Activity Reports

Activity Report 2022

P-Campus activity report


Activity Report 2021                              Activity Report 2020

P-Campus activity report       P-Campus Activity Report 2020


Activity Report 2019                              Activity Report 2018

P-Campus Activity Report 2019      P-Campus Activity Report 2018                                          


Activity Report 2017                             Activity Report 2016              



Activity Report 2015                             Activity Report 2013/2014

     Activity Report 2013/2014


Projects funded by the ScienceCampus (summaries and contact persons):

Evaluation of different P-digestion methods for diverse environmental materials (EvaPhoN)

Various digestion procedures for total phosphorus were compared. Extracted materials were dry mass and ash from plants, animal tissues soil and sediments as well as seston. It was not primarily the aim to find a best way, but to identify the most important steps and to make the respective comparisons as a reference available to the ScienceCampus. In addition, the original sources of the methods, reviews and methods comparisons were compiled. We also provide some ashes as a reference material. The already thoroughly prepared work instructions will be regularly supplemented with the aim to create a methodological manual in the long run.

Contact person: PD Dr. Rhena Schumann (University of Rostock)

Genetic and nutritional effects on the efficiency of P use of monogastric animals

In order to identify measures to increase the efficiency of phosphorus (P) of monogastric animals, we investigated the physiological and transcriptional responses to modulated dietary P supply in growing pigs. The dietary P intake below and above current requirements was reflected in physiological serum parameters like inorganic phosphate, calcium, parathyroid hormone, vitamin D3 and cathepsin K, while the growth performance and feed intake were unaffected. The P supplementation above recommendations persistently affected animals as shown by microstructural bone parameters (increased Bone Mineral Density and Structure Model Index) and altered abundances of transcripts associated with bone morphology. Because of the multidisciplinary collaboration in this project, we were able to reveal the functional biodiversity of the animals regarding coping with a modulated dietary P supply. Genes found to be differentially expressed due to variable P supply are potential candidate genes for improved P efficiency.

Contact person: Prof. Dr. Klaus Wimmers (FBN)

Method Development for the Determination of particulate Glyphosate in Marine Environments; Bioavailability of Glyphosate

This study focused on glyphosate which is the active ingredient in commercial herbicide products such as Roundup®. This project was aiming for i. the method development for the extraction of glyphosate from particulate matter, ii. analysis of adsorption properties to soils from agricultural areas in Mecklenburg-West Pomerania and iii. analysis of the microbial degradation capacity and thus, the potential bioavailability of glyphosate for the Baltic Sea. Therefore, glyphosate was adsorbed to particulate matter such as sand, marine sediments with low and high organic carbon content and minerals. Glyphosate was extractable at different pH values depending on the type of particulate matter present. High extraction yields were obtained for glyphosate from minerals. However, extraction efficiency from sediments is insufficient, yet, and needs further improvements for glyphosate analysis from marine sediments. Adsorption isotherms for the soils from areas representative for the lowland landscape of Mecklenburg-West Pomerania indicate strong affinity of glyphosate to the selected soils. Cell culture experiments were conducted with Nodularia spumigena which is the predominant cyanobacterium for the Baltic Sea. The results of this project are currently under survey and will serve as the basis to develop further experimental strategies in order to identify factors which define glyphosate adsorption characteristics.  

Contact person: Dr. Marion Abraham (IOW)

Phenotypic and molecular characterization of P utilization and uptake efficiency of Solanum tuberosum

The aim of this project was to obtain knowledge about the genetic resources of potato with particular attention to the phosphorus efficiency (P-efficiency) and to submit a proposal for a follow up project. The data from the preliminary experiment show that different potato genotypes vary in their P-efficiency, which is in agreement with data from the literature. Based on these findings a project proposal with the topic “P-efficiency of potato” will be submitted to the German “Fachagentur für Nachwachsende Rohstoffe e.V. (FNR)”.

Contact person: Prof. Dr. Ralf Uptmoor (University of Rostock)

Recycling of phosphorus based organocatalysts through nanofiltration (RON)

In this project we demonstrated the application of organic solvent nanofiltration (OSN) as a sustainable alternative to distillation for the recycling of bifunctional phosphonium salts. We optimized the reaction and filtration process in respect to various process parameters (catalyst, solvent, membrane etc.) Under the optimized conditions the organocatalyst was retained up to 99% and could be recycled four times. The resulting paper was submitted to an internationally peer-reviewed journal.

Contact person: Dr. Thomas Werner (LIKAT)

Seed Projects Funding Period 2 (2019-2023)

EpiPTG - Dietary effects on DNA methylation in porcine parathyroid glands

M. Oster, (FBN) K. Wimmers (FBN), P. Wolf (UR), B. Vollmar (UMR)

It has been proposed that an adaptive response termed ‘Metabolic Programming’ offers the possibility to induce different and stable phenotypes. To improve phosphorus (P) efficiency in pig husbandry, a feeding experiment was conducted in 2018. Sows were supplied with variable amounts of dietary P during pregnancy and lactation, which had an indirect impact on the offspring. Thus the transgenerational design of this feeding study included nutritional challenges for the progeny of pigs during foetal and postnatal development. Results of RNAseq data retrieved from the parathyroid glands of the challenged offspring revealed transcriptional variations of a number of key genes involved in mineral homeostasis, such as parathyroid hormone (PTH) and fibroblast growth factor receptor 1 (FGF1R).
In this context, the relevance of possible epigenetic modifications must be clarified. To consider any long-term effects with regard to a P homeostasis in finisher pigs, RNA-Seq data will be complemented by the analysis of targeted DNA-methylation marks obtained via bisulfite sequencing.
In addition, directly affected parameters such as the serum level of PTH (released from the parathyroid glands) and its effects on bone mineralization will be assessed. The comprehensive molecular and phenotypic characterization forms the basis for the possible implementation of dietary P conditioning in monogastric animals.

P-CAT - Development of enantioselective catalytic Wittig reactions based on chiral phosphorus compounds as catalysts

T. Werner (LIKAT), A. Börner (UR)

Overall, the synthesis of the Wittig precursor 1 has been established in a multi-gram scale starting from 3.6 g substrate 2 to obtain 2.6 g of the desired compound 1 which is an overall yield of 36%. So far on a 0.4 mmol scale we were able to isolate 65% (range: 58–71%) of the desired product chiral bis-nor Wieland Miescher ketone with an average of 77% ee (range: 66–87%). Which represents a significant improvement compared to our previous report. The results were submitted as a solicitation proposal to Organic Synthesis (by invitation by Prof. Dirk Trauner). Unfortunately, the proposal was turned down at the present stage.

P-ChemBind - Phosphorus-protein interactions in cross-linking

J. von Langermann (UR), T. Werner (LIKAT), U. Kragl (UR)

The aim of the seed project "P-ChemBind" was to develop an efficient short-cut method for binding P-based side chains to proteins. In sum, it was found that the more demanding reaction conditions required here result almost entirely in a direct denaturation or undesirable modification of the protein. The target compound could only be produced in low yields.
The conclusion to be drawn from this short project is that the proposed method is not experimentally promising. The lengthy alternative route, which is now necessary after all, is being worked on in project III.2 "Application of P-based organocatalysts and biocatalysts for the resolution of racemic carbonates".

PIAG - Plasma-induced degradation reactions in glyphosate-containing substrates

V. Brüser (INP), P. Leinweber (UR)

In this study, surface corona discharges were shown to be able to effectively degrade glyphosate (GLP) in water without the need for additional chemical or biological additives. It was also shown that GLP removal in water can be achieved within a short time and could thus be implemented in sewage treatment plants. The established analytical methods for detecting degradation proved to be suitable and easy to perform. To evaluate the postulated degradation pathway, an in-depth analysis of the intermediate and final products after GLP degradation needs to be carried out, which will also help to improve the system. Corona discharges are a promising technique to address the problems of GLP removal in water.

PQ4N - Phosphorus as a cue regulating microbial N2O production

N. Wrage-Mönnig (UR), M. Voss (IOW)

Phosphorus (P) has been shown to interact with nitrogen (N) transformations in soils, altering microbial sources of nitrous oxide (N2O) emissions. However, this P-regulated N response remains largely unclear. Interactions with water content as well as P-fertilisation history have rarely been investigated. Within this project, we carried out an incubation and a mesocosm experiment to increase understanding of the interactions.
Using a 15N-labelled NO3 tracer in a soil incubation experiment, we studied the influence of P addition on N conversions and N2O emission under soil water-holding capacities (WHC) of 45 and 60 %. We conclude from the results that P availability could increase N conversion via mineralization, decrease nitrification and increase denitrification, coupled with an increase in N2O production from denitrification, which was the main N2O source here despite moderate water contents.
In the mesocosm experiment, we studied effects of P-fertilisation history on reactions of N2O production processes to P addition. Therefore, soils from two treatments of a long-term P fertilisation experiment were incubated with or without P addition. Fluxes of NO, N2O and CO2 were measured continuously and event-based samples taken for isotopomeric measurement of N2O and molecular analysis of the microbial community. Largest cumulative N2O production was found on the low-P soil with P fertilisation. Preliminary isotopic signatures did not suggest differences in N2O sources among treatments, but over time of incubation. Molecular results are pending due to constraints caused by pandemic measures.
Overall, the seed project has shown that P has an effect on N conversions and N2O production. This effect depends on P fertilisation history and probably on the microbial community.

ProCycle - The role of protists in the phosphorus cycle of biological soil crusts

M. Albrecht, (UR), K. Glaser, (UR), M. Labrenz (IOW), P. Leinweber (UR)

The role of protists in biological soil crusts in general and in the metabolic cycle of P has received very little attention and study so far. In other habitats and communities, such as plankton and the rhizosphere, the prominent role of protists and thus the microbial loop is well known. Therefore, this seed project aims to investigate a simplified model system regarding the P cycle with 3 of the most important components of a biocrust: protists, bacteria and algae.
Various organisms were tested for suitability (size, growth, countability, etc.) and good candidates were identified, grown in various combinations in P-depleted medium. Samples for P analysis were taken at the beginning and end of the experiment and samples for cell determinations of all three organisms were also taken on two days.
The results for P showed that there was more molbydate-reactive phosphate in the presence of the protist than without. The cell counts prove that the protist has ingested and digested the bacteria offered. However, due to the fact that the P samples were only taken at two points in time, it is not clear whether the increase in P results from an active release or from the dieback of the protists.
The preliminary and main experiments of the seed project phase have shown that the setup works in principle. Various optimisation possibilities could be identified. The selection of organisms has already been optimised as part of the seed project, but requires further testing with more resistant protists.

Seed Projects Funding Period 1 (2015-2019)

AMPA - Synthesis of isotope-labeled AMPA for qualitative and quantitative analysis of glyphosate degradation in soil

M. Kanwischer (IOW), P. Leinweber (UR), A. Schulz (UR), T. Werner (LIKAT)

Wirth, M.A., Longwitz, L., Kanwischer, M., Gros, P., Leinweber, P., Werner, T. (2021) AMPA-15N – Synthesis and application as standard compound in traceable degradation studies of glyphosate. Ecotoxicology and Environmental Safety 225, DOI: 10.1016/j.ecoenv.2021.112768

Isotopically labelled substances are often used in tracer experiments to track them or their correspondingly labelled degradation products, e.g. by using sensitive instrumental analysis. In this particular case, however, the use of commercially available isotopically labelled glyphosate leads to the formation of a 15N-AMPA degradation product, which cannot be quantified and analytically verified using conventional analytical approaches.
In the AMPA project, synthesised 15N-AMPA was used to prove that the degradation of the 13C-15N glyphosate used in a lysimeter experiment took place via 15N-AMPA. Contents of 15N-AMPA could be quantified in the soil samples of the experiment after re-analysis.

Crysphos - Separation of organic phosphates by crystallization

J. von Langerman (UR), T. Werner (LIKAT)

The seed project "Crysphos" investigated the targeted crystallisation of organic phosphates using metallic ions from the lanthanide group, which should ultimately enable potential recycling. The experimental work clearly showed that an almost quantitative separation is possible for almost all organic phosphates investigated, whereby the solubility differences between lanthanum and yttrium salts can additionally be exploited.

Desalting - Desalting of marine water through electrodialysis

M. Kanwischer (IOW), U. Kragl (UR), D. Schulz-Bull (IOW)

Wirth, M.A., Sievers, M., Habedank, F., Kragl, U., Schulz-Bull, D.E., Kanwischer, M. (2019) Electrodialysis as a sample processing tool for bulk organic matter and target pollutant analysis of seawater. Marine Chemistry 217, DOI: 10.1016/j.marchem.2019.103719

Electrodialysis (ED) is an advancing seawater sample processing tool that enables the separation of analytes from the often interfering salt matrix. In this study, we present the evaluation of a laboratory scale ED system for both dissolved organic matter (DOM) and target pollutant analysis of seawater.
The developed sample processing protocol yields reproducible data and was found to be robust towards moderate changes in sample composition. At the final salinity of 0.1, the average recovery of DOM in the form of dissolved organic carbon, nitrogen and phosphorus (DOC, DON and DOP) was 44, 53 and 89%, respectively. DOM loss occurred mainly in the late stage of the ED process.
When investigating specific ED processing parameters, it was discovered that the initial sample salinity does not influence DOM recovery. The final salinity, by contrast, is a dominant influence factor on DOM recovery. Furthermore, DOC and DOP recoveries could be improved by 8% by refining the electrical current in the ED cell. Surprisingly, adjustments of the sample pH did not lead to any improvements in DOM recovery.
The experiments with target analytes showed that the recovery of individual molecules is determined by their n-octanol water partition coefficients logKow. High recoveries > 80% were achieved for compounds with medium logKow of −1 to 3. Hydrophobic compounds with logKow > 3 were lost through surface adsorption to the system walls and tubing. Small, polar and charged compounds with logKow < −1 are prone to loss via ED membrane passage, which occurred predominantly in the late stage of the ED process. Consequently, sample processing with ED was deemed beneficial for the LC-MS or GC–MS analysis of polar target compounds, because they are often difficult to enrich from seawater. Furthermore, during LC-MS or GC–MS analyses, matrix-dependent ion suppression was reduced in ED isolates, giving rise to increased signal responses of 25 to 620%, which resulted in improved instrumental sensitivity.

DFG proposal - DFG proposal preparation "Influence of glyphosate and AMPA on biodiversity & biological activity in terrestrial and aquatic systems"; based on AMPA proposal

M. Kanwischer (IOW), P. Leinweber (UR)

The project will present the state of knowledge on interactions of glyphosate (GLP) with soil organisms and organism communities in terrestrial and aquatic ecosystems. Out of 629 scientific papers dealing with the above-mentioned interactions (search "Glyphosate + Organisms", Scopus, June 30, 2019), 127 were selected and evaluated during the two-month processing period. For the selection of publications to narrow down the topics, only bacteria, fungi and algae of soil and aquatic ecosystems were considered, as well as their effect on GLP degradation, nutrient cycling, and influences on plant nutrition and health. Higher organisms were not considered. After evaluation of the publications, such knowledge gaps were identified on the basis of contradictory findings or open problems, which can be investigated in the interdisciplinary network of the P-Campus and can provide important new insights into the behavior of GLP in the environment.

EvaPhon II & III - Evaluation of phosphorus digestion of natural materials

R. Schumann (UR)

see project P-Digest

Extremophile - Novel mechanisms of P-dependent energy transductions in an animal extremophile

I. Sokolova (UR), E. Sokolov (IOW), M. Zettler (IOW)

Hypoxia is a common stressor in the ocean oxygen minimum zones (OMZ) and is currently enhanced by the global climate change and anthropogenic input of nutrients into the ocean. Most marine metazoans cannot tolerate persistent hypoxia as reflected in mass mortalities and major decreases in biodiversity when the ambient oxygen concentration drops below 2 mg/L. However, a recent study of the OMZ off the Namibian coast led to a discovery of a unique bivalve species, Lembulus bicuspidatus, that thrives at extremely low oxygen concentrations (< 0.7 mg/L) where it forms abundant populations with high biomass. This ecological success of L. bicuspidatus at the OMZ margins implies existence of unique physiological and molecular mechanisms that regulate ATP production and P-dependent energy fluxes under extremely hypoxic conditions. We have sequenced the genome of L. bicuspidatus collected at the OMZ margin and obtained sequence information covering ~82 % of the Lembulus genome. Over 35,000 genes were identified and annotated, and based on these data, specific primers were designed to investigate the transcriptomic response of L. bicuspidatus to different oxygen conditions. The ongoing bioinformatics analysis is expected to generate the complete assembly of the mitochondrial genome and a partial (~82%) assembly of the nuclear genome of L. bicuspidatus, followed with annotation, phylogenetic and functional analysis. These data will be used as a basis of at least three peer-reviewed publications and a DFG proposal submitted in 2020-2021.

H-POP - Immobilization of P‐based organocatalysts by plasma techniques

V. Brüser (INP), T. Werner (LIKAT)

MitoP - The role of reversible phosphorylation in regulation of mitochondrial bioenergetics

I. Sokolova (UR), K. Wimmers (FBN)

Mitochondria are key intracellular targets of hypoxia-reoxygenation (H/R) stress due to their central role in ATP production and reactive oxygen species (ROS) generation. Intertidal bivalves such as oysters Crassostrea gigas are adapted to frequent H/R cycles and maintain aerobic function despite frequent oxygen fluctuations. To gain insight into the molecular mechanisms of H/R tolerance, we assessed the shifts in mitochondrial (phospho)proteome and functional changes in C. gigas mitochondria during hypoxia and recovery. Oyster mitochondria maintained OXPHOS capacity despite a decline in cytochrome c oxidase activity during H/R stress. Rearrangements of the mitochondrial proteome involved upregulation of mitochondrial electron transport system and ironbinding proteins and suppression of the metabolic pathways that channel electrons to ubiquinone, possibly as a mechanism to limit ROS production during H/R stress. H/R stress led to upregulation of a mitophagic activator PGAM5 and dephosphorylation of metalloendopeptidase OMA1, indicating stimulation of mitochondrial quality control mechanisms. Changes in abundance and phosphorylation levels of key proteins involved in the mitochondrial protein homeostasis indicate suppression of the protein synthesis during hypoxia, likely as an energy-saving mechanism. Thus, shifts in the mitochondrial (phospho- )proteome might play an important role in resistance to H/R stress of oysters ensuring mitochondrial integrity and function during oxygen fluctuations. This study provides insights into the potential role of proteomic shifts in adaptive response to H/R stress and serves as an important benchmark to understand the mechanisms underlying mitochondrial sensitivity to hypoxia (ischemia) and reoxygenation.

Sokolov, E.P., Sokolova, I.M. (2018) Compatible osmolytes modulate mitochondrial function in a marine osmoconformer Crassostrea gigas (Thunberg, 1793). Mitochondrion 45, 29-37, DOI: 10.1016/j.mito.2018.02.002

Sokolov, E.P., Markert, S., Hinzke, T., Hirschfeld, C., Becher, D., Ponsuksili, S., Sokolova, I.M. (2018) Effects of hypoxia-reoxygenation stress on mitochondrial proteome and bioenergetics of the hypoxia-tolerant marine bivalve Crassostrea gigas. J Proteomics 194, 99-111, DOI: 10.1016/j.jprot.2018.12.009

P-Aktiv - Evaluation of new P-based organocatalysts

A. Schulz (UR), T. Werner (LIKAT)

PAS - Plasma-based methods for digestion of biological substrates for P-analysis

V. Brüser (INP), P. Leinweber (UR), T. Leipe (IOW), R. Schumann (UR)

see project P-Digest

P-Digest - Compilation of long-term data and interlaboratory data on P digestion from different natural materials within the P-Campus for the Internet P-Handbook

V. Brüser (INP), P. Leinweber (UR), R. Schumann (UR), D. Zimmer (IOW)

Summary (from the projects EvaPhon II & III, PAS and P-Digest)
Within the framework of the cooperation between the partners of the P-Campus, it was found that different digestion and analysis methods are used for the analysis of total P in the individual working groups, the results of which are not always comparable one-to-one. In order to make it easier for young scientists in particular to familiarise themselves with the different working groups and to minimise the errors that may arise due to the different demands of the digestion and analysis methods, the existing methods were compiled in individual working groups and evaluated with their advantages and disadvantages or demands. The results of this work were compiled as part of the EvaPhoN seed projects as a "Handbook on the Selection of Methods for Digestion and Determination of Total Phosphorus in Environmental Samples" (e-Manual P Analytics). The resulting and still emerging chapters will be published online on the P-Campus website and will be freely available to P-Campus members as well as anyone else, after registration. The handbook is constantly being expanded. In 2020, work began on translating the chapters only available in German into English and putting them online.
As part of the work on the e-Manual P Analytics, the idea arose to test and evaluate novel digestion methods. Within the framework of the seed project PAS, different environmental samples (in dried and ashed state, e.g. water samples, plants, soil, sediment) were therefore investigated both with established digestion methods and with the plasma digestion method to be tested. The aim of the PAS project was to investigate whether physical plasma is suitable as an alternative digestion method of dried organic samples for the determination of phosphate content. A promising plasma source was a spark discharge in water for testing. For the experiments, the samples were suspended in distilled water and continuously exposed to the spark. Based on the results, it could be determined that the spark discharge in the existing system is only suitable to a limited extent for digesting the sample types used. It is therefore recommended to recheck the samples by another plasma source or to reconfigure the system used. Following the PAS project, it became apparent that the flood of data generated in the entire seed projects (EvaPhonN and PAS), as well as through several bachelor's and master's theses, dissertations, the BMBF joint project BACOSA, and through the testing of more and more materials by further doctoral students, also from outside the P-Campus, must be evaluated and compiled accordingly. This was done as part of the seed project P-Digest. Among other things, it was confirmed that the digestion method and the determination method must be well coordinated, since, for example, P cannot be determined by means of molybdenum blue in an aqua regia digestion due to the high HNO3 concentrations.

PIPAPo - Unraveling molecular signaling pathway involved in phosphorus acquisition of potato

K. Dehmer (IPK), R. Uptmoor (UR)

The phosphorus uptake of potato is low, but there are genotypic differences. The micro-RNAs miR399 and miR827 play an important role in P signaling. The seed project investigated whether potato genotypes with different P-acquisition efficiencies differ in the expression of the micro-RNAs and whether these micro-RNAs play a role in potato P-acquisition. For this purpose, two potato genotypes with different P-acquisition efficiency were grown with and without phosphate supply. The expression of the micro RNAs miR399 and miR827 in leaves and roots and the root-associated phosphatase activity were measured at different points in time. The phosphatase activity was significantly increased without phosphate supply at the first measurement time point after two weeks, the micro RNA expression in the roots after three weeks. No P-deficiency-induced increase in expression levels was detected in the leaves. A strong local signal for an increase in phosphatase activity (phosphorus deficiency at the roots) might have masked the systemic signal (increased micro-RNA expression) here. A direct correlation between micro-RNA expression and phosphatase activity could not be demonstrated. Differences between genotypes with different phosphorus acquisition efficiencies were not found.

In the PhD project "IV.2 Sustainability of potato production: Cloning and sequencing of candidate genes improving P acquisition efficiency to reduce fertilizer inputs" (start May 2020), the allelic variation of candidate genes for improving P uptake in potatoes on P-deficient soils will be evaluated for the first time.

P-NMR - 31P-NMR spectroscopy: further development of methods and application to P compounds and fluxes in the environment

P. Leinweber (UR), D. Michalik (LIKAT), D. Schulz-Bull (IOW)

Phosphorus (P) is an indispensable nutrient for living organisms in both terrestrial and aquatic ecosystems. However, an excess can trigger serious environmental problems, such as eutrophication of freshwater and marine ecosystems. The release of P from sediments into the water column depends on the P speciation, occurrence and lability of the different P forms. Therefore, the main objective of this project was to use the method of 31P nuclear magnetic resonance spectroscopy (31P-NMR) to achieve the most accurate characterisation of a sample set of sediments along a transect from northern German coastal waters to the central Baltic Sea. The results of the 31P-NMR spectroscopy show that the diversity of the different mono- and diester-P compounds decreases with increasing distance from the coast and that high proportions of more stable orthophosphate are present especially in greater water depths. There is a trend from many labile to fewer but more stable P compounds with decreasing terrestrial and increasing aquatic influence in accordance with the results of the complementary methods of sequential P fractionation and synchrotron-based X-ray absorption spectroscopy (XANES). This information can support the development of measures to reduce excess P inputs to aquatic environments and thus make a fundamental contribution to environmental protection.

Prüter, J., Leipe, T., Michalik, D., Klysubun, W., Leinweber, P. (2019) Phosphorus speciation in sediments from the Baltic Sea, evaluated by a multi-method approach. Journal of Soils and Sediments, DOI: 10.1007/s11368-019-02518-w

P-Recyclate - Process engineering concepts for the recovery of agriculturally usable P-recyclates from residues of animal production

C. C. Metges (UR), J. Tränckner (UR)

The aim of this project is to develop a technological concept for the utilisation of valuable substances such as phosphorus contained in liquid manure and sludge from fish farms. The concept development was laboratory-based in order to develop suitable and mutually compatible methods for the following technological questions:
▸ Phase separation
▸ Digestion of phosphorus from the solids contained in the liquid manure
▸ Precipitation of phosphorus mainly with calcium
▸ Drying or separation of the obtained P-containing recyclates

To investigate a possible increase in phosphorus digestion, the samples were subjected to anaerobic pre-treatment. The fermentation significantly increased the phosphorus content in the liquid phase and slightly increased the phosphate content. Acid digestion of the phosphorus contained in the samples was investigated using sulphuric acid, citric acid and hydrochloric acid in various volume proportions. The highest mobilisation was achieved with sulphuric acid, so that almost all the phosphorus could be mobilised at a ratio of 1:0.8. A maximum of 80% of the phosphorus was mobilised with citric acid and hydrochloric acid. Precipitation mainly as calcium phosphates took place from a pH value of 8. The digestibility of the obtained P-recyclates was highest at low drying temperatures with 55%, where no calcium hydroxide had to be added. In evaluation of the test results, the conception of a process for phosphorus recovery from liquid manure and similar sludges was created. This concept was presented to small and medium-sized enterprises and discussed, resulting in a research proposal for further process development. Within the framework of this project outline, which has already been positively evaluated, a prototype is being built for phosphorus and nitrogen separation from liquid manure and similar media.

Based on the results, an application was successfully submitted to the BMBF (KMU innovativ): Optimisation of material cycles in agriculture through targeted fractionation of liquid manure into phosphorus; nitrogen and organic carbon (abbreviation: PNC-Processing).

P-Redox - Cyclovoltammometric measurements on phosphorus ligands

R. Francke (UR), C. Hering-Junghans (LIKAT)

Within the framework of this project, an electrochemical measuring stand was to be set up and the methodology established in the Hering-Junghans working group. With the help of such a measuring stand, electrochemical analyses such as cyclic voltammetry and differential pulse polarography can be carried out, which allow information to be obtained about the redox chemistry of chemical compounds.
An electrochemical measuring stand consists of a potentiostat, a measuring cell with electrodes and a control computer. This equipment was procured with the help of a "material cost grant" from the FCI and should now be installed and prepared for routine measurements as part of this project. To ensure an efficient setup, the Hering-Junghans junior research group collaborated with Dr. Robert Francke's junior research group at the University of Rostock. The Francke Group deals solely with electrochemical issues and represented a perfect contact for the realisation of this project. The seed project was successfully completed and the Hering-Junghans working group is now able to routinely perform electrochemical measurements under inert gas. In a first application, it was possible to show that triphosphiranes are irreversibly reduced, which was an important contribution to a publication in Chemical Science. In addition, CV measurements were carried out for the working group of Prof. Dr. Axel Schulz, which will potentially also result in a publication.

SERAIP - Shifted excitation Raman difference spectroscopy testing for analysis of inorganic phosphorus, inositol phosphates (InsPx) and myo-inositol in environmental and animal samples

K. Sowoidnich (FBH), M. Oster (FBN), B. Sumpf (FBH), M. Maiwald (FBH), R. Schumann (UR), P. Leinweber (UR), G. Tränkle (FBH), K. Wimmers (FBN)

In the diets of poultry and pigs, most of the daily requirement of phosphorus (P) is obtained from plants in the form of inositol phosphates (InsPx), which, however, cannot be used efficiently due to a lack or absence of endogenous phytase activity. Analytical measurements to improve the use of InsPx are therefore essential to reduce the environmental impact of animal husbandry and to conserve valuable mineral P resources. In the seed project, selected P-containing compounds were detected in complex matrices such as feed, faeces and soil/sediments via Raman spectroscopy or SERDS (e.g. phytate, InsP5, InsP3, myo-inositol, Ca(H2PO4)2, CaHPO4, Ca3(PO4)2, Ca2O7P2, β-glycerophosphate, DL-α-glycerol-6-phosphate). These alternative physical techniques thus represent an alternative to the costly and time-consuming chemical analysis. The results achieved in the seed project help to trace the whereabouts of P along the agricultural cycle in feed, animals, farm manure, soil and water.

Sowoidnich, K., Oster, M., Wimmers, K., Maiwald, M., Sumpf, B. (2021) Shifted excitation Raman difference spectroscopy as enabling technique for the analysis of animal feedstuff. Journal of Raman Spectroscopy, DOI: 10.1002/jrs.6140

Graduate School II (2019-2023)
I.1 Risks and benefits of rewetting coastal wetlands after agricultural use
I.2 P Pools and mobilization potential in lowlands and coastal regions

PhD student: Julia Prüter (dissertation completed)

Summary of the project results
Phosphorus (P) is an indispensable nutrient element for all organisms but at the same time contributes significantly to excessive eutrophication in aquatic ecosystems. Knowledge about the chemical P speciation is essential to assess possible risks of P transport towards vulnerable aquatic ecosystems. To date, this knowledge, especially for transects including soil and sediment samples from terrestrial to aquatic ecosystems, is still insufficient. Thus, the general objective of the present work was to characterize the P speciation and to detect transformation processes along transport pathways at the fluent boundaries between land and sea including terrestrial soils, semiterrestrial wetlands and aquatic sediments. Besides analyses of elemental concentrations and water contents, terrestrial/semiterrestrial soils and aquatic sediments from micro-, meso- and macroscale ecosystems were analyzed by a multi-method approach including sequential P fractionation, P K-edge X-ray absorption near edge structure (XANES) spectroscopy and 31P nuclear magnetic resonance (NMR) spectroscopy. The detection of specific organic P species with terrestrial origin in arable soils as well as in adjacent sediments supported the assumption of direct P transport processes from terrestrial towards aquatic ecosystems. The complementary results confirmed a transition from labile and moderately labile Fe- and Al-associated P and great variety of organic P species in terrestrial soils towards more stable Ca- and Mg-P and less different organic P species in aquatic sediments. Kettle hole sediments, coastal wetland soils and Baltic Sea lagoon sediments acted as sinks for accumulations of especially stable P and complex organically bound P species. Some of the stable P species in aquatic sediments at the bottom of lake or sea waters can originate from Ca-P dominated fish fecal matter. To protect vulnerable aquatic ecosystems from further P inputs, kettle holes, coastal wetland buffer strips and deeper areas in shallow Baltic Sea lagoons have to be preserved and maintained or created in areas where they have not been available so far. Forthcoming studies have to focus on possible P recycling from terrestrial as well as aquatic sinks to contribute to closing P cycles in agricultural fertilization and adjacent ecosystems.

Publications from the project

Prüter, J., Schumann, R., Klysubun, W., Leinweber, P. (2023) Characterization of Phosphate Compounds along a Catena from Arable and Wetland Soil to Sediments in a Baltic Sea lagoon. Soil Syst., 7, 15. DOI: 10.3390/soilsystems7010015

Prüter, J., McLaren, T.I., Pätzig, M., Hu, Y., Leinweber, P. (2022) Phosphorus speciation along a soil to kettle hole transect: sequential P fractionation, P XANES, and 31P NMR spectroscopy. Geoderma 429:116215. DOI: 10.1016/j.geoderma.2022.116215

Prüter, J., Hu, Y., Leinweber, P. (2022) Influence of sample pretreatment on P speciation in sediments evaluated with sequential fractionation and P K-edge XANES spectroscopy. Communications in Soil Science and Plant Analysis, 53:14, 1712-1730, DOI: 10.1080/00103624.2022.2063317

Prüter, J., Strauch, S. M., Wenzel, L., Klysubun, W., Palm, H.W., Leinweber, P. (2020) Organic matter composition and phosphorus speciation of soild waste from an African Catfish Recirculating Aquaculture System. Agriculture, 10, 466. DOI: 10.3390/agriculture10100466

Prüter, J., Leipe, T., Michalik, D., Klysubun, W., Leinweber, P. (2019) Phosphorus speciation in sediments from the Baltic Sea, evaluated by a multi-method approach. Journal of Soils and Sediments 20, 1676–1691. DOI: 10.1007/s11368-019-02518-w

I.3 Analysis of glyphosate and glufosinate in sea water and as indicator compounds for industrial cropping

PhD student: Marisa Wirth (dissertation completed)

The aim of subproject I.3 was to develop measurement methods for the environmentally relevant organophosphorus herbicides glyphosate and glufosinate, as well as for the glyphosate metabolite AMPA in seawater. Prior to this, the target analytes were not detectable in the presence of the salt matrix in the marine environment due to methodological difficulties. By using suitable solid phase extraction materials, the enrichment of the analytes and the separation of the salt matrix could be realized, which allowed the development and validation of suitable methods for seawater.

II.1 P recycling in animal husbandry

PhD student/processor: Jonathan Schleyken / Felix Gumpert

Summary (only available in German)
Das Projekt "P-Recycling in der Tierproduktion" war Bestandteil von Cluster II - Suffizienz und Effizienz der P-Nutzung, P-Rückgewinnung des Leibniz-WissenschaftsCampus Phosphorforschung Rostock. Mit dem Start im Juli 2019 und dem Ende im September 2022 wurde das Projekt etwas mehr als drei Jahre bearbeitet. Die Bearbeitung fand hauptsächlich an der Professur für Wasserwirtschaft der Agrar- und Umweltwissenschaftlichen Fakultät der Universität Rostock statt und wurde von der Professur für Aquakultur unterstützt.
Als Bearbeiter und Promovend wurde Herr Jonathan Schleyken eingestellt. Trotz guter fachlicher Fortschritte entschied sich Herr Schleyken Ende 2021, die Promotion abzubrechen, um eine für ihn attraktive Position bei einem Wirtschaftsunternehmen anzutreten. Wir beantragten deshalb beim Vorstand des WissenschaftsCampus die Fortsetzung der Arbeiten mit einem neuen Bearbeiter. Diesem Antrag wurde stattgegeben. Als neuer Bearbeiter wurde zum Januar 2022 Herr Felix Gumpert eingestellt. Aufgrund der kurzen verbleibenden Restlaufzeit von ca. 9 Monaten war für ihn das Ziel einer Promotion zu diesem Thema nicht erreichbar. Vielmehr verständigten wir uns darauf, die bereits vorliegenden experimentellen Ergebnisse und Stoffstromanalysen systematisch aufzuarbeiten und ein bis zwei gemeinschaftliche Veröffentlichungen beider Bearbeiter zu nutzen.
Ziel des Projektes war die Nutzbarmachung alternativer P-Quellen und einer damit verbundenen P-Rückgewinnungstechnologie aus den Abwässern und Schlämmen von Rezirkulierenden Aquakultursystemen (RAS). Die überschüssigen Nährstoffe sollten zurückgewonnen werden und im Anschluss in ein verdauliches und pflanzenverfügbares Calciumphosphat synthetisiert werden. In der gängigen Praxis wird lediglich ein Teil der zugeführten Nährstoffe (abhängig von Fütterungsstrategie, Fischgröße und der artspezifischen Nährstoffretention) für die Produktion der Organismen verwendet. Die überschüssigen Nährstoffe werden im weiteren Verlauf über regelmäßigen Wasseraustausch und/oder spezielle Filtereinheiten und Absetzbecken reduziert, um Grenzwerte für die Entsorgung des Prozesswasser einzuhalten und artgerechte Haltungsbedingungen für die produzierten Organismen zu gewährleisten.
Für die Nutzung der Reststoffe (Schlamm und Abwasser) gibt es verschiedene Möglichkeiten. Eine Möglichkeit ist die Ausbringung des Schlamms auf landwirtschaftliche Flächen (Brod & Øgaard, 2021; Burducea et al., 2022). Dies erfordert eine entsprechende landwirtschaftliche Nachfrage in der Nähe. Ähnlich wie bei Klärschlamm besteht in Abhängigkeit von Haltungsbedingungen und Fütterungsregime allerdings die Gefahr, dass Schwermetalle und pharmazeutische Stoffe direkt in die Umwelt gelangen. (Kirchmann et al., 2016; Zuloaga et al., 2012). Eine andere Möglichkeit bietet die Aquaponik. Hier können die Restnährstoffe des Abwassers für den Anbau von meist gartenbaulichen Pflanzen genutzt werden (Palm et al., 2018).
Wenn eine direkte stoffliche Nutzung nicht möglich ist, ist die chemische Rückgewinnung von P eine weitere Option. Für den Bereich kommunaler Klärschlämme wurden in den letzten Jahren zahlreiche chemische sowie einige thermische Verfahren zur Rückgewinnung eines P-reichen Rückstands aus organischen Materialien entwickelt. Basierend auf Vorversuchen wurde für die Bearbeitung dieses Projektes das Hauptaugenmerk auf eine Mobilisierung der vorwiegend partikulär gebundenen P-Fraktionen mit anschließender Fällung des gelösten P gelegt.
Ähnliche Verfahren in der Abwassertechnik sind das Gifhorner- (auch bekannt als Seaborne-Verfahren), das Stuttgarter- und das Extraphos-Verfahren (Ohtake & Tsuneda, 2019). Jedoch ist die Stoffmatrix von Aquakulturschlämmen deutlich abweichend zu anaerob stabilisierten Klärschlämmen. Die Übertragung und Weiterentwicklung bekannter Verfahren auf die Abwässer und Schlämme aus Aquakulturanlagen war ein zentraler Bestandteil des Projektes.
Eine parallel zu bearbeitende Fragestellung war die Ermittlung der P-Flüsse in landbasierten rezirkulierenden Aquakultursystemen, um das labortechnisch ermittelte Rückgewinnungspotential in das Gesamtsystem einordnen zu können

Project report

II.2 Efficiency of recovered phosphorus for monogastric animals

PhD student: Mohammad Mahdi Seyedalmoosavi

II.3 P efficiency of forage legumes and their capacity to utilize P from recycling products

PhD student: Yue Hu

III.1 Synthesis of novel P-based ligands for complexes to activate small molecules

PhD student/processor: Jan-Erik Siewert, Dr. Fabian Dankert

III.2 Application of P-based organocatalysts and biocatalysts for the resolution of racemic carbonates

PhD student: Constanza Terazzi

III.3 Synthesis of potential anti-tumor and adhesion-promoting agents by P-based organocatalysis for oncology and biomedical engineering

PhD student: Jan Tönjes

IV.1 Gene expression in biogeochemical cycling of phosphorus in biological soil crusts of sand dunes of the Baltic Sea

PhD student: Sandra Kammann

The project results pointed to a conspicuous shift of the phototrophic biocrust community with the development of the dunes along each chronosequence, as reflected in different successional stages. Furthermore, the different geographical regions revealed a considerable impact on the biocrust species composition, which can be explained by habitat-specific factors. The enrichment of organic matter and nutrient contents, along with increased soil moisture and stability, are the key functions that originate from the metabolic activities in the different stages of biocrusts. The increase in total P in the biocrusts along both chronosequences could mainly be explained by the increased biomass formation. Consequently, biocrusts strongly shape dune development and contribute to geomorphological processes. In addition, the biocrust key functions offer opportunities for rehabilitation and restoration approaches, such as preventing sediment erosion in coastal dune areas.

Project report

IV.2 Sustainability of potato production: Cloning and sequencing of candidate genes improving P acquisition efficiency to reduce fertilizer inputs

PhD student: Julian Kirchgesser

IV.3 The role of inorganic phosphate supply on the development of cyanobacterial summer blooms in the Baltic Sea

PhD student: Mariano Santoro

IV.4 Phosphorus as a metabolic regulator during environmental stress in animals

PhD student: Linda Adzigbli

IV.5 Molecular mechanisms of phosphate homeostasis and osteoimmunological processes and their consequence for health and welfare

PhD student: Maruf Hasan

V. Governance options for closed P cycles - the GAP 2020 revision

PhD student: Katharine Heyl

The project ‘Governance options for closed P cycles - the CAP 2020 revision’ was situated in Cluster V P-Governance of the Leibniz ScienceCampus Phosphorus Research Rostock. Having started in July 2019, the project covered a little more than three years and came to an end in September 2022. The project was based on a cooperation between the P-Campus, the Faculty of Agricultural and Environmental Sciences of the University of Rostock and the Research Unit Sustainability and Climate Policy in Leipzig. It built on research findings of earlier work on policy instruments for a sustainable transition in general and sustainable P management in particular including the P-Campus Graduate Academy, InnoSoilPhos, Bioacid and two scholarships (DBU and HBS).
The project aimed to assess the role of subsidies in transitioning to sustainability in general and closing P cycles in particular by investigating the subsidies of the reformed Common Agricultural Policy (CAP). To this end, analyses at the EU level and the national level (Germany) were undertaken. Accompanying the analyses on the subsidies of the CAP, other P relevant topics such as governance options to address food waste and to extend organic farming, and other subsidy relevant topics such as agricultural trade agreements were addressed as well. The findings of the project were published in several peer-reviewed articles some of which will be submitted as cumulative dissertation in early 2023.

Project report

Graduate School I (2015-2019)
Subproject 1: Mechanisms of P mobilization in the rhizosphere involving weeds and crop plants

PhD student: Anika Zacher (dissertation completed)

Summary (only available in German)
Die Verknappung der P-Ressourcen für die Düngemittelproduktion hat zur Folge, dass die Landwirtschaft die bestehenden P-Pools der Ackerböden für die Pflanzenproduktion effizienter nutzen muss. Unkrautregulierung reduziert die Konkurrenz der Unkrautvegetation gegenüber der Kulturpflanze, verhindert jedoch zugleich die Nutzung potenzieller bodenökologischer Vorzüge einer erhöhen Wurzelaktivität zur P-Mobilisierung.
Die vorliegenden Untersuchungen prüfen daher im Gefäß- und Feldversuch die Wirkung der Vergesellschaftung von Kulturpflanzen mit typischer Unkrautvegetation auf die P-Versorgung in P-defizienten Böden. Als Modell-Kulturpflanzen wurden Mais (Zea mays L.) und Kartoffeln (Solanum tuberosum L.) gewählt, die einen hohen P-Bedarf besitzen und zugleich im kommerziellen Anbau strikter Unkrautregulierung unterliegen. Die getesteten Unkrautarten (Chenopodium album, Echinochloa crus-galli, Tripleurospermum perforatum, Solanum nigrum, Polygonum convolvulus, Viola arvensis) sind Vertreter der typischen Samen-Unkrautgemeinschaft unter diesen Kulturen mit sehr diverser Wurzelmorphologie.
Die Ergebnisse belegen, dass die Vergesellschaftung mit Unkräutern zu einer erhöhten P-Mobilisierung (gemessen als Phosphataseaktivität und Konzentration pflanzenverfügbarem P im Boden) führen kann. Jedoch hat die Witterung einen signifikanten Einfluss auf das Ausmaß der Wirkung auf die P-Mobilisierung. Vergesellschaftung mit Unkräutern führte zu einer erhöhten Mykorrhizierungsrate der Kulturpflanze, unabhängig davon, ob die jeweilige Unkrautart selbst eine geringe oder hohe Mykorrhizierungsneigung aufwies. Die meisten der getesteten Unkrautarten wiesen eine eher geringe Mykorrhizierungsneigung, jedoch ein intensives Feinwurzelwachstum auf. Die P-Nutzungseffizienz der Unkräuter als Maß von Mobilisierung zu Pflanzenaufnahme und Wachstum variierte signifikant zwischen den Arten.
Die Ergebnisse des Rhizobox-Versuches belegen, dass der zymographische Nachweis von Phosphataseaktivitäten im Boden sehr gut geeignet ist, um die P-Mobilisierung unterschiedlicher Unkrautarten in der Rhizosphäre zu bewerten. Die Ergebnisse der Gefäß- und Feldversuche belegen, eine temporäre Toleranz von Unkräutern im Bestand signifikant zu verbesserter P-Versorgung der Kulturpflanzen beitragen kann. Die praktische Umsetzung einer solchen Maßnahme muss jedoch im Feldversuch optimiert und unter verschiedenen Witterungsbedingungen getestet werden, bevor sie zur Nachahmung empfohlen werden kann. Der mykorrhizierungsfördernde Effekt einer temporären Unkrauttoleranz sollte in Folgeuntersuchungen auf seine bodenökologische Bedeutung getestet werden, da die P-Versorgung nur einen Teilaspekt der Mykorrhizierungswirkung umfasst.

Subproject 2: Genetic regulation of phosphatase production and activity to increase P uptake from deficient soils

PhD student: Katrin Wacker (project completed)

Summary (only available in German)
Die Kartoffel hat eine niedrige P-Aufnahmeeffizienz und einen hohen Bedarf an Phosphor (P). Ziele dieser Arbeit waren die Evaluierung der P-Aufnahme- und Nutzungseffizienz von Genbankakzessionen der Kartoffel, die Identifizierung morphologischer und physiologischer Mechanismen zur Verbesserung der P-Aufnahme und die Charakterisierung der Rolle, die Phosphatasen bei der P-Aufnahmeeffizienz spielen. Hierfür wurden im Gefäß 28 Genbankakzessionen bei P-Mangel und optimaler Versorgung getestet und solche mit hoher und niedriger P-Effizienz wurden selektiert. Die selektierten Genotypen wurden in mehreren Versuchen mineralisch und organisch gedüngt bzw. P-Mangel ausgesetzt. Neben agronomischen Parametern wurde die P-Aufnahme ermittelt, Expressionsmuster von Phosphatasegenen wurden erstellt, die Phosphataseaktivität in der Rhizosphäre wurde ermittelt und die Wurzelmorphologie der Genotypen wurde erfasst. Eine weitere Evaluierung der Genotypen fand in Feldversuchen statt.

Innerhalb des aus 28 Genotypen bestehenden Diversitätssets gab es deutliche Unterschiede sowohl in der P-Aufnahme als auch in der P-Effizienz. Die selektierten Genotypen zeigten zwar Unterschiede im Expressionslevel der sauren Phosphatasegene PAP2 und PAP3, diese korrelierten allerdings nur schwach mit der Phosphataseaktivität im Boden. Offensichtlich besteht ein enger Zusammenhang zwischen der Ausprägung des Wurzelsystems und der PAufnahme. Im Feld konnten die genotypischen Unterschiede hinsichtlich der Trockenmassebildung und Ertragsunterschiede der selektierten Genotypen verifiziert werden, es zeigte sich jedoch kein statistisch signifikanter Effekt der Düngung auf den Ertrag, obwohl die niedrigsten Knollenerträge für alle Genotypen in der ungedüngten Kontrolle gemessen wurden.

Da P im Vergleich zu anderen Pflanzennährstoffen im Boden wenig mobil ist, scheint die intensive Durchwurzelung des Bodens einen erheblichen Beitrag zur Verbesserung der PAufnahmeeffizienz zu leisten. Die Bedeutung der Phosphatasen und der Phosphataseaktivität in der Rhizosphäre konnte im Rahmen dieser Studie nicht eindeutig belegt werden. Es gibt allerdings eine Reihe weiterer saurer Phosphatasen, die in der vorliegenden Arbeit nicht berücksichtigt wurden, und im Projekt PIPAPo konnte ein eindeutiger Zusammenhang zwischen der P-Versorgung des Bodens und der Aktivität von Phosphatasen direkt an den Wurzeln gezeigt werden. Die Ergebnisse von Feldversuchen haben verdeutlicht, dass selbst eine P-Unterversorgung nach aktueller Düngeempfehlung nicht zwangsläufig zur signifikanten Ertragsreduktion führen muss. Diese Ergebnisse decken sich z.T. mit Erfahrungen aus der Landwirtschaft und lassen darauf schließen, dass auch die pflanzenbauliche Praxis mit aktuellen Sorten noch einiges an Potential zur Reduktion des Einsatzes P-haltiger Düngemittel aufzuweisen hat.

Subproject 3: Phosphatases – Development of new quantitative assays along terrestrial-aquatic gradients

PhD student: Iris Schaub (dissertation completed)

Summary (only available in German)
Phosphatasen (Pasen) sind Schlüsselenzyme in der aquatischen Umwelt, mit denen Mikroalgen und Bakterien den gelösten organischen Phosphor (DOP) Pool nutzbar machen. Reguliert wird die Pase-Produktion durch die externe Phosphatkonzentration (Pi). In der vorliegenden Doktorarbeit sollte die Rolle der Phosphataseaktivität (PA) in aquatischen und terrestrischen Habitaten untersucht und derer Indikatorfunktion als Phosphor (P) Limitationsparameter bewertet werden. Zum ersten Mal wurde die Michaeliskonstante (KM) als potenzieller Indikatorwert betrachtet und die Rolle der Phosphataseaktivität in biologischen Bodenkrusten (BSC) einer Küstendüne untersucht.
Da die Pasen von unterschiedlichen Organismen produziert und über vielfältige Mechanismen in das wässrige Milieu gelangen, war die Bestimmung des Ursprungs der PA und die Suche nach einem Referenzparameter, um die PA unterschiedlicher Gewässer zu normieren und vergleichen zu können, nur teilweise erfolgreich. Von den getesteten Referenzparameter erwies sich nur das partikuläre organische Material (POM) als geeignet. Die Ergebnisse zeigten, dass der KM kein geeigneter Parameter für die Bewertung einer P Limitation ist. Vergleiche zwischen der PA und anderen P Limitationsparametern ergaben ebenfalls keine einheitlichen Abhängigkeiten. Von der Nutzung der PA als alleiniger Parameter zur Bestimmung einer möglichen P Limitation muss damit abgeraten werden. Die PA war in der untersuchten BSC sehr gering, da das Wachstum der Mikroalgengemeinschaft Wasser- und dann Stickstofflimitiert war. Generell konnten in der BSC, im Vergleich zum ansonsten sehr nährstoffarmen Dünensand, eine Nährstoffakkumulation festgestellt werden. Die Verteilung von verschiedenen Sukzessionstadien der BSC hing zudem von der Exposition zum Windstress ab.

Project report

Subproject 4: The P cycle and its application in land-based integrated aquaculture systems

PhD student: Sebastian Strauch (dissertation completed)

The production of African catfish (Clarias gariepinus) is becoming increasingly important in Germany, where it is produced exclusively in recirculating aquaculture systems (RAS). Due to the natural accumulation of plant-relevant nutrients in the process water of such RAS and a high tolerance of the African catfish towards reduced water quality, this combination offers a high potential for an economical aquaponic application in Germany. As a part of this dissertation, the term aquaponics was newly defined. Subsequently, the properties of the rearing water of African catfish RAS for subsequent use in commercial aquaponics were assessed under different production intensities – extensive, semi-intensive and intensive. Finally, the ability of the African catfish to cope with elevated levels of ortho-phosphate (ortho-P) originating from specific fertilizers to increase plant growth in hydroponics was assessed.

This dissertation demonstrates that under commercial conditions, African catfish RAS can be used to supply plant production sufficiently with nutrients, to comply with the definition of aquaponics in the sense of Palm et al. (2018a). Due to suboptimal nutrient concentrations, relatively low fish production and high labor costs, the semi-intensive production cannot be recommended due to a negative total cost benefit balance. Extensive and intensive production is possible and can be adjusted with different aquaculture species to meet the local market demand. Nutrient supplementation (i.e. ortho-P) can be performed up to levels that favor optimal growth of plants.

Project report

Subproject 5: Genetic and nutritional effects on the efficiency of P use of monogastric animals

PhD student: Christian Gerlinger (project completed)

Phosphorus (P) is an important element of various metabolic and signalling processes, including bone metabolism and immune function. Sufficient supply of pigs with calcium (Ca) and phosphorus (P) is essential for animal health and welfare during the growth period but frequently exceeds age specific requirements in practice. However, the P content in animal manure is considered as a cause of massive environmental problems in soil and aquatic ecosystems. The objective of this study is the investigation of effects of a reduced and increased dietary P supplementation in combination with constant or variable Ca levels on bone mineralization and bone structure compared to the current dietary recommendation. Further, possible serum markers that would allow the assessment of adequacy of P supply for bone health during growth should be found. To elucidate the routes of P homeostasis and utilization, a five-week feeding study was conducted with weaned piglets receiving a diet with recommended amounts of P and Ca (M), or a diet with lower (L) or higher (H) P values and a constant Ca:P-ratio. Furthermore the effect of a variation in dietary P and Ca was compared to a variable Ca:P-ratio with constant dietary Ca levels. Dietary responses were deduced via performance parameters, bone characteristics (MicroCT), genome-wide transcriptomic profiles of peripheral blood mononuclear cells (PBMCs) and molecular data retrieved from serum, intestinal mucosa, and kidney cortex.
Animals of the L group showed attempts to maintain mineral homoeostasis via intrinsic mechanisms, whereas the high-fed animals adapted at the expense of growth and development. MicroCT revealed significantly lower bone mineral density, trabecular number, and mechanical fracture load in (L). Gene expression analyses showed transcripts of 276 and 115 annotated genes with higher or lower abundance in the (H) than (L) that were related to basic cellular and metabolic processes as well as response to stimuli, developmental processes and immune system processes. Transcripts associated with vitamin D hydroxylation (Cyp24A1, Cyp27A1, Cyp27B1) were regulated by diet at local tissue sites.
The result validated that the recommended Ca and P supply is sufficient, without the addition of microbial phytases. However, addition of P has no further beneficial effects on bone stability, while P supplementation below the recommended level affects bone development and growth performance.
This study shows the many molecular routes involved in P homeostasis that should be considered to improve endogenous mechanisms of P utilization. Further fine-tuning of the P supply in conjunction with an appropriate Ca supply will contribute to a reduction in P losses along the agricultural value chain and associated environmental impact while maintaining animal health and welfare.

Project report

Subproject 6: Quality, Quantity and Transformation of P losses from diffuse sources to the Baltic Sea

PhD student: Sandra Jahn (project completed)

Summary (only available in German)
Phosphor (P) wird entlang der Fließgewässer von der Quelle bis zum Meer transportiert. Da P ständig zwischen den verschiedenen Fraktionen transformiert wird, ist das Verständnis der P-Dynamik entlang der Fließgewässer von entscheidender Bedeutung, um die Belastung zu reduzieren. In diesem Projekt wurden die Konzentrationen, Fraktionen und die Form, in der P an suspendiertem Material gebunden ist, im Einzugsgebiet der Zarnow, einem Teileinzugsgebiet der Warnow, untersucht. Dazu wurden 8 Stationen vom Dränauslass, dem angrenzenden Graben und weiter entlang des Baches bis zum übergeordneten Fluss, der Warnow, beprobt. In einer separaten Studie wurde der Dränauslass mit anderen Dränauslässen verglichen, um zu sehen wie repräsentativ dieser Dränauslass ist. Ferner wurde die Bioverfügbarkeit der Fraktionen bestimmt. Die Untersuchungen wurden vom 1. November 2015 bis zum 2. Mai 2017 durchgeführt. Ergänzende Arbeiten erfolgten bis zum Frühjahr 2018. Wir fanden eine räumliche und zeitliche Variation der Gesamt P (TP)-Konzentrationen und seiner Zusammensetzung. Extrem hohe TP- Konzentrationen wurden an der Station Prisannewitz im Sommer beobachtet, was wahrscheinlich auf Eintrag von Siedlungen oder Stallanlagen zurückzuführen ist. Die Beseitigung dieser Quellen kann die P-Last der Warnow deutlich reduzieren. Im untersuchten Warnow-Bereich findet durch Phytoplanktonproduktion eine Transformation von gelöstem reaktivem P (DRP) in partikuläres nichtreaktives P (PNP) PNP statt. Außer DRP sind auch partikulärer reaktives P (PRP) und gelöstes nichtreaktives P (DNP) teilweise bioverfügbar. In der Summe aller drei Fraktionen sind 45-47% der TP bioverfügbar. Bei der Annahme, dass nur DRP bioverfügbar ist, wird das Eutropierungspotential von TP um die Hälfte unterschätzt.

Project report

Subproject 7: Processing of alternative P sources for fertilization in agriculture

PhD student: Sina Jahanbakhsh (dissertation completed)

The aim of the project was the investigation of atmospheric pressure plasma discharges for utilization of bone char as fertilizer in agriculture.
Bone char is a promising candidate that involves the element phosphor. The treatment of bone char could convert the surface characteristics to improved phosphor uptake by plants and enhance the adsorption capability for additional loading with nutrients. Plasma technology is known as an innovative method for surface and material processing but so far no attempts on the modification of bone char has been made.
Barrier corona (BC) arrangements are employed in different plasma-based applications such as material surface and exhaust gas treatments. Due to the geometry and material of the arrangement, the discharge behaviour depends significantly on the two polarities of the applied sinusoidal voltage. The investigation of this behaviour was an important issue of the project. For the voltage amplitude being applied, mostly two micro discharges (MD) appear in the anodic pin half-cycles. It is observed that the breakdown mechanism in both MDs is a positive streamer starting near the anode, similar to the single MDs in symmetric dielectric barrier discharges (DBDs). However, the second MDs have different properties, such as longer duration of the bulk plasma and broader current pulses. It is considered that the differences are mainly due to the positive surface charges deposited by the first MDs on the dielectric. It is proposed, for the first time, that the current pulse derivative maximum corresponds to the arrival of the streamer head at the cathode surface. This is used to synchronize the spatio-temporal development of the MDs with their current pulses. The accuracy of the synchronization is limited to the rise-time of the current probe (350 ps). In each cathodic pin half-cycle, only one major MD appears. The appearance and amplitude of the MDs are more erratic compared to the anodic pin polarity. The TC-SPC recordings show that the MDs appearing at low applied voltages have a similar spatio-temporal development to the MDs of the anodic pin polarity. On the other hand, at high applied voltages a development similar to transient sparks, i.e. a double-streamer starting near the tip of the pin (cathode), is observed. The statistical study shows that in DBD-like MDs the current pulse amplitude is not dependent on the appearance phase (or applied voltage), but this is not the case for the transient sparks.

Project report

Subproject 8: Synthesis of new heterocyclic ring systems containing P

PhD student: Tobias Täufer (project completed)

Summary (only available in German)
Die zu Beginn der Promotion von Herrn Täufer gesteckten Ziele der Generierung neuartiger, P,N-haltiger Ringsysteme ausgehend von Cyclisierungsreaktionen geeigneter Alkene, Diene und Alkine mit in situ-generierten ungesättigten P-N-Bausteinen führte leider zu keinem allgemeinen Syntheseprotokoll für die Herstellung solcher Verbindungen, obwohl eine Vielzahl von Reaktionen mit unterschiedlichen Reagenzien durchgeführt wurden. Die Umsetzungen liefen entweder gar nicht ab oder führten ansonsten in der Regel zu einer Reihe von Nebenprodukten. Ein Grund dafür waren vermutlich die Reaktionsbedingungen zur Erzeugung der P-N-Spezies, für die starke Lewis-Säuren notwendig sind. Daraus ergibt sich leider, dass die beabsichtigten selektiven Umsetzungen, die nach Wissen und Erfahrung der beteiligten Arbeitsgruppen erwartbar waren, leider nicht realisiert werden konnten. Möglicherweise kann dies nach Entwicklung eines neuen Zugangs bzw. anderer Reaktionsbedingungen für die Erzeugung der P-N-Spezies und der anschließenden Cyclisierungsreaktion realisiert werden.
Erwähnenswert sind allerdings einige Resultate und Nebenprojekte im Rahmen des Gesmatprojektes. So konnten beispielsweise mit Isopren eine Spezies der Summenformel [PN(Isopren)]4 isoliert und charakterisiert werden. Im Rahmen der Synthese von neuen Indenyl-Cobalt-Komplexen konnte ein neuer chiraler Bisphosphit-Komplex synthetisiert und in katalytischen Reaktionen getestet werden.

Subproject 9: Large scale application of P based organocatalysts in batch and flow for the synthesis of fatty acid derived cyclic carbonates

PhD student: Johannes Steinbauer (dissertation completed)

In this project new catalyst systems for the conversion of CO2 with epoxides to the corresponding cyclic carbonates were developed. In this context bifunctional phosphonium salts were initially used as one‐component catalysts as well as the new catalyst systems based on earth abundant metals. In this regard, bifunctional one‐component catalysts combine a nucleophilc and an electrophilic function for an effective activation of the epoxides. Two different homogeneous bifunctional phosphonium salt catalysts were developed, which were used on one hand for the conversion of fossil resources derived epoxides and on the other hand for the conversion of internal bio‐based epoxides. Moreover a heterogeneous bifunctional phosphoniumsalt catalyst was synthesized and evaluated, which showed high activities under relatively mild
conditions. Additionally, this catalyst was reused up to 15 times and the deactivation of the catalyst was thoroughly investigated. In addition, a binary catalyst system based on a monofunctional nucleophilic phosphoniumsalt and
an electrophilic iron salt co‐catalyst for the conversion of biobased epoxides was developed. Furthermore, three different catalyst systems based on CaI2 in combination with different halides and/or co‐catalysts were reported. These
catalysts were used for the synthesis of terminal as well as internal carbonates under very mild reaction conditions and investigations regarding the reaction mechanisms were conducted. All in all in this thesis seven different catalyst
systems were extensively evaluated and described. For all the described catalyst systems the reaction conditions for the synthesis of cyclic carbonates have been systematically optimized and a broad variety of cyclic carbonates
were synthesized and isolated in excellent yields. This work was accompanied by detailed mechanistic investigations. Furthermore a flow system was assembled and initial test reactions using the developed immobilized catalyst
were performed. However, the conversion of (bio‐based)epoxides with CO2 under the chosen flow conditions proofed to be difficult.

Subproject 10: Political-legal P governance by means of certificate markets and charges

PhD student: Jessica Stubenrauch (dissertation completed)

Summary (only available in German)
Die Dissertation zur rechtsvergleichenden P-Governance widmet sich einem Querschnittsthema der humanwissenschaftlichen Nachhaltigkeitsforschung. Politisch-rechtliche Regelungsansätze unterschiedlicher Länder (Deutschland, Costa Rica und Nicaragua) werden hinsichtlich deren Steuerungswirkung bezüglich der P-Ressourcenschonung und dem Schutz der hiermit verknüpften Umweltmedien analysiert und auf mögliche Optimierungsoptionen hin befragt. Als Ausgangspunkt kommen neben naturwissenschaftlichen und naturräumlichen Befunden auch ethische und rechtliche Fragen nach den anzustrebenden Zielen in den Blick, ohne jedoch im Mittelpunkt der Arbeit zu stehen. Die Analyse möglicher politisch-rechtlicher Ansatzpunkte ergab, dass es aller Voraussicht nach nur durch eine Kombination von Effizienz-, Konsistenz- und Suffizienzstrategien ermöglicht wird, P zukünftig effizient im Kreislauf zu führen und gleichzeitig bestehende Wasser- und Bodenschutzziele sowie international verbindlich festgelegte Klima- und Biodiversitätsziele zu erreichen. Auf diese Art kann auch ein Beitrag zur Ernährungssicherung durch den dauerhaften Erhalt der natürlichen Lebensgrundlagen geleistet werden. Effizienzansätze beziehen sich in der P-Governance im Wesentlichen auf eine an den Standort und die jeweilige Kultur angepasste, präzise P-Düngung, betreffen jedoch auch die Verminderung der weltweiten Nahrungsmittelverluste. Konsistenz kann zum Beispiel durch eine Förderung des P-Recyclings und der Wiedergewinnung von P aus Abfallströmen umgesetzt werden oder auch durch eine vornehmlich organische- sowie Gründüngung erzielt werden. Eine wichtige Suffizienzmaßnahme im Bereich der P-Governance ist die Minderung des Konsums tierischer Nahrungsmittel insbesondere in den Industrieländern und den Oberschichten der Schwellen- und Entwicklungsländer. Denn die intensive Tierhaltung geht häufig mit einer – räumlich weit von der Tierhaltung entfernten – monokulturellen Futtermittelproduktion einher, welche regelmäßig mit einer hohen Nachfrage nach mineralischen P-Düngemitteln verknüpft ist. Andererseits entstehen PNährstoff-Hotspots aufgrund der Überschüsse an organischen Düngemitteln (überwiegend Gülleüberschüsse) am Ort der Intensivtierhaltung. Ein Schließen der P-Kreisläufe wird hierdurch verhindert. Bestenfalls sollten Futtermittel daher durch eine in den Pflanzenbau integrierte Tierhaltung in gemischten landwirtschaftlichen Betrieben im Rahmen einer an den Standort angepassten, wechselnden Fruchtfolge angebaut werden. Neben einem insgesamt besseren Systemverständnis von P sind mithin auch strukturelle Änderungen in den einzelnen Landwirtschaftssektoren unumgänglich, um P-Kreisläufe zukünftig schließen zu können. Vor allem Suffizienzstrategien als ein unverzichtbarer Teil der P-Governance sind dabei in allen drei Beispielstaaten bisher jedoch noch nicht rechtlich verankert und werden durch die europäischen Rechtsetzung nicht angeregt.

Die Förderung des P-Recyclings aus Abwasserströmen als ein möglicher Beitrag zur Konsistenz wird durch die novellierte Klärschlammverordnung in Deutschland zukünftig rechtlich vorgeschrieben, während eine entsprechende rechtliche Regulierung großtechnischer Maßnahmen zum P-Recycling – insbesondere auch aufgrund der diesbezüglich fehlenden Infrastruktur – in Nicaragua und Costa Rica noch nicht vorgesehen ist. Durch das Düngemittelrecht werden bisher alternative und rezyklierte P-Dünger jeweils nicht explizit hinsichtlich deren Marktzugang gefördert – insbesondere aufgrund einer fehlenden bzw. nur wenig ambitionierten Grenzwertsetzung für Schwermetalle wie Uran (U) oder Cadmium (Cd) in mineralischen Düngemitteln. Besonders innovative, rezyklierte P-Düngemittel aus Abfallströmen wie Struvit oder Biochar sind dabei regelmäßig noch gar nicht von dem geltenden Düngemittelrecht umfasst. Insofern ist eine zeitnahe Anpassung des Rechts notwendig.

Regelungen zu einer effizienten und standortangepassten P-Düngung werden durch die gute fachliche Praxis in der Landwirtschaft vorgegeben. Trotz der Novellierung der Düngeverordnung in Deutschland im Jahr 2017 verbleibt die gute fachliche Praxis in der Landwirtschaft auch in Deutschland rechtlich unbestimmt und hegt die landwirtschaftliche P-Düngung nur unzureichend rechtlich ein. In Costa Rica und Nicaragua bestehen bereits dem Grunde nach nur freiwillige Vorgaben zur guten fachlichen Praxis. Auch die im Hinblick auf die Schließung der P-Nährstoffkreisläufe positiv wirkenden ökologischen und agrarökologischen Landwirtschaftspraktiken werden in allen drei Ländern nur unzureichend gefördert. Die Gemeinsame Europäische Agrarförderung (GAP) stellt darüber hinaus nicht ausreichend auf die Zukunftsherausforderungen im Landwirtschaftssektor ab, welche auch mit dem Schließen der P-Nährstoffkreisläufe verbunden sind.

Bei alledem wurde deutlich, dass sich die Umsetzung der kleinteiligen ordnungsrechtlichen Regelungen sowie die Kontrolle und der Vollzug dieser in Bezug auf die alltägliche landwirtschaftliche Düngepraxis besonders schwierig gestaltet. Geographisch möglichst breit ansetzende ökonomische Politikinstrumente, welche zunächst die rechtliche Regulierung großer Schadverursacher (fossile Brennstoffe und die intensive Nutztierhaltung) in den Blick nehmen und in der Folge (nur noch) ordnungsrechtlich ergänzt werden, so dass auch der Kontrollaufwand insgesamt minimiert wird, erschienen daher als effektivste rechtliche Lösung im Hinblick auf die zukünftige P-Governance. Eine Umsetzung effektiver Politikinstrumente, welche sich klar an den Vorgaben internationaler Umweltschutzabkommen (insbesondere an dem Paris-Abkommen und der Biodiversitätskonvention) orientieren, ist jedoch gleichzeitig an einen schwierigen gesamtgesellschaftlichen Prozess gekoppelt, welcher die Überwindung
bestehender Motivationsprobleme in einem Wechselspiel aller Akteure bedingt.

Project report

Subproject 11: Natural and anthropogenic organic P compounds – inositolphosphates, phospholipids and glyphosate

PhD student: Constantin Recknagel (dissertation completed)

Baltic Sea eutrophication is frequently observed even if inorganic P is very low. It was demonstrated that also the organic P pool is partially bioavailable and, thus, might contribute as nutrient source (Nausch and Nausch, 2006; Nausch and Nausch, 2007).

The majority of the organic P pool presumably derives from phosphate esters, the biochemical backbone of contemporary life, which are highly abundant as nucleotides for energy production (e.g., ATP) or informational storage (e.g., DNA) and structural integraty of membranes (phospholipids). Less is known about the natural occurring organophosphonates (Figure 1). Harboring a C-P bond their biochemical utilization requires higher energy demand for cleavage and a dierent enzymatic machinery for organisms than cleaving the oxygen containing C-O-P phosphate group (McGrath et al., 2013). Considering the reducing atmosphere of early Earth life organophosphonates are considered as the preceding form of phosphate in early life forms.

Metabolic pathways for C-P cleavage have been conserved among a number of organisms in particular for those of the marine environment. It was shown through 31P NMR analysis that phosphonates make up about 25 % of the high molecular weight dissolved organic phosphate pool (Clark et al., 1999) and some marine species were shown to be potential sources for phosphonates in the marine environment (Clark et al., 1999; Dyhrman et al., 2009). Therefore, organophosphonate compounds presumably relevantly contribute to the marine biogeochemical P cycle.

Also anthropogenic organic P compounds, such as the herbicide compound glyphosate which is one of the major herbicides applied in Germany contribute to the environmental organic P pool.

This project aims a better understanding of the relevance of organic P compounds for the marine environment. In this regard organic P compounds were selected and it was the aim to implement suitable analytical methods to enable their analysis in samples from the Baltic Sea environment to study their relevance and behavior at marine sites. These compounds were the

• myo-inositolhexakisphosphate (IP6)
• phospholipids
• methyl phosphonate (MPhn)
• 2-aminoethylphosphonate (2-AEP)
• glyphosate and its metabolite aminomethylphosphonic acid (AMPA)

Seed Projects Incentive Fund (2013-2015)

EvaPhoN - Evaluation of phosphorus digestion in most diverse natural materials

Different digestion methods for total phosphorus were compared. Dry masses and ashes of plants, animal tissues, soil and sediments, and seston were materials digested. The primary goal was not to find a best method, but to identify the most important work steps and provide the respective comparisons to the ScienceCampus for reference. In addition, the original sources of methods, reviews and method comparisons have been compiled. We further provide some ashes as reference material. The already thoroughly prepared working instructions will continue to be supplemented regularly, so that in a few years a methods manual will be created.

Contact: PD Dr. Rhena Schumann (University of Rostock)

P-Eff-Mo - Genetic and nutritional influences on the efficiency of phosphorus use in the diets of monogastric animals

With the aim of deriving measures for improving phosphorus (P) efficiency in monogastric animals, the molecular and physiological responses to varying P supply in weaned piglets were investigated in a first experiment. The amount of P fed above and below currently applicable recommendations was reflected in the deflection of physiological serum parameters such as inorganic phosphate, calcium, vitamin D3, parathormone, and cathepsin K, while zootechnical parameters such as live weight and feed intake showed no differences. Increased P intake had an effect on bone tissue at the structural (increased Bone Mineral Density and Structure Model Index) and transcriptional levels (activation of signaling pathways associated with bone metabolism). Multidisciplinary collaboration on the project has made it possible to detect P-dependent changes in metabolism using physiological, molecular, and bone morphological parameters. Genes that were expressed in a diet-dependent manner are the basis for finding candidate genes for breeding P-efficient animals.

Contact: Prof. Dr. Klaus Wimmers (FBN)

Method development for the determination of particulate glyphosate in the marine environment; bioavailability of glyphosate

Glyphosate is the active ingredient in herbicidal formulations such as Roundup®. The aim of the project was firstly to develop methods for the extraction of marine particulate glyphosate, and secondly to analyze its adsorption properties on agricultural soils in Mecklenburg-Vorpommern. Furthermore, the microbial degradation and potential bioavailability of glyphosate for the Baltic Sea should be investigated. Adsorption experiments were carried out with Baltic Sea sediments with high and low organic carbon content, sand and minerals. Glyphosate could be extracted by varying the pH depending on the soil type. While high extraction yields were achieved for glyphosate from minerals, the extraction efficiency from sediments was not yet satisfactory and needs further development. The adsorption isotherms generated for the collected soil samples, which are representative for the landscape of Mecklenburg-Vorpommern, indicate a very high affinity for glyphosate to the soils. Cell culture experiments with the cyanobacterium Nodularia spumigena, which is typical for the Baltic Sea, were performed. The results of the project will be used to develop further strategies, especially to identify the factors that significantly determine the adsorption properties of glyphosate.

Contact: Dr. Marion Kanwischer (IOW)

Phenotypic and molecular characterization of P use and uptake efficiency in Solanum tuberosum

This project aimed to gain initial knowledge on potato genetic resources with a focus on phosphorus efficiency (P-efficiency) and then submit a project proposal for a follow-up project. Data from the preliminary experiment conducted showed that different potato genotypes differ in their P efficiency, which is also consistent with data from the literature. Based on these findings, a project application with the topic "P-Efficiency of Potatoes" will be submitted to the Fachagentur für Nachwachsende Rohstoffe e.V. (FNR).

Contact: Prof. Dr. Ralf Uptmoor (University of Rostock)

RON - Recycling of phosphorus-based organocatalysts by nanofiltration

In this project, commercially available and organic solvent nanofiltration membranes (OSN) were investigated as a sustainable alternative for the separation of bifunctional phosphonium salts by distillation. The reaction and filtration process were optimized with respect to various process parameters (catalyst, solvent, membrane, etc.). Under the optimized conditions, catalyst retention was up to 99%, and it could be reused four times. The results have been submitted as a publication in an international peer-reviewed journal.

Contact: Dr. Thomas Werner (LIKAT)