This session invites contributions that improve our quantitative understanding of the sources and pathways, mass fluxes, the fate and transport and the mitigation of micropollutants in the soil-groundwater-river continuum of catchments.
Topics cover:
- Novel sampling and monitoring concepts and devices
- New analytical methods such as new detection methods for micropollutants, non-target screening
- Experimental studies to improve process understanding and to quantify diffuse and point source inputs
- Biogeochemical interactions and impact on micropollutant behaviour
- Fate studies on parent compounds and transformation products
- Modelling approaches (including hydrology and sediment transport) to simulate pollutant transport and fate at several spatial and temporal scales
- Spatial and temporal monitoring to elucidate transport processes and to support modelling
- Modelling tools for decision support
- Setup of mitigation measures and evaluating their effectiveness.
- Methods to evaluate water quality modelling uncertainty, and/or combining data and modeling (data assimilation)
Orals: Tue, 5 May, 08:30–10:15 | Room 2.31
Antimicrobial resistance (AMR) is an emerging environmental contaminant with direct implications for human and animal health, reinforcing the One Health premise that environmental integrity is foundational to health outcomes. We conducted a pilot catchment-scale study in western India to assess AMR prevalence and to distinguish dominant pathways associated with poultry expansion, poultry litter reuse, and human habitation. Four sub-catchments were selected to represent contrasting antibiotic pressure sources: i.e dense poultry farming (4 farms km⁻²), sparse poultry farming (2 farms km⁻²), agricultural fields receiving poultry litter as manure, and habitation (village), along with a reference control. We evaluated antimicrobial resistance using culture-based enumeration of antibiotic-resistant bacteria (ARB) and isolation of multidrug-resistant (MDR) species, complemented by a multiple antibiotic resistance (MAR) index to compare contamination pressure across settings. Poultry litter contained high ARB loads, with 2.5 × 10^7 CFU g⁻¹ resistant to tetracycline and 1.7 × 10^7 CFU g⁻¹ resistant to erythromycin. Seven MDR bacterial species were identified in litter, and five species had MAR index values > 0.2, indicating substantial antibiotic selection pressure. In contrast, no evidence of AMR bacteria was detected in soil and water samples collected immediately surrounding poultry farms, suggesting that strict disinfection protocols afect the prevelance of AMR around farm premises. However, agricultural soils located approximately 0.5 km from the nearest poultry farm, where poultry litter was applied as manure, showed clear AMR signals, including seven MDR species and two species with MAR index values > 0.2. Soil and water samples from manured (poultry litter) fields exhibited markedly higher resistance than unmanured fields, particularly to erythromycin, ampicillin, vancomycin, penicillin, and ciprofloxacin. Resistance was highest for vancomycin in soil (9%) and penicillin in water (52%) from manured fields. By comparison, unmanured fields exhibited <1% resistance in soil and 15% in water. Escherichia coli and Enterobacter spp. were detected in village and control soils with MAR index values < 0.2, consistent with comparatively lower antibiotic contamination.
Overall, the results indicate that land application of untreated poultry litter, rather than proximity to poultry farms alone, can be a key pathway for spread of ARB and resistance determinants into receiving agricultural environments. The study demonstrates a source-differentiated catchment approach to establish baseline AMR assessment protocols that can help disentangle contributions from animal husbandry, manure management, domestic sewage, and background resistance. We recommend the development and implementation of treatment, handling, and disposal protocols for poultry litter to enable safer agricultural reuse and reduce further AMR propagation.
How to cite: Jamwal, P., Ashwini, A., and Tamim Vanak, A.: Tracking antimicrobial resistance pathways in a poultry-intensive catchment, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3832, https://doi.org/10.5194/egusphere-egu26-3832, 2026.
The intensifying use of antibiotics in agriculture is accelerating the dissemination of antibiotic resistance genes (ARGs) in aquatic environments, posing an increasing threat to global water security. Despite their intrinsic link, surface water and groundwater are frequently studied as isolated compartments, overlooking the role of hydrological connectivity and the combined influence of agricultural pressures on ARG transport and risks.
This study investigated the antibiotic resistome within a hydrologically connected surface-groundwater system in an agricultural catchment characterized by intensive crop cultivation, livestock farming, and aquaculture. Using metagenomic sequencing and resistance risk assessment, we reveal that groundwater, generally assumed to be protected by natural filtration, is actually a critical yet overlooked hotspot of antibiotic resistance.
Groundwater exhibited approximately twofold higher ARG abundance, diversity, and resistance risk than surface water, dominated by multidrug resistance genes. While surface water resistome was more homogenized by hydrodynamic mixing, groundwater ARG profiles were strongly shaped by hydrogeological conditions and agricultural activity intensity. Livestock-impacted units showed the highest ARG loads and resistance risks in groundwater, reflecting intensive antibiotic usage and manure-derived inputs. Notably, aquaculture impacts were strongly influenced by hydrogeological conditions, with significantly higher ARG abundance and risks observed in high-permeability sandy aquifers compared to clay-dominated settings, likely reflecting rapid vertical infiltration and limited adsorption during subsurface transport.
Our findings identify groundwater as a major reservoir of antibiotic resistance in agricultural regions, emphasizing the urgent need to integrate groundwater into resistance monitoring frameworks and strengthen manure and aquaculture waste management to protect water security.
How to cite: Chen, T., Ruan, X., Stewart, D. I., and Chen, X.: Groundwater as an overlooked hotspot of antibiotic resistance in hydrologically connected agricultural catchments, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14521, https://doi.org/10.5194/egusphere-egu26-14521, 2026.
Pharmaceuticals are increasingly recognised as a class of emerging contaminants of concern in rivers. Their continuous release from human use and variable removal in sewage treatment works (STWs) can produce ecologically relevant concentrations and contribute to antimicrobial resistance. We developed a probabilistic catchment-scale model based on a Bayesian Belief Network (BN) to quantify pharmaceutical concentrations and the probability of exceeding predicted no-effect concentrations (PNECs) at a monthly time step. The BN embeds a stochastic mass-balance linking monthly prescribing rates, excretion fractions, STW removal efficiencies and river discharge to produce posterior distributions of concentrations for 16 pharmaceuticals at 20 monitoring points in a medium size Scottish catchment. Model inputs were derived from Scotland’s National Health Service (NHS) prescribing records, a literature compilation of excretion and removal data, and a calibrated SWAT hydrological model. Simulated posterior concentration distributions generally agreed with observations and were typically within one order of magnitude for most compounds, indicating satisfactory performance. Highest exceedance probabilities were predicted for azithromycin, diclofenac, ibuprofen and clarithromycin, particularly at heavily impacted sites and during low-flow summer months. Scenario analyses show that future drier summers (UKCP18 RCP8.5) increase exceedance probabilities, and that substantial reductions in prescribing or markedly improved STW removal efficiencies are needed to reduce risks for high-impact compounds. The BN framework transparently captures uncertainty, supports diagnostic inference to prioritise interventions and is readily extensible to include additional sources (e.g. combined storm overflow and septic tanks) and pollutant mixture risk assessment.
How to cite: Glendell, M., Troldborg, M., Gagkas, Z., Adams, K., Negri, C., Taylor, P., Zhang, Z., Cooper, P., Brown, A., May, L., Corrochano-Fraile, A., Beevers, L., and Tyler, A.: Probabilistic modelling of pharmaceutical pollution risk from sewage treatment work discharges using a Bayesian Network: application to a Scottish river catchment, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3135, https://doi.org/10.5194/egusphere-egu26-3135, 2026.
The occurrence of emerging persistent pharmaceuticals (PPPs) in groundwater (GW) systems is a growing environmental concern, particularly in areas under combined urban and agricultural pressure. This study applies an integrated numerical modeling approach to assess the fate and potential sources of PPPs in the Campina de Faro aquifer system (CF), southern Portugal. To simulate the hydrogeological dynamics of the study area, a GW flow model was developed and calibrated using MODFLOW-2005. Calibration was supported by field measurements and literature-derived hydrogeological parameters. Flow model outputs were used to perform backward particle tracking, enabling a probabilistic assessment of contaminant transport pathways and the identification of likely source areas. A reactive transport model was subsequently developed using MT3DMS to simulate the dispersion and fate of selected PPPs, incorporating processes such as advection, dispersion, and biodegradation. Moreover, a principal component analysis (PCA) was conducted which agrees with our modeling hypothesis, thus showing a discontinuity in the Cretaceous formation at the northwestern boundary of the aquifer system. PCA showed that some of the abstraction points are extracting from a different aquifer than previously believed, giving new insight into the conceptual understanding of the study area. The modeling framework demonstrates its effectiveness in delineating areas of contamination, potential sources, and characterization of PPP behavior in GW. This approach provides a valuable support tool for GW quality management and mitigation of risks associated with emerging contaminants such as PPPs in vulnerable aquifer systems.
How to cite: Tufoni, P.: Tracking pharmaceutical contamination in coastal aquifers: An integrated modeling framework for source identification and risk management in the Campina de Faro aquifer system (Portugal), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4946, https://doi.org/10.5194/egusphere-egu26-4946, 2026.
Human pharmaceuticals are essential in healthcare, but their discharge from wastewater treatment plants (WWTPs) poses a growing risk to aquatic ecosystems due to their biological activity at low concentrations. The amended EU Urban Wastewater Treatment Directive (UWWTD) in 2025 mandates quaternary treatment for large WWTPs (>150,000 population equivalents (PE)) to remove micropollutants and requires a risk-based prioritization for mid-sized plants (10,000-150,000 PE). A significant implementation gap has been identified, as the UWWTD does not yet specify a unified risk assessment methodology. In addition, numerous small WWTPs, frequently situated in vulnerable low-flow waters, are not directly addressed despite their cumulative impact and lack of monitoring data.
To address this issue and support decision-making, the APRIORA project developed an improved monitoring concept and a complementary, spatially high-resolution tool to provide estimates of pharmaceutical concentrations and related environmental risks in QGIS. This deterministic, steady-state model calculates annual per-capita loads discharged by each WWTP based on pharmaceutical sales data and WWTP-connected inhabitants. Substance-specific excretion and removal rates are incorporated either based on available monitoring data or literature. Point source emissions are transferred to the river network, and concentrations in different river sections are estimated using flow data. The regionalized yearly average flow data can be either integrated from external sources, or modelled using an integrated hydrological model in the QGIS plugin. Elimination processes occurring in the receiving waters, such as biodegradation, photodegradation and sorption to sediment particles, are neglected to ensure a conservative estimate. The resulting Predicted Environmental Concentrations (PECs) are used for calculating risk quotients (RQ). The modelling approach was piloted in five catchments (Germany, Finland, Latvia, Poland, Sweden).
To support the development of cost-effective mitigation strategies on a catchment scale, the tool allows for scenario assessment. Mitigation measures include: (I) upgrading the treatment type at a WWTP (e.g. from tertiary to quarternary treatment with higher removal efficiency), (II) relocating emissions by merging effluents of smaller WWTPs into larger facilities, and (III) redirecting the discharge point to a larger or less-sensitive receiving water body. The effectiveness of selected mitigation measures is directly visualized in mitigated risk maps. Testing mitigation measures for diclofenac in a German catchment showed that upgrading the three largest WWTPs (>10,000 PE) to quaternary treatment effectively reduced risks directly downstream. However, this measure alone did not mitigate risks in numerous other sections, underscoring the limited effect of focusing solely on mid-sized plants in rural areas with scattered, smaller WWTPs (Figure 1).
This easy implementable tool is designed for environmental authorities providing a consistent, spatially explicit methodology for prioritizing interventions to close the gap between regulatory requirements and practical water resource management. Beyond pharmaceuticals, the modelling approach is transferable to other substances where point-source emissions can be quantified, e.g., PFAS from industrial sites.
Acknowledgement - The authors thank the IBSR funding programme – co-founded by the European Union (ERDF) – and the APRIORA project.
How to cite: Seidenfaden, A., Guidi, C., Marzahn, P., and Tränckner, J.: Decision-Support Tool in QGIS for Pharmaceutical Emission Modelling, Risk Assessment and Mitigation Measures, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11236, https://doi.org/10.5194/egusphere-egu26-11236, 2026.
The environmental impact of pandemics is often evaluated by measuring disinfectant or drug concentrations in surface waters. This approach assumes that increased used of those chemicals leads directly to higher environmental concentrations. However, this assumption does not consider microbial degradation. Quaternary ammonium compounds (QACs), a group of emerging pollutants which were widely used during the COVID-19 pandemic, offer a clear example of this limitation in riverine systems.
In this study, we investigated the relationship between QAC concentrations and microbial biodegradation capacity in five major Turkish rivers sampled seasonally over one year. Summer samples were used as reference conditions, characterized by low COVID-19 case numbers obtained during the wastewater surveillance program. Winter and spring showed with statistically higher case numbers. Surface waters were analyzed for six QACs using LC-MS/MS. Total QAC concentrations ranged from <2 nM in low-impact rivers to >200 nM in urban-influenced systems. Despite relatively high COVID-19 cases, QAC concentrations during winter and spring often remained low (typically 1-10 nM) in several rivers.
Microbial measurements revealed that low QAC concentrations during peak pandemic periods were not due to reduced inputs but to enhanced biodegradation. Culture-based assays showed strong seasonal enrichment of QAC-degrading bacteria during winter and spring. Quantitative PCR targeting the QAC biodegradation gene qxyA showed copy numbers 2-5 fold higher in winter and spring samples compared to summer reference conditions. In multiple rivers, high qxyA copy numbers coincided with low or non-detectable QAC concentrations. In addition, microbial community resistance to fluoroquinolone antibiotics, which is also related to QAC exposure, substantially increased during winter and spring.
These results demonstrate a feedback mechanism in which increased QAC use selects for specialized degraders that rapidly remove QACs from the water column. As a result, chemical measurements alone underestimate the ecological impact of disinfectant use. Functional markers such as qxyA provide a more reliable indicator of anthropogenic pressure and microbial adaptation in riverine ecosystems under global change.
How to cite: Tezel, U., Altınbağ, R. C., Vardar, S., and Ateş, H.: Biodegradation masks the overall chemical impact of seasonal pandemics on riverine systems: The case of quaternary ammonium disinfectants during COVID-19, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5295, https://doi.org/10.5194/egusphere-egu26-5295, 2026.
Aquifers may naturally contain undesirable and toxic trace elements, known as geogenic contaminants. The presence of these micropollutants poses a major challenge for groundwater management, and has health, economic, and environmental consequences.
Areas with high concentrations, either elevated or exceed the guideline value of water standards, are generally identified through the analysis of groundwater data. However, it should be possible to predict these occurrences based on their presence in the solid matrices of aquifers and their mobilization controlled by the physicochemical conditions of the water.
To better predict the occurrence of inorganic natural pollutants, we have developed a methodology, based on an integrated approach to better understand the distribution of these elements in aquifers, the conditions controlling their presence, and their evolution in groundwaters.
The methodology combines two complementary approaches: i) predictions of geogenic elements content in rocks, including their speciation, using a source to sink methodology are cross-correlating with ii) hydrogeochemistry to identify water-rock interaction processes and the potential mobility of the elements according to physicochemical conditions (e.g., redox conditions). This makes it possible to predict the spatial distribution of geogenic elements (e.g. As, Se, F, etc.) as well as the processes of mobilization in groundwater.
Using a geographic information system (GIS), this study compares predicted occurrences using a source-to-sink (S2S) approach with available data including a large dataset on groundwater quality data (ADES data base, a national database publicly available). By interpretating the chemical composition of water, geochemical modelling via PHREEQC and geological data, it is possible to confirm but also to contribute to the S2S modelling.
The study focuses on aquifers linked to the Massif Central (France). Geological source-to-sink paleomaps and drilling data are used to correlate the availability in sedimentary deposits of elements such as arsenic (As), selenium (Se), fluorine (F), with the main periods of erosion, transfer, deposit and remobilisation between the end of the Cretaceous and the Miocene. Arsenic, in particular, is studied in various geological layers with a focus on its speciation and mobilization in confined aquifers such as the Beauce calcareous confined aquifer (Southern Paris Basin).
This approach presents a real interest in terms of groundwater quality, as it helps to anticipate water quality degradation linked to groundwater exploitation in aquifer impacted by the natural presence of geogenic metals.
This work is part of the PEPR OneWater DEESAC project (France 2030), illustrating a transdisciplinary approach combining geology, geophysics, geochemistry, and hydrogeology.
How to cite: Lions, J., Lasseur, E., Alus, L., Claveau, A., Lerouge, C., Durand, V., Briais, J., and Marlin, C.: Integrated approach for predicting geogenic contaminants in groundwater, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19712, https://doi.org/10.5194/egusphere-egu26-19712, 2026.
In addition to common pollutants such as organic matter and nutrients, an ever-growing range of chemicals increasingly threatens the quality of rivers and lakes, as well as the health of aquatic ecosystems. Understanding the main sources and transport pathways of these substances therefore represents a key scientific and management challenge.
Within the framework of the Tethys project, a hazardous substance emission model was developed for the Danube River Basin (DRB) through close cooperation among nine Danube countries. The modelling work was based on the systematic collection of concentration and emission data for multiple transport pathways, resulting in a substance-specific inventory that served as the foundation for emission modelling.
A common Danube-wide modelling tool was implemented using the MoRE (Modelling of Regional Emissions) framework. The model represents between four and eleven emission pathways for three substance groups: potentially toxic elements (PTEs), including six heavy metals and arsenic; industrial chemicals represented by the two most widespread per- and polyfluoroalkyl substances (PFOS and PFOA); and human pharmaceuticals represented by a widely used analgesic (diclofenac) and a psychoactive compound (carbamazepine). In addition to major point sources, the model accounts for numerous diffuse pathways, including groundwater, surface runoff, tile drainage, erosion, atmospheric deposition, and various legacy pollution sources such as landfills, aerodromes, and industrial disposal sites.
The modelling framework includes a newly developed retention approach that explicitly accounts for riverine retention for each substance group, as well as an uncertainty assessment module designed to quantify parameter uncertainty. This module is implemented within an R-based computational engine of the MoRE model.
Model validation was performed using long-term river monitoring data from existing operational monitoring networks, complemented by additional datasets collected by partner institutions during project implementation. Discharge data were provided by the participating countries.
The modelling results indicate that erosion, groundwater, municipal and industrial wastewater systems are the dominant emission pathways for PTEs, with pronounced spatial variability along the DRB. Point source contributions dominate in the Upper Danube, whereas agricultural-related diffuse pollution becomes increasingly important in the Lower Danube. For PFASs and pharmaceuticals, municipal wastewater represents the main emission pathway in most sub-catchments. In the case of PFASs, soils also act as relevant reservoirs, and associated pathways such as surface runoff, erosion, groundwater flow, and tile drainage may contribute substantially to riverine loads.
How to cite: Jolankai, Z., Kardos, M. K., Dudas, K., Lajko, T., Poto, V., Honti, M., and Clement, A.: Tracing Hazardous Substances from Source to River in the Danube River Basin, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20637, https://doi.org/10.5194/egusphere-egu26-20637, 2026.
India contributes approximately 3.75% of global pesticide consumption and applies comparatively low amounts per unit area (≈0.5 kg ha⁻¹); however, pesticide usage is strongly insecticide-dominated, with insecticides accounting for nearly 80% of total application. This study examines the occurrence, distribution, and transformation of pesticides in surface water and groundwater across agro-urban catchments of Guwahati, Assam, a rapidly urbanizing region influenced by intensive agriculture. Pesticides were widely detected in surface waters, reflecting combined inputs from agricultural runoff, irrigation return flows, and stormwater, whereas groundwater generally contained only trace concentrations (<1 ng L⁻¹), indicating effective subsurface attenuation. Surface water concentrations ranged from 0.01 to 92 µg L⁻¹, with the highest cumulative loads (>100 ng L⁻¹) observed in agro-urban catchments directly receiving agricultural drainage. Neonicotinoid insecticides dominated the chemical profiles, contributing more than 50% of total pesticide mass, with thiamethoxam, imidacloprid, clothianidin, and acetamiprid detected in over 70% of samples at typical concentrations of 10¹–10³ ng L⁻¹ and maxima approaching ~90 µg L⁻¹ at agriculturally influenced sites. Several transformation products, including thiamethoxam-urea and desnitro-imidacloprid, were consistently detected and in some cases exceeded parent compounds, accounting for 20–40% of the total neonicotinoid signal and indicating slow degradation and sustained environmental release. In contrast, herbicides such as 2,4-D, diuron, and metolachlor occurred less frequently (<40%) and at lower concentrations (<5 µg L⁻¹). Strong positive correlations among neonicotinoids and their metabolites (r > 0.7) suggest shared sources and transport pathways, while upstream sites showed lower pesticide diversity, underscoring the dominant influence of agro-urban activities on surface water contamination.
How to cite: Dogra, K., Kumar, M., Chakraborty, P., and Goswami, R.: From Fields to Rivers: Tracking Neonicotinoid-Dominated Pesticide Contamination in Agro-Urban Waters of Northeastern India, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20879, https://doi.org/10.5194/egusphere-egu26-20879, 2026.
Environmental and water resources agencies run comprehensive monitoring programs of pesticides and their transformation products in surface and groundwater systems to determine water pollution and to comply with the reporting obligations of the EU. Besides, institutions carry out additional monitoring programs serving different purposes, including a review of the registration process, finding evidence for risks that have been underrated so far, determining application errors or improper handling, and deriving recommendations for agricultural and water resources management. However, these programs are often considered to be of marginal value for research. Among others, usually pesticide application and management data are scarce, the input of other sources like, e.g., deposition of trifluoroacetate (TFA), is unknown, soil properties exhibit enormous but purely known spatial heterogeneity, and knowledge about transformation pathways of the active ingredients is limited.
Thus, there is urgent need for developing a blueprint for the analysis of such monitoring data that makes maximum use of the information but avoiding pitfalls of unjustified basis assumptions. We present an approach based on the analysis of a 4.5 years monitoring program with monthly sampling in twenty shallow groundwater wells in the Federal State of Schleswig-Holstein in North Germany. Agricultural management data were available for part of the capture zones of some wells but were not complete. Thus, a forward modelling was not possible. Instead, in a first step we aimed at assessing the effects of vadose zone and aquifer properties, filter screen depth, and weather conditions on the observed spatial and temporal patterns of the concentration of pesticide and transformation products (TP). Canonical correlation analysis of time courses of solute concentration and of groundwater head at the twenty groundwater wells revealed very close resemblance between both. In fact, groundwater head dynamics proved to be a very powerful predictor of pesticide and TP dynamics. This provides clear evidence that most of the observed dynamics reflects transient immobilisation and later remobilisation in the vadose zone rather than direct effects of pesticide application.
In a next step, support vector machine models were set up separately for various substances. They explained more than 90% of the total variance for most substances. There were some cases of characteristic deviation between the observed and simulated concentration that could be ascribed to recent applications of the respective active ingredients. In most cases, however, there was clear evidence for a long-term stock of substances being occasionally flushed to the groundwater during short episodes. In regard to TFA our analysis revealed strong indications for a major and increasing contribution of deposition from non-agricultural sources in peri-urban regions. We conclude that analysis of the residuals of the support vector machine models is a powerful tool for making efficient use of monitoring data, even in face of incomplete data about the boundary conditions.
How to cite: Kröcher, J., Lischeid, G., and Pfannerstill, M.: Deciphering complex signals: What can science learn from environmental pesticide monitoring? , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2713, https://doi.org/10.5194/egusphere-egu26-2713, 2026.
Posters on site: Tue, 5 May, 10:45–12:30 | Hall A
Nitrification inhibitors (NI) and urease inhibitors (UI) have been used in agriculture since the 1970s to inhibit key microbial and enzymatic nitrogen transformation processes in soil. When mixed into nitrogen-fertilizer, they reduce nitrate (NO3-) leaching, extend nitrogen availability in the form of ammonium (NH4+) and decrease ammonia emissions. But are there side-effects of this “magic” compounds?
In a soil column study, the leaching and transformation of five inhibitors (3,4-dimethylpyrazole phosphate [DMPP], dicyandiamide [DCD], 4-amino-1,2,4-triazole [ATC], reaction mass of N-((5-Methyl-1Hpyrazol-1-yl)methyl)acetamide, N-((3-Methyl-1H-pyrazol-1-yl)methyl)acetamide [MPA] and N-(2-nitrophenyl)phosphoric triamide [2-NPT]) were examined in two different field topsoils at two temperatures (13 and 19 °C). After 280 days, ATC showed the highest persistence among all examined NI and UI, with 15 - 30% of the applied mass remaining in the soil. The recovery rate depended on soil temperature, indicating biodegradation as a dominant process. The recovery rates of the other inhibitors were substantially lower (DMPP: 1.1 – 6.7%, DCD: 0.1 – 0.3%, MPA & 2-NPT < 0.1%). Also, evidence was found, that a compound in the soil was transformed into 1,2,4-triazole (TZ), as the masses of TZ increased by a factor of 8.2 - 9.8. Possible parent compounds were identified to be either ATC or pesticides which might have been in soil before the experiment and are known to transform into TZ.
To confirm ATC as a parent compound of TZ, we designed an aerobic transformation study following OECD Test Guidelines 307 for 90 days, with two different soils, two temperatures (16/30 °C) and two soil moistures (20/60% WHC). First preliminary results show that TZ is formed while ATC is degraded.
A second soil column study in which field subsoil was used, identical temperatures and the same masses of inhibitors without fertilizer were applied. The results indicate that at least 60% of the applied ATC mass (90 µg) was transformed into TZ. Only 0 - 0.02% of the applied ATC mass was found in the percolation water, while no ATC was detectable in the soil after 316 days.
Overall, ATC transport showed differences between topsoil and subsoil conditions. At a lower organic carbon content in the subsoil (Corg= 0.16%, 0.36%) compared to topsoil (Corg= 1.10%, 1.36%) no leaching of ATC was observed, and ATC was completely transformed. The clear formation of TZ across all studies confirms ATC as a relevant parent compound of a ubiquitously found metabolite.
How to cite: Krug, P., Weidemann, E., and Gassmann, M.: Another parent of 1,2,4-triazole? - Fate and transformation of 4-amino-1,2,4-triazole (ATC) in soil, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11076, https://doi.org/10.5194/egusphere-egu26-11076, 2026.
After decades of using nitrification and urease inhibitors (NI and UI) in agriculture to delay the rapid conversion of urea into ammonia (UI) as well as the nitrification, to reduce nitrate leaching and to maintain plant-available ammonium in the soil for a longer period, substantial knowledge gaps about their environmental fate still exist.
Synthetic compounds such as NI and UI can pose considerable risks, as their true environmental impacts are sometimes only revealed after extensive use, as demonstrated by historical cases of PFAS, DDT and PCBs. This underlines the necessity of studying the fate of synthetic chemicals as well as their potential transformation products before the damage is done.
For this purpose, an extensive meta-analysis of publications published after 1990, as well as databases such as the registration dossiers provided by the European Chemicals Agency (ECHA), was performed, focusing on transformation behavior, potential transformation paths and products, adsorption behavior in soils as well as physicochemical properties such as water solubility. This analysis included eight NIs and three UIs currently used in commercially available agricultural fertilizers: 1,2,4-triazole (1,2,4-T), 4-amino-1,2,4-triazole (ATC), 3-methyl-1H-pyrazole (3-MP), reaction mass of N-((5-Methyl-1H-pyrazol-1-yl)methyl)acetamide and N-((3-Methyl-1H-pyrazol-1-yl)methyl)acetamide (MPA), 3,4-dimethylpyrazole phosphate (DMPP), reaction mass of 2-(3,4-dimethylpyrazole-1-yl)-succinic acid and 2-(4,5-dimethylpyrazole-1-yl)-succinic acid (DMPSA), Dicyandiamide (DCD), 2-chloro-6-(trichloromethyl)-pyridine (Nitrapyrin) as well as N-(2-nitrophenyl)-phosphoric triamide (2-NPT), N-(n-Butyl)-thiophosphoric triamide (NBPT), N-(n-Propyl)-thiophosphoric triamide (NPPT).
The results showed that the availability of information varies greatly among the inhibitors. DCD, which was already used as a fertilizer at the beginning of the 20th century as well as nitrapyrin, are among the most widely used nitrification inhibitors and those with the most available information about their environmental behavior. Key parameters influencing degradation include temperature, soil water content and inhibitor concentration, which are closely linked to microbial processes; however, prior exposure to soil organisms and soil composition were also found to be influential.
In many publications about inhibitors, such as in the case of DMPP, the dissipation of the substance is focused. However, the whole transformation path and the dissipation processes such as volatilisation can be relevant, as dissipation does not necessarily imply the absence of environmental risk. Furthermore, DT50 values were found to be calculated inconsistently across studies; therefore, all values were recalculated using the same methodology. Also, new data was created using figures from publications which didn’t provide DT50 values or degradation rates were calculated using the emergence of its transformation products.
Information about other NIs, such as ATC, which is not among the most used inhibitors, or DMPSA, which was just introduced to the market in the last years, is scarce or not available. Regarding UIs, much information about the fast-dissipating NBPT is available, such as transformation paths and influences such as concentration and pH value. Almost no information was available about the structurally similar NPPT and scarce information for 2-NPT.
How to cite: Weidemann, E. and Gassmann, M.: The Environmental Afterlife of Nitrification and Urease Inhibitors: A meta-analysis of Transformation and Fate, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7117, https://doi.org/10.5194/egusphere-egu26-7117, 2026.
Per- and polyfluoroalkyl substances (PFAS) are a class of widespread anthropogenic chemicals that have raised serious health concerns over the last decades because of their potential as endocrine disruptors and carcinogenic effects. PFAS precursors (i.e., polyfluorinated compounds that are degraded biotically to short-chained, perfluorinated end products) stand out due to their high hydrophobicity and strong sorption to soils. Their strong sorption behaviour significantly slows down degradation; half-life times (DT50) can reach years. This study focuses on polyfluoroalkyl phosphate diesters (diPAPs) and their biodegradation behaviour under aerobic conditions. DiPAPs are used as coatings in paper products and are of particular interest due to their widespread occurrence in the environment, and particularly in Rastatt and Baden-Baden (South-West Germany) where the application of large amounts of contaminated paper sludge to agricultural soils led to a heavy PFAS contamination (Fabregat-Palau et al., 2025).
An uncontaminated soil was suspended in ultrapure water (liquid to solid ratio 10 L/kg) and spiked with 300 µg of 6:2 diPAP to check whether biodegradation occurred over a time span of 100 days. Known degradation products were found in an expected distribution at the end of the experiment. Perfluorohexanoic acid accounted for 23 % of spiked precursor, while perfluoropentanoic acid and perfluorobutanoic acid accounted only for 4.5 % and 0.7 % respectively. Perfluoroheptanoic acid was also detected (0.05 %) as a minor product. Although degradation products indicate defluorination steps, no significant increase in dissolved fluoride could be measured due to high background levels in soil. Concentrations of the intermediate product 5:3 fluorotelomer carboxylic acid showed a small increase at early times, but stagnated and finally decreased again over the course of the experiment, suggesting a kinetic limitation of the degradation further up the reaction chain. During the experimental run of 100 days, only 30 % of 6:2 diPAP was degraded. DT50 values were 247 days, which agrees with the few other data for 6:2 diPAP in other soils. Interestingly, the degradation seemed to speed up towards the end of the experiment. To evaluate the role of sorption, a parallel experiment was set up with an aqueous soil extract (at a liquid to solid ratio of 10 L/kg) that contained the necessary microbes but where all soil particles were filtered out, hence negating interference by sorption. In this system DT50 was 130 days, proving that without sorption biodegradation gets faster due to higher bioavailability of 6:2 diPAP.
Fabregat-Palau, J.; Zweigle, J.; Renner, D.; Zwiener, C.; Grathwohl, P. (2025). Assessment of PFAS Contamination in Agricultural Soils: Non-target Identification of Precursors, Fluorine Mass Balance and Microcosm Studies. J. Hazard. Mat., 490, 137798. DOI: 10.1021/acs.estlett.4c00442
How to cite: Hugger, P. T., Liu, B., Grathwohl, P., and Fabregat-Palau, J.: Determining the microbial degradation of diPAPs and the effect of sorption on their biotransformation, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11492, https://doi.org/10.5194/egusphere-egu26-11492, 2026.
Chemicals in the aquatic environment can be harmful to biota and may cause toxic risks to the aquatic ecosystems. A high number of these chemicals originate from households, manufacturing and industries and are released to the aquatic environment as point source when connected to wastewater treatment plants (WWTP´s). A subset of the substances is permanently released and the load is proportional to the number of people connected to WWTPs, while the concentration of these substances shows higher variability. Especially at low discharges of the receiving waters the toxic risk may increase due to reduced dilution.
With a hydrologically informed approach that combines river network hierarchy, river discharge, wastewater loads and spatial allocation of point sources we developed a parsimonious model to calculate the total toxicity risk at each location of wastewater treatment plant (WWTP) discharges. The total toxicity risk was calculated as the sum of individual risks for 42 substances selected from a reference mixture of chemicals being considered as representative for European wastewater treatment plant effluents for a river network in Central Germany with about 300 WWTP´s of various sizes.
The results showed consistent patterns of substance specific cumulative toxicity and allowed an assessment of toxicity risks locally and at catchment scale. Different scenarios were analyzed to evaluate the consequences of different strategies to minimize toxic risks either by (1) source control, (2) relocation of WWTPs or their effluents or (3) end-of-pipe solutions like the 4th treatment level depending on local conditions. With these capabilities the approach and model may support the implementation of the revised European Urban Wastewater Treatment Directive.
How to cite: Büttner, O., Finckh, S., Borchardt, D., Brack, W., Jawitz, J., and Busch, W.: Hydrologically-informed toxicity risks across river networks for mixtures of micropollutants discharged from wastewater treatment plants, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11581, https://doi.org/10.5194/egusphere-egu26-11581, 2026.
Aquatic ecosystems are continuously threatened by PAH contamination that represents significant toxicological risks to both environmental and human health. These pollutants enter water bodies mainly through atmospheric deposition or surface runoff, and their environmental fate is governed by complex physico-chemical factors and bioaccumulation processes. To evaluate PAH levels and their distribution patterns, the occurrence of 16 priority compounds was analyzed in various river matrices. The monitoring program included abiotic (bottom sediments, suspended solids, water) and biotic (fish, benthic organisms, biofilm) matrices. Samples were collected at 28 locations covering all major river basins in the Czech Republic during 2025. PAHs were detected in all matrices, with distribution of individual compounds depending on affinity for organic carbon or lipid. Levels of fluoranthene and benzo[a]pyrene in biota exceeded environmental quality standards at a number of monitored locations. Results also revealed spatial variability among the locations, reflecting diverse levels of anthropogenic pressure across the river basins. Overall, multi-matrix monitoring is essential for a comprehensive contamination assessment, as the unique properties of each compartment lead to uneven pollutant distribution in aquatic ecosystems.
How to cite: Roztočilová, H., Kodeš, V., and Mikl, L.: Distribution and fate of PAHs across multiple biotic and abiotic compartments in aquatic ecosystems, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16862, https://doi.org/10.5194/egusphere-egu26-16862, 2026.
Urban shallow aquifers are increasingly impacted by trace organic contaminants (TrOCs) originating from diffuse urban sources, often limiting their potential use as alternative water resources. At the same time, low-enthalpy geothermal energy (LEGE) systems are being implemented in cities as a sustainable solution for heating and cooling, inducing subsurface thermal perturbations that may influence biogeochemical processes and contaminant fate. This study investigates how LEGE systems affect the natural attenuation potential of TrOCs in a shallow urban aquifer, using a real-scale case study at the Mercat de Sant Antoni (Barcelona, NE Spain). The site hosts a large thermo-active foundation system directly interacting with the Barcelona plain aquifer. Groundwater was sampled monthly between October 2024 and July 2025 from upstream (TABO) and downstream (MABO) piezometers. Physicochemical parameters were monitored alongside the ongoing analysis of selected TrOCs, including pharmaceuticals, personal care products and pesticides, commonly detected in urban groundwater. Preliminary results have shown differences between up and downstream piezometers of the system regards to groundwater temperatures. These thermal differences are accompanied by marked shifts in redox-sensitive parameters. Dissolved oxygen concentrations decrease from 3–4.5 mg L⁻¹ upstream to values below 2 mg L⁻¹ downstream, while redox potentials shift towards more reducing conditions, reaching values as low as −350 mV at MABO. Electrical conductivity, pH and alkalinity show spatial variability across the system, whereas dissolved organic carbon (DOC) remains within a relatively narrow range (~1–2 mg L⁻¹). Such low-oxygen and reducing conditions downstream are consistent with environments where microbially mediated transformation processes may become more relevant for contaminant attenuation. High-resolution mass spectrometry is being applied for compound detection and quantification, and statistical analyses are ongoing. This contribution presents early observations aimed at assessing whether LEGE-induced perturbations influence TrOC attenuation and which physicochemical conditions control compound persistence or removal.
Acknowledgements: Financial support from MCIU/AEI/10.13039/501100011033 and (i) FEDER “one way to make Europe” through the grant PID2021-128995OA-I00, (ii) FSE+ through the grant RYC2022-037083-I, and (iii) European Union NextGenerationEU/PRTR through the grant CNS2023-144051.
How to cite: Badia, S., Gómez, S., Jurado, A., Pérez, S., Teixidó, M., and Pujades, E.: Do thermally activated foundations affect trace organic contaminant fate in urban aquifers? A case study from Barcelona, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10553, https://doi.org/10.5194/egusphere-egu26-10553, 2026.
1,4-Dioxane is commonly found as a co-contaminant at chlorinated solvent sites, most notably alongside 1,1,1-trichloroethane (1,1,1-TCA). To a lesser extent, it can also occur as a primary contaminant at sites where it is used as a solvent, such as in the pharmaceutical industry. Due to its widespread occurrence and classification as a likely human carcinogen, understanding its environmental fate is of significant interest.
The biodegradation of 1,4-dioxane occurs primarily under aerobic conditions, whereas anaerobic degradation has been shown to be negligible. Aerobic degradation may proceed either metabolically or co-metabolically and is initiated by monooxidation of the dioxane ring, followed by spontaneous oxidation and ring cleavage, ultimately leading to complete mineralization.
An increasing number of laboratory studies have investigated 1,4-dioxane–degrading bacteria, which may facilitate its removal. However, relatively few studies have directly assessed the relevance of these processes under field conditions. The primary objective of this study was to examine the in situ degradation of 1,4-dioxane in groundwater at various sites using compound-specific carbon isotope analysis (δ¹³C). The δ¹³C values of 1,4-dioxane extracted from these sites will be presented and discussed.
How to cite: Bernstein, A.: Degradation of 1,4-Dioxane in Groundwater – Field Study Integrating Compound-Specific Isotope Analysis, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3412, https://doi.org/10.5194/egusphere-egu26-3412, 2026.
Human pharmaceuticals have been detected in surface waters around the globe (Wilkinson et al. 2022), posing risk to ecosystems (Bouzas‐Monroy et al. 2022; Fent et al. 2006) as well as to human exposure through e.g. swimming (Duarte et al. 2022), entering drinking water (Zanni et al. 2025) or the food chain (Sleight et al. 2023). While the presence of pharmaceuticals in Europe has been proven through measurements widely (compared to other global regions) (Dusi et al. 2019), spatially explicit modelling approaches – including historical development of pharmaceutical pollution - rarely exist. This study addresses this shortcoming by presenting the grey water footprint and related water pollution levels of selected human pharmaceuticals across Europe from 1990-2019.
The grey water footprint is a volumetric indicator for water pollution, defined as the ratio of pollutant load to the maximum allowed concentration. For this study, the load was determined based on pharmaceutical sales data, human excretion rates and waste water treatment removal rates (Wöhler et al. 2020). Respective data was acquired through public sources and scientific literature. Both, spatial and temporal gaps were addressed by inter-and extrapolation and assumptions. For the maximum allowed concentration, EU’s WFD water quality standards and literature values are used. Resulting grey water footprints are compared to the available runoff to indicate water pollution levels (WPL) per (sub)catchment.
The results present the first Europe-wide grey water footprint analysis over a timespan of three decades. WPLs make an interpretation of the severity of pollution possible, indicating temporal trends and geographical hotspots.
References
Bouzas‐Monroy, Alejandra, John L. Wilkinson, Molly Melling, and Alistair B. A. Boxall. 2022. “Assessment of the Potential Ecotoxicological Effects of Pharmaceuticals in the World’s Rivers.” Environmental Toxicology and Chemistry 41 (8): 2008–20. https://doi.org/10.1002/etc.5355.
Duarte, Daniel J., Rik Oldenkamp, and Ad M. J. Ragas. 2022. “Human Health Risk Assessment of Pharmaceuticals in the European Vecht River.” Integrated Environmental Assessment and Management 18 (6): 1639–54. https://doi.org/10.1002/ieam.4588.
Dusi, E., M. Rybicki, and D. Jungmann. 2019. The Database “Pharmaceuticals in the Environment” - Update and New Analysis. German Environment Agency (UBA).
Fent, Karl, Anna A. Weston, and Daniel Caminada. 2006. “Ecotoxicology of Human Pharmaceuticals.” Aquatic Toxicology 76 (2): 122–59. https://doi.org/10.1016/j.aquatox.2005.09.009.
Sleight, Harriet, Alistair B. A. Boxall, and Sylvia Toet. 2023. “Uptake of Pharmaceuticals by Crops: A Systematic Review and Meta-Analysis.” Environmental Toxicology and Chemistry 42 (10): 2091–104. https://doi.org/10.1002/etc.5700.
Wilkinson, John L., Alistair B. A. Boxall, Dana W. Kolpin, et al. 2022. “Pharmaceutical Pollution of the World’s Rivers.” Proceedings of the National Academy of Sciences 119 (8): e2113947119. https://doi.org/doi:10.1073/pnas.2113947119.
Wöhler, Lara, Gunnar Niebaum, Maarten Krol, and Arjen Y. Hoekstra. 2020. “The Grey Water Footprint of Human and Veterinary Pharmaceuticals.” Water Research X 7 (May): 100044. https://doi.org/10.1016/j.wroa.2020.100044.
Zanni, Stefano, Vincenzo Cammalleri, Ludovica D’Agostino, Carmela Protano, and Matteo Vitali. 2025. “Occurrence of Pharmaceutical Residues in Drinking Water: A Systematic Review.” Environmental Science and Pollution Research 32 (16): 10436–63. https://doi.org/10.1007/s11356-024-34544-8.
How to cite: Wöhler, L.: Europe’s grey water footprint of human pharmaceuticals, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9725, https://doi.org/10.5194/egusphere-egu26-9725, 2026.
Rapid agro-industrial growth has intensified the heavy metal contamination in ungauged regions through changing land use and water quality. It is still unclear how to continuously monitor heavy metal pollution when it is influenced by urban wastewater, agricultural runoff, and industrial discharge. This study assesses the effects of agriculture and industrial expansion on water resources by combining hydrogeochemical assessment, hydrological modeling, and land-use change analysis. Remote sensing data were used to evaluate land-use change from 2005 to 2023, while a hydrological model was developed for the period of 2010-2023 to quantify variations in the water balance components. Seasonal water sampling was conducted across 64 sites in 2023, and samples were analyzed for heavy metals, major ions, and physicochemical parameters. The results indicate that between 2005 and 2023, built-up areas expanded by 1.5%, and agricultural land increased by 0.5%, leading to a 2% reduction in bare land and increased pressure on water supplies. Hydrological modeling revealed that intensified water extraction for industrial and irrigation purposes reduced groundwater recharge by approximately 40%, resulting in a corresponding 41% decline in water yield. These hydrological alterations have exacerbated regional water quality degradation. Water quality analysis showed that aluminum concentrations exceeded permissible limits in all samples during the pre-monsoon season. In contrast, elevated manganese concentrations were detected in all groundwater samples and 96% of surface water samples. Post-monsoon analysis further revealed widespread cadmium and mercury contamination in groundwater, with mercury exceeding safe limits in all samples. Among major ions, nitrate concentrations exceeded permissible limits in 64% of surface water and 12% of groundwater samples, while pH values ranged between 5.5 and 9.1. Collectively, these findings indicate that the reductions in regional water availability are associated with changing land-use patterns that are seasonally regulated and help in driving heavy metal movement across the region. This emphasizes the need for strengthened pollution control strategies, improved wastewater treatment infrastructure, and awareness of water management among stakeholders.
How to cite: Dwivedi, P. and Yadav, B. K.: Impact of agro-industrial expansion on heavy metal contamination in water resources of a poorly gauged basin., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16291, https://doi.org/10.5194/egusphere-egu26-16291, 2026.
In agro-ecosystems, heterogeneous sources and variable pathways of non-point source pollution complicate the understanding of antibiotic dynamics across the land-river continuum. A quantitative understanding of the mechanisms governing source-transport-fate processes of antibiotic dynamics remain limited. This study developed a distributed and process-based model to simulate daily fluxes of four tetracyclines (TCs) in an agricultural watershed and to identify key transport mechanisms and rainfall-driven controls. Results revealed that transport processes significantly influence TCs fate, with riverine processes outweighing terrestrial transport and source input. Rivers dissipated 74.3 % of terrestrial TCs, significantly related to cumulative riverine transport distance. Riverbed sediment acted as a source for 92.3 % of the year via diffusion, resuspension, and deposition, and high-flow conditions converted it from source to sink. Extreme rainfall events, heavy rainfall events, and prolonged rainfall events were identified as the three patterns driving antibiotic transport and fate from event-based results. Prolonged rainfall events, often overlooked, pose chronic risks through groundwater discharge and sediment diffusion. These findings underscore the critical role of in-stream processes and three distinct rainfall event patterns in governing antibiotic pollution, highlighting the necessity of integrating riverine management with rainfall-driven strategies in watershed-scale pollution control.
How to cite: Xie, H., Dong, J., Shang, M., Li, Y., and Lai, X.: Tracing micropollutants in the land-river continuum: mechanistic insights into antibiotic dynamics via high-resolution process-based modeling, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18099, https://doi.org/10.5194/egusphere-egu26-18099, 2026.
Antibiotics are synthetic broad-spectrum antibiotics that are widely used in human medicine, animal husbandry and aquaculture. China is a major producer of antibiotics. Poyang Lake is the largest freshwater lake in China. At present, there are still few research methods and applications for the simultaneous detection of multiple antibiotics in environmental water bodies. In this research, automatic solid phase extraction-ultra high performance liquid chromatography-mass spectrometry technology was used to simultaneously detect 27 antibiotics in 5 categories of macrolides, tetracyclines, quinolones, nitroimidazoles and sulfonamides in water. Based on this method, the concentration and distribution of 27 antibiotics in surface water, groundwater and wastewater of Poyang Lake Basin were analyzed. The ecological risk quotient method was used to evaluate the ecological risk of Poyang Lake Basin, in order to provide data support for ecological environment protection and antibiotic pollution prevention and control in Poyang Lake Basin. The results show that:
(1) Automatic solid phase extraction was used as the pretreatment method for antibiotic detection in water, and the process steps of the technology were optimized. Most of the recovery of ultrapure water was between 51.07% and 112.58%, and the recovery of matrix was between 56.16% and 137.57%. The limits of detection were 0.01-0.44 ng·L-1, and the limits of quantitation were 0.03-1.36 ng·L-1.
(2) The water around Poyang Lake was sampled, and its species characteristics and concentration levels were preliminarily analyzed. There are antibiotic pollutions around Poyang Lake and the tributaries of Ganjiang River, such as Jinjiang River and Yuanhe River. The overall detection of species: Poyang Lake surrounding surface water 24, groundwater 23, Jinjiang 24, Yuanhe at least 20. Overall concentration comparison: surface water around Poyang (26.81~503.06 ng·L-1)> groundwater around Poyang Lake (12.66 ~ 286.85 ng·L-1). Jin River (69.51~ 567.90 ng·L-1) > Yuan River (47.33~ 873.52 ng·L-1).
(3) Compared with other river basins, the surface water around Poyang Lake was polluted by two antibiotics, and the average concentrations of doxycycline and chlortetracycline were 6.93 ng·L-1and 14.54 ng·L-1. The groundwater around Poyang Lake had a high degree of roxithromycin pollution, with an average concentration of 31.86 ng·L-1. The contamination levels of the two antibiotics in Jinjiang were relatively high, and the average concentrations of roxithromycin and sulfamethoxazole were 22.52 ng·L-1 and 188.55 ng·L-1. The contamination levels of the three antibiotics in Yuan River were relatively high, and the average concentrations of roxithromycin, doxycycline and sulfamethoxazole were 33.92 ng·L-1, 7.49 ng·L-1 and 138.07 ng·L-1. On the whole, roxithromycin and sulfamethoxazole in all regions of the Poyang Lake Basin are at high levels, which should be paid full attention.
(4) The risk quotient method was used to evaluate the ecological risk of single antibiotics at each sampling point. The results showed that the antibiotics with medium risk to aquatic organisms in surface water of Poyang Lake Basin were SMX, and the low risk were DOC, CTC, RTM, SMZ and DMZ. Ecological risk: Poyang Lake surface water > Jinjiang > Poyang Lake groundwater > Yuan River.
How to cite: Li, J., Dong, Y., Sun, Z., Liu, Y., and Li, Z.: Detection, distribution and ecological risk assessment of typical antibiotics in water around Poyang Lake, Southeast of China, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18816, https://doi.org/10.5194/egusphere-egu26-18816, 2026.
Pesticides and pharmaceuticals comprise hundreds of compounds applied in agricultural systems, either directly for pest control or indirectly via irrigation with treated wastewater, posing risks to downstream aquatic ecosystems. Advances in analytical chemistry now allow the simultaneous detection of dozens of micropollutants per sample, yielding extensive datasets. Identifying hydrological controls on compound occurrence from such datasets remains challenging due to strong non-linearities and complex compound behavior.
We investigated two agricultural fields located along the Kishon Stream (Israel), characterized by heavy clay soils and subsurface drainage systems that enable direct sampling of distinct hydrological flowpaths, including subsurface drainage discharge, surface runoff, and shallow groundwater. Sampling focused on first-storm conditions, when compound mobilization is most pronounced. While qualitative differences in compound occurrence among flowpaths were evident, quantitative attribution was hindered by the complexity of compound–flowpath relationships.
To address this, we applied Kernel Canonical Correlation Analysis (KCCA), a machine-learning method that captures non-linear associations through kernel mapping while retaining interpretability in a latent canonical space. KCCA was combined with non-parametric analyses and applied to both the original and transposed datasets. The analysis shows that pesticide and pharmaceutical distributions are strongly structured by hydrological flowpaths. Compound mobility and degradability modulate their occurrence within and across these pathways. We further define a dominant flowpath for individual compounds, identified as the pathway in which a compound attains its maximum representative concentration, providing a concise compound-level descriptor of flowpath association.
These results demonstrate the utility of KCCA for revealing hydrological structure and chemical properties in complex environmental datasets and highlight the importance of flowpath-specific distributions for understanding micropollutant occurrence in agricultural catchments.
How to cite: Nussboim, S. and Rein, F. O.: Machine learning reveals flowpath-structured distributions of pesticides and pharmaceuticals, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-22134, https://doi.org/10.5194/egusphere-egu26-22134, 2026.
Posters virtual: Wed, 6 May, 14:00–18:00 | vPoster spot A
EGU26-16687 | ECS | Posters virtual | VPS9
Assessment of Pesticide-Related Water Pollution in the Ankara River Watershed: A Combined SWAT and Grey Water Footprint ApproachWed, 06 May, 14:57–15:00 (CEST) vPoster spot A
Agriculture poses severe impacts on water quality and health due to diffuse pollution via pesticide use. In this study, the impact of pesticide use on water quality in the Polatlı district—a region of intensive agriculture within the Ankara River Watershed—was assessed using the Grey Water Footprint (GWF) methodology. The study analyzed 34 active ingredients utilized in the 2023 production cycle of wheat, barley, onion, and sugar beet. District-level data on cultivated areas (ha) for each crop were obtained from the Turkish Statistical Institute (TURKSTAT) for 2023. For the GWF calculations, the natural background concentration was assumed to be zero, while the maximum allowable concentrations for each pesticide were retrieved from local regulations. A watershed-scale hydrological model, namely Soil and Water Assessment Tool (SWAT) were constructed for the study area and calibrated against observed streamflow data to ensure reliable simulation of pesticide transport. Pesticide applications were integrated into the model based on actual usage data. The pollutant loads transported from the Polatlı district to the Ankara River were calculated and subsequently utilized in the grey water footprint equation.
Our findings reveal that pesticide impacts vary significantly with respect to crop and active ingredient levels. For example, SWAT model simulation results for deltamethrin reveal a high environmental transport efficiency despite its low application rate (250 ml/ha) compared to other pesticides. This pesticide has an extremely high affinity for soil particles as clear from the organic carbon-water partition co-efficient value (Koc = 1,000,000 L/kg); it binds strongly to soil rather than dissolve in water. The transport of deltamethrin is entirely driven by soil erosion, leading to its accumulation in riverine sediments. Due to its extreme Koc value, the pesticide remains associated with suspended solids and bed sediments, posing a significant long-term threat to benthic organisms and aquatic biodiversity. This sediment-related pollution indicates that the GWF of the basin is not only a function of dissolved pollutants, but it can be heavily influenced by sediment quality. No leaching to groundwater or dissolved transport was observed, confirming its strong soil-binding behavior. This substantial variability in GWFs underscores the necessity for region-specific water quality standards to more accurately assess and manage the environmental impact of pesticide use. Our analysis addresses the complexities of mixed cropping systems typical of semi-arid regions, where water scarcity and intensive pesticide use converge to create critical water quality challenges. This study provides a framework for similar assessments in other agricultural regions, aiding in the development of more informed pesticide management strategies to enhance water resource sustainability. Our results highlight specific pesticides requiring priority attention: replacing or limiting high-GWF pesticides is essential for progress toward sustainable water management in the Ankara River basin.
How to cite: Dogan, F. N. and Capar, G.: Assessment of Pesticide-Related Water Pollution in the Ankara River Watershed: A Combined SWAT and Grey Water Footprint Approach, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16687, https://doi.org/10.5194/egusphere-egu26-16687, 2026.
