@inproceedings{FischerGypserSubbotinaetal., author = {Fischer, Thomas and Gypser, Stella and Subbotina, Maria and Veste, Maik}, title = {Hydraulic and nutritional feedback controls surface patchiness of biological soil crusts at a post-mining site}, series = {European Geosciences Union, General Assembly 2015, Vienna, Austria, 13 April - 17 May 2015}, booktitle = {European Geosciences Union, General Assembly 2015, Vienna, Austria, 13 April - 17 May 2015}, publisher = {European Geophysical Society}, address = {Katlenburg-Lindau}, language = {en} } @inproceedings{HirschBonhageBauriegeletal., author = {Hirsch, Florian and Bonhage, Alexander and Bauriegel, Albrecht and Schneider, Anna and Raab, Alexandra and Raab, Thomas and Gypser, Stella}, title = {Occurrence, soil parameters and genesis of Rhodic Arenosols ('Fuchserden') in northeastern Germany}, series = {European Geosciences Union, General Assembly 2018, Vienna, Austria}, booktitle = {European Geosciences Union, General Assembly 2018, Vienna, Austria}, publisher = {European Geophysical Society}, address = {Katlenburg-Lindau}, language = {en} } @misc{HirschBonhageBauriegeletal., author = {Hirsch, Florian and Bonhage, Alexander and Bauriegel, Albrecht and Schneider, Anna and Raab, Thomas and Raab, Alexandra and Gypser, Stella}, title = {The occurrence, soil parameters and genesis of rubified soils ('Fuchserden') of northeastern Germany}, series = {Catena}, volume = {175}, journal = {Catena}, issn = {0008-7769}, doi = {10.1016/j.catena.2018.11.039}, pages = {77 -- 92}, language = {en} } @misc{FischerGypserSubbotinaetal., author = {Fischer, Thomas and Gypser, Stella and Subbotina, Maria and Veste, Maik}, title = {Synergic hydraulic and nutritional feedback mechanisms control surface patchiness of biological soil crusts on tertiary sands at a post-mining site}, series = {Journal of Hydrology and Hydromechanics}, volume = {62}, journal = {Journal of Hydrology and Hydromechanics}, number = {4}, issn = {0042-790X}, doi = {10.2478/johh-2014-0038}, pages = {293 -- 302}, abstract = {In a recultivation area located in Brandenburg, Germany, five types of biocrusts (initial BSC1, developed BSC2 and BSC3, mosses, lichens) and non-crusted mineral substrate were sampled on tertiary sand deposited in 1985- 1986 to investigate hydrologic interactions between crust patches. Crust biomass was lowest in the non-crusted substrate, increased to the initial BSC1 and peaked in the developed BSC2, BSC3, the lichens and the mosses. Water infiltration was highest on the substrate, and decreased to BSC2, BSC1 and BSC3. Non-metric multidimensional scaling revealed that the lichens and BSC3 were associated with water soluble nutrients and with pyrite weathering products, thus representing a high nutrient low hydraulic feedback mode. The mosses and BSC2 represented a low nutrient high hydraulic feedback mode. These feedback mechanisms were considered as synergic, consisting of run-off generating (low hydraulic) and run-on receiving (high hydraulic) BSC patches. Three scenarios for BSC succession were proposed. (1) Initial BSCs sealed the surface until they reached a successional stage (represented by BSC1) from which the development into either of the feedback modes was triggered, (2) initial heterogeneities of the mineral substrate controlled the development of the feedback mode, and (3) complex interactions between lichens and mosses occurred at later stages of system development.}, language = {en} } @misc{GypserSchuetzeFreese, author = {Gypser, Stella and Sch{\"u}tze, Elisabeth and Freese, Dirk}, title = {Crystallization of single and binary iron- and aluminum hydroxides affect phosporus desorption}, series = {Journal of Plant Nutrition and Soil Science}, volume = {182}, journal = {Journal of Plant Nutrition and Soil Science}, number = {5}, issn = {1522-2624}, doi = {10.1002/jpln.201700543}, pages = {741 -- 750}, abstract = {In acidic soils, phosphorus availability is affected by its strong affinity for mineral surfaces, especially Fe- and Al-hydroxides. Plant roots have developed adaptive strategies to enhance the availability of phosphorus, including producing and exuding low molecular weight organic acids with a high affinity for phosphorus that competes with high molecular weight organic ligands formed during humification and mineralization. The aim of this study was to characterize the kinetics and mechanism of phosphorus desorption from Fe- and Al-hydroxides of variable crystallinity, as well as binary Fe:Al-hydroxide mixtures. Long-term desorption experiments (56 days) were conducted with CaCl₂, CaSO₄, citric acid, and humic acid as competitive sorptives. CaCl₂ and CaSO₄ were selected as general inorganic sorptives and citric and humic acids were selected as organic ligands produced by organisms in the rhizosphere or following humification. The cumulative phosphorus desorption increased following the order CaCl₂< CaSO₄< humic acid < citric acid. Amorphous ferrihydrite and Fe-rich Fe:Al-hydroxides exhibited much less desorption when exposed to inorganic solutions than the crystalline and Al-rich Fe:Al-hydroxide mixtures. Models of the desorption data suggest phosphorus desorption with citric acid is diffusion- controlled for ferrihydrite and Fe-rich amorphous Fe:Al-hydroxides. When humic acid was the sorptive, metal-organic complexes accumulated in the solution. The results suggest organic compounds, especially citric acid, are more important for liberating phosphorus from Fe- and Al-minerals than inorganic ions present in the soil solution.}, language = {en} } @inproceedings{GypserFreese, author = {Gypser, Stella and Freese, Dirk}, title = {Mechanisms of adsorption and desorption of phosphorus on crystalline iron, aluminum, manganese (hydr)oxides as well as iron and calcium phosphates in comparison to amorphous iron-aluminum compounds}, series = {8th International Phosphorus Workshop IPW8, Rostock, Germany, September 12-16, 2016}, booktitle = {8th International Phosphorus Workshop IPW8, Rostock, Germany, September 12-16, 2016}, editor = {Kr{\"a}mer, Inga and H{\"a}berle, Stephanie}, address = {Rostock}, doi = {10.12754/procs-2016-ipw8}, pages = {S. 73}, abstract = {Inorganic phosphorus (P) plays an important role as plant nutrient in fertilizers, but also as a major pollutant to aquatic ecosystems by leaching from arable land. The mobility and bioavailability of P depends on adsorption, desorption and precipitation processes at soil mineral surfaces. In the soil matrix, P can be found in the forms of iron, aluminum or calcium complexes, adsorbed on mineral surfaces. P reactions in soil, especially the fixation on iron and aluminum (hydr) oxides, have been thoroughly studied. But the much slower process of P release has to be attended as well regarding the prospective supply of fertilizers and the use of plant available P pools in arable soils. The P adsorption ability of pedogenic oxides depends on their crystallinity, while soils contain both crystalline minerals such as goethite or ferrihydrite, as well as amorphous iron and aluminum compounds. In this study, long-term adsorption and desorption experiments were carried out to investigate the P binding mechanism during the sorption processes at certain time steps. For adsorption experiments, various experimental conditions such as pH, P ionic strength, competitive ions such as SO4 2- and Ca2+ as well as time will be considered. For desorption experiments, a Flow-Through-Reactor-Technique will be applied to investigate desorption kinetics and processes under nearly natural conditions without disturbance of the mineral-solution interface. Additionally, the release of P from the iron and calcium phosphates vivianite and hydroxyapatite, a main supplier of inorganic P and model substance for bone char, will be investigated. By using Fourier-Transformation-Infrared-Spectroscopy, changes of P binding mechanisms during ad- and desorption processes and easily as well heavily purgeable P can be detected. Aim is to identify fundamental processes of P fixation and mobilization as well as to specify similarities and differences of P binding on crystalline and amorphous reactive surfaces of pedogenic oxides.}, language = {en} } @misc{GypserFreese, author = {Gypser, Stella and Freese, Dirk}, title = {Phosphorus release from vivianite and hydroxyapatite by organic and inorganic compounds}, series = {Pedosphere}, volume = {30}, journal = {Pedosphere}, number = {2}, issn = {1002-0160}, doi = {10.1016/S1002-0160(20)60004-2}, pages = {190 -- 200}, abstract = {Based on recent mining rates and the exhaustion of global phosphorus (P) reserves, there is a need to mobilize P already stored in soils, and its recovery from secondary resources such as Ca- and Fe-phosphates is important. The Ca-phosphate hydroxyapatite forms a good fertilizer source, while vivianite is formed in waterlogged soils and sediments. During sludge treatment, the formation of vivianite has been identified, being mainly Fe-phosphate. Long-term P release from both hydroxyapatite and vivianite was studied using different inorganic (CaCl2 and CaSO4) and organic (citric and humic acid) reagents during batch experiments. Reagents CaCl2 and CaSO4 represent the soil solution, while citric and humic acids as organic constituents affect P availability in the rhizosphere and during the process of humification. Additionally, the flow-through reactor (FTR) technique with an infinite sink was used to study the long-term P release kinetics. The cumulative P release was higher by organic acids than by inorganic compounds. The cumulative P release rates were higher in the FTR with CaCl2 as compared to the batch technique. The infinite sink application caused a continuously high concentration gradient between the solid and liquid phases, leading to higher desorption rates as compared to the batch technique. The predominant amount of the total P released over time was available for a short term. While inorganic anion exchange occurred at easily available binding sites, organic acids affected the more heavily available binding sites, which could be embedded within the mineral structure. The results showed that organic compounds, especially citric acid, play a superior role as compared to the inorganic constituents of the soil solution during the recovery of already stored P from the tertiary phosphates vivianite and hydroxyapatite.}, language = {en} } @misc{GypserHirschSchleicheretal., author = {Gypser, Stella and Hirsch, Florian and Schleicher, Anja M. and Freese, Dirk}, title = {Impact of crystalline and amorphous iron- and aluminum hydroxides on mechanisms of phosphate adsorption and desorption}, series = {Journal of Environmental Sciences}, volume = {70}, journal = {Journal of Environmental Sciences}, doi = {10.1016/j.jes.2017.12.001}, pages = {175 -- 189}, language = {en} } @inproceedings{MykhailovaRaabGypseretal., author = {Mykhailova, Larysa and Raab, Thomas and Gypser, Stella and Fischer, Thomas}, title = {Development and hydrology of biological soil crusts -- first results from a surface inoculation experiment}, series = {European Geosciences Union, General Assembly 2016, Vienna, Austria, 17 April - 22 May 2016}, booktitle = {European Geosciences Union, General Assembly 2016, Vienna, Austria, 17 April - 22 May 2016}, publisher = {European Geophysical Society}, address = {Katlenburg-Lindau}, language = {en} } @misc{MantovaniVesteGypseretal., author = {Mantovani, Dario and Veste, Maik and Gypser, Stella and Halke, Christian and Koning, Laurie Anne and Freese, Dirk and Lebzien, Stefan}, title = {Transpiration and biomass production of the bioenergy crop Giant Knotweed Igniscum under various supplies of water and nutrients}, series = {Journal of Hydrology and Hydromechanics}, volume = {62}, journal = {Journal of Hydrology and Hydromechanics}, number = {4}, issn = {0042-790X}, doi = {10.2478/johh-2014-0028}, pages = {316 -- 323}, abstract = {Soil water availability, nutrient supply and climatic conditions are key factors for plant production. For a sustainable integration of bioenergy plants into agricultural systems, detailed studies on their water uses and growth performances are needed. The new bioenergy plant Igniscum Candy is a cultivar of the Sakhalin Knotweed (Fallopia sachalinensis), which is characterized by a high annual biomass production. For the determination of transpiration-yield relations at the whole plant level we used wicked lysimeters at multiple irrigation levels associated with the soil water availability (25, 35, 70, 100\%) and nitrogen fertilization (0, 50, 100, 150 kg N ha-1). Leaf transpiration and net photosynthesis were determined with a portable minicuvette system. The maximum mean transpiration rate was 10.6 mmol m-2 s-1 for well-watered plants, while the mean net photosynthesis was 9.1 μmol m-2 s-1. The cumulative transpiration of the plants during the growing seasons varied between 49 l (drought stressed) and 141 l (well-watered) per plant. The calculated transpiration coefficient for Fallopia over all of the treatments applied was 485.6 l kg-1. The transpiration-yield relation of Igniscum is comparable to rye and barley. Its growth performance making Fallopia a potentially good second generation bioenergy crop.}, language = {en} } @misc{GypserHerppichFischeretal., author = {Gypser, Stella and Herppich, Werner B. and Fischer, Thomas and Lange, Philipp and Veste, Maik}, title = {Photosynthetic characteristics and their spatial variance on biological soil crusts covering initial soils of post-mining sites in Lower Lusatia, NE Germany}, series = {Flora}, volume = {Vol. 220}, journal = {Flora}, issn = {0367-2530}, doi = {10.1016/j.flora.2016.02.012}, pages = {103 -- 116}, abstract = {Following surface disturbance, quaternary sands are the basic substrate for soil development in the Lusatian reclamation area. These substrates mostly contain few organic matter and, hence, are nutrient poor. Accumulation of soil carbon is an important factor for ecosystem development, where biological soil crusts initially influence soil processes and promote ecosystem succession. The compositional structures of biological soil crusts at various developmental stages and their photosynthetic properties were investigated on two former open-cast lignite sites, currently under reclamation, an artificial sand dune in Welzow S{\"u}d, and a forest plantation in Schlabendorf S{\"u}d (Brandenburg, Germany). As development of biological soil crusts progressed, their contents of organic carbon and total chlorophyll increased. The ratio of these parameters, however, varied with the relative contribution of lichens and mosses in particular. Also maximum photochemical efficiency, net photosynthesis and respiration increased with crustal development. An additional evaluation of NDVI and chlorophyll fluorescence images showed that especially moss-dominated biocrusts had higher photosynthetic capacity compared to green algae-dominated biocrusts or soil lichens, so the photosynthetic capacity showed to be highly species-specific. The ratio of gross photosynthesis to respiration indicated a higher ecological efficiency of biocrusts dominated by green algae than of lichen-dominated biocrusts. The occurrence of soil lichens reduced net CO2 fixation and increased CO2 release due to the enhanced mycobiontic respiration. During crustal succession, the rise of photosynthesis-related parameters is not necessarily linear as a result of the highly heterogenic distribution of the different crustal organisms between biocrusts of similar developmental stages as well as between those growing at the two study sites. Therefore, the evaluation of relevant ecophysiological parameters highlighted that not all biocrust-forming organisms similarly contribute to the ecophysiological behavior of biological soil crusts. Nevertheless, the occurrence of the biological soil crusts promoted soil formation and accumulation of soil carbon in initial soils.}, language = {en} } @misc{GypserVesteFischeretal., author = {Gypser, Stella and Veste, Maik and Fischer, Thomas and Lange, Philipp}, title = {Infiltration and water retention of biological soil crusts on reclaimed soils of former open-cast lignite mining sites in Brandenburg, north-east Germany}, series = {Journal of hydrology and hydromechanics}, volume = {64}, journal = {Journal of hydrology and hydromechanics}, number = {1}, doi = {10.1515/johh-2016-0009}, pages = {1 -- 11}, abstract = {Investigations were done on two former open-cast lignite mining sites under reclamation, an artificial sand dune in Welzow S{\"u}d, and a forest plantation in Schlabendorf S{\"u}d (Brandenburg, Germany). The aim was to associate the topsoil hydrological characteristics of green algae dominated as well as moss and soil lichen dominated biological soil crusts during crustal succession with their water retention and the repellency index on sandy soils under temperate cli-mate and different reliefs. The investigation of the repellency index showed on the one hand an increase due to the cross-linking of sand parti-cles by green algae which resulted in clogging of pores. On the other hand, the occurrence of moss plants led to a de-crease of the repellency index due to absorption caused by bryophytes. The determination of the water retention curves showed an increase of the water holding capacity, especially in conjunction with the growth of green algae layer. The pore-related van Genuchten parameter indicate a clay-like behaviour of the developed soil crusts. Because of the inho-mogeneous distribution of lichens and mosses as well as the varying thickness of green algae layers, the water retention differed between the study sites and between samples of similar developmental stages. However, similar tendencies of water retention and water repellency related to the soil crust formation were observed. Biological soil crusts should be considered after disturbances in the context of reclamation measures, because the ini-tial development of green algae biocrusts lead to an increasing repellency index, while the occurrence of mosses and a gain in organic matter enhance the water holding capacity. Thus, the succession of biocrusts and their small-scale succes-sion promote the development of soil and ecosystem.}, language = {en} } @misc{GypserVesteFischeretal., author = {Gypser, Stella and Veste, Maik and Fischer, Thomas and Lange, Philipp}, title = {Formation of soil lichen crusts at reclaimed post-mining sites, Lower Lusatia, North-east Germany}, series = {Graphis Scripta}, volume = {27}, journal = {Graphis Scripta}, number = {1-2}, issn = {0901-7593}, pages = {3 -- 14}, abstract = {Biological soil crusts were investigated at reclaimed post-mining sites near Welzow and Schlabendorf in Lower Lusatia (Brandenburg, Germany). Various development stages from initial biological soil crusts built up by green algae, to more developed soil crusts with mosses, as well as moss-soil lichen crusts, were classified. The spatial-temporal dynamics during the development resulted in a moss-lichens cover with discrete patches of pioneer organisms like green algae in between. At the study sites, 13 species of terricolous lichens were identified. The formation of the biological soil crust is important for the accumulation of soil organic matter in the first millimeters of the topsoil of these pioneer ecosystems. A correlation between cryptogamic biomass and soil carbon content were found.}, language = {en} } @misc{AhmedGypserFreeseetal., author = {Ahmed, Ashour A. and Gypser, Stella and Freese, Dirk and Leinweber, Peter and K{\"u}hn, Oliver}, title = {Molecular level picture of the interplay between pH and phosphate binding at the goethite-water interface}, series = {Physical Chemistry Chemical Physics}, volume = {22}, journal = {Physical Chemistry Chemical Physics}, number = {45}, issn = {1463-9084}, doi = {10.1039/d0cp04698a}, pages = {26509 -- 26524}, abstract = {The soil pH plays a substantial role in controlling phosphorus (P) adsorption and mobilization. These processes are strongly affected by the phosphate interaction strength with P-fixing soil minerals such as goethite. The target of the current contribution is to draw a molecular level picture of the interplay between pH and phosphate binding at the goethite-water interface via a joint experimental-theoretical approach. Periodic density functional theory (DFT) calculations were carried out to provide a molecular level understanding of the pH dependence of P adsorption. To validate the modeling approach, adsorption experiments of phosphate at goethite were performed in the pH range of 4-12. There was agreement between experiments and simulations in the description of the adsorption behavior by two pH-dependent successive stages. The adsorption increases along the pH change from 4 to 8. A further increase of pH leads to a decrease of adsorption. By comparing with literature data it is concluded that the first stage will be observed only if there is no significant change of the surface charge at low pH. Moreover, the molecular modeling results point to the abundance of the monodentate (M) binding motif at both extremely low and high pH ranges. Otherwise, the bidentate (B) one is predominant along the intermediate pH range. These observations could resolve the existing debate about the assignment of phosphate-goethite binding motifs. Furthermore, the results point to a decrease of pH upon phosphate sorption due to an induced acidification of soil solution. The present joint experimental-theoretical approach provides a better understanding and description of the existing phosphate sorption experiments and highlights new findings at the atomistic/molecular scale.}, language = {en} } @misc{GypserSchuetzeFreese, author = {Gypser, Stella and Sch{\"u}tze, Elisabeth and Freese, Dirk}, title = {Single and binary Fe- and Al-hydroxides affect potential phosphorus mobilization and transfer from pools of different availability}, series = {Soil Systems}, volume = {5}, journal = {Soil Systems}, number = {2}, doi = {10.3390/soilsystems5020033}, pages = {1 -- 21}, abstract = {Phosphorus (P) fixation is a global problem for soil fertility and negatively impacts agricultural productivity. This study characterizes P desorption of already fixed P by using KCl, KNO3, histidine, and malic acid as inorganic and organic compounds, which are quite common in soil. Goethite, gibbsite, and ferrihydrite, as well as hydroxide mixtures with varying Fe- and Al-ratio were selected as model substances of crystalline and amorphous Fe- and Al-hydroxides. Especially twoand multi-component hydroxide systems are common in soils, but they have barely been included in desorption studies. Goethite showed the highest desorption in the range from 70.4 to 81.0\%, followed by gibbsite with values in the range from 50.7 to 42.6\%. Ferrihydrite had distinctive lower desorption in the range from 11.8 to 1.9\%. Within the group of the amorphous Fe-Al-hydroxide mixtures, P desorption was lowest at the balanced mixture ratio for 1 Fe: 1 Al, increased either with increasing Fe or Al amount. Precipitation and steric effects were concluded to be important influencing factors. More P was released by crystalline Fe-hydroxides, and Al-hydroxides of varying crystallinity, but desorption using histidine and malic acid did not substantially influence P desorption compared to inorganic constituents.}, language = {en} } @misc{SchuetzeGypserFreese, author = {Sch{\"u}tze, Elisabeth and Gypser, Stella and Freese, Dirk}, title = {Kinetics of phosphorus release from vivianite, hydroxyapatite, and bone char influenced by organic and inorganic compounds}, series = {Soil Systems}, volume = {4}, journal = {Soil Systems}, number = {1}, issn = {2571-8789}, doi = {10.3390/soilsystems4010015}, pages = {1 -- 20}, abstract = {The availability of P is often insuffcient and limited by accumulation in soils. This led to the necessity of solutions for the recovery as well as recycling of secondary P resources. Batch experiments were conducted with CaCl2 and citric acid to characterize P release kinetics from vivianite, hydroxyapatite, and bone char. While the P release during the CaCl2 treatment was so low that only vivianite and hydroxyapatite showed a slightly higher release with increasing CaCl2 concentration, the increase of dissolved P was more pronounced for citric acid. The application of citric acid resulted in a 32,190-fold higher P release for bone char. Fourier-transform infrared spectroscopic data suggested higher instability of hydroxyapatite than for bone char. The kinetic data showed that bone char, especially at a lower particle size, had a higher long-term P release than hydroxyapatite or vivianite. The suitability of hydroxyapatite and bone char as a poorly soluble, but sustainable P source is better than that of vivianite. However, the efficiency as a P fertilizer is also dependent on present soil P mobilization processes. The results underline the importance of the accessibility of fertilized or naturally bound P for plant roots to benefit from the excretion of organic acids.}, language = {en} }