@misc{OkofoMartienssen, author = {Okofo, Louis Boansi and Martienssen, Marion}, title = {A three-dimensional numerical groundwater flow model to assess the feasibility of managed aquifer recharge in the Tamne River basin of Ghana}, series = {Hydrogeology Journal}, volume = {30}, journal = {Hydrogeology Journal}, number = {4}, issn = {1431-2174}, doi = {10.1007/s10040-022-02492-7}, pages = {1071 -- 1090}, language = {en} } @misc{AhmedMartienssenBryantetal., author = {Ahmed, Naveed and Martienssen, Marion and Bryant, Isaac Mbir and Vione, Davide and Bruzzoniti, Maria Concetta and Riedel, Ramona}, title = {Investigation on UV Degradation and Mechanism of 6:2 Fluorotelomer Sulfonamide Alkyl Betaine, Based on Model Compound Perfluorooctanoic Acid}, series = {ChemEngineering}, volume = {8}, journal = {ChemEngineering}, number = {2}, issn = {2305-7084}, doi = {10.3390/chemengineering8020032}, abstract = {The UV treatment of 6:2 FTAB involves the mitigation of this persistent chemical by the impact of ultraviolet radiation, which is known for its resistance to environmental breakdown. UV treatment of PFOA and/or 6:2 FTAB, and the role of responsible species and their mechanism have been presented. Our investigation focused on the degradation of perfluorooctanoic acid (PFOA) and 6:2 fluorotelomer sulfonamide alkyl betaine (6:2 FTAB, Capstone B), using UV photolysis under various pH conditions. Initially, we used PFOA as a reference, finding a 90\% decomposition after 360 min at the original (unadjusted) pH 5.6, with a decomposition rate constant of (1.08 ± 0.30) × 10-4 sec-1 and a half-life of 107 ± 2 min. At pH 4 and 7, degradation averaged 85\% and 80\%, respectively, while at pH 10, it reduced to 57\%. For 6:2 FTAB at its natural pH 6.5, almost complete decomposition occurred. The primary UV transformation product was identified as 6:2 fluorotelomer sulfonic acid (6:2 FTSA), occasionally accompanied by shorter-chain perfluoroalkyl acids (PFAAs) including PFHpA, PFHxA, and PFPeA. Interestingly, the overall decomposition percentages were unaffected by pH for 6:2 FTAB, though pH influenced rate constants and half-lives. In PFOA degradation, direct photolysis and reaction with hydrated electrons were presumed mechanisms, excluding the involvement of hydroxyl radicals. The role of superoxide radicals remains uncertain. For 6:2 FTAB, both direct and indirect photolysis were observed, with potential involvement of hydroxyl, superoxide radicals, and/or other reactive oxygen species (ROS). Clarification is needed regarding the role of 𝑒-𝑎𝑞 in the degradation of 6:2 FTAB.}, language = {en} } @misc{OkofoAdonadagaMartienssen, author = {Okofo, Louis Boansi and Adonadaga, Melvin-Guy and Martienssen, Marion}, title = {Groundwater age dating using multi-environmental tracers (SF6, CFC-11, CFC-12, δ18O, and δD) to investigate groundwater residence times and recharge processes in Northeastern Ghana}, series = {Journal of Hydrology}, volume = {Vol. 610}, journal = {Journal of Hydrology}, issn = {1879-2707}, doi = {10.1016/j.jhydrol.2022.127821}, pages = {1 -- 18}, language = {en} } @misc{AfitiriAramMartienssen, author = {Afitiri, Abdul-Rahaman and Aram, Simon Appah and Martienssen, Marion}, title = {Sytematic review of the effects of Advanced Oxidation Processes integration with solar water disinfection for improved drinking water production}, series = {Waste Management Bulletin}, volume = {1}, journal = {Waste Management Bulletin}, number = {4}, issn = {2949-7507}, doi = {10.1016/j.wmb.2023.08.005}, pages = {52 -- 59}, language = {en} } @misc{BoellmannMartienssen, author = {B{\"o}llmann, J{\"o}rg and Martienssen, Marion}, title = {Seasonal Variability of Cultivable Nitrate-Reducing and Denitrifying Beacteria and Functional Gene Copy Number in Fresh Water Lake}, series = {Microorganisms}, volume = {12}, journal = {Microorganisms}, number = {3}, issn = {2076-2607}, doi = {10.3390/microorganisms12030511}, language = {en} } @misc{RiedelBraunBoellmannetal., author = {Riedel, Ramona and Braun, Burga and B{\"o}llmann, J{\"o}rg and Martienssen, Marion}, title = {Neuer Standard-Abbautests f{\"u}r synthetische Phosphonate}, series = {BIOspektrum : Das Magazin f{\"u}r Biowissenschaften}, volume = {30}, journal = {BIOspektrum : Das Magazin f{\"u}r Biowissenschaften}, issn = {1868-6249}, doi = {10.1007/s12268-024-2194-x}, pages = {345 -- 347}, abstract = {The evaluation of the ready biodegradation of organic substances is usually carried out using the standardised OECD test methods 301 (A-F). However, this can become a great challenge for substances such as aminophosphonates which are chemically imbalanced and do not automatically promote microbial growth in standardized tests. Here, we report on the development of a standardized batch test that is suitable for phosphonates and overcomes important obstacles of the test methods above-mentioned.}, language = {de} } @misc{RiedelCommichauBenndorfetal., author = {Riedel, Ramona and Commichau, Fabian M. and Benndorf, Dirk and Martienssen, Marion}, title = {Biologischer Abbau von Aminophosphonaten}, series = {BIOspektrum : Das Magazin f{\"u}r Biowissenschaften}, volume = {30}, journal = {BIOspektrum : Das Magazin f{\"u}r Biowissenschaften}, issn = {1868-6249}, doi = {10.1007/s12268-024-2179-9}, pages = {348 -- 350}, abstract = {Application of commercial aminophosphonates such as glyphosate (GS) or chelating agents in detergent are daily used at large scale worldwide. Only little is known about the potential biodegradation of the latter. Here we describe the characterization of the new strain Ochrobactrum sp. BTU1 isolated from a LC/MS standard solution. The strain is capable to degrade all investigated aminophosphonates including GS.}, language = {de} } @misc{RiedelMeissnerKaschubowskietal., author = {Riedel, Ramona and Meißner, Karsten and Kaschubowski, Arne and Benndorf, Dirk and Martienssen, Marion and Braun, Burga}, title = {Laundry isolate Delftia sp. UBM14 capable of biodegrading industrially relevant aminophosphonates}, volume = {12}, number = {8}, issn = {2076-2607}, doi = {10.3390/microorganisms12081664}, pages = {20}, abstract = {Phosphonates such as ethylenediaminetetra (methylenephosphonic acid) (EDTMP) and aminotris (methylenephosphonic acid) (ATMP) are used every day in water treatment processes or in household products. Their consumption is still increasing, regardless of the debates on their environmental impact. Here, the microbial characterisation and determination of the biodegradation potential of selected industrially relevant phosphonates for the isolate Delftia sp. UMB14 is reported. The opportunistic strain was isolated from a biofilm that was derived from a conventional washing machine using conventional detergents containing phosphonates. In antimicrobial susceptibility testing, the strain was only susceptible to sulfonamide, tetracycline, and chloramphenicol. Physiological and biochemical characteristics were determined using the BIOLOG EcoPlate assay. Most importantly, the strain was shown to convert D-malic acid and D-mannitol, as confirmed for strains of Delftia lacustris, and thus the new isolate could be closely related. Biodegradation tests with different phosphonates showed that the strain preferentially degrades ATMP and EDTMP but does not degrade glyphosate (GS) and amino (methylphosphonic acid) (AMPA). A specific gene amplification confirmed the presence of phnX (phosphonoacetaldehyde hydrolase) and the absence of PhnJ (the gene for the core component of C-P lyase). The presence of PhnCDE is strongly suggested for the strain, as it is common in Delftia lacustris species.}, language = {en} } @misc{RiedelKrahlBuderetal., author = {Riedel, Ramona and Krahl, Kathrin and Buder, Kai and B{\"o}llmann, J{\"o}rg and Braun, Burga and Martienssen, Marion}, title = {Novel standard biodegradation test for synthetic phosphonates}, series = {Journal of Microbiological Methods}, volume = {Vol. 212}, journal = {Journal of Microbiological Methods}, issn = {1872-8359}, doi = {10.1016/j.mimet.2023.106793}, pages = {1 -- 13}, abstract = {Determination of biodegradation of synthetic phosphonates such as aminotris(methylenephosphonic acid) (ATMP), ethylenediamine tetra(methylenephosphonic acid) (EDTMP), or diethylenetriamine penta(methylenephosphonic acid) (DTPMP) is a great challenge. Commonly, ready biodegradability of organic substances is assessed by OECD 301 standard tests. However, due to the chemical imbalance of carbon to phosphorus synthetic phosphonates do not promote microbial growth and, thus, limiting its biodegradation. Therefore, standard OECD test methods are not always reliable to predict the real biodegradability of phosphonates. In the presented study, we report the development of a standardized batch system suitable to synthetic phosphonates such as ATMP, EDTMP, DTPMP and others. The novel standard batch test is applicable with pure strains, activated sludge from different wastewater treatment plants (i.e., municipal and industrial), and with tap water as inoculum. We optimized the required calcium and magnesium exposure levels as well as the amount of the start inoculum biomass. We demonstrated that our test also allows to determine several parameters including ortho-phosphate (o-PO43􀀀 ), total phosphorus (TP), ammonium (NH4+) and total organic carbon (TOC). In addition, also LC/MS analyses of cell-free medium is applicable for determining the mother compounds and metabolites. We applied our optimized standardized batch with selected phosphonates and evidenced that the chemical structure has a major influence of the microbial growth rates. Thus, our novel batch test overcomes drawbacks of the OECD 301 test series for determination of easy biodegradability for stoichiometric imbalanced organic compounds such as phosphonates.}, language = {en} } @misc{RiedelCommichauBenndorfetal., author = {Riedel, Ramona and Commichau, Fabian M. and Benndorf, Dirk and Hertel, Robert and Holzer, Katharina and Mardoukhi, Mohammad Saba Yousef and Noack, Laura and Martienssen, Marion}, title = {Biodegradation of selected aminophosphonates by the bacterial isolate Ochrobactrum sp. BTU1}, series = {Microbial Research}, volume = {280}, journal = {Microbial Research}, issn = {0944-5013}, doi = {10.1016/j.micres.2024.127600}, pages = {1 -- 12}, abstract = {Aminophosphonates, like glyphosate (GS) or metal chelators such as ethylenediaminetetra(methylenephosphonic acid) (EDTMP), are released on a large scale worldwide. Here, we have characterized a bacterial strain capable of degrading synthetic aminophosphonates. The strain was isolated from LC/MS standard solution. Genome sequencing indicated that the strain belongs to the genus Ochrobactrum. Whole-genome classification using pyANI software to compute a pairwise ANI and other metrics between Brucella assemblies and Ochrobactrum contigs revealed that the bacterial strain is designated as Ochrobactrum sp. BTU1. Degradation batch tests with Ochrobactrum sp. BTU1 and the selected aminophosphonates GS, EDTMP, aminomethylphosphonic acid (AMPA), iminodi(methylene-phosphonic) (IDMP) and ethylaminobis(methylenephosphonic) acid (EABMP) showed that the strain can use all phosphonates as sole phosphorus source during phosphorus starvation. The highest growth rate was achieved with AMPA, while EDTMP and GS were least supportive for growth. Proteome analysis revealed that GS degradation is promoted by C-P lyase via the sarcosine pathway, i.e., initial cleavage at the C-P bond. We also identified C-P lyase to be responsible for degradation of EDTMP, EABMP, IDMP and AMPA. However, the identification of the metabolite ethylenediaminetri(methylenephosphonic acid) via LC/MS analysis in the test medium during EDTMP degradation indicates a different initial cleavage step as compared to GS. For EDTMP, it is evident that the initial cleavage occurs at the C-N bond. The detection of different key enzymes at regulated levels, form the bacterial proteoms during EDTMP exposure, further supports this finding.}, language = {en} } @misc{OkofoBeduAddoMartienssen, author = {Okofo, Louis Boansi and Bedu-Addo, Kenneth and Martienssen, Marion}, title = {Characterization of groundwater in the 'Tamnean' Plutonic Suite aquifers using hydrogeochemical and multivariate statistical evidence: a study in the Garu-Tempane District, Upper East Region of Ghana}, series = {Applied Water Science}, volume = {12}, journal = {Applied Water Science}, number = {2}, publisher = {Springer International Publishing}, issn = {2190-5487}, doi = {10.1007/s13201-021-01559-2}, pages = {22}, abstract = {The 'Tamnean' Plutonic Suite aquifer is the main public water supply for the Garu-Tempane District. Thus, hydrogeochemical characterization is essential to provide valuable insights into pollution sources and the main controls on groundwater chemistry. In this regard, multivariate statistical methods, conventional hydrochemical graphical methods, and various ionic ratios complemented with PHREEQC geochemical modelling were carried out using 38 groundwater samples collected from the Tamnean Plutonic Suite aquifers, Ghana. The ionic ratio plots, the chloro-alkaline indices, and the graphical diagrams indicate that the major sources of groundwater chemistry are silicate mineral dissolution and cation exchange coupled with the leaching of domestic solid waste and nitrogen-based fertilizers. The Q-mode hierarchical cluster analysis reveals three spatial groundwater zones. Groundwater from recharge areas consists of Ca-Na-HCO3 water types in cluster 1. The intermediate zone is characterized by Ca-Mg-Na-HCO3 water types of moderate ionic compositions in cluster 2, and this evolves into a discharge zone in cluster 3 mainly of Ca-Mg-Na-HCO3-NO3 water types. The principal component analysis (PCA) reveals three factors, which account for 81\% of the total variance, and this suggests most of the groundwater chemistry had longer interaction with the lithological materials. The PHREEQC geochemical modelling consisting of mineral saturation index indicates that groundwater is mostly supersaturated with respect to dolomite and undersaturated with respect to calcite, anhydrite, fluorite, gypsum, and halite. Based on the water quality index, the groundwater in the district is generally suitable for drinking water purposes. All the samples are within the World Health Organization acceptable limits for drinking water except for lower pH, elevated nitrate and bromide concentrations in some of the wells. About 10.5\% of the groundwater samples are contaminated with nitrate, which may pose a health danger to the inhabitants in the communities. The finding of this study will not only contribute to solving the research paucity regarding the Tamnean Plutonic Suite aquifers in the Garu-Tempane District but will serve as a valuable document for water managers and decision-makers in Ghana.}, language = {en} } @misc{AfitiriAfrifaMartienssen, author = {Afitiri, Abdul-Rahaman and Afrifa, Ernest Kofi Amankwa and Martienssen, Marion}, title = {Understanding the potential of mixed photocatalysis for optimization of water disinfection}, series = {Pollutants}, volume = {5}, journal = {Pollutants}, number = {2}, editor = {Lasagni, Marina}, publisher = {MDPI}, address = {Basel}, issn = {2673-4672}, doi = {10.3390/pollutants5020013}, pages = {1 -- 17}, abstract = {The use of ultraviolet (UV) for water disinfection is known for its chemical-free process and with no harmful disinfection by-products. Yet, the disinfection process remains time-consuming, and many studies are limited to disinfection of one or two microbial species. Direct photolytic and glass-embedded TiO2 photocatalytic disinfection of four different bacterial species (Staphylococcus aureus, Salmonella senftenberg, Bacillus subtilis, and Escherichia coli) were assessed using UV-LED radiation with wavelengths of 365 nm. The optimization of the UV disinfection under different masses of the TiO2 photocatalyst was evaluated. Additionally, the order of disinfection of the different bacteria species was assessed. The disinfection effects were measured based on the potential to reduce the number of bacteria species, calculated in colony-forming units/mL and log reduction units. The disinfection of Staphylococcus aureus was enhanced from 1.46 log reduction units in the UV-alone treatment to a high of 5.65 log reduction units in the UV + 0.08 g TiO2 treatment. Regarding Salmonella senftenberg, disinfection was enhanced from 1.26 log reduction units to 3.85 log reduction units in UV-alone experimental treatments and UV + 0.04 g TiO2, respectively. Similarly, an increase in Bacillus subtilis reduction was achieved from a low of 0.69 log reduction units to a high of 2.98 log reduction units in UV-alone treatments and UV + 0.08 g TiO2, respectively. The disinfection of Escherichia coli was enhanced from 2.49 log reduction units (UV-alone treatment) to a high of 6.35 log reduction units (UV + 0.02 g TiO2). The findings provide key implications and new insights into the studied bacteria species and the future application of porous glass-embedded TiO2 photocatalysts to enhance bacteria disinfection using UV light for improved water.}, language = {en} } @misc{BoellmannRiedelMartienssen, author = {B{\"o}llmann, J{\"o}rg and Riedel, Ramona and Martienssen, Marion}, title = {Inhibition of Pseudomonas aeruginosa with silver in a new synthetic medium : investigation on the MIC, growth rate and lag-phase at the lower limit}, series = {Journal of microbiological methods}, volume = {230-231}, journal = {Journal of microbiological methods}, publisher = {Elsevier Bv}, address = {Amsterdam}, issn = {1872-8359}, doi = {https://doi.org/10.1016/j.mimet.2025.107095}, pages = {1 -- 9}, abstract = {The antimicrobial properties of silver are well-known and widely applied. Although it is known, that silver interacts and binds on complex organic substances like proteins, many experiments on the sterilisation efficiency and inhibiting properties are still carried out in complex culture media. Given, that silver is often applied in environments with no or few organic substrates, like cooling circuits or in the treatment of tap and process water, further insight on the minimum inhibition concentration and lethal concentration at those conditions is of interest. We have developed a defined medium for the standard bacterium Pseudomonas aeruginosa that is free of complex organic carbon with equal cultivation properties like commonly used nutrient solutions. With this medium we could narrow the range of the MIC between 2.5 μg to 10 μg∙L-1, which very much overlaps with the bactericidic concentration depending on the initial concentration of bacteria cells. These results might help to optimise the technical application of silver. We further observed a delayed growth of bacterial cultures of up to three days compared to silver free controls, which is caused either by a partial sterilisation down to theoretical one surviving cell or by a prolonged lag phase. Based on these observations we recommend a prolonged incubation for experiments on sterilisation with silver and the use of defined media, which do not interact with the disinfecting agent.}, language = {en} } @misc{RiedelSchowarteSemischetal., author = {Riedel, Ramona and Schowarte, Julia and Semisch, Laura and Gonzalez Castano, Miriam and Ivanova, Svetlana and Martienssen, Marion and Arellano-Garcia, Harvey}, title = {Improving the photocatalytic degradation of EDTMP : effect of doped NPs (Na, Y, and K) into the lattice of modified Au/TiO2 nano-catalysts}, series = {Chemical engineering journal}, volume = {506}, journal = {Chemical engineering journal}, doi = {10.1016/j.cej.2025.160109}, pages = {14}, abstract = {This study presents the photocatalytic degradation of the aminophosphonate ethylenediaminetetra(methylenephosphonic acid) (EDTMP) with a range of different doped nanoparticles (NP). The photocatalysts were based on TiO2 benchmark P25 and gold (Au) doped either with sodium (Na), potassium (K) or yttrium (Y). The synthesized photocatalysts were characterized via TEM, XRF, XRD, UV-DRS (band gap estimation) and N2-physisorption. Photocatalytic pre-screening at pH values of 3, 7 and 10 indicated highest o-PO4 release of EDTMP at pH 7 and 10 for NP either doped with K or Y. The results of LC/MS analysis showed that the NPs doped with 5 \% Y (Au2/Y5/P25) resulted in the fastest degradation of EDTMP. The target compound was completely degraded within 60 min, 4 times faster than photochemical treatment of unadulterated EDTMP. Importantly, also the transformation products were accelerated by the photocatalytic treatment with Au2/P25 either doped with 5 \% Y or 10 \% K. The results of scavenger experiments indicated that the enhanced photocatalytic degradation of EDTMP is primarily attributable to the presence of hydroxyl radicals in the bulk and to a lesser extent to •O2- and electron-holes (h+) at the surface of the catalysts. The study demonstrates that the catalytic efficiency of TiO2 nanocomposites is significantly influenced by the choice of dopants, which affect particle size, band gap, and photocatalytic activity. Yttrium at low concentrations (i.e., 5 wt\% Y) doping emerged as particularly effective, enhancing both the visible light absorption and h+ separation, leading to superior photocatalytic performance in the degradation of EDTMP. The Au content also plays a crucial role in enhancing the photocatalytic efficiency. However, the combination of Au and Na doping was found to be less effective for this photocatalysis in aqueous media, potentially due to larger particle sizes and insufficient dopant contents. In conclusion, the findings emphasise the necessity of optimising both the selection of dopants and the design of catalysts in order to enhance photocatalytic applications.}, language = {en} } @misc{SchowarteRiedelHelleetal., author = {Schowarte, Julia and Riedel, Ramona and Helle, Sven and Martienssen, Marion and Arellano-Garcia, Harvey}, title = {Synergistic enhancement of PFOA and 6:2-FTAB photodegradation using Au/Y-doped TiO₂ nanocatalysts}, series = {Chemical engineering journal advances}, volume = {26}, journal = {Chemical engineering journal advances}, publisher = {Elsevier BV}, address = {Amsterdam}, issn = {2666-8211}, doi = {10.1016/j.ceja.2026.101121}, pages = {1 -- 12}, abstract = {Efficient degradation of perfluoroalkyl substances (PFAS) requires photocatalysts capable of promoting strong C-F bond cleavage and selective interfacial charge transfer. In this proof-of-concept-study, a dual-doped TiO2 nanophotocatalyst (Au2/Y5/P25) was synthesized by combining gold (Au) nanoparticles and yttrium (Y) dopants to enhance charge separation and reactive oxygen species (ROS) generation. Structural characterization supported Au deposition on the TiO2 surface and Y incorporation into the lattice, accompanied by a slight band-gap narrowing. Under UV irradiation in aqueous solution (unbuffered pH 5.8, room temperature) the nanophotocatalyst exhibited distinct degradation pathways for 1000 µg L-1 of two representative PFAS, perfluorooctanoic acid (PFOA) and Capstone B (6:2 FTAB), reflecting environmentally prevalent groups. PFOA underwent 99 \% degradation within 100 min via a stepwise CF2-cleavage mechanism, generating a sequence of perfluorocarboxylic acids down to perfluorobutanoic acid (PFBA), consistent with enhanced electron-hole separation. In contrast, Capstone B showed rapid, single-step S-N bond cleavage to 6:2 perfluorooctanesulfonic acid (6:2 PFOS), primarily driven by hole- and •OH-mediated oxidation under oxygen-rich conditions. This process achieved 96 \% degradation within 20 min but did not proceed to further defluorination, indicating oxidative limitations. Dissolved oxygen analysis revealed efficient electron utilization and sustained oxidative turnover without excessive oxygen depletion. The findings demonstrate that Au/Y co-doping promotes selective PFAS activation, enabling rapid precursor oxidation while exposing the kinetic limits of secondary C-F bond cleavage. These discoveries offer new insights into the design of plasmonic-rare-earth-modified TiO2 photocatalysts for efficient PFAS degradation through interface-driven oxidation pathways.}, language = {en} } @misc{MartienssenRiedelKuehne, author = {Martienssen, Marion and Riedel, Ramona and K{\"u}hne, Tom}, title = {Contribution of professional cleaning to indoor air and sewage pollution}, series = {Sustainable Chemistry}, volume = {5}, journal = {Sustainable Chemistry}, number = {4}, doi = {10.3390/suschem5040019}, pages = {275 -- 286}, language = {en} }