Due to the increasing demand of water, urban aquifers are an alternative source of water supply. However, they are at risk of contamination from persistent and mobile organic compounds (PMOCs), especially per- and polyfluoroalkyl substances (PFASs), which are artificial organic substances widely used across various industrial sectors. PFASs are considered toxic, mobile and persistent, and have therefore gained significant attention in environmental chemistry. Moreover, PFASs precursors transform into more recalcitrant and mobile products under natural conditions. Therefore, it is needed to investigate the fate of PFASs when they reach aquifers to use groundwater safely. However, there is limited information about the processes which affect their behaviour in groundwater, especially at the field-scale. In this context, the aim of this investigation is to assess and identify processes that control the evolution of PFASs in an urban aquifer in Barcelona, where groundwater behaves analogously to a river bank filtration system. A part from PFASs, 4 PMOCs were also analysed. During a summer campaign, 21 groundwater and 6 river samples were collected revealing the presence of 17 PFASs products, 3 novel PFASs and 4 PMOCs non-PFASs. PFASs products were found to be ubiquitous, with the highest concentrations found in PFBS, TFA and TFSA. Non-PFASs and novel PFASs, with the exception of Sulfanilic acid, were found to be present in very low concentrations. It was observed that the redox conditions influence the behaviour of a number of PFASs controlling their attenuation capacity or recalcitrant behaviour. Most substances showed accumulation, possibly explained by sorption/desorption processes or by transformation processes, highlighting the challenges associated with PFASs remediation. In addition, the PFAS TFSA and two of the longest chain PFASs detected presented removals at different intensities. Our results will have tremendous implications for establishing the evolution of PFASs along the groundwater flow and might be extended to similar research areas such as Manage Aquifer Recharge techniques.

How to cite: Sáez Camacho, C., Bautista, A., Nikolenko, O., Scheiber, L., Farré, M., Jurado, A., and Pujades, E.: Occurrence and fate of perfluoroalkyl and polyfluoroalkyl substances (PFASs) in an urban aquifer located at the Besòs River Delta (Spain), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-658, https://doi.org/10.5194/egusphere-egu24-658, 2024.

Nitrification inhibitors and urease inhibitors are organic chemicals that have been used in agriculture for decades to slow down nitrification in order to keep plant-available ammonium in the soil for longer and to reduce the leaching of nitrate. Furthermore, they serve to reduce the rapid conversion of urea to ammonia, which also has a positive effect on climate protection. Being applied to agricultural fields, there is a high risk that these substances are contaminating water bodies. We therefore initiated both an environmental sampling campaign and a lab study of the environmental fate characteristics of selected nitrification inhibitors and urease inhibitors.

In our first study, we took samples in Northern Hesse and the area of Goettingen (Germany) from streams, lakes and groundwater between October and December, mainly in agricultural areas. The samples were then analysed for six different nitrification and urease inhibitors (1) 3,4-dimethylpyrazole phosphate (DMPP), (2) 4-amino-1,2,4-triazole (ATC), (3) Dicyandiamide (DCD), (4) N-(2-nitrophenyl)phosphoric triamide (2-NPT), (5) Mixture of N-((5-methyl-1H-pyrazol-1-yl)methyl)acetamide and N-((3-methyl-1H-pyrazol-1-yl)methyl)acetamide (MPA) and (6) H-1,2,4-Triazol. We found solely two of the inhibitors in the samples, DCD and H-1,2,4-Triazol, which corresponds to the results of a study from 2014 published by the DVGW.

In a second study, we wanted to examine under what circumstances and with what dynamics the inhibitors are transferred to deeper soil zones and what influence they have on the leaching of nitrate at different temperatures and in different soils. For this purpose, we chose the above mentioned five nitrification or urease inhibitors (1-5), which are currently used in agricultural fertilizers in Germany. In order to obtain information about their behavior in the environment, we have planned a study to investigate their leaching and transformation behavior in the unsaturated soil zone. For this purpose, agricultural topsoils were selected and filled into 25 cm high columns with a diameter of 7 cm. Three fertilizers containing the above-mentioned compounds were applied separately to the soil columns at an application rate of 150 kg N/ha. Each of the variants was tested in triplicate in two different temperature ranges (12 °C, 20 °C). Irrigation was carried out over 12 weeks with a groundwater recharge rate of the fall/winter period. The leachate was analyzed 1-2 times a week and at the end of the study the soil was analyzed at two different depths for the inhibitors as well as nitrate and nitrite.

How to cite: Weidemann, E., Dülfer, J., Matthes, K., and Gassmann, M.: Nitrification inhibitors in the soil-groundwater-river continuum of Germany, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2088, https://doi.org/10.5194/egusphere-egu24-2088, 2024.

Treated and untreated wastewater enters estuaries via point source discharges, after which complex estuarine hydrodynamics can retain high concentrations of pathogens in these systems for days to weeks, posing a serious risk to public health. Through comprehensive fine scale three-dimensional numerical modelling, this research aims to study drivers of pathogen dispersal in estuaries and pathways of pathogen distribution. An interdisciplinary approach, combining knowledge from numerical modelling with laboratory derived data on pathogen behaviour and interactions with sediments, has been taken to improve the reliability of the model: 1) key fine-scale estuarine processes, i.e. current (including density current), turbulent mixing, and sediment transport have been studied using a process-based numerical model; 2) decay curves of target pathogens obtained through laboratory experiments for different water temperature, salinity, UV radiation have been implemented in the model; 3) the model also aims to incorporate pathogen attachment to sediments, their deposition, resuspension and subsequently altered decay rates.

The Conwy estuary in North Wales, UK, has been used as our case study. The estuary holds considerable historical and contemporary significance in terms of shellfishery and tourism. With a catchment area of 678 km² supporting a population of ~80,000 and large pastures, the estuary is susceptible to a range of pathogens, posing a public health risk via ingestion of bathing waters and indirectly via sea food.  The transport of pathogens from point sources, including wastewater discharge and sewage overflow, into the coastal environment has been studied under both current and future climate conditions such as sea level rise, warmer coastal waters, stronger river flow and population growth drawn from climate projections. As a further aspect of this research, conceptual estuarine systems will also be used to study fate and transport of pathogens under common estuarine dynamics and under representative climate scenarios.  This integration will allow for a more holistic approach that widens the applicability of the findings.

This research will provide improved understanding of pathogen dispersal in coastal waters and the impact of climate change on pathogen distribution and potential exposure to humans. It will also provide insights for the development of adaptation strategies to protect public health under changing environmental conditions.

How to cite: Li, X., Robins, P., Kevill, J., Malham, S., and Jones, D.: Modelling pathogen dispersal and distribution in estuarine systems under changing environment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2535, https://doi.org/10.5194/egusphere-egu24-2535, 2024.

Numerous chemicals enter surface waters via various emission pathways. One important group of those are biocides, which are used in a broad range of products, e.g. as disinfectants, agents against insects, for rodent control, or as material preservatives. Biocides are primarily used in urban areas, collected and transported in sewer systems either to sewage treatment plants (STP) or directly to the receiving water body (stormwater outfalls). During heavy rainfall events, however, sewage treatment plants cannot completely treat the increased sewage volume. Therefore, a part of the untreated sewage water, that contains also biocides, enters the surface waters as combined sewer overflow (CSO).

To assess the importance of different urban emission pathways of biocides, a study was conducted in Germany in the exemplary catchment of the river Alb flowing through the city of Karlsruhe. Water quality decreases by passing the city area from a good status to a bad status as defined in the Water Framework Directive (WFD). It is questioned if and which urban entry pathway contributes to which extent to the increasing pollution of the river Alb. Between 03/2021 and 12/2023 in total 130 samples were taken from the river Alb, the effluent of the municipal STP, combined sewer overflow and storm water outfalls and subsequently analysed for 42 biocidal substances, mainly disinfectants, material preservatives and pest control products. 26 out of 42 substances were detected: 13 in the river water while 26 substances were detectable in the urban emission pathways. These substances are mainly used as material preservatives, e.g. carbendazim, diuron, isoproturon and terbutryn, and were detected in approximately 90 % of all samples. For some substances the environmental quality standard (EQS) or the predicted no effect concentration (PNEC) are exceeded. For example, in CSO-samples the concentration of the insecticide permethrin exceeds 6 to 12-fold the PNEC for surface water. Even in consideration of a regulatory dilution factor of 10 for the discharge into surface waters, the PNEC is exceeded. This can be seen as an indication that pyrethroids used in urban areas are mainly transported into surface waters via CSOs, where they pose a risk to aquatic organisms. Due to low environmental concentrations and associated challenging analytical methods, other pyrethroids were not or only seldom detected.

Present results show that biocidal substances used in material preservation products are (continuously) released via numerous pathways into surface waters, and combined sewer overflows are important emission sources of biocides in the aquatic environment. However, the findings of a part of the substances investigated cannot be unambiguously attributed to a biocidal application, since the same substances can be used as, for example, human or veterinary pharmaceuticals. Nevertheless, the project provided important insights into the occurrence of biocides in urban runoff components and identified combined sewer overflows as a relevant emission pathway in urban areas which needs further to be investigated.

How to cite: Meier, C., Ziegler, K., Kopp, L., Sacher, F., and Fuchs, S.: Release of biocides in an exemplary urban river in Germany, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5835, https://doi.org/10.5194/egusphere-egu24-5835, 2024.

Braided rivers were deeply investigated as regards their morphodynamical evolution, conversely less interest was shown for the role that their peculiar topology can play in other phenomena, such as transport processes.

Our work deals with the link between the river network structure and the downstream transport of scalars, for example chemical substances (nutrient or pollutant) or suspended sediments. The river network acts as a mixer on the injected substance, thus causing a dispersion effect on the transport process. This phenomenon - known as geomorphological dispersion in the river networks at basin scale - becomes particularly relevant in braided rivers due to the complexity of their networks and their possible crucial impact on fluvial water quality.

Adopting the approach of GIUH theory, we develop a mathematical model for the dispersion in braided rivers. In particular, we assume to inject a given initial distributions of the scalar in the network inlets and aim to compute the outlet discharge by only considering the network properties, i.e. discharges at bifurcations, branches travel times, and network topology.

What we observe from the results is a strong dominance of the network topology over branch-specific hydraulic properties with regard to the outlet distributions, meaning that the properties at the network scale seem to have more influence than those relative to the scale of the individual branch. Moreover, we show how the outlet distributions depend on network properties. We find that, as the network grows, temporal distributions become closer and closer to Gaussians.  This behaviour - expected in light of the central limit theorem - is caused by the succession of bifurcations and reconnections interspersed with branches having different travel times.

How to cite: Vendruscolo, M., Camporeale, C. V., and Ridolfi, L.: Dispersion induced by braided river morphology, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7656, https://doi.org/10.5194/egusphere-egu24-7656, 2024.

Comprehensive monitoring of priority pollutants and emerging contaminants is considered necessary to provide insights concerning the quality of ecosystems. Chemicals such as plant protection products, pharmaceuticals, illicit drugs, personal care products, as well as per- and polyfluoroalkyl substances (PFAS) often end up in the environment and are distributed in different compartments. Human related activities and sewage facilities’ inability to remove them from the wastewater stream seem to be the main sources of contamination of the marine ecosystem. Upon ending up in the natural environment, both biotic and abiotic processes, such as hydrolysis and photolysis, take place, producing transformation products (TPs), suspected to be the cause of even more potent effects compared to parent compounds.

The region of Thessaly, Greece, was severely struck by sequential major storm events named “Daniel” and “Elias”, during the fall of 2023. Approximately 1.5 million tons of water per square kilometer rained down the surrounding area of Pagasitikos Gulf (Aegean Sea, Eastern Mediterranean) each day the phenomena were in effect. Naturally induced environmental change such as these may increase the number of chemicals, which end up in the marine ecosystem and relate to anthropogenic activities, often causing unpredictable damage to indigenous fauna and flora. Many of these compounds reach humans through the food chain and are classified as persistent, bioaccumulative and toxic (PBT).

Aiming to extract as many contaminants as possible from the studied samples, generic sample preparation protocols were applied using multilayer mixed-mode SPE cartridges to enrich the final extracts with thousands of LC-amenable, non-volatile, thermal unstable, semi-polar to polar, organic micropollutants.

The analytes were chromatographically separated using Reversed Phase Liquid Chromatography (RPLC). The chromatographic system was linked to a hybrid Trapped Ion Mobility Spectrometer coupled to High Resolution Mass Spectrometer (TIMS-HRMS). The occurrence of more than 2,000 chemicals from different chemical classes was investigated in the acquired HRMS-data through wide-scope target analysis based on strict identification criteria. TIMS provides an additional dimension of separation, adding increased value of confidence to the identification criteria, minimizing false positive selection, further optimizing wide-scope target screening methodology via HRMS analysis.

Preliminary results indicate the presence of numerous plant protection products in seawater and sediment samples, associated with agricultural activities, such as Azoxystrobin and Atrazine along with their respective TPs: Azoxystrobin acid and 2-hydroxy-atrazine, desethyl-atrazine and desisopropyl-atrazine. Pharmaceutical compounds were also detected in some cases, especially in areas close to wastewater treatment plants, such as Carbamazepine, along with its’ metabolites: 10,11-epoxy-carbamazepine and 10-hydroxy-carbamazepine, findings that could be attributed to reported overflowing of nearby sewage treatment plants, during the flood events. The presence of PFAS is also confirmed, following the detection of compounds such as Perfluorooctanesulfonic acid (PFOS) and Perfluorooctanoic acid (PFOA), possibly linked to the destruction of industrial and port infrastructure.

This work was funded by the Ministry of Development & Investment, National Strategic Reference Framework (NSRF) - Operational Program: “OP Transport Infrastructure, Environment and Sustainable Development”, in the frame of the Monitoring program for the ecological quality of rivers, transitional and coastal waters according to WFD 2000/60/ΕΕ

How to cite: Lougkovois, R., Parinos, K., Gkotsis, G., Nika, M.-C., Thomaidis, N., Pavlidou, A., and Hatzianestis, I.: Monitoring the presence of priority pollutants and emerging contaminants at Pagasitikos Gulf, Greece, following “Daniel” and “Elias” storm events, utilizing the technique of LC-VIP-HESI-TIMS-HRMS, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7985, https://doi.org/10.5194/egusphere-egu24-7985, 2024.

The increasing worldwide release of anthropogenic chemicals compounds into the aquatic ecosystems has led serious contamination of freshwater resources.  This study investigated the chemical composition of the water and sediments of L'Albufera Natural Park, Valencia, Spain, an area heavily impacted by intensive agriculture, surrounded by an industrial belt, highly urbanized and historically polluted. The goal was to assess the different water sources and anthropogenic influence in this managed area using nontarget analysis (NTA) combined with high-resolution mass spectrometry (HRMS). Surface water and sediment samples were collected from 51 sites during two sampling events in the May/June 2019 and September/October 2019. These two periods were selected because the most relevant crop in the area are rice fields and these two periods coincides with the starting of the cultivation and the harvest. The HRMS data was processed using Compound Discoverer™ version 3.3, and the results were analyzed using Principal Component Analysis (PCA). Agricultural practices are one of the most important sources of contaminants (mostly pesticides) including at concentrations >100 ng L^-1 acetamiprid, azoxystrobin, chlorfenvinfos, chlorpyrifos, difenoconazole, dimethoate, fluvalinate, imazalil, imidacloprid, omethoate, propazine, tebuconazole, terbumeton deethyl, terbuthylazine, thiabendazole and tricyclazole. Increased presence and intensity of organic contaminants along the waterway was observed, indicating significant anthropogenic influence in the area. The NTA and post-processing were evaluated for reproducibility, demonstrating robustness with a 71.2% average reproducibility for compounds detected the 2 sampling trips. A detection frequency of 80% was the set criterion for detected compounds suggested as tracers. To prioritize samples, hierarchical cluster analysis was employed, and potential tracers for each water source were determined. Additionally, urban-influenced contaminants such as insect repellents, pharmaceuticals, and non-agricultural herbicides were identified along the channels that transports treated wastewater to the Natural Park. This study highlights the impact of human activities on L’Albufera Natural Park and demonstrates the effectiveness of NTA in differentiating and tracking water sources. The results emphasize the importance of reproducibility in NTA and provide guidance on implementing monitoring strategies by prioritizing samples based on chemical compositions.

How to cite: Picó, Y., Soriano, Y., and Andreu, V.: Suspected and non-targeted analysis of environmental contaminants in water and sediments of L’Albufera Natural Park by liquid chromatography-high resolution mass spectrometry, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10676, https://doi.org/10.5194/egusphere-egu24-10676, 2024.

Water columns and bottom sediments in freshwater bodies are two interacting environmental compartments that exchange microorganisms during both high-flow events and periods of base flow. The objective of this work was to quantify the coupled dynamics of FIB populations in water columns and bottom sediment using the three years of weekly monitoring E. coli and enterococci at forested, agricultural, and suburban land use locations along the montane creek in Pennsylvania, USA. Sediment was sampled in triplicate from the surface 0-1.5 cm layer. For both E. coli and enterococci, two population characteristics were used: (a) logarithm of concentrations in MPN per unit of mass of water or sediment, (logC_water and logC_sediment) and (b) areal density in MPN cm^-2. The annual cycle of logC_water and logC_sediment annual cycle mimicked the sine-like changes in air temperature with amplitudes of 3 to 3.5 orders of magnitude. For both organism groups, relationships between water and sediment populations were convex; slopes of linear regressions of logC_watervs. logC_sediment varied from 0.756 to 0.918 and from 0.274 to 0.533 for E. coli and enterococci, respectively; the least of the nonlinearity was observed at the forested site. Weekly increments of the E. Coli logCsediments nonlinearly increased with the total precipitation over the week with the rate of about 0.012 per mm precipitation. In the absence of precipitation during the week E. coli logC_sediment decreased with weekly rates of 0.205±0.040 and 0.089 ±0.065 over warm and cold periods respectively. The ratio of the areal densities of FIB populations in water and sediment was overall large at the agricultural and suburban sites compared with the forested site.  The ratio tended to increase as the water stage increased. The bulk of the E. coli and enterococci populations was in the water column at agricultural and suburban sites and in the sedimentsat low flows. 

How to cite: Pachepsky, Y., Harriger, M. D., Panko Graf, C., and Stocker, M.: Coupled dynamics of indicator bacteria populations in water columns and bottom sediments of a mountain creek, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11480, https://doi.org/10.5194/egusphere-egu24-11480, 2024.

The microbial quality of irrigation water is a major worldwide health concern. Assessments of irrigation water quality are conducted via the measurement of the fecal indicator bacteria Escherichia coli. More recently, the levels of antibiotic resistant bacteria in irrigation water have been highlighted as an emerging concern as they may be spread from surface waters to crops and soils. Composite sampling has been recommended in cases when larger sample sets cannot be collected across a waterbody. However there have been no reports which have compared the results of composite sampling with the spatial means or medians of fecal and antibiotic resistant bacteria within irrigation waters. The objectives of this work were to evaluate the representativeness of composite samples for estimating the levels of fecal and antibiotic bacteria in several irrigation ponds. In August and September of 2022, water samples were collected from dense sampling grids within five irrigation ponds in Maryland and Georgia, USA. Concentrations of generic, tetracycline, and cefotaxime-resistant E. coli and total coliforms were enumerated in all samples. Three composite samples were created for each pond: a composite of the interior, bank, and full sample sets. In general, we found the distributions of generic and antibiotic resistant bacteria concentrations did not significantly differ between bank and interior samples. Concentrations of antibiotic resistant bacteria ranged substantially across all the waterbodies. On average, the composite samples fell between the 60^th and 70^th percentile of the concentration distributions. In only a 9 and 14.5 % of cases (n = 90) did the composite sample value significantly differ (p < 0.05) from the mean or median, respectively, of the entire sample sets. Results of this work indicate that composite sampling may accurately be used to estimate the spatial mean or median of generic and antibiotic resistant bacteria concentrations in irrigation waters. These results will be used to improve the estimation of fecal contamination of irrigation waters as well as the presence of antibiotic resistant bacteria. 

How to cite: Stocker, M., Smith, J., and Pachepsky, Y.: Assessment of composite sampling for determining the levels of fecal indicator and antibiotic resistant bacteria in irrigation water, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12548, https://doi.org/10.5194/egusphere-egu24-12548, 2024.

The Brazilian biomes degradation puts the quality and integrity of aquatic ecosystems at risk. The disorderly advancement of human activities such as industry, livestock and agriculture make water resources vulnerable to contamination. In this way, the use and occupation of land in the river catchment directly reflects the possible contaminants that may be detected in surface waters. The Uruguay River catchment comprises the Pampa and Atlantic Forest Biomes in southern Brazil, in addition to parts of Argentina and Uruguay. It is estimated that there is a small portion of vegetation remaining in relation to the initial vegetation cover in this catchment, with a high fragmentation degree, due to intense degradation. Therefore, the objective of this study is to evaluate the emerging contaminants presence in the Uruguay River and biomarkers in fish Astyanax sp. exposed to the mixture of these contaminants in situ. To this end, samples of water, sediment and fish were collected over a year in 5 locations distributed along the Uruguay River (around 300km). The occurrence of metals, pesticides, medicines for human and animal use and hormones in water samples was analyzed, and the presence of pesticides in sediments and fish muscles. The presence of 14 active pesticide ingredients was detected, the insecticide imidacloprid being the most common, 13 medicines, 1 female hormone and 7 metals in the water. The presence of 4 pesticides and 3 pesticides bioaccumulated in the fish muscles were detected in the sediments. The results obtained in this study are extremely important for evaluating the contamination of a river basin of international importance. With this, it is possible to determine the possible river contamination sources, and, thus, define or propose improvements in management and mitigation measures aimed at improving environmental quality.

How to cite: Clasen, B., Storck, T., Tiecher, T., and Silveira, A.: Biomonitoring of emerging contaminants in a river in southern Brazil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13136, https://doi.org/10.5194/egusphere-egu24-13136, 2024.

Resource scarcity has increased interest in the circular economy (CE) for environmental, economic, and social sustainability. The goal is to minimize waste generation and efficiently incorporate waste back into production processes without adversely impacting human health or the environment.

By recognising the importance of assessing the potential accumulation of chemicals and associated  risks within the CE, the Horizon 2020 project PROMISCES focuses specifically on the so-called "forever chemicals" such as per- and polyfluoroalkyl substances (PFAS) in five CE routes, including semi-closed water cycles for drinking water (DW), wastewater reuse in agriculture, nutrient recovery from sewage sludge, material recovery from dredged sediments, and groundwater and land remediation for safe reuse.

Based on the results from literature reviews, experiments and case studies, the project addresses the fate and transfer of PFAS across these CE routes. Despite the challenge of analysing PFAS in complex matrices such as sludge and wastewater, robust and sensitive methods have been developed and the following conclusions can be obtained:

Wastewater treatment provides a limited removal efficiency, especially when wastewater treatment plants receive large contributions from industrial wastewater streams. Advanced wastewater treatment technologies implemented for micro-pollutant removal are not fully effective for all PFAS. Additionally, degradation of precursors can result in increased PFAS concentrations in the effluent. Consequently, until new treatment solutions are implemented, PFAS hotspots may not be able to implement wastewater reuse (e.g. for irrigation).

Riverbank filtration, as a first DW treatment stage, demonstrates limited removal of PFAS. Accordingly, in the presence of an upstream emission source, DW providers may need to implement advanced water treatment technologies.

During wastewater and landfill leachate treatment, particularly long-chain PFAS may accumulate in sludge. Although low level of targeted PFAS compounds were quantified, the presence of precursors in sludge is suspected and may present a barrier to its agronomic valorization. To date, PFAS content in sewage sludge is not regulated and depending on the country, sludge may be spread on agricultural land, incinerated, or disposed in landfills. 

Valorisation of dredged sediment as secondary raw material has the advantage of limiting the cost of management and limiting the use of raw materials. Depending on the nature of the sediment (in particular organic matter content) and on the PFAS loads, different treatments result in different removal efficiencies. Moreover, treatments can result in the formation of new persistent PFAS from precursors. When initial loads are low, it seems possible to eliminate PFAS from the solid fraction. Nevertheless, the destruction of residual PFAS in the washing solution is necessary.

In situ and on-site treatments of water and soil are confronted with environmental realities. Even if treatment trains can help overcome the complexity of PFAS treatment, the process efficiency is highly dependent on the alkyl chain length and the functional groups. As for sediment, although various treatment techniques exist, such as PFAS immobilisation, these do not result in complete degradation or removal of PFAS. This stands in the way of achieving a CE, as only after full removal of PFAS, safe reuse of resources can be guaranteed.

How to cite: Lions, J., Togola, A., Groot, H., Bakker, M., van Hullebusch, E. D., Miehe, U., Zhiteneva, V., Dulio, V., Boucard, P., Hartmann, J., Heine, N., Track, T., Sperlich, A., Zessner, M., Bosch, C., Sgroi, M., Fatone, F., Jou Claus, S., and Colombano, S. and the H2020 PROMISCES project partners: Fate and behaviour of PFAS in natural resources: towards a safe circular economy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16438, https://doi.org/10.5194/egusphere-egu24-16438, 2024.

Persistent elevated levels of heavy metals in river water used for irrigation can accumulate in aquatic and terrestrial organisms, disrupting the food chain, altering species compositions, and leading to ecosystem instability. An integrated risk assessment is thus essential to comprehend the cumulative effects of ongoing contamination, offering insights into the severity of hazards associated with heavy metal containing river water. The present research aims to analyze the spatial and temporal variations in the hazard index (HI) and ecological risk index (ERI) based on surface water samples collected along the Kali River. Further, this study pinpoints major heavy metals posing heightened risks, aiming to identify hotspot zones within the river basin. Seasonal water quality monitoring revealed elevated concentrations of Cr, Mn, and Ni during the pre-monsoon. Conversely, in the post-monsoon period, Cr, Fe, Mn, Zn, Cd, and Pb exceeded the drinking water standards established by BIS 2012 across the entire stretch of the Kali River. The ERI findings indicated that during the post-monsoon season, none of the water samples fell into the low ecological risk, whereas about 80% of samples were classed as low ecological risk during the pre-monsoon season. The observed seasonal shift in the computed ecological risk is likely attributed to the wash-off effect and the discharge of agro-industrial waste during the post-monsoon period. Moreover, the values of the ecological risk are higher at the upstream water sampling locations compared to downstream, indicating the effect of the dilution caused by domestic sewage originating from economically developed districts in western Uttar Pradesh state. Similarly, the findings from HI associated with human health indicate that both adults and children face potential carcinogenic and non-carcinogenic risks at all water sampling locations during post-monsoon season. However, in pre-monsoon season, only 34% of water sampling sites reported non-carcinogenic risk. Finally, a correlation was established between predicted risk indices and the observed data encompassing human health, community feedback, and ecological survey results. The findings indicate a robust correlation of 76% among sampling locations along the Kali River, indicating elevated environmental vulnerability in the basin. This study highlights the degraded condition of the Kali River ecosystem, posing threats to both humans and ecology. This necessitates immediate action for effective mitigation strategies to safeguard public health, preserve ecosystems, ensure the safety of agricultural and aquatic resources, and adhere to regulations for sustainable water management in the basin.

How to cite: Dwivedi, P. and Yadav, B. K.: Assessment of Integrated Health and Ecological Risks linked with Heavy Metal Pollutants in the Agro-industrial basin of Kali River, India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16658, https://doi.org/10.5194/egusphere-egu24-16658, 2024.

Shiga toxin-producing Escherichia coli (STEC) are zoonotic agents causing human gastroenteritis, with symptoms ranging from asymptomatic/mild to bloody diarrhoea and in rare cases haemolytic uraemic syndrome (HUS) and death. STEC serogroups O157 and O26 are most commonly linked to infection. Waterborne transmission represents a key exposure route and occurs through contamination of drinking water sources with human or mammalian faeces. Ireland has consistently reported the highest STEC infection rates across the EU. This study sought to investigate STEC concentrations in surface water bodies and groundwater wells located in the Corrib catchment in western Ireland over the peak human infection periods.

From late May to early December 2023, 19 sites comprising river (n=5) and private groundwater wells (n=14) were sampled on a fortnightly basis in the Black River sub-catchment of the Corrib catchment. Colilert-18® and quantitative PCR were employed to monitor the presence of total coliforms, E. coli and STEC serogroups targets O157 (rfbE) and O26 (wzx). Measured physico-chemical parameters included pH, temperature, and dissolved oxygen content, in addition to river discharge and groundwater table. These were amalgamated with publicly available data, including groundwater vulnerability and rainfall data from Geological Survey Ireland (GSI) and Met Éireann, and continuous river level and discharge data from the Office of Public Works (OPW).

Overall, 265 samples were collected comprising 75 river samples and 190 groundwater samples. E. coli was detected in 178 samples (67%), including all 75 river samples and 103 (54%) of groundwater samples.

STEC was detected in 225 samples (85%) overall and in 119 (67%) of E. coli positive samples. A total of 168 samples (64%) tested positive for STEC O157, comprising 34 rivers (45%) and 134 groundwaters (71%). STEC O26 was detected in 56 samples overall (21%) and was more prevalent in rivers (n=22, 30%) than groundwater (n=34, 18%). Of 103 E. coli positive groundwaters, 86 were STEC positive, giving a STEC to generic E. coli detection ratio of 83.5%. STEC O157 was detected in 82 (80%) and STEC O26 was detected in 24 (23%) of E. coli positive groundwaters.

Rainfall peaked in July (224.1mm), leading to increases in river discharge (2.137 m³/s mean peaking at 6.058 m³/s in mid-July) and groundwater level (10.11m mean peaking at 9.77m two weeks after heavy rainfall). STEC O157 concentrations peaked in the river samples during August (80% positive, mean concentration of 1.3x10⁶ copies), and later in groundwaters (64% positive, mean concentration of 3.1x10⁵ copies) during September. STEC O26 concentrations peaked earlier in late July for river samples (10% positive samples, mean concentration of 3.58x10⁵copies) and early July for groundwater (22% positive, mean concentration of 2.9x10⁶ copies).

We describe the dynamics of STEC in surface and groundwaters of a catchment in western Ireland. The peaks for STEC serogroups O157 and O26 in groundwaters correlate with “traditional” human peaks of infection for these serogroups in Ireland and are preceded by peaks in surface water concentrations. Findings will be useful in designing strategies for source protection and risk management of drinking water supplies.

How to cite: Hynes, R., Alfahl, Z., O'Connor, L., De Bock, F., Burgess, C., Hynds, P. D., O'Dwyer, J., and Burke, L. P.: Longitudinal monitoring of Shiga toxin-producing Escherichia coli (STEC) concentrations in surface waters and groundwater supplies within an Irish catchment., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16975, https://doi.org/10.5194/egusphere-egu24-16975, 2024.

The presence of pharmaceuticals in the aquatic environment is known to scientists and is constantly being investigated. Such micropollutants with bactericidal, virucidal, or fungicidal properties are commonly used in households, which results in their presence in raw sewage flowing to wastewater treatment plants. The content of pharmaceuticals may vary depending on the lifestyle of the inhabitants or the intensity of drug consumption. This study analysed the content of antibiotics, virucidal and fungicidal substances in raw and treated sewage from one of city located in southern Poland with a population equivalent of 680,000. Furthermore, the study was conducted in the summer and autumn-winter seasons.

Microplastics are one of the largest pollutants in the world. Since the 1970s, it has already existed, but there has been no better alternative than plastic. It is related to easy and cheap production, high availability, and specific properties of plastics, such as plasticity, chemical resistance, and lightness.

In the research, samples of stabilized sewage sludge were analyzed in terms of quantitative and qualitative analysis. The separation of microplastics was carried out in two stages. First, the sample matrix was digested with 15% hydrogen peroxide. The next step was density separation, where a saturated solution of calcium chloride was used. Separated microplastics were counted and their sources of origin were analyzed using a Raman confocal microscope and ATR FT-IR spectrometer. The samples were divided according to the month of their collection.
The production of organic-mineral fertilizers from sewage sludge is one of the ecological possibilities of their management. Pharmaceuticals and their derivatives, as well other micropollutants which get in the sludge during the treatment of wastewater, can be a problem. The negative impact of these micropollutants on the environment has been scientifically proven, and the pharmaceuticals and microplastics contained in the sludge may also be detected in fertiliser products.

Acknowledgments: Research supported by the Polish National Agency for Academic Exchange in the Bekker programme (no. PPN/BEK/2020/1/00243/) as well by the Polish National Science Centre (grant no. 2022/45/B/ST10/02108). Research was partially supported by the program ‘Initiative for Excellence – Research University’ for the AGH University of Krakow. Research supported under the Implementation Doctorate in the program of the Ministry of Science and Higher Education.

How to cite: Styszko, K., Bolesta, W., Worek, J., Kaleta, D., Nalepa, A., Pyssa, J., Cwynar, K., Prus, Z., and Frydel, L.: The occurence of pharmaceuticals and other micropollutants in wastewater treatment plant in the aspect of interaction with microplastics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20853, https://doi.org/10.5194/egusphere-egu24-20853, 2024.

Iodinated Contrast Media agents (ICMs), essential in diagnostic imaging, have seen a surge in usage within the healthcare sector. This rise has sparked significant environmental concerns, primarily due to the fact that ICMs can evade capture by standard wastewater treatment facilities, subsequently accumulating in environmental waters [1]. This situation underscores the urgent necessity to develop more sustainable and effective methods for the removal and recovery of ICMs from aquatic systems. Over the past ten years, the scientific community has been actively exploring various materials that could serve as potential adsorbents to extract ICMs from natural waters [2]. Although practical experiments have demonstrated the effectiveness of different adsorbents in removing ICMs, there is a pressing need for a detailed mechanistic understanding of the adsorption process. In response to this need, our research delves into the mechanistic adsorption behaviour of ICMs using a model of activated carbon, represented by a monolayer graphene surface. By focusing on the interactions at the molecular level, we aim to advance the predictive modelling of ICM adsorption and contribute to the development of more targeted and efficient removal strategies for these pervasive substances in our water systems. We utilized molecular docking and Density Functional Theory (DFT) simulations to scrutinize the adsorption process on a molecular level [3]. Additionally, we applied Quantitative Structure-Activity Relationship (QSAR) modelling to link molecular characteristics with adsorption energy, aiding in understanding the influential factors in the adsorption process and building a predictive model [4]. We developed a variety of QSAR models through the combination of Multiple Linear Regression and genetic algorithm. To evaluate and prioritize these models, our study employs Maximum Likelihood estimation alongside established evaluative criteria. These criteria aid in determining the probability for model accuracy of each model, thereby refining the QSAR methodologies. Based on our results for 24 ICMs involved in this study we observed the varying adsorption energies from -4.40 Kcal/mol (Methiodal) to -40.35 Kcal/mol (Iobitiridol) suggesting a selective adsorption of ICMs. We observed that van der Waals interactions such as π-π stacking to be the primary mechanism of adsorption. Our DFT results also highlighted a significant correlation between adsorption energy and the Molecular weight of the ICMs. Furthermore, based on our final QSAR model, we observed that structural properties such as molecular complexity, presence/absence of Iodine atoms and molecular complexity play a strong role in the adsorption of ICMs on the adsorbent.

References:

1. Sengar, A., Vijayanandan, A., 2021. Comprehensive review on iodinated X-ray contrast media: Complete fate, occurrence, and formation of disinfection byproducts. Science of the total environment 769, 144846.

2. Dekker, H.M., Stroomberg, G.J., Prokop, M., 2022. Tackling the increasing contamination of the water supply by iodinated contrast media. Insights into Imaging 13, 30.

3. Orio, M., Pantazis, D.A., Neese, F., 2009. Density functional theory. Photosynthesis research 102, 443–453.

4. Roy, K., 2017. Advances in QSAR modeling. Applications in Pharmaceutical, Chemical, Food, Agricultural and Environmental Sciences; Springer: Cham, Switzerland 555, 39.

How to cite: Khan, A. U., Porta, G. M., Riva, M., and Guadagnini, A.: Mechanistic study of the adsorption of Iodinated Contrast Media agents on monolayer Graphene surface, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21920, https://doi.org/10.5194/egusphere-egu24-21920, 2024.

Sulfamethoxazole is a sulfonamide class antibiotic commonly used to cure infections caused by bacteria in humans and animals. Sulfamethoxazole is considered a contaminant of emerging concern and is one of the most frequently found antibiotics in the environment. It has proven to be highly stable and persistent in the environmental matrices, with a half-life of more than 100 days in an aqueous environment under specific environmental conditions. This causes a severe threat to human and environmental health. The presence of residue of sulfamethoxazole in water matrices shows hazardous effects on aquatic life, affecting the physiological behaviour and reproductive capacity of aquatic organisms. Sulfamethoxazole also showed potential negative impacts on the microbial communities. The persistence of these compounds for an extended period in the environment leads to the formation of antibiotic-resistant genes in bacteria, which can affect the proper functioning of the ecosystem. In this current study, the effectiveness of the electrooxidation process on the removal of sulfamethoxazole using graphite electrodes was investigated. The effect of different parameters like the electrolysis time, current density, initial concentration of sulfamethoxazole, electrolyte concentration (NaCl or Na₂SO₄), and initial pH of the sample solution were evaluated. Out of the various parameters, it was found that current density (1-10 mA/cm²), electrolyte concentration (100- 500 mg/ L), and the electrolysis time (0-1h) are the key parameters that determine the efficiency of the electrooxidation treatment process. It was found that for the current density value of 10 mA/ cm², within 45 min of electrolysis time, nearly 99% of the sulfamethoxazole degradation occurred. The possible sulfamethoxazole degradation mechanisms and resulting by-products were analyzed using the Liquid chromatography-mass spectroscopy (LC-MS). Degradation kinetics were also evaluated for the electrooxidation treatment process. The results from the current study showed that electrooxidation could be a favourable treatment technique for the removal of sulfamethoxazole from water matrices.

How to cite: Joshy, A. and Goel, S.: Electrooxidation for the removal of Sulfamethoxazole using graphite electrodes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-983, https://doi.org/10.5194/egusphere-egu24-983, 2024.

Cyanotoxins in agricultural irrigation waters pose a potential human and animal health risk. Cyanotoxins can be transported to crops and soil during irrigation; they can remain in the soils for extended periods and be absorbed by root systems. Spatial and temporal variations of cyanotoxin concentrations have been reported for various freshwater sources. However, little has been reported for agricultural irrigation ponds. The objective of this research is to determine if persistent spatial and temporal patterns of the cyanotoxin microcystin occur in agricultural irrigation ponds over several years. The study was performed at a commercial irrigation pond in Maryland, USA, during the 2022-2023 summer sampling campaign over a fixed spatial 10-location grid on 16 sampling dates. Microcystin concentrations were determined using ELISA microcystin-ADDA kits. Ten water quality parameters were obtained using fluorometry and in-situ sensing. Temporal and spatial persistence was assessed using mean relative differences (MRDs) between measurements in each location and averaged measurements across the pond on each sampling date. Positive (negative) MRDs were found in locations where concentrations were predominantly larger (smaller) than the pond’s average. Persistent spatial patterns of microcystin concentrations were found. The pond’s flow conditions and bank proximity to sample locations were indicative of the MRD values signs and amplitudes. The highest absolute values of correlation coefficients were found between microcystin and pH, and microcystin and phycocyanin. The lowest absolute values for correlation coefficients were found for CDOM and chl-a. Results of this work show that microcystin concentrations can follow stable spatial and temporal patterns in irrigation ponds over multiple years, indicating that water quality sampling for cyanotoxins and placement of water intake should not be arbitrary. Research of the spatiotemporal variability of other cyanotoxin concentrations as well as understanding the degree of site-specificity of cyanotoxin concentration relationships with water quality parameters presents an interesting research avenue.

How to cite: Smith, J., Stocker, M., and Pachepsky, Y.: Multiyear spatial and temporal variability of microcystin concentrations in an irrigation pond in Maryland, USA, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6395, https://doi.org/10.5194/egusphere-egu24-6395, 2024.

Rapid and efficient quantification of E. coli levels is the important goal of the microbial water quality assessment. To address this, remote sensing and machine learning algorithms have been used recently. Application of these techniques encounter challenges from a limited number of samples and imbalances in water quality datasets. This study focused on estimating E. coli concentrations in a Maryland irrigation pond during the summer season. We utilized demosaiced drone-based RGB imagery across visible and infrared spectrum ranges along with 14 water quality parameters. Employing four machine learning algorithms (Random Forest, Gradient Boosting Machine, Extreme Gradient Boosting, and K-nearest Neighbor) under three scenarios, the research explored the utilization of only water quality parameters, both water quality and drone-based RGB data, and finally, only RGB data. Two data splitting methods, traditional random data splitting (ordinary data splitting) and quantile data splitting, were employed, with the latter providing a constant splitting ratio across each decile of the E. coli concentration distribution. Quantile data splitting resulted in a very good model performances and smaller differences between training and testing datasets. The RF, GBM, and XGB models, trained with quantile data splitting and hyperparameter optimization, resulted in R² values above 0.847 for training and 0.689 for the test dataset. The integration of water quality and imagery data led to larger R² values exceeding 0.896 for the test dataset. Shapley additive explanations (SHAP) highlighted the visible blue spectrum intensity and water temperature as the most influential inputs to the RF model. Overall, demosaiced RGB imagery proved to be a valuable predictor for E. coli concentration across the studied irrigation pond.

How to cite: Hong, S., Morgan, B., Stocker, M., Smith, J., Kim, M., Cho, K. H., and Pachepsky, Y.: Estimating Escherichia coli levels using drone-based RGB imagery and machine learning techniques, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6648, https://doi.org/10.5194/egusphere-egu24-6648, 2024.