TY - GEN A1 - Geppert, Helmut A1 - Fischer, Thomas T1 - CHROMATOGRAPHIE-Festphasenmikroextraktion von polaren Verbindungen T2 - Labor Praxis Y1 - 2009 SN - 0344-1733 VL - 33 IS - 1 SP - 46 EP - 47 ER - TY - CHAP A1 - Fischer, Thomas A1 - Veste, Maik A1 - Lange, Philipp A1 - Wiehe, Wolfgang T1 - How biological soil crusts are stabilizing the soil surface? The development of organo-mineral interactions in the initial phase T2 - EGU General Assembly 2009, held in Vienna, Austria, 19 – 24 April 2009 Y1 - 2009 UR - http://meetingorganizer.copernicus.org/EGU2009/EGU2009-8635.pdf N1 - EGU2009-8635 PB - European Geophysical Society CY - Katlenburg-Lindau ER - TY - GEN A1 - Fischer, Thomas A1 - Veste, Maik A1 - Bens, Oliver A1 - Hüttl, Reinhard F. T1 - Dew formation on the surface of biological soil crusts in central European sand ecosystems T2 - Biogeosciences N2 - Dew formation was investigated in three developmental stages of biological soil crusts (BSC), which were collected along a catena of an inland dune and in the initial substrate. The Penman equation, which was developed for saturated surfaces, was modified for unsaturated surfaces and used for prediction of dewfall rates. The levels of surface saturation required for this approach were predicted using the water retention functions and the thicknesses of the BSCs. During a first field campaign (2–3 August 2011), dewfall increased from 0.042 kg m−2 for the initial sandy substrate to 0.058, 0.143 and 0.178 kg m−2 for crusts 1 to 3, respectively. During a second field campaign (17–18 August 2011), where dew formation was recorded in 1.5 to 2.75-h intervals after installation at 21:30 CEST, dewfall increased from 0.011 kg m−2 for the initial sandy substrate to 0.013, 0.028 and 0.055 kg m−2 for crusts 1 to 3, respectively. Dewfall rates remained on low levels for the substrate and for crust 1, and decreased overnight for crusts 2 and 3 (with crust 3 > crust 2 > crust 1 throughout the campaign). Dew formation was well reflected by the model response. The suggested mechanism of dew formation involves a delay in water saturation in near-surface soil pores and extracellular polymeric substances (EPS) where the crusts were thicker and where the water capacity was high, resulting in elevated vapor flux towards the surface. The results also indicate that the amount of dewfall was too low to saturate the BSCs and to observe water flow into deeper soil. Analysis of the soil water retention curves revealed that, despite the sandy mineral matrix, moist crusts clogged by swollen EPS pores exhibited a clay-like behavior. It is hypothesized that BSCs gain double benefit from suppressing their competitors by runoff generation and from improving their water supply by dew collection. Despite higher amounts of dew, the water availability to the crust community decreases with crust development, which may be compensated by ecophysiological adaptation of crust organisms, and which may further suppress higher vegetation or mosses. Y1 - 2012 U6 - https://doi.org/10.5194/bg-9-4621-2012 SN - 1726-4189 VL - 9 SP - 4621 EP - 4628 ER - TY - GEN A1 - Brankatschk, Robert A1 - Fischer, Thomas A1 - Veste, Maik A1 - Zeyer, Josef T1 - Succession of N Cycling Processes in Biological Soil Crusts on a Central European Inland Dune T2 - FEMS Microbiology Ecology N2 - Biological soil crusts (BSCs) are microbial assemblages that occur worldwide and facilitate ecosystem development by nitrogen (N) and carbon accumulation. N turnover within BSC ecosystems has been intensively studied in the past; however, shifts in the N cycle during BSC development have not been previously investigated. Our aim was to characterise N cycle development first by the abundance of the corresponding functional genes (in brackets) and second by potential enzyme activities; we focussed on the four processes: N fixation (nifH), mineralisation as proteolysis and chitinolysis (chiA), nitrification (amoA) and denitrification (nosZ). We sampled from four phases of BSC development and from a reference located in the rooting zone of Corynephorus canescens, on an inland dune in Germany. BSC development was associated with increasing amounts of chlorophyll, organic carbon and N. Potential activities increased and were highest in developed BSCs. Similarly, the abundance of functional genes increased. We propose and discuss three stages of N process succession. First, the heterotrophic stage (mobile sand without BSCs) is dominated by mineralisation activity. Second, during the transition stage (initial BSCs), N accumulates, and potential nitrification and denitrification activity increases. Third, the developed stage (established BSCs and reference) is characterised by the dominance of nitrification. Y1 - 2013 U6 - https://doi.org/10.1111/j.1574-6941.2012.01459.x SN - 1574-6941 VL - 83 IS - 1 SP - 149 EP - 160 ER - TY - GEN A1 - Xiao, Bo A1 - Wang, Huifang A1 - Fan, Jun A1 - Fischer, Thomas A1 - Veste, Maik T1 - Biological soil crusts decrease soil temperature in summer and increase soil temperature in winter in semiarid environment T2 - Ecological Engineering N2 - In hot and wet conditions in summer, the biological soil crusts (BSCs) decreased soil temperature by up to 11.8 °C, 7.5 °C, 5.4 °C, and 3.2 °C at surface, 5 cm, 15 cm, and 30 cm, respectively; while in cold and dry conditions in winter the BSCs increased soil temperature by up to 1.2 °C, 1.2 °C, and 1.1 °C at 5 cm, 15 cm, and 30 cm, respectively. The daily mean soil temperatures of the BSCs in a whole year were averagely increased by 0.57 ± 0.04 °C, 0.31 ± 0.04 °C, and 0.22 ± 0.04 °C at 5 cm, 15 cm, and 30 cm, respectively. The effects of the BSCs on soil temperature were positively correlated with air temperature and soil moisture, and decreased with soil depth from surface to deep soil. We concluded that BSCs relieved the extreme hot and cold soil micro-environments in desert ecosystem to some extent. Therefore their effects on soil temperature are positive for improving water and nutrient availability and biological community structure, thus decreasing susceptibility to desertification. These results would be helpful for understanding the ecological and hydrological functions of BSCs in semiarid environment. Y1 - 2013 U6 - https://doi.org/10.1016/j.ecoleng.2013.06.009 SN - 0925-8574 VL - 58 SP - 52 EP - 56 ER - TY - GEN A1 - Fischer, Thomas A1 - Yair, Aaron A1 - Veste, Maik A1 - Geppert, Helmut T1 - Hydraulic properties of biological soil crusts on sand dunes studied by 13C-CP/MAS-NMR: a comparison between an arid and a temperate site T2 - Catena N2 - Using principal component analysis (PCA), we studied the relationships between hydraulic properties and 13C-CP/MAS-NMR shift regions of biological soil crusts (BSCs) on sand dunes under arid and temperate conditions. The arid study site was located near Nizzana, in the northwestern Negev, Israel and the temperate site was near Lieberose, Brandenburg, Germany. BSCs were sampled at each site near the dune crest, at the center of the dune slope and at the dune base. The soil texture was finer and water holding capacities (WHCs) were higher in Nizzana, whereas surface wettability was reduced in Lieberose. At both sites, BSCs caused extra WHC compared to the mineral substrate. Infiltration after wetting along both catenas generally reached a maximum after 10 min and decreased after 30 min. Carbohydrates were the dominating components in all of the BSCs studied, where the relative peak areas of carbohydrate-derived structures (60–110 ppm) amounted to 28–46% and to 10–14% of total C-peak areas, respectively. PCA revealed that the WHC of the substrate was closely related to the amount of silt and clay, whereas the BSC induced extra WHC was closely related to carbohydrates. It was further found that water repellency was positively related to carbohydrate C, but negatively related to alkyl C. Infiltration kinetics was attributed to polysaccharide hydration and swelling. Our findings support the hypothesis that hydraulic properties of BSCs are determined by extracellular polymeric substances (EPS) and soil texture. Hydraulic properties in BSCs result from the combination of chemical properties related to C compounds mainly dominated by carbohydrates and physical surface properties related to texture, porosity and water holding capacity. Y1 - 2013 U6 - https://doi.org/10.1016/j.catena.2013.06.002 SN - 0341-8162 VL - 110 SP - 155 EP - 160 ER - TY - CHAP A1 - Iurchenko, Valentina A1 - Mykhailova, Larysa A1 - Fischer, Thomas T1 - Kinetic Characteristics of Petrochemicals Transposition and Accumulation in Soils of Roadside Area T2 - Transbaltica 2013 Conference Proceedings, 09.-10. May 2013, Vilnius, Lithuania Y1 - 2013 U6 - https://doi.org/10.3846/transbaltica2013.016 ER - TY - GEN A1 - Mykhailova, Larysa A1 - Fischer, Thomas A1 - Iurchenko, Valentina T1 - Distribution and fractional composition of petroleum hydrocarbons in roadside soils T2 - Applied and Environmental Soil Science Y1 - 2013 U6 - https://doi.org/10.1155/2013/938703 VL - 2013 IS - ID 938703 SP - 1 EP - 6 ER - TY - GEN A1 - Wang, Haijing A1 - Geppert, Helmut A1 - Fischer, Thomas A1 - Wieprecht, Wolfgang A1 - Möller, Detlev T1 - Determination of volatile organic and polycyclic aromatic hydrocarbons in crude oil with efficient gas-chromatographic methods T2 - Journal of Chromatographic Science N2 - Determination of volatile organic compounds (VOCs) in crude oil, such as super volatile organic compounds (super VOCs) and simple polycyclic aromatic hydrocarbons (PAHs), is vital for targeting crude oil spill spots. In this study, a static headspace gas chromatography flame ionization detection method was established for determination of super VOCs in crude oil with both external and internal standard determination, which can be used in the field when using portable gas chromatography. Identification was done by comparing the retention time with the corresponding standards and quantitation was done with a new one-drop method. Another simplified and efficient method was performed to analyze volatile PAHs in crude oil, which can also be used in field analysis. Toluene was used as the extraction solvent for PAHs in crude oil. Method validation for both analyses was satisfactory. The result showed that n-butane and n-pentane were maximum super VOCs and naphthalene, phenanthrene and fluorene were the main PAHs in the crude oil studied. The super VOCs quantity ranged from 3 to 6% and the main PAHs consisted of 0.02–0.06% of studied crude oil. Y1 - 2014 U6 - https://doi.org/10.1093/chromsci/bmu113 SN - 1945-239X VL - 53 IS - 5 SP - 647 EP - 654 ER - TY - GEN A1 - Mykhailova, Larysa A1 - Fischer, Thomas A1 - Iurchenko, Valentina T1 - Deposition of petroleum hydrocarbons with sediment trapped in snow in roadside areas T2 - Journal of Environmental Engineering and Landscape Management N2 - Total petroleum hydrocarbon (TPH) deposition rates were determined along various roads using the natural snow cover as deposition trap. Daily deposition rates decreased with distance from the roads, which coincided with long-term TPH accumulation in roadside soils. Scanning electron microscopy (SEM-EDX) of the snow meltwater sediment revealed occurrence of carbon-rich plaques, which were identified as hydrocarbons using FTIR-microscopy. GC-MS revealed that the compounds extracted from the sediment consisted of an unresolved complex hydrocarbon mixture (UCM). Individual n-alkanes could not be resolved in the sediment extract, whereas TPHs extracted from soils contained a series of n-alkanes peaking at C25-C27. The proportion of UCM compounds from TPHs decreased with distance from road. We conclude that high-boiling hydrocarbons bind to coarse mineral dust and/or to splash water and vehicle spray, which preferentially deposit within a 10 m roadside strip. Y1 - 2014 U6 - https://doi.org/10.3846/16486897.2014.889698 SN - 1822-4199 VL - 22 IS - 3 SP - 237 EP - 244 ER - TY - CHAP A1 - Fischer, Thomas A1 - Veste, Maik A1 - Mykhailova, Larysa T1 - Ecological Maturity and Drought Stress of Biological Soil Crusts along a Central European Inland Dune Catena T2 - European Geosciences Union, General Assembly 2014, Vienna, Austria, 27 April – 02 May 2014 Y1 - 2014 N1 - EGU2014-11377 PB - European Geophysical Society CY - Katlenburg-Lindau ER - TY - CHAP A1 - Fischer, Thomas A1 - Yair, Aaron A1 - Geppert, Helmut A1 - Veste, Maik T1 - Water repellency and infiltration of biological soil crusts on an arid and a temperate dunes T2 - European Geosciences Union, General Assembly 2014, Vienna, Austria, 27 April – 02 May 2014 Y1 - 2014 N1 - EGU2014-12175 PB - European Geophysical Society CY - Katlenburg-Lindau ER - TY - CHAP A1 - Fischer, Thomas T1 - Initial pedogenesis in biological soil crusts T2 - Nasledie I. V. Tjurina v sovremennych issledovanijach v počvovedenii: materialy Meždunarodnoj naučnoj konferencii, Kazan', 15 - 17, oktjabrja 2013 Y1 - 2013 UR - http://kpfu.ru/docs/F928601744/Materialy.konferencii.Tjurina._1_.pdf SN - 978-5-9222-0726-3 SP - 19 EP - 21 PB - Izdat. Otečestvo CY - Kazan', Russian Federation ER -