Micro-organic contaminants in groundwater harm the environment and human health. They result from current human activities and past pollution. A study in the Palancia River Basin examined the occurrence and concentrations of these contaminants in water. In this study, 10 groundwater and 10 surface water samples were collected, analyzing a total of 100 contaminants for this study. Carbamazepine and caffeine indicate urban pollution, while pesticides and their metabolites (terbuthylazine, desethylterbuthylazine, metolachlor, simazine, propazine) mainly signal crop production. All chosen MO were found in both the aquifer and Palancia River. In groundwater, the most common were terbutylazine (detected in 50 % with a max concentration of 101.0 ng L⁻¹), carbamazepine (40%, 50.0 ng L⁻¹), and desethylterbuthylazine (35%, 15.0 ng L⁻¹). In addition to the selected contaminants identified as indicators of pollution, up to 18 different pesticides, 12 pharmaceuticals, and various industrial-origin products were found. Comparisons with global studies suggest concentrations reflect the specific land use in recharge areas.

Acknowledgements.- This work has been supported by Grant PID2022-138556OB-C22 funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”

How to cite: Picó, Y. and Andreu, V.: Spatial distribution characteristics and analysis of groundwater pollution in the Palancia River Basin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4742, https://doi.org/10.5194/egusphere-egu24-4742, 2024.

Groundwater is consumed by over 2 billion people worldwide, though it is susceptible to microbial and chemical contamination (Alley et al., 2002; Parker et al., 2010). In East Africa, as in many places, displacement from rural to urban areas increases stress on local infrastructure including water and sanitation (UNCDF, 2018). In this study, we utilise wastewater tracers to examine urban-derived inputs to groundwater under rapidly developing urban areas in Gulu District, Northern Uganda. Bulk and fluorescent dissolved organic matter (DOM), microorganisms (total coliforms and E.coli) and inorganic tracers of anthropogenic waste (NO₃^–, SO₄^2–, Cl/Br) were characterised from boreholes (from 3–76 m depth; n = 113), protected springs (n = 20) and surface water from handpump drainage pools (n = 2; Richards et al., 2023). Our results indicate that NO₃^– was elevated in water sources in the Gulu city urban area and the Cl/Br ratio was elevated in springs, compared to concentrations in the more rural Aswa County area (p < .05; both). Interestingly, human and animal waste indicators E.coli and Tryp:FA ratios (Baker, 2002) displayed no significant difference between the rural and urban settings (p > .05). Some construction and maintenance-related aspects of the boreholes, as spot assessed by sanitary risk observations, did not apparently correspond to the indicators of microbial contamination. Rather, results suggest that DOM prevalence is primarily depth controlled in Gulu District. We considered the distribution of organic, inorganic and microbial analytes with regards to the potential source and fate of contaminants. As the population of many urban areas increase, this study offers valuable insights useful for water management planning.

Acknowledgements

A Dame Kathleen Ollerenshaw Fellowship is acknowledged for LAR and for GJLW’s PhD studentship. A UKRI-GCRF-Newton-ODA 2022-2023 Award via UoM to LAR et al. supported this project. We thank field support from Nancy Aromo and Monica Adokorach (Gulu University). 

References

Alley, W.M., Healy, R.W., LaBaugh, J.W., Reilly, T.E., 2002. Flow and storage in groundwater systems. Science 296, 1985–1990.

Baker, A., 2002. Fluorescence properties of some farm wastes: Implications for water quality monitoring. Water Res. 36, 189–195. https://doi.org/10.1016/S0043-1354(01)00210-X

Parker, A.H., Youlten, R., Dillon, M., Nussbaumer, T., Carter, R.C., Tyrrel, S.F., Webster, J., 2010. An assessment of microbiological water quality of six water source categories in north-east Uganda. J. Water Health 8, 550–560. https://doi.org/10.2166/wh.2010.128

Richards, L.A., Wilson, G.J.L., Wu, R., Muloogi, D., Hamisi, R., Denwood, T., Nuwategeka, E., Bhattacharya, P., Huck, J., Polya, David A., 2023. Water Quality in East Africa: Bringing Together Traditional Monitoring, Community Science and Artificial Intelligence Approaches. Presented at the AGU Annual Meeting 2023, San Francisco.

UNCDF, 2018. Local Assessment for Equitable Growth in Gulu and Mbale Municipalities, Uganda. UN Capital Development Fund, New York.

How to cite: Wilson, G. J. L., Hamisi, R., Denwood, T., Muloogi, D., Bhattacharya, P., Nuwategeka, E., Gooddy, D. C., Polya, D. A., Huck, J. J., and Richards, L. A.: Geochemical tracers reveal urban-derived contamination of groundwater and springs in Gulu city, Uganda, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9232, https://doi.org/10.5194/egusphere-egu24-9232, 2024.

Biocides leached from facades can reach urban groundwater, where they can have adverse environmental impacts. They are used in film preservatives and enter groundwater via swale-trench systems or diffuse pathways. However, there is little information on occurring biocide loads along different pathways to urban groundwater. The aim of this study is to quantify the input, transport and degradation of biocides to groundwater via different pathways, namely infiltration (1) in swale-trench systems, (2) adjacent to facades via vegetated soils, and (3) through permeable pavements. The study area (38ha) is located in the city of Freiburg, south-west Germany. There are a number of groundwater monitoring wells due to a chlorinated hydrocarbon (CHC) contamination site. Three biocides (diuron, octylisothiazolinone, terbutryn) and various transformation products were detected in groundwater during nine events over a six-year sampling period. In addition, more than a decade of groundwater level data and biannual sampling data from the CHC plume are available. Biocide concentrations in groundwater are assessed through the combination of four models. First, biocide leaching from facades is quantified (COMLEAM). Second, a water balance model (RoGeR_WB_Urban) calculates water infiltration into the swale-trench system and in the remaining district. Third, the results are combined to calculate biocide leaching through the soil at a depth of 1m (FOCUS-PELMO). This leachate forms the input to a groundwater flow and transport model (MODFLOW with MT3D-USGS). Terbutryn, a commonly used biocide, is chosen as the model compound. Concentrations in groundwater are modeled in daily time steps covering a period of more than two years at a spatial resolution of 5x5m. CHC measurements are used to calibrate the groundwater model. Additional biocide measurements on the facades and in the swale water help to validate the model chain. A first scenario assumes that all biocides enter groundwater via the swale-trench systems but overestimates the measured biocide concentration in groundwater by a factor of 15. A second scenario also includes diffuse pathways via vegetated soils and permeable pavements and more realistically reproduces measured terbutryn concentrations in groundwater in the range of a few ng/l. These results suggest that the diffuse entry of biocides via vegetated soils and permeable pavements is important at the urban district scale.  Hence, end of pipe measures to prevent biocide leaching into groundwater have limited efficiency in swale infiltration systems, biocide use should rather be avoided at the source.

How to cite: Linke, F., Skodras, D., Leistert, H., Zimmermann, F., and Lange, J.: Biocides in urban groundwater – modeling entry pathways at a district level , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12147, https://doi.org/10.5194/egusphere-egu24-12147, 2024.

In urban contexts where contamination persists in areas with limited accessibility, the use of sustainable and non-invasive remediation technologies becomes crucial to effectively address and mitigate environmental risks. The presence of chlorinated solvents in the environment raises significant concerns due to their persistent nature and potential health risks. These solvents, characterized by high density and limited solubility, are classified as DNAPLs (dense non-aqueous phase liquids). During their downward migration, they tend to become trapped in the microporosities of saturated and unsaturated zones, persisting in an adsorbed form. This phenomenon results in a gradual and slow-release secondary source, which contributes to the formation of long lasting contamination plumes. This study focuses on a heavily anthropized area affected by chlorinated solvents. In particular, this paper outlines a meticulous approach to remediating a tetra-chloroethylene (PCE) plume within an urban district characterized by a complex hydrological context and limited accessibility. The process included fundamental steps. Initially, an integrated geodatabase was reconstructed, combining all hydrogeochemical characterization data such as geological borehole, membrane interface probe (MIP) investigations, and chemical analyses on water samples. This facilitated detailed geomodelling, merging geological and hydrochemical information to reveal the hydrogeological structure of the subsurface, providing valuable information on groundwater quality and the evolution of the contamination plume. In addition, the incorporation of high-resolution site characterization data obtained with the MIP technique improved and parameterized the multi-source model. The fusion of the hydrogeological and physico-chemical data culminated in the development of a comprehensive conceptual site model (CSM). The CSM functions as a robust, data-driven decision support system that enables the design and customisation of two innovative and non-invasive remediation technologies. These technologies include coaxial groundwater circulation (CGC) wells with air sparging (AS) for the removal of chlorinated solvents from environmental matrices into a gaseous stream that is treated at the surface, and the injection of micrometric zero-valent iron (S-MicroZVI®) and colloidal activated carbon (PlumeStop®) to enhance chemical reduction and adsorption in situ. Hydrochemical monitoring serves as a valuable tool to unveil the intricate dynamics involved in decontamination processes. As a result, the physical approach reveals the efficacy of contamination containment, while the chemical-biological approach demonstrates the potential to reduce contaminant concentrations in urban groundwater. These results underline the importance of remediation geology via a coupled hydrogeochemical methodology to address complex contamination scenarios. This approach is key to shaping an efficient remediation strategy and promoting innovative, adaptable, sustainable, and effective solutions specifically designed for remediation actions in urban industrialised areas.

How to cite: Felli, G., Ciampi, P., Esposito, C., Nielsen, C., Ledda, L., and Petrangeli Papini, M.: Urban context remediation: a targeted and sustainable hydrogeochemical technique to face chlorinated solvent plumes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16966, https://doi.org/10.5194/egusphere-egu24-16966, 2024.

The direct photodegradation of sulfamethoxazole (SMX) represents a significant dissipation process in wetlands. However, distinguishing photodegradation from concurrent processes such as microbial and plant degradation in these environments presents a challenge. Therefore, our objective was to employ novel isotope concepts to characterize and differenciate the specific mechanisms involved in photodegradation processes. The GC-IRMS method developed for SMX includes carbon, hydrogen, and nitrogen isotope analysis, while the GC-MC-ICP-MS method specifically caters to sulfur isotope analysis. SMX exhibits varying protonation states at different pH levels, significantly affecting its degradation kinetics. We conducted direct photodegradation of SMX in simulated sunlight (>280nm) at pH 3 and pH 7. Degradation was faster at pH 3 than at pH 7. We observed normal carbon and sulfur isotope fractionation, yielding carbon isotope fractionation values (ε_C) of -1.9 ± 0.2 at pH 7 and -2.7 ± 0.4 at pH 3. The sulfur isotope fractionations (ε_34S) were -3.7 ± 0.5 at pH 7 and -6.3 ± 0.5 at pH 3, while ε_33S values were -6.4 ± 1.2 at pH 7 and -7.5 ± 1.1 at pH 3. In contrast, an inverse nitrogen isotope fractionation was observed, with ε_N = 3.0 ± 0.2 at pH 7 and 3.6 ± 0.1 at pH 3. These results support the idea of an involvement of carbon, nitrogen, and sulfur in the bond cleavage during the rate-limiting step. However, insignificant changes in the hydrogen isotopic compositions of SMX during degradation suggest that either hydrogen was not significantly involved in the bond cleavage or the transformation realted to the hydrogen bond cleavage played a minor role in the overall degradation process. Overall, the isotope data highlighted distinct transformation pathways during direct photodegradation at different pH levels. At pH 7, the dominant transformation products were sulfonilic acid, 3-amino-5-methylisoxazole (3A5MI) from N-S bond cleavage, 5-methylisoxazol-3-yl)sulfamate from C-S bond cleavage, and sulfanilamide from C-N bond cleavage, which aligned with the observed isotope fractionation data. Conversely, at pH 3, different dominant transformation products, including sulfonilic acid, 3A5MI, N4-hydroxylation of sulfanilamide and SMX isomerization, suggest that transformation pathways differed from those observed at pH 7. Altogether, the specific isotope fractionation signatures derived from multi-element CSIA for direct photodegradation of SMX represent a unique reference enabling future comparisons with other degradation pathways.

How to cite: liu, X., Köpke, J., akay, C., Kümmel, S., Richnow, H. H., and Imfeld, G.: Characterization of Sulfamethoxazole Direct Photodegradation through Multi-Element Compound-Specific Isotope Analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18104, https://doi.org/10.5194/egusphere-egu24-18104, 2024.

Water resources are affected by climate change, especially in the south of Europe, where droughts will be more frequent, intense and long. Hence, research into alternative sources of freshwater, such as urban groundwater (UGW) is essential.  Urban aquifers are a potential solution to obtain freshwater, but they are frequently polluted by contaminants of emerging concern (CECs). Therefore, there is a need to ascertain whether CECs are a water management challenge as they might limit the use of groundwater as safe drinking water.

To answer this question, it is required to assess the human health-risk effects of CECs in the groundwater and to understand their subsurface behaviour at a field-scale. This research compiles data about the presence of CECs in the aquifers of the Barcelona city and its metropolitan area, evaluates health risk effects of measured CECs in the groundwater and presents approaches implemented to identify and quantify the coupled hydro-thermo-chemical processes that govern the fate of these substances in the subsurface.

Based on detected concentration in urban groundwater, there are some CECs that might be harmful to humans such as 5-methyl-1H-benzotriazole and the pharmaceuticals azithromycin valsartan, valsartan acid, lamotrigine, venlafaxine and lidocaine, which show very high to intermediate health risk effects. The number of harmful CECs and the level of their hazard increase from the groups of adults and teens to those of 4 – 8 and 1 – 2 years old children. Thus, some CECs can limit the use of groundwater in Barcelona as potential drinking water source. Finally, knowledge gaps in understanding how to integrate these processes into urban water resources management plans are highlighted, which will help to define groundwater potential uses and to assure protection of the human health

How to cite: Jurado, A., Nikolenko, O., Saéz, C., Teixidó, M., and Pujades, E.: Contaminants of emerging concern in urban aquifers: Do they limit the use of groundwater?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20128, https://doi.org/10.5194/egusphere-egu24-20128, 2024.

Today, traditional water sources are starting to struggle to meet current urban demands. Alternative sources such as rainwater, urban stormwater runoff, or aquifers must be considered. Stormwater could represent a very interesting option to augment local water supplies. However, it is widely recognized that stormwater is a large contributor to diffuse pollution. In this context, DOM can be used as a biogeochemical cycle tracer and a proxy for stormwater quality, enabling an effective and sustainable urban water management. However, few studies have addressed the quality at small-scale catchment. To address this, we conducted six sampling campaigns in the city of Barcelona including different water matrices: rainwater, urban runoff (pedestrian and vehicular streets), and influents/effluents from Sustainable Urban Drainage Systems (SUDS). SUDs are urban green infrastructures primarily designed to prevent city flooding by enhancing permeability and facilitating aquifer recharge. Dissolved organic matter (DOM) quality was evaluated by spectroscopic techniques, i.e., measuring specific ultraviolet absorbance (SUVA₂₅₄), along with fluorescence excitation-emission matrices (FEEM). Results highlighted that concentration of dissolved organic carbon (DOC) followed: rain < SUDS < Pedestrian Street < Conventional Street, providing an initial estimation of contamination levels. The SUVA₂₅₄ index followed the sequence: rain < Pedestrian Street < Conventional Street < SUDs, indicating the enrichment in aromaticity of Dissolved Organic Matter (DOM) after percolating through the SUDS. Furthermore, calculated fluorescence indices (HIX, BIX, FI, α/β) aided in identifying the origin and maturity of organic matter in the different matrices. Our findings suggest that rainwater was comprised mostly of fresh, microbially derived DOM, while SUDS contained more matured DOM, primarily from terrestrial origin. In contrast, streets contained a different DOM composition, predominantly freshly and microbially derived. Additionally, FEEM together with the MCR-ALS chemometric method allowed us to identify up to six components (i.e., soluble microbial-like, fulvic-like, protein-like tryptophan, protein-like tyrosine, terrestrial humic-anthropic-like, marine and terrestrial-like). Our observations showed that the quantity of DOM decreased through its passage in the SUDS (street to SUD), indicating that these systems can change the quality and quantity of urban organic matter, potentially impacting the water quality of aquifers.

How to cite: Schmidlin, D., Platikanov, S., Teixidó, M., Tauler, R., and Váquez-suñé, E.: Dissolved organic matter pathways and transformation across the urban environment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21862, https://doi.org/10.5194/egusphere-egu24-21862, 2024.

In developing countries like India, a tremendous thrust is observed on installation of sewage and septage treatment, which is an essential requirement for environmental protection . However, many cities, urban and rural areas do not have proper sewerage network facilities and subsequent sewage treatment plants. Septic tank, twin-pit toilets, etc. are the onsite soltions of wastewater management. In this context, the major chalanges is associated with the safe disposal of treated/partially treated sludge of onsite treatment facilities to prevent environmental pollution from highly contaminated faecal sludge or septage.

Faecal sludge treatment plant with different technologies are adopted in different areas, although a pronounced challenge is associated with the efficacy, economy, land requirement and effluent quality meeting the desired effluent or discharge standard. In the present research, a novel “Enhanced Digestion and Multi-Stage Bioreactor (EDMSB)” is developed as an efficient and cost effective technolgy with less plant foot print  (Indian Patent No: 202331055337).

EDMSB is based on advanced hybrid system of anaerobic digestion for sludge and solid-liquid separation followed by moving bed bio-reactor based aerobic treatment associated with inclied plate-settler and denitrifyning unit for the treatment of supernatant water. Suitable pre- (screen, non-degradable fraction and scum removal unit) and post-treatment (multi-grade filtration, activated carbon filtration and ozonation) are provided to enhance the treatment facility and to meet the reuse/disposal standard. The novelty of the proposed invention lies in its unit design and appropriate process flow circumscribing compactness, modular arrangement, cost effectiveness, efficiency and space saving set up. The system is capable to handle the variation of faecal sludge characteristics, i.e., fresh faecal or partially/mineralized sludges from septic tanks with cleaning intervals of wide variation. EDBSM exhibited a significant efficiency (BOD >99%, COD >99%, TSS >99%, Faecal coliform >99%, TKN>98%) for the high pollunat load of fresh faecal or septage. In addition, the proposed system has also established a significant reduction of cost (Capital cost~60% and operation cost~70%) and land requirement (> 80%) compared to other popular technologies like phytorid based system. The units of proposed inventions are completely odorless as compared to other technologies adopted in field and free from flying nuisance which creates a better working environment for the plant operators and maintains an immaculate surrounding environment. The stabilized sludge volume is very low which creates a significant reduction in the sludge handling facility. The quality of digested sludge ensures its use as good manure. The present invention brings an significant advancement in faecal sludge and septage management, which can be adopted in various developing countries like India as an efficient, cost-effective and space saving opportunity in this field.     

Keywords: Faecal sludge and septage management, Anearobic digestor, Moving bed bio-reactor, Environmental pollution, Aerobic and anaerobic treatment 

How to cite: Sahu, S. and Ghosal, P. S.: Development of Enhanced Digestion and Multi-Stage Bioreactor (EDMSB) reactor for faecal sludge and septage treatment: A pragmatic low-cost and space saving robust technical solution for developing countries , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16525, https://doi.org/10.5194/egusphere-egu24-16525, 2024.

Efficient and scalable nano-adsorbents have emerged as promising solutions for vast anthropogenic environmental contamination, demonstrating high capacities in removing heavy metal cations and oxy-anions. However, their widespread adoption raises critical questions about the safe disposal and long-term environmental impact. We delved into the fate of contaminant-sorbed nano-adsorbents in soil and landfill conditions, addressing concerns such as desorption, dissolution, and the release of toxic constituents. Our research explores various nanocomposites for their toxic ions sorption capacities, and redox-transformation/degradation capabilities along with distinct contaminant removal mechanisms. Furthermore, we have tried to investigate their soil fractionation and leaching behaviors through a sequential leaching approach in simulated landfill conditions to comment on long-term fate and process sustainability.

Results suggest that to assess the environmental applicability of nanocomposites, it's crucial to consider the long-term fate of adsorbent wastes post-contaminant removal. Understanding soil fractionation and leaching in landfills informs disposal strategies, minimizing environmental risks. Redox-active nanoparticles limit recyclability due to strong binding, favoring safe disposal. Conversely, weak binders like layered double hydroxides allow for contaminant recovery and potential reuse.

How to cite: Khandelwal, N.: Nanoadsorbents for Pollutants Cleanup: Balancing Efficiency and Environmental Sustainability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-235, https://doi.org/10.5194/egusphere-egu24-235, 2024.