Thomas Fischer

Biological soil crusts (BSCs) play a crucial role in regulating water infiltration into surface substrates; however, their exact hydrological effects remain a subject of ongoing debate. This study quantitatively investigates the kinetics of water immobilization through sorption and the swelling behavior of extracellular polymeric substances (EPS) during the wetting of dry BSCs on recultivated temperate dunes in Brandenburg. Crust samples dominated by the green alga Zygogonium ericetorum were collected from an inland dune in the Lusatian post-mining area. Following a multi-week drying phase, rehydration experiments were conducted using deuterium oxide (D ₂ O) to avoid spectral interference with the O–H groups of the EPS. Using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), the time-dependent shift of the O–D stretching vibrations was analyzed to determine the sorption kinetics of the biological crusts relative to an undisturbed mineral control. In parallel, gravimetric measurements monitored evaporation, while the EPS composition was characterized via ATR-FTIR spectroscopy. Spectroscopic analysis identified alginate as the primary organic component of the crust EPS. While the uncoated mineral control showed almost immediate water infiltration, the BSC samples exhibited a pronounced plateau in OD vibrations during the first three minutes, indicating an initial phase of free water at the surface. Between the 3rd and 12th minutes, a distinct redshift toward lower wavenumbers followed, reflecting the ongoing functional group reorganization, hydration, and EPS swelling, until thermodynamic equilibrium was reached after approximately 12 minutes. Gravimetric data also revealed a significantly higher and faster evaporation rate for the BSCs compared to the control. These results demonstrate that the alginate and EPS matrix of the biological soil crust acts as a water reservoir that hydrologically seals the surface, drastically limiting vertical infiltration into deeper soil layers while retaining water in a highly accessible surface pool. Furthermore, it is conceivable that this delayed water immobilization by the swelling EPS matrix provides a vital ecological benefit by buffering the crust microbiome against severe hypo-osmotic shock during rapid rewetting. However, direct microbial analyses are required to confirm this effect. By moving beyond conventional visual assessments or indirect macro-hydraulic inferences, this approach provides unprecedented molecular-scale insights into the rapid physicochemical transition from free to matrix-bound water during EPS hydration. To our knowledge, this study represents the first application of time-resolved diffuse reflectance infrared spectroscopy (DRIFTS) combined with deuterium oxide (D ₂ O) rehydration to directly track water immobilization kinetics in biological soil crusts. By eliminating spectral interference from biopolymer hydroxyl groups, this approach provides unprecedented insights into the rapid physicochemical transition from free to matrix-bound water.

The long-term application of immobilized quorum quenching (QQ) bacteria requires carrier materials with sufficient mechanical stability and durability across various operating conditions. This study aims to enhance the durability and stability of polyvinyl alcohol (PVA) beads and to evaluate their performance for long-term operation. The beads were synthesized using two PVA brands with different molecular weights (MWs), and the effect of cross-linking conditions and reagent purity on bead stability was also investigated. Primarily, their physical strength was evaluated under centrifugal forces. Additionally, polyvinyl alcohol and sodium alginate (PVA-SA) beads were incorporated with cellulose to enhance their strength. The structural and chemical characteristics of the beads were examined using scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). The results showed that PVA 100 kDa beads withstood centrifugal forces up to 11,000 rpm without breakage, whereas lower MW (PVA 85 kDa) beads failed at 5000 rpm. Bead quality was critically sensitive to calcium chloride purity, as impurities and reduced Ca²⁺ availability caused poor crosslinking and structural collapse. The results revealed that PVA 100 kDa increases the number of polymer chain entanglements and intermolecular interactions, which enhance the structural integrity. Bead quality is strongly influenced by the purity of calcium chloride in the crosslinking solution, as well as by the solution pH. SEM analysis showed that cellulose-incorporating beads exhibited a denser and more uniform pore structure, with median equivalent pore diameters reduced from 50 µm (PVA-SA) to 22.4 µm upon cellulose incorporation, while maintaining sufficient porosity for nutrient diffusion. Similarly, FTIR analysis confirmed that cellulose was successfully integrated, with increased hydroxyl interactions and modified C–O vibrational characteristics, indicating strong hydrogen bonding within the composite matrix. Principal component analysis (PCA) confirmed that hydroxyl interactions and C–O vibrational modes are the main contributors to spectral variation, indicating that cellulose acts as a structural modifier in the PVA-SA network. These results demonstrate the effectiveness of this strategy in designing durable PVA-SA-cellulose based composite beads for long-term QQ applications.

In this study, we investigated the impact of varying iron (Fe) and aluminum (Al) contents on the adsorption of phosphonates to activated sludge. Phosphonates originating from household applications account for up to 40% of the non-reactive dissolved phosphorus in domestic sewage treatment plants and thus can contribute to the eutrophication of water bodies. Although these substances are not readily degradable, substantial quantities, ranging from 40% to more than 90%, are removed by sludge adsorption. The results demonstrate a strong correlation between the adsorption of aminophosphonates and the Fe³⁺ content of the sludge. The maximum phosphonate loadings were 5.94 mmol g⁻¹ Fe³⁺ for ATMP, 4.94 mmol g⁻¹ Fe³⁺ for EDTMP, 4.74 mmol g⁻¹ Fe³⁺ for DTPMP, and 2.25 mmol g⁻¹ Fe³⁺ for glyphosate. In contrast to pure ferric hydride flocs, the adsorption of phosphonates was approximately threefold higher when the hydroxides were located within activated sludge flocs. It is concluded that native sludge flocs provide larger iron surfaces than ferric hydroxide alone. Based on the weight of the adsorbents, aluminum salts were four times less efficient than ferric salts. In sludge without ferric or aluminum hydroxides, phosphonate adsorption was negligible.

In this study, we investigated the impact of varying iron (Fe) and aluminum (Al) contents on the adsorption of phosphonates to activated sludge. Phosphonates originating from household applications account for up to 40% of the non-reactive dissolved phosphorus in domestic sewage treatment plants and thus can contribute to the eutrophication of water bodies. Although these substances are not readily degradable, substantial quantities, ranging from 40% to more than 90%, are removed by sludge adsorption.The results demonstrate a strong correlation between the adsorption of aminophosphonates and the Fe3+ content of the sludge. The maximum phosphonate loadings were 5.94 mmol g-1 Fe3+ for ATMP, 4.94 mmol g-1 Fe3+ for EDTMP and 4.74 mmol g-1 Fe3+ for DTPMP, and 2.25 mmol g-1 Fe3+ for Glyphosate. In contrast to pure ferric hydride flocs, the adsorption of phosphonates was approximately threefold higher when the hydroxides were located within activated sludge flocs. It is concluded that native sludge flocs provide larger iron surfaces than ferric hydroxide alone. Based on the weight of the adsorbents, aluminum salts were four times less efficient than ferric salts. In sludge without ferric or aluminum hydroxides, phosphonate adsorption was negligible.

Perfluorooctanoic acid (PFOA), a persistent environmental pollutant, poses significant health and ecological risks. This study investigates for the first time the photocatalytic degradation of PFOA using novel doped perovskite catalysts under polychromatic UV–VIS irradiation with a peak emission at 366 nm. A series of nickel‐ and lanthanide‐doped perovskites (NiMn ₂ O ₄ , LaMnO ₃ , NdMnO ₃ , and their nickel‐doped variants) were synthesized via a facile co‐precipitation technique and characterized using X‐ray diffraction (XRD), UV–VIS diffuse reflectance spectroscopy (UV–VIS‐DRS), scanning electron microscopy with energy‐dispersive X‐ray spectroscopy (SEM–EDX), N ₂ ‐physisorption, and microwave plasma atomic emission spectroscopy (MP‐AES). Photocatalytic experiments revealed that Ni/NdMnO ₃ exhibited the highest degradation efficiency toward PFOA, likely due to its small band gap energy of 1.5 eV, facilitating efficient C–C bond cleavage.

Protophormia terraenovae is a colonizer of decomposing bodies and is known to cause pre-mortem myiasis as the female flies lay eggs in uncleaned wounds. In this study the effects of different concentrations of antibiotics levofloxacin and ceftriaxone on maggot development, weight, length, and mortality were examined. The maggot length and weight were significantly increased by therapeutical doses of levofloxacin and ceftriaxone. The maggot development time was significantly decreased in every levofloxacin treatment compared to the control. The time to start pupation was significantly increased in the control compared to the antibiotic treatments. Levofloxacin significantly increased the survivability of the maggots. Every levofloxacin treatment significantly improved the rearing conditions for the maggots. Reaching the third instar was delayed by 24 h in the control compared to the Levo 3.57 treatment. The Pupation in the control was delayed by an average of 48 h compared to the Levo 3.57 treatment. The significantly reduced development time of the maggots in the antibiotic treatments might lead to an overestimation of the post-mortem interval and therefore an incorrect time of death determination. The improved rearing conditions may be an indication of the potential of a combined application of antibiotics and maggot therapy.

It is commonly accepted that CO₂ efflux increases with soil water content in aerated soils and that rewetting after periods of soil drying can result in respiration pulses. It has further been shown that soil pores may become water logged which can impede soil gas exchange. The present study aimed to quantify the carbon response of moss (Polytrichum piliferum) and lichen (Cladonia coniocraea) biocoenoses to different quantities of rain in an artificial catchment, which granted that the starting point of the development of both biocoenoses was the same. To address this aim, we conducted in situ soil moisture and soil respiration measurements, where soil respiration was hypothesised to emerge from a cryptogamic vegetation layer and from mineral soil beneath. We found that higher water‐holding capacity of the moss layer and higher accumulation of organic matter in the upper mineral soil under mosses result in higher amounts of water stored near the surface. As a consequence, evaporation of water as well as pulses of CO₂ efflux after moderate rain following a period of drought were higher in the moss biocoenosis, where the upper mineral soil was of key importance. In contrast, the lichen biocoenosis facilitated penetration of rainwater into the deep soil. Superimposing rewetting pulses, near‐saturation of soil pores with water after severe rain resulted in gas exchange inhibition and diminished soil respiration until subsequent aeration in both biocoenoses.

Lucilia sericata is one of the most studied species in forensic entomology due to its widespread distribution, forensic importance as well as medical use. The growth and development stage of maggots is often used to determine the post‐mortem interval in forensic cases. L. sericata can cause myiasis in humans who are not able to maintain personal hygiene due to age or medical condition and can therefore be used to determine the time period of neglect. The influence of the temperature on the maggot development has been examined in various studies. Different examinations on the effects of toxic substances on the maggot development and survival have been conducted in order to test the influence and resulting deviations. In this study, the effects of different therapeutical doses of the antibiotics ceftriaxone and levofloxacin were examined on L. sericata in order to determine and compare deviations in maggot development and survival. The used antibiotics did not significantly influence the maggot weight and length. A significant delay in the time of pupation has been determined in the treatments with high concentrations of levofloxacin. The mortality was significantly increased in all treatments with antibiotics compared to the control, whereby the survivability of all treatments remained over 80%. Because of the high doses needed to produce an effect, we concluded that an overestimation of the post‐mortem interval is unlikely but higher antibiotic concentrations or possible interactions with other medications could increase the maggot development time.