infection was quantified by linking the virus concentrations at a popular beach with QMRA. The model framework was then applied to model current situations as well as future scenarios under climate change. In the simulations of year 2019, it was found that environmental stressors noticeably reduce the infection probability exerted by viruses with low background inactivation in summer, but effects in the winter are minor. Norovirus appeared to be the most abundant species and also led to the highest infection probability, which was at least 10 times greater than that of the other viruses studied. In addition, the model highlighted the role of the wind field in conveying the contamination plume and hence in determining infection probability. The simulations for the future revealed an increase of virus inactivation rates in summer times due to higher water temperature as well as increased radiation levels due to reduced cloud coverage. The enhanced inactivation in summer could compensate for the higher virus loading caused by population growth. In contrast, in winter minor temperature changes and inconsequential radiation variation would not offset the increased virus loading. However, even in the winter cases the future infection risks would not undergo significant change compared with the current situation.  The proposed model framework is flexible and could be relatively easily refined and adapted for other locations and scenarios. This study highlights the potential of combining water quality simulation and virus-specific risk assessment for a safe water resources usage and management.

How to cite: Li, C., Sylvestre, É., Julian, T., and Kohn, T.: Risk assessment of waterborne virus in Lake Geneva: the present and the future, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4946, https://doi.org/10.5194/egusphere-egu23-4946, 2023.

Synthetic DNA tracers are a promising tool for tracking water contamination pathways. However, quantitative data are lacking on their degradation and adsorption in environmental matrices. Laboratory experiments were conducted to exam the degradation of multiple DNA tracers in stream water, groundwater, and domestic and dairy-shed effluent, and adsorption to stream sediments, soils, coastal sand aquifer media and alluvial sandy gravel aquifer media. The selected DNA tracers were double stranded 302 base pair (bp) and 352 bp in lengths. Their internal amplicons used for qPCR detection were almost the same, but the 352 bp tracers had longer non-amplified flanking regions.

Overall, 352 bp tracer degradation was significantly slower than that of the 302 bp tracers (p = 0.018). Results of thermodynamic analysis indicated that the 352 bp tracers had greater tracer stability. These findings are consistent with our previous field observations that 352 bp tracer reductions were consistently lower than 302 bp tracer reductions in stream water, groundwater, and soils. These findings suggest that longer non-amplified flanking regions may better protect DNA tracers from environmental degradation. In general, the DNA tracers degraded more quickly in the stream water and effluent samples than in the groundwater samples, and fast DNA tracer degradation was associated with high bacterial concentrations.

The two sets of DNA tracers differed little in their adsorption to stream sediment-stream water or aquifer media-groundwater mixtures (p > 0.067). However, the 352 bp tracers adsorbed significantly less to soil-effluent mixtures than the 302 bp tracers (p = 0.005). Compared to their adsorption to the aquifer media-groundwater and stream sediment-stream water mixtures, DNA tracer adsorption to soil-effluent mixtures was relatively less. A plausible explanation is that DNA tracers may compete with like-charged organic matter for adsorption sites, thus were less adsorbed to environmental media in the presence of organic matter.

Our study findings provide insights into the fate of DNA tracers in the aquatic environment and may assist with the future design of DNA tracers for environmental studies. The DNA tracer degradation rates established in this study for a range of environmental conditions could be used to inform the design of future field investigations, such as injection concentrations, sampling distances and experimental durations.

How to cite: Pang, L., Heiligenthal, L., Premaratne, A., Hanning, K., Abraham, P., Sutton, R., Hadfield, J., and Billington, C.: DNA tracer degradation and adsorption in environmental matrices, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1765, https://doi.org/10.5194/egusphere-egu23-1765, 2023.

Nitrification and urease inhibitors (NUI) are used in conjunction with nitrogen (N) fertilizers on agricultural soils to improve the efficiency of N fertilizers and reduce the emission of greenhouse gases. After application, NUI might transfer to aquatic environments through leaching or surface runoff. Nowadays, NUI such as 1,2,4-triazole, 3,4-dimethylpyrazole (3,4-DMPP) and dicyandiamide (DCD) are frequently found in surface waters with concentrations in the magnitude of µg/L. The fate of NUI in bank filtration (BF) is currently poorly known. BF is a sustainable water treatment system providing high quality water by efficiently removing numerous organic micropollutants from the source water. Herein, sorption and degradation of NUI in simulated BF under near-natural conditions was investigated. Besides, the effect of NUI on the microbial biomass of slowly growing microorganisms and the role of microbial biomass on NUI removal was investigated. Duplicate sand columns (length 1.7 m), fed with surface water were spiked with a pulse consisting of four nitrification (1,2,4-triazole, DCD, 3,4-DMPP and 3-methylpyrazole) and two urease inhibitors (n-butyl-thiophosphoric acid triamide and n-(2-nitrophenyl) phosphoric triamide). The average spiking concentration of each NUI was 5 µg/L. The flow velocity was adjusted to 0.2 m/d. Breakthrough curves of tracer (sodium chloride) and the NUI appeared at same time; therefore, sorption may be ruled out. Additionally, experimental and modeled breakthrough curves of NUI suggested no retardation for any of the inhibitors. Therefore, biodegradation was identified as the main elimination pathway for all substances and was highest in zones of high microbial biomass. N-butyl-thiophosphoric acid triamide was completely removed within a hydraulic retention time (HRT) of 24 hours and proved to be a highly degradable substance. Nitrification inhibitors showed 50% mass recovery (except for 3,4-DMPP) after an HRT of 4 days. A slight effect of NUI on microbial biomass was observed. This study highlights that hydraulic retention time and microbial biomass are key indicators for the degradation of NUI.

How to cite: Zeeshan, M., Scheurer, M., Förster, C., Kuebeck, C., Ruhl, A. S., and Klitzke, S.: The fate of nitrification and urease inhibitors in simulated bank filtration, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9942, https://doi.org/10.5194/egusphere-egu23-9942, 2023.

Karst aquifers are vulnerable to contaminations due to their specific characteristics which allow for a rapid recharge and high velocities within the saturated zone. Contaminants such as pathogenic bacteria, viruses, and antibiotic resistance genes (ARG) can enter the groundwater and reach springs at high concentrations (Auckenthaler et al., 2002). This poses a potential threat, especially considering that drinking water treatment is less effective against microbial contaminations (Auckenthaler & Huggenberger, 2003) or missing, particularly in developing countries. Potential input of such contaminants is related for example to spills and leaks of waste water or application of manure. Many small-scale laboratory studies have been performed to understand the mobility of virus and bacteria, yet only little is known from large scale field tracer tests.

We performed tracer tests using different non-pathogenic bacteria, bacteriophages, and extracellular DNA as surrogates for pathogens and ARGs together with uranine within the catchment of the Gallusquelle karstic spring. The average flow velocities in the groundwater system were about 30 and 87 m/h during our tracer tests. Tracers were injected as instantaneous input (10 minutes input time). Periodical sampling for the biological tracers started with the first detection of uranine about 80 to 90 hours after injection. Bacterial and eDNA tracers were analysed using qPCR methods while bacteriophages were additionally analysed using a culture-based method (plaque assay) to count active phages. First data indicates that all tracer materials were successfully injected into the groundwater and detected at the Gallusquelle spring. Results of the first tracer test suggest that all used tracer materials were transported over at least 3 km within the system. Furthermore, active bacteriophages of the second tracer test were transported over 9 km from a stormwater detention basin to the spring within 90 hours. 1D-transport modelling revealed much lower mass recovery for these active phages compared to the soluble tracer uranine (about 1% as maximum compared to approximately 31% for uranine).

Auckenthaler, A., Raso, G. & Huggenberger, P. (2002): Particle transport in a karst aquifer: natural and artificial tracer experiments with bacteria, bacteriophages and microspheres. Water Sci. Technol., 46, 131-138

Auckenthaler, A. & Huggenberger, P. (2003): Schlussfolgerungen und Empfehlungen. In: Auckenthaler, A. & Huggenberger, P. [eds.]: Pathogene Mikroorganismen im Grund- und Trinkwasser. Birkhäuser Verlag, Basel, 184 S.

How to cite: Serbe, R., Schiperski, F., Stelmaszyk, L., Stange, C., and Scheytt, T.: Transport of bacteria, bacteriophages, and extracellular DNA as surrogates for pathogens and antibiotic resistance genes in a karst aquifer (Gallusquelle, South-West Germany), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11903, https://doi.org/10.5194/egusphere-egu23-11903, 2023.

Leptospirosis is a zoonosis caused by pathogenic Leptospira shed in the urine of mammals, able to survive in water and soils and remobilized during rainy events. Pathogenic Leptospira (PL) concentrations were measured together with hydrological variables in the upper Thiem river, near the Touho village, a hot spot for leptospirosis in the main island of New Caledonia (a small tropical island itself a hot spot for leptospirosis). Two hundred twenty-six water samples were collected at the outlet of as 3 km² sub-watershed, which is frequented by invasive mammals (rodents, deer and wild pigs) known to be animal reservoirs for leptospirosis. The main features of our results highlight that (i) samples collected at the beginning of a rain event occurring after a dry period may contain high PL concentrations (ii) PL concentrations at the heart of a wet period exhibit significant correlation with rainfall, water level and suspended matter concentration (SMC) (iii) elevated PL concentration may be observed a few days after the main flood event and within weakly turbid waters, (iV) the largest PL concentrations were observed in the middle and at the end of a wet rain season. Comparison of PL concentrations with hydrological data (rainfall, water level, SMC, soil moisture) reveals that they cannot be explained by a linear combination of hydrological variables. Indeed, nonlinear machine learning models provided a fair fit to observed data (99% of explained variance on their decimal logarithm and a mean ratio of 2.5 between raw observed data and modeled values). Comparison of identical machine learning models of water levels, SMC and PL concentration shows that the remaining error in PL concentration data does not only result from the limited dataset but rather from the intrinsic characteristics of the Leptospira signal. Our results may help to refine recommendations for leptospirosis control towards local populations. Further studies in larger watersheds draining in more populated areas will be conducted to confirm and extend these findings

How to cite: Genthon, P., Thibeaux, R., Selmaoui-Folcher, N., Tramier, C., Kainiu, M., Soupé-Gilbert, M.-E., Wijesuriya, K., and Goarant, C.: Hydrological driver for leptospiroses abundance in a small tropical catchment ? Example from the New Caledonian leptospirosis hot-spot, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1646, https://doi.org/10.5194/egusphere-egu23-1646, 2023.

Chromium (VI) [Cr(VI)] is abundantly used for several industrial applications especially in stainless steel production and as an anti-corrosive agent in ceramics, textile industries and tanneries. Despite its versatile uses, Cr (VI) is a major environmental threat and is a known carcinogen. Therefore, proper precaution must be implemented while working with Cr (VI) or while disposing it after use. Due to improper handling and lack of proper care, Cr(VI) is still found in industrial wastewaters or landfill sites. The Cr(VI) in landfills can leach into the ground during rainfall and can risk the contamination of the groundwater causing a health catastrophe when consumed. This study focuses on effective Cr(VI) remediation by the process of adsorption. Magnetite particles synthesized by co-precipitation method at various temperatures (room temperature of 25^οC, 60^οC and 90^οC) are used as an absorbent for achieving maximum removal efficiency of Cr(VI) from water. An initial concentration of 10mg/l at pH 7.2 and time of contact 10 minutes is taken as the starting parameters for Cr(VI) for the batch adsorption studies. The surface morphology, chemical composition and the magnetic properties of the magnetite particles are determined from FESEM (Field Emission Scanning Electron Microscope), EDS (Energy-Dispersive  Spectroscopy) and VSM (Vibrating Sample magnetometer) characterization methods, respectively. The synthesis of the magnetite particles at various temperatures can affect both its physical (mainly pore size, shape, texture etc.) and magnetic properties and therefore can pose significant changes on the adsorption efficiency. The effect of the magnetite particle dose, pH of Cr(VI), time of contact between the magnetite particles and Cr(VI) and the effect of the change in the concentration of Cr(VI) are predicted in this study. A special focus is given on determining the variation in the magnetic properties of the magnetite particles due to different temperatures of synthesis. In case of any such noteworthy change in the magnetic properties, the alteration in the individual adsorption capacities of the iron-oxide particles are highlighted in this study. Langmuir and Freundlich isotherm models are used to predict the adsorption mechanisms.

Keywords: Adsorption; Magnetite particles; Characterization; Magnetic properties; Langmuir and Freundlich isotherms.

How to cite: Ganguly, S. and Ganguly, S.: Adsorption of Hexavalent Chromium by magnetite particles synthesized at various temperatures: effect of magnetic properties of the particles on individual adsorption mechanisms, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-160, https://doi.org/10.5194/egusphere-egu23-160, 2023.

Applications of nitrification and urease inhibitors (NUI) with nitrogen fertilisers on agricultural soils are intended to improve the efficiency of nitrogen fertilisers and also to prevent nitrogen emissions from the fertilisers. However, the deliberate release of chemicals into the environment carries a certain degree of risk due to spreading in the water systems. Both sensitive ecosystems and water supplies may be affected. Processes that need to be considered for a reliable assessment regarding the fate and distribution of these substances in the different compartments are manifold. So far, reliable predictions in literature are scarce and regulatory approaches are based on limited information on substance fate.

Yet, two out of the ten NUIs currently approved in Germany, have been found in surface waters, prompting further investigation. In this context, no analytical method has been established so far for some of the other NUIs, thus there is no information available on the occurrence of these substances. In order to gain transparency on the actual environmental fate and implications for drinking water production of these NUI has been analyzed In addition to legal approval procedure different processes and scenarios relevant to their fate were investigated in the INHIBIT project.

Following a comprehensive literature review, experimental investigations were carried out to further evaluate the environmental behaviour of these substances on an empirical basis. Initially, a multi-method was developed for the simultaneous determination of 1H-1,2,4-triazole (triazole), dicyandiamide (DCD), 3,4-Dimethylpyrazol-phosphate (DMPP), 3-Methylpyrazole (3-MP), N-(n-butyl)thiophosphoric triamide (NBPT) and N-(2-nitrophenyl)phosphoric triamide (2-NPT) in soil pore water. Experiments conducted in this research project provided essential empirical information on the hydrolysis stability, degradation behaviour and sorption tendency in soils for selected NUI. In addition, vessel, column, lysimeter and practical field application tests were carried out to obtain empirical information on the leaching risk of these substances via the transport pathway unsaturated zone-leachate-groundwater. Furthermore, the indirect input pathway via infiltrating surface waters (bank filtration) was investigated. Studies were carried out on different soils and using different parameters in order to depict different site conditions.

Results indicated a high hydrolysis stability for the nitrification inhibitors (NI) DCD, DMPP, 3-MP and triazole. The hydrolysis stability of the urease inhibitors (UIs) NBPT and 2-NPT is strongly pH-dependent. While NBPT is particularly unstable in an acidic environment, 2-NPT shows the lowest stability in a more alkaline environment. Sorption tendency to soils of all compounds was low. Microbial degradation of NI in soils was lower compared to urease inhibitors (UIs). Overall, the NI triazole, DCD, 3-MP and DMPP were found to be potentially relevant substances for drinking water production. The NI active substances DCD and triazole were additionally monitored in several surface waters and were frequently detected, in some cases at very high concentrations of several µg/L. These findings underline the relevance of these substances for water resources.

How to cite: Karges, U., Kübeck, C., aus der Beek, T., Sturm, S., Beisecker, R., Seith, T., Zeeshan, M., and Klitzke, S.: Nitrification and urease inhibitors - From fields to drinking water resources?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13821, https://doi.org/10.5194/egusphere-egu23-13821, 2023.

The number of trace pollutants released by anthropogenic activities is increasing exponentially, their distribution in the environment is often ubiquitous and tracking their fate in river systems via monitoring would require a prohibitive financial effort due to high analytical costs. In this context, models are an irreplaceable tool to identify and quantify emissions loads and to estimate concentration levels in unmonitored catchments. Within the Interreg project Danube Hazard m3c, a novel combined approach has been applied in the Danube River Basin. Firstly, the pathway-oriented MoRE model (Modeling of Regionalized Emissions) was applied at the mesoscale in seven largely diverse river catchments (sub catchments of 40-650 km2) located in four different countries. This semi-empirical and relatively data intensive model could be robustly applied thanks to a rarely available data basis, which was achieved via a targeted and harmonized measurement campaign carried out in multiple environmental and engineered compartments for selected trace pollutants representative of larger groups of substances with comparable patterns of diffuse and point emissions, namely agricultural biocides, industrial chemicals, pharmaceuticals and contaminants of both natural and anthropogenic origin. The high parametrization efforts of the MoRE model yield a quite accurate analysis of emission pathways (e.g. wastewater treatment plant discharges, groundwater and interflow, soil erosion) and estimation of contaminants concentration in the rivers. In a second step, the system understanding gained through MoRE was utilized to improve the performance of the DHSM (Danube Hazardous Substance Model, based on the EU SOLUTIONS model), also applied in the same seven catchments for comparison. This second tool is a source-oriented fate process-based model, with only limited regional data requirements (primarily hydrological data) and which thus requires a much easier parametrization. The parallel application of the two models in the test catchments revealed major differences in the identification of emission pathways, e.g. diffuse emissions of industrial chemicals (PFOS and PFOA) and pharmaceuticals, and in the estimation of emission loads of metals from hotspots, e.g. from mining sites. As last step, the improved version of DHSM was applied to the whole Danube River Basin to quantify the relevance of different sources and pathways of emissions for the selected indicator contaminants and to estimate the risk of exceedance of the environmental quality standards in unmonitored surface water bodies. An early application of the DHSM for 17 target contaminants revealed Danube River Basin-wide emissions ranging between 0.1 and about 4,000 tonnes per year, with the share of point sources ranging between < 1% to >95%. This contribution focuses on the enhanced system understanding and improved modelling performance gained through the novel combined application of both approaches and will include final updated and validated basin-wide emission estimates.

How to cite: Zoboli, O., Broer, M. B., Gabriel, O., van Gils, J., Loos, S., Kittlaus, S., and Zessner, M.: Coupling targeted monitoring, pathway-oriented data intensive modelling and fate process-based modelling to estimate emission loads and concentrations of trace pollutants in the Danube River Basin, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7290, https://doi.org/10.5194/egusphere-egu23-7290, 2023.

Treated and untreated domestic wastewaters that are discharged into surface waters often contain a variety of chemical substances, including residuals of pharmaceuticals that are not fully metabolized by the human body. These substances may be harmful to the health of aquatic ecosystems and to humans who rely on them as a source of water supply. Despite growing concerns and their frequent detection in wastewaters and surface waters, the concentrations of pharmaceuticals are not regularly monitored in water bodies. As an alternative to comprehensive monitoring campaigns that tend to be very resource intensive, contaminant fate models may be used to provide information to support the development of targeted local monitoring schemes in regions of highest exposure to pharmaceuticals in the environment as well as the prioritization of substances for further investigation.

In this work, a global contaminant fate model (called HydroFATE) was developed with the objective of estimating the concentration of contaminants of emerging concern (including pharmaceuticals) in the global river network at a high spatial resolution (500 m). The contaminant emission is calculated based on consumption per capita and population density. Then, the contaminant loads of treated or untreated wastewaters are reduced in the model either by centralized or decentralized wastewater treatment, by natural attenuation in soils and runoff, and/or by decay processes in rivers and lakes. HydroFATE’s structure is based on a vector routing structure, which besides its spatial precision being higher than in global pixel-based models, it is also fast to process. This key aspect allows for more complex analyses, including repeated execution of multiple substances and different scenarios in a short period of time, making HydroFATE a capable tool to inform on the prioritization of substances.

The model’s performance was validated by comparing predicted concentrations in river reaches worldwide against literature reports of measured concentrations of 22 broadly consumed antibiotics for which at least sparsely monitored data existed. The sensitivity of the model’s predictions was tested by altering key model parameters. This validation process showed that HydroFATE is generally able to predict aquatic concentrations measured worldwide to within one order of magnitude, which is judged to be sufficient for the intended purposes of the model.

Finally, HydroFATE was applied to estimate the concentrations of the 40 most widely used antibiotics in households worldwide and to compare these concentrations, both individually and cumulatively, to established no-effect thresholds of environmental exposure. It was estimated that a total of 8,500 tonnes of antibiotics per year are discharged into the river system. We found that 6.0 million km of rivers worldwide may have environmental exposure levels that exceed the no-effect concentration of antibiotic pollution during low streamflow conditions, with the largest extent of these rivers being in Southeast Asia, the most densely populated region in the world. The main contributors of exposure were found to be the widely and heavily used antibiotics amoxicillin, ceftriaxone, and cefixime.

How to cite: Ehalt Macedo, H., Lehner, B., Nicell, J., Khan, U., Klein, E., and Grill, G.: Modelling multitudes of pharmaceuticals in the global river system at high spatial resolution, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16837, https://doi.org/10.5194/egusphere-egu23-16837, 2023.

The near ubiquitous presence of pharmaceutical compounds in environmental waters represents an emerging cause for concern, but gaps remain in our understanding of how human and veterinary pharmaceuticals enter and travel through river catchments. A more holistic approach is needed in order to develop effective management strategies that conform to the catchment-based approach, although this is complicated by the patchy nature of available monitoring data for river water and by the significant seasonal variation in concentrations which makes comparisons even within datasets tenuous. Here, an exploration of pharmaceutical concentrations across the Aire catchment in the UK aims to provide insight into how the underlying connectivity of the catchment system, conceptualized as a source-pathway-receptor model, may determine observed patterns of contamination. To account for temporal variations of inputs and flow, samples collected on two separate occasions (corresponding to low and high flow conditions, respectively) were used to create two spatial snapshots for contamination with nine representative compounds. The snapshots were then used to explore spatial patterns in the catchment and what factors – topographic, physico-chemical, or related to potential sources and pathways for pharmaceutical pollution – may influence them. For the first snapshot, conducted in low flow conditions, none of the locations had concentrations above the limit of detection for five of the nine target analytes (Atenolol, Diclofenac, Erythomycin, Iopromide and Sulphadiazine). Results for the detected compounds have emphasized the difference in spatial patterns based on use category: as opposed to the veterinary use compound (Cypermethrin), the human use compounds (Carbamazepine, Lidocaine and Sucralose) showed significant correlation to contributing area, as well as to population served by the wastewater treatment plants upstream of the sampling sites and corresponding estimates for amounts of prescribed active ingredient. Sucralose also produced strong correlations to Carbamazepine and Lidocaine, supporting its use as a proxy for contamination with human pharmaceuticals, alongside the more frequently cited Carbamazepine. Ultimately, this research will inform the development of a graph representation of the system, used to assess the relative contribution of different pathways as they connect to the river channel and to inform as to the best intervention points within the catchment.

How to cite: Costescu, J., Bracken, L., Turnbull-Lloyd, L., Reaney, S., and Crilly, D.: Understanding the connectivity of pharmaceutical pollution in river catchments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17381, https://doi.org/10.5194/egusphere-egu23-17381, 2023.

Dublin Bay is a shallow bay located on the east coast of Ireland in Irish Sea. The water body is bounded to the west by Dublin City and to the east by the Irish Sea, with its northern and southern extents being defined by Howth Head and Dalky, respectively.  The southern side of the Bay includes the designated bathing waters of Sandymount Strand and the non-designated (but monitored) bathing waters of Merrion Strand. The water quality of these bathing areas remains vulnerable to numerous microbial pollution inputs, and these continue to present risks to recreational and economic activities that underpin much of the ecosystem service provision in the area, particularly during the bathing water that extends from June to September each year. Microbial pollutants are known to derive from agricultural diffuse sources in upland catchments and from point discharges from the wastewater drainage network, specifically during wet weather events when combined sewer overflows (CSOs) are active.  However, while accepted as being problematic in the overall pollution ‘mix’, concentrations of faecal indicator bacteria (FIB) from the faeces of dogs (dog fouling) and from local bird communities are less well understood – Dublin Bay was designated a 'biosphere reserve' by UNESCO in 2015 and remains home to numerous species of seabirds, many of which are present in internationally important numbers.

Here we present an assessment of the significance of FIB inputs from dogs and birds in their contribution to total faecal pollution in Dublin Bay.  The extent of dog fouling was assessed through five daily ‘beach sweeps’ on both Sandymount and Merrion Strands from 2019 to 2021. Eighty-one dog fouling events (30 and 51 on Sandymount and Merrion Strands, respectively) were observed, equating to an average of six fouling ‘events’ per day at Sandymount and 10 ‘events’ per day at Merrion. Laboratory testing was undertaken to determine average Escherichia coli (E. coli) and enterococci concentrations in the dog faeces.  BirdWatch Ireland (an independent bird protection organisation in Ireland) data from the Dublin Bay Birds Project (2013 to 2016) was used to quantify E. Coli and enterococci pollution loadings to Dublin Bay bathing waters deriving from the presence of both migratory and non-migratory bird populations during the bathing water season.

A coupled hydrodynamic and water quality model was integrated with sediment-bacteria interaction model which was further developed to simulate the inputs from dogs and birds. The model was then calibrated and validated with extensive water quality and ADCP (current speed and direction) measurements collected in nearshore areas around Dublin Bay to simulate the transport and fate of FIB in the study area.  The model included the freshwater (river) inputs carrying diffuse agricultural pollutants to the Bay, and the known point source pollution releases from within wastewater drainage network.  A dynamic decay rate, which included the effects of  temperature and light intensity was included in the model.

This research (Acclimatize) was part funded by the European Regional Development Fund through the Ireland Wales Cooperation Programme.

How to cite: Gao, G., O'Sullivan, J., Corkery, A., Reynolds, L., Martin, N., Sala-Comorera, L. S.-C., O’Hare, G., and Meijer, W.: Understanding the impacts of dogs and birds on faecal pollution of bathing waters in Dublin Bay, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10140, https://doi.org/10.5194/egusphere-egu23-10140, 2023.

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.

How to cite: Ameen, A., Steinbacher, S. D., Lun, D., Lindner, G., Derx, J., Sommer, R., Demeter, K., Linke, R., Blöschl, G., Blaschke, A. P., Kirschner, A. K. T., and Farnleitner, A. H.: Navigating the Danube: A data-driven approach to evaluate the impact of inland shipping on faecal pollution, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4369, https://doi.org/10.5194/egusphere-egu23-4369, 2023.

Livestock-breeding relies on a large array of pharmaceuticals. Many of them may pose a risk to aquatic life if they reach surface water bodies.  Depending on their physicochemical properties, some pharmaceuticals present strong sorption coefficients and are thus not expected to reach surface water bodies under most conditions. Mediterranean climate is characterized by a dry summer followed by intense storm events. We studied the effect of this climatic condition on the risk of transfer of pharmaceutical residues to streams at the catchment-scale. The study area is the 42km² Claduègne catchment in the French Ardèche department. It is characterized by extensive agricultural land-use under Mediterranean climate.

Surveys with local livestock farmers were conducted in order to identify the commercial pharmaceutical products and the active ingredients systematically used in the study area as well as their application rate, frequencies and seasonal patterns. Stream water was analyzed on high frequency (up to 3h^-1) during flood events and compared to some samples outside of flood events. A total of 32 liquid water samples were collected and analyzed for 3 veterinary pharmaceuticals systematically used in the study area as well as 14 molecules of various use. They were concentrated via solid phase extraction and analyzed using high performance liquid chromatography (HPLC) coupled to a tandem mass spectrometer. The concentration values where below the limits of detection (0.1 - 1 ng L^-1) most of the time, but peaked at high concentrations for short periods during flood events. The concentration reached up to 355 times the Predicted No Effect Concentration (PNEC) for Fenbendazole FBZ, the antiparasitic used in pork in the region. This indicates that rapid transfer processes during flood events represent an elevated risk of transfer of these molecules toward streams. Parallel transit time modelling revealed high event water fractions during flood events in the studied catchment.

We conclude that under these climatic conditions, special care should be taken after treatment application to avoid pastures that are hydrologically connected to surface water bodies. In addition, the results suggest that low-frequency monitoring is not sufficient to detect these high concentration levels that exist during very short durations of a few hours or less.

How to cite: Hachgenei, N., Nord, G., Spadini, L., Robinet, N., Baduel, C., and Duwig, C.: Transfer patterns of pharmaceuticals used in agriculture into streams under Mediterranean climate at the catchment-scale, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15047, https://doi.org/10.5194/egusphere-egu23-15047, 2023.