@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} } @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} } @inproceedings{FischerYairGeppertetal., author = {Fischer, Thomas and Yair, Aaron and Geppert, Helmut and Veste, Maik}, title = {Water repellency and infiltration of biological soil crusts on an arid and a temperate dunes}, 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} } @misc{WangGeppertFischeretal., author = {Wang, Haijing and Geppert, Helmut and Fischer, Thomas and Wieprecht, Wolfgang and M{\"o}ller, Detlef}, title = {Determination of Sucrose in Honey with Derivatization/Solid-Phase-Microextraction and Gas-Chromatography/Mass Spectrometry.}, series = {Journal of Chromatographic Science}, volume = {53}, journal = {Journal of Chromatographic Science}, number = {9}, doi = {10.1093/chromsci/bmv044}, pages = {1427 -- 1431}, abstract = {A new method for the determination of sucrose in honey with derivatization solid-phase microextraction and gas chromatography/mass spectrometry (D-SPME-GC/MS) was developed. The method incorporates a sample derivatization with acetic anhydride using N-methylimidazole as the catalyst and the subsequent enrichment of the analyte in a Polyacrylate-SPME fiber. Results show that 100 µL N-methylimidazole and 800 µL acetic anhydride were sufficient to complete the acetylation for sucrose in 100 µL aqueous sample at room temperature. For SPME, an enrichment time of 30 min was sufficient. SPME was performed by immersing the fiber into the solution with additional vibration. Then, the analyte was desorbed for 5 min at 280°C in the GC/MS injection port with splitless mode. The present method exhibits good linearity at a concentration range of 0.3-8\% of sucrose in honey with excellent regression (R = 0.9993). The method has been successfully applied to the control of sucrose adulteration in honey.}, language = {en} } @misc{KuhnTothGeppertetal., author = {Kuhn, Ramona and T{\´o}th, Elisabeth and Geppert, Helmut and Fischer, Thomas and Martienssen, Marion}, title = {Identification of the Complete Photodegradation Pathway of Ethylenediaminetetra(methylenephosphonic acid) in Aqueous Solution}, series = {Clean - soil, air, water : a journal of sustainability and environmental safety}, volume = {45}, journal = {Clean - soil, air, water : a journal of sustainability and environmental safety}, number = {5}, issn = {1863-0669}, doi = {10.1002/clen.201500774}, pages = {1 -- 8}, abstract = {This study aims at investigating the abiotic degradation pathway of ethylenediaminetetra(methylenephosphonic acid) (EDTMP) simulated applying UV irradiation. The degradation of EDTMP and formation of degradation products was determined using LC-MS and ³¹P-NMR. In the laboratory scale experiments, EDTMP was degraded within 30 min and the degradation products, iminodi(methylenephosphonic acid) (IDMP), ethylaminobis(methylenephosphonic acid) (EABMP), and amino- (methylenephosphonic acid) (AMPA), were simultaneously released. IDMP was the main degradation product of EDTMP. Therefore, we conclude that the initial cleavage of EDTMP is a heterolytically driven process, which starts the degradation process at the intramolecular C-N bond. In contrast, the main product of a possible homolytic C-C cleavage of methylaminobis(methylenephosphonic acid) could not be confirmed with either LC-MS or ³¹P-NMR. Additionally, there was no evidence for a primary attack on the C-P bond. All identified degradation products of EDTMP have been mineralized to carbon dioxide (CO₂). Three additional degradation products (M1, M2, and M3) have been found using the ³¹P-NMR analysis but have not yet been quantified using LC-MS. We assume that the unidentified degradation product M1 is related to m/z 312, M2 to m/z 341, and M3 to m/z 409. Thus we concluded that EDTMP undergoes photochemical conversion to IDMP, the main degradation product. EABMP and AMPA also accumulate, but in smaller amounts. All intermediates are further mineralized to CO₂.}, language = {en} }