Rapid biotic molecular transformation of fulvic acids in a karst aquifer   总被引：2，自引：0，他引：2  

Florian Einsiedl  Norbert Hertkorn  Moritz Frommberger  Boris P. Koch 《Geochimica et cosmochimica acta》2007,71(22):5474-5482

The study of molecular transformation processes of dissolved organic carbon (DOC) in the environment significantly contributes to a better understanding of the global biogeochemical organic matter cycle. In an oxic karst groundwater system, in which the most powerful abiotic DOC degradative reactions, photodegradation and metal-mediated redox chemistry, are at best marginal contributors, a near complete turnover of fulvic acids (FAs) has been observed within decades (∼60 years). Depletion of oxygen for a very extensive range of aliphatic and aromatic carbon chemical environments has been confirmed as well as the formation of novel classes of compounds, suggesting a major contribution from biotic processes. From these results we infer that FAs must be perceived as a rather active participant in the global carbon cycle. Molecular-level alterations of such magnitude and rapidity on such short-time scales ought to be considered as widespread in the processing of “refractory” DOC in the environment.  相似文献   

Comprehension and appropriateness of complex mobile pictographs for crisis communication     

Waidyanatha  Nuwan  Frommberger  Lutz 《Natural Hazards》2022,114(1):583-604

Natural Hazards - In crisis situations, illiterates and people with other linguistic challenges are unable to understand text messages to inform or be informed of a situation. Pictographic...  相似文献   

Chemical and spectroscopic characterization of marine dissolved organic matter isolated using coupled reverse osmosis-electrodialysis     

J.-F. Koprivnjak  P.H. Pfromm  T.A. Vetter  P. Schmitt-Kopplin  M. Frommberger  E.M. Perdue 《Geochimica et cosmochimica acta》2009,73(14):4215-634

The coupled reverse osmosis-electrodialysis (RO/ED) method was used to isolate dissolved organic matter (DOM) from 16 seawater samples. The average yield of organic carbon was 75 ± 12%, which is consistently greater than the yields of organic carbon that have been commonly achieved using XAD resins, C₁₈ adsorbents, and cross-flow ultrafiltration. UV-visible absorbance spectra and molar C/N ratios of isolated samples were consistent with the corresponding properties of DOM in the original seawater samples, indicating that DOM samples can be isolated using the coupled RO/ED method without any bias for/against these two properties. Five of the samples were desalted sufficiently that reliable measurements of their ¹³C and ¹HNMR spectra and their Fourier transform ion cyclotron resonance (FTICR) mass spectra could be obtained. The ¹³C and ¹HNMR spectra of RO/ED samples differed distinctly from those of samples that have been isolated in much lower yields by other methods. In particular, RO/ED samples contained a relatively lower proportion of carbohydrate carbon and a relatively greater proportion of alkyl carbon than samples that have been isolated using cross-flow ultrafiltration. From the FTICR mass spectra of RO/ED samples, samples from the open ocean contained a much lower proportion of unsaturated compounds and a much higher proportion of fatty acids than coastal samples.  相似文献