@inproceedings{FischerVeste, author = {Fischer, Thomas and Veste, Maik}, title = {Small scale spatial heterogeneity of biological soil crusts during initial ecosystem development}, series = {Abstract Book of the 12th European Ecological Federation Congress, 25-29 September 2011, Avila, Spain}, booktitle = {Abstract Book of the 12th European Ecological Federation Congress, 25-29 September 2011, Avila, Spain}, pages = {S. 250}, language = {en} } @inproceedings{FischerVeste, author = {Fischer, Thomas and Veste, Maik}, title = {Biological soil crusts on inland dunes in NE Germany: Can we link succession with hydrology?}, series = {Book of Abstracts Workshop "Biological Soil Crusts in Ecosystems - their Diversity, Ecology, and Management", 22-25. August 2010, Zellingen-Retzbach, Germany}, booktitle = {Book of Abstracts Workshop "Biological Soil Crusts in Ecosystems - their Diversity, Ecology, and Management", 22-25. August 2010, Zellingen-Retzbach, Germany}, pages = {S. 52}, language = {en} } @misc{GeppertFischer, author = {Geppert, Helmut and Fischer, Thomas}, title = {CHROMATOGRAPHIE-Festphasenmikroextraktion von polaren Verbindungen}, series = {Labor Praxis}, volume = {33}, journal = {Labor Praxis}, number = {1}, issn = {0344-1733}, pages = {46 -- 47}, language = {de} } @inproceedings{FischerVesteLangeetal., author = {Fischer, Thomas and Veste, Maik and Lange, Philipp and Wiehe, Wolfgang}, title = {How biological soil crusts are stabilizing the soil surface? The development of organo-mineral interactions in the initial phase}, series = {EGU General Assembly 2009, held in Vienna, Austria, 19 - 24 April 2009}, booktitle = {EGU General Assembly 2009, held in Vienna, Austria, 19 - 24 April 2009}, publisher = {European Geophysical Society}, address = {Katlenburg-Lindau}, language = {en} } @misc{FischerVesteBensetal., author = {Fischer, Thomas and Veste, Maik and Bens, Oliver and H{\"u}ttl, Reinhard F.}, title = {Dew formation on the surface of biological soil crusts in central European sand ecosystems}, series = {Biogeosciences}, volume = {9}, journal = {Biogeosciences}, issn = {1726-4189}, doi = {10.5194/bg-9-4621-2012}, pages = {4621 -- 4628}, abstract = {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.}, language = {en} } @misc{BrankatschkFischerVesteetal., author = {Brankatschk, Robert and Fischer, Thomas and Veste, Maik and Zeyer, Josef}, title = {Succession of N Cycling Processes in Biological Soil Crusts on a Central European Inland Dune}, series = {FEMS Microbiology Ecology}, volume = {83}, journal = {FEMS Microbiology Ecology}, number = {1}, issn = {1574-6941}, doi = {10.1111/j.1574-6941.2012.01459.x}, pages = {149 -- 160}, abstract = {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.}, language = {de} } @misc{XiaoWangFanetal., author = {Xiao, Bo and Wang, Huifang and Fan, Jun and Fischer, Thomas and Veste, Maik}, title = {Biological soil crusts decrease soil temperature in summer and increase soil temperature in winter in semiarid environment}, series = {Ecological Engineering}, volume = {58}, journal = {Ecological Engineering}, issn = {0925-8574}, doi = {10.1016/j.ecoleng.2013.06.009}, pages = {52 -- 56}, abstract = {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.}, language = {en} } @misc{FischerYairVesteetal., author = {Fischer, Thomas and Yair, Aaron and Veste, Maik and Geppert, Helmut}, title = {Hydraulic properties of biological soil crusts on sand dunes studied by 13C-CP/MAS-NMR: a comparison between an arid and a temperate site}, series = {Catena}, volume = {110}, journal = {Catena}, issn = {0341-8162}, doi = {10.1016/j.catena.2013.06.002}, pages = {155 -- 160}, abstract = {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.}, language = {en} } @inproceedings{IurchenkoMykhailovaFischer, author = {Iurchenko, Valentina and Mykhailova, Larysa and Fischer, Thomas}, title = {Kinetic Characteristics of Petrochemicals Transposition and Accumulation in Soils of Roadside Area}, series = {Transbaltica 2013 Conference Proceedings, 09.-10. May 2013, Vilnius, Lithuania}, booktitle = {Transbaltica 2013 Conference Proceedings, 09.-10. May 2013, Vilnius, Lithuania}, doi = {10.3846/transbaltica2013.016}, pages = {4}, language = {en} } @misc{MykhailovaFischerIurchenko, author = {Mykhailova, Larysa and Fischer, Thomas and Iurchenko, Valentina}, title = {Distribution and fractional composition of petroleum hydrocarbons in roadside soils}, series = {Applied and Environmental Soil Science}, volume = {2013}, journal = {Applied and Environmental Soil Science}, number = {ID 938703}, doi = {10.1155/2013/938703}, pages = {1 -- 6}, language = {en} } @misc{WangGeppertFischeretal., author = {Wang, Haijing and Geppert, Helmut and Fischer, Thomas and Wieprecht, Wolfgang and M{\"o}ller, Detlev}, title = {Determination of volatile organic and polycyclic aromatic hydrocarbons in crude oil with efficient gas-chromatographic methods}, series = {Journal of Chromatographic Science}, volume = {53}, journal = {Journal of Chromatographic Science}, number = {5}, issn = {1945-239X}, doi = {10.1093/chromsci/bmu113}, pages = {647 -- 654}, abstract = {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.}, language = {en} } @misc{MykhailovaFischerIurchenko, author = {Mykhailova, Larysa and Fischer, Thomas and Iurchenko, Valentina}, title = {Deposition of petroleum hydrocarbons with sediment trapped in snow in roadside areas}, series = {Journal of Environmental Engineering and Landscape Management}, volume = {22}, journal = {Journal of Environmental Engineering and Landscape Management}, number = {3}, issn = {1822-4199}, doi = {10.3846/16486897.2014.889698}, pages = {237 -- 244}, abstract = {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.}, language = {en} } @inproceedings{FischerVesteMykhailova, author = {Fischer, Thomas and Veste, Maik and Mykhailova, Larysa}, title = {Ecological Maturity and Drought Stress of Biological Soil Crusts along a Central European Inland Dune Catena}, series = {European Geosciences Union, General Assembly 2014, Vienna, Austria, 27 April - 02 May 2014}, booktitle = {European Geosciences Union, General Assembly 2014, Vienna, Austria, 27 April - 02 May 2014}, publisher = {European Geophysical Society}, address = {Katlenburg-Lindau}, language = {en} }