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  • 1
    Language: English
    In: Analytical chemistry, 06 October 2015, Vol.87(19), pp.9563-6
    Description: The analysis of dissolved organic matter (DOM) using high-field Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) poses challenges in molecular formula assignment. The consideration of (13)C isotopes provides new insights into the consistent elemental formula solutions. Modern software helps to overcome misinterpretation, but false assignments of molecular classes to mass peaks have rarely been elucidated until now. It will be demonstrated that this can be important with formula assignments comprising exactly five nitrogen and two sulfur atoms in DOM data sets: the molecular class CHON5S2. The existence of such components in DOM under tripeptide Met-His-Cys formed with the formula C14H23O4N5S2 cannot be excluded; however, components containing 5 N and 2 S should be suspected to not be highly abundant. The true elemental compositions of such unusual "N5S2 moieties" were calculated using Suwannee River fulvic acid (SRFA) data from the literature and one data set from acidic pit lake pore water. The replacement of a H3N5S2 moiety with a (13)C1(12)C5O4 moiety explained more than 95% of the questionable "N5S2 moieties". This finding was proved by calculation of δ(13)C‰ values from relative peak intensities.
    Keywords: Software ; Computer Programs ; Lakes ; Fourier Transforms ; Data Sets ; Dissolved Organic Matter ; Porosity ; Mathematical Analysis ; Analysis (MD) ; Chemical Analysis (Ep) ; Chemical Analysis (Ed) ; Chemical Analysis (EC);
    ISSN: 00032700
    E-ISSN: 1520-6882
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  • 2
    Language: English
    In: Water Research, 15 October 2017, Vol.123, pp.513-523
    Description: Streams are important sites of transformation of dissolved organic matter (DOM). The molecular characterization of DOM-quality changes requires sophisticated analytical evaluation techniques. The goal of our study was to link molecular DOM transformation with bacterial activity. We measured the degradation of leaf leachate over a gradient of bacterial production obtained by different rates of percolation of sediments in seven experimental flumes on five sampling dates. We developed a new strategy for evaluating molecular formula data sets obtained by ultra-high resolution Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS), in which the time-dependent change of component abundance was fitted by a linear regression model after normalization of mass peak intensities. All components were categorized by calculating the slope (change of percent intensity per day) in each of the seven flumes. These slopes were then related to cumulative bacterial production. The concentration of DOM decreased quickly in all flumes. Bacterial activity was higher in flumes with percolated sediment than in those without percolation, whereas plankton bacterial activity was higher in flumes without percolation or without sediment. There were no differences in molecular-DOM characteristics between flumes, but there were distinct changes over time. Positive slopes, i.e. increasing intensities over time, were found for small molecules (MW 〈 450 Da) and high O/C ratios, whereas decreasing intensities were observed less often and only for large molecules and low O/C ratios. The positive slopes of produced components showed a positive relationship to bacterial production for small and for oxygen-rich components. The negative slopes of degraded components were negatively related to bacterial production for large and for oxygen-deficient molecules. Overall, the approach provided new insights into the transformation of specific molecular DOM components.
    Keywords: Bacterial Production ; Biofilm ; DOM ; Fticr MS ; Leaf Leachate ; Stream ; Engineering
    ISSN: 0043-1354
    E-ISSN: 1879-2448
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  • 3
    Language: English
    In: Analytical and Bioanalytical Chemistry, 2014, Vol.406(30), pp.7977-7987
    Description: Formula assignment is one of the key challenges in evaluation of dissolved organic matter analyses using ultrahigh resolution mass spectrometry (FTICR MS). The number of possible solutions for elemental formulas grows exponentially with increasing nominal mass, especially when non-oxygen heteroatoms like N, S or P are considered. Until now, no definitive solution for finding the correct elemental formula has been given. For that reason an approach from the viewpoint of chemical feasibility was elucidated. To illustrate the new chemical formula assignment principle, a literature data set was used and evaluated by simplified chemical constraints. Only formulas containing a maximum of one sulphur and five nitrogen atoms were selected for further data processing. The resulting data table was then divided into mass peaks with unique component solutions (singlets, representing unequivocal formula assignments) and those with two or more solutions (multiple formula assignments, representing equivocal formula assignments). Based on a [double bond equivalent (DBE) versus the number of oxygen atoms ( o )] frequency contour plot and a frequency versus [DBE minus o ] diagram, a new assessment and decision strategy was developed to differentiate multiple formula assignments into chemically reliable and less reliable molecular formulas. Using this approach a considerable number of reliable components were identified within the equivocal part of the data set. As a control, a considerable proportion of the assigned formulas deemed to be reliable correspond to those which would have been obtained by CH 2 -based Kendrick mass defect analysis. We conclude that formula assignment in complex mixtures can be improved by group-wise decisions based on the frequency and the [DBE minus o ] values of multiple formula assignments. Graphical Abstract A typical frequency versus [DBE − o] diagram and assessment of molecular classes for their reliability
    Keywords: FTICR MS ; DOM ; Formula assignment ; DBE minus ; Δ
    ISSN: 1618-2642
    E-ISSN: 1618-2650
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  • 4
    Language: English
    In: Analytical and Bioanalytical Chemistry, 2016, Vol.408(10), pp.2461-2469
    Description: Molecular formula assignment is one of the key challenges in processing high-field Fourier transform ion cyclotron resonance mass spectrometric (FT-ICR-MS) datasets. The number of potential solutions for an elemental formula increases exponentially with increasing molecular mass, especially when non-oxygen heteroatoms like N, S or P are included. A method was developed from the chemical perspective and validated using a Suwannee River Fulvic Acid (SRFA) dataset which is dominated by components consisting exclusively of C, H and O (78 % CHO). In order to get information on the application range and robustness of this method, we investigated a FT-ICR-MS dataset which was merged from 18 mine pit lake pore waters and 3 river floodplain soil waters. This dataset contained 50 % CHO and 18 % CHOS on average, whereas the former SRFA dataset contained only 1.5 % CHOS. The mass calculator was configured to allow up to five nitrogen atoms and up to one sulphur atom in assigning formulas to mass peaks. More than 50 % multiple-formula assignments were found for peaks with masses 〉 650 Da. Based on DBE −  O frequency diagrams, many CHO, CHOS 1 , CHON 1 and CHON 1 S 1 molecular series were ultimately assigned to many m / z and considered to be reliable solutions. The unequivocal data pool could thus be enlarged by 523 (6.8 %) CHOS 1 components. In contrast to the method validation with CHO-rich SRFA, validation with sulphur-rich pit lake samples showed that formulas with a higher number of non-oxygen heteroatoms can be more reliable assignments in many cases. As an example: CHOS molecular series were reliable and the CHO classes were unreliable amongst other molecular classes in many multiple-formula assignments from the sulphur-rich pit lake samples. Graphical abstract An exemplary frequency versus DBE −  O diagram. CHOS components but not CHO (and not CHON 2 or CHON 2 S) components were considered here reliable
    Keywords: DOM ; FT-ICR-MS ; Formula assignment ; CHOS/CHON molecular series ; Validation
    ISSN: 1618-2642
    E-ISSN: 1618-2650
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  • 5
    Language: English
    In: Science of the Total Environment, 15 December 2015, Vol.537, pp.129-138
    Description: Chile is the second largest producer of salmonids worldwide. The first step in the production of salmonids takes place in land-based aquacultures. However, the effects of the discharge from these aquacultures on stream dissolved organic matter (DOM) content, molecular composition and degradability are unknown. The aim of this study was thus to investigate the inputs of anthropogenic DOM from land-based aquaculture to the predominantly pristine river systems of North Patagonia. We hypothesized, that i) DOM exported from land-based aquaculture mainly consists of protein-like fluorescence (tyrosine and tryptophan) released from fish feces and food remains, and that ii) this DOM is highly degradable and therefore rapidly turned-over within the receiving streams. In the North Patagonian region we conducted a screening of ten land-based aquacultures and an intensive sampling campaign for one aquaculture. This was combined with longitudinal transects and a degradation experiment in order to couple the composition of DOM exported from land-based aquacultures to its degradability in streams. We measured dissolved organic carbon (DOC) concentration by high-temperature catalytic oxidation and DOM composition by fluorescence spectroscopy and parallel factor analysis. In the effluent of the ten screened aquacultures and in the repeated sampling of one aquaculture, we consistently found an increase of DOC concentrations and a dominance of protein-like fluorescence. The protein-like fluorescence rapidly disappeared downstream of the aquacultures, and in the degradation experiment. 21% of the DOC export from the repeatedly sampled aquaculture resulted from food addition and 76% from fish production. We conclude that large amounts of degradable DOM are exported from land-based aquacultures. This probably has strong effects on the ecological structure and function of North Patagonian streams, and similarly affected streams worldwide.
    Keywords: Aquaculture ; Organic Contamination ; Dissolved Organic Matter ; Fluorescence Spectroscopy ; Fish Farms ; Environmental Sciences ; Biology ; Public Health
    ISSN: 0048-9697
    E-ISSN: 1879-1026
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  • 6
    Language: English
    In: Science of the Total Environment, 15 May 2017, Vol.586, pp.770-781
    Description: Peatlands can be a potential source of dissolved organic matter (DOM) in fresh water catchment areas. The quantity and quality of DOM can differ between pristine, degraded and rewetted peatlands. Due to the large scale and continuing losses of peatlands, their conservation and restoration has been increasingly emphasized. Mostly rewetting measures are required to improve the hydrology of damaged peatlands, which is a precondition for the resettlement of peat-forming plant species. Thus, in term of DOM, there is a special need to understand how rewetting measures affect DOM characteristics and concentrations. To estimate the potential leaching of humic substances from rewetted areas two natural sites were compared with four artificially rewetted sites in a peatland area of the Harz Mountains National Park, Germany. This was done with regards to DOM quality by combining the results from Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS, measured at one time in Spring) and excitation-emission-matrix fluorescence spectroscopy (EEMF, measured monthly for the period of one year). The DOM quality was significantly less variable in the pristine peatland soil water compared to the rewetted peatland soil waters, from both a spatial and a seasonal perspective. The soil water from the rewetted peatland sites showed a higher degree of humification compared to pristine peatland. DOC concentration was mostly consistent in the pristine peatland over the year. The rewetted peatlands showed higher DOC levels in Summer months and lower DOC in Winter months compared to the pristine peatland. It can be concluded that the rewetting of peatlands is coupled with high concentrations of DOC in soil water and its quality is highly aromatic (as reflected by the observed values from the humification index) during times with elevated temperature. The results may have a significant input for dynamic catchment area studies with regards to rewetting peatland sites.
    Keywords: Doc ; Fluorescence Indices ; Van Krevelen Diagrams ; Spatial Resolution ; Seasonality ; Harz Mountains ; Germany ; Environmental Sciences ; Biology ; Public Health
    ISSN: 0048-9697
    E-ISSN: 1879-1026
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  • 7
    Language: English
    In: Environmental Earth Sciences, 2013, Vol.69(2), pp.479-489
    Description: Stormwater runoff from urban areas and subsequent stormwater-induced effluents from sewer systems may deteriorate the quality of the receiving water sediments by emitting particulate matter and associated pollutants. However, the relevance of stormwater and combined sewer effluents for the pollution of bed sediments was not yet quantified. Therefore, we applied a multivariate mixing model of composite fingerprints to investigate how much stormwater effluent may contribute to the accumulation of fines and associated pollutants in the bed sediment of the Bode River, Germany. In our study, stormwater and combined sewer effluents contribute about 10 % of the fines accumulated in the bed sediment. As stormwater overflow fines are a major carrier of C, N, P, Cu and Zn, up to 40 % of these pollutants in the bed sediment originate from stormwater effluents. Especially N and Zn have to be seen critically because high nutrient concentrations trigger excessive macrophyte growth within the studied river stretch and Zn contents exceed German sediment quality standards (LAWA 1998) in the bed sediment.
    Keywords: Stormwater ; Combined sewers overflow ; Particulate matter ; Bed sediment ; Mixing model ; Composite fingerprint ; Pollutants ; Sediment trap
    ISSN: 1866-6280
    E-ISSN: 1866-6299
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  • 8
    Language: English
    In: Environmental Monitoring and Assessment, 2013, Vol.185(5), pp.4333-4346
    Description: Sediments of the Elbe River have been extremely polluted by contaminants originating from previous large-scale hexachlorocyclohexane (HCH) production and the application of γ-HCH (lindane) in its catchment in the second half of the twentieth century. In order to gain knowledge on bioaccumulation processes at lower trophic levels, field investigations of HCHs in macroinvertebrates were carried out along the longitudinal profile of the Elbe and tributary. Among the sites studied, concentrations in macroinvertebrates ranged within five orders of magnitude (0.01–100 μg/kg). In general, lower values of HCH isomers were observed at all Czech sites (mostly 〈1 μg/kg) compared with those in Germany. At the most contaminated site, Spittelwasser brook (a tributary of the Mulde), extremely high concentrations were measured (up to 234 μg/kg α-HCH and 587 μg/kg β-HCH in Hydropsychidae). In contrast, the Obříství site, though also influenced by HCH production facilities, showed only negligibly elevated values (mostly 〈1 μg/kg). Results showed that fairly high levels of α-HCH and β-HCH compared to γ-HCH can still be detected in aquatic environments of the Elbe catchment, and these concentrations are decreasing over time to a lesser extent than γ-HCH. Higher HCH concentrations in sediments in the springtime are considered to be the result of erosion and transport processes during and after spring floods, and lower concentrations at sites downstream are thought to be caused by the time lapse involved in the transportation of contaminated particles from upstream. In addition, comparison with fish (bream) data from the literature revealed no increase in tissue concentrations between invertebrates and fish.
    Keywords: Bioaccumulation ; Biomagnification ; Elbe River ; Freshwater macroinvertebrates ; HCH isomers ; Lindane
    ISSN: 0167-6369
    E-ISSN: 1573-2959
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  • 9
    In: Journal of Phycology, October 2018, Vol.54(5), pp.630-637
    Description: Encrustation and element content of six charophyte species from two hard‐water lakes were investigated monthly for a period of 1 year. Seasonal patterns were analyzed for the interaction of water chemistry. Encrustation followed a seasonal pattern for , and in Lake Krüselin and for and in Lake Lützlow. However, no seasonality in the precipitated Ca was observed for in Lake Lützlow and for in Lake Krüselin, indicating a lake‐specific dependency. Species‐specific encrustation was found. and encrusted the most in June and August, whereas and exhibited lowest encrustation in March and April. The precipitated Ca of charophytes correlated negatively to the concentration of total inorganic carbon in both lakes. Element content of plant dry weight was species‐specific for Ca and K, and lake‐specific for Mg. No specific pattern was found for the and Fe contents. The results showed seasonal, species, and lake‐specific influences on the encrustation of charophytes.
    Keywords: Biomass Ion Composition ; Carbonate Precipitation ; Characeae ; Total Inorganic Carbon ; Water Chemistry
    ISSN: 0022-3646
    E-ISSN: 1529-8817
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  • 10
    Language: English
    In: Environmental Science and Pollution Research, 2015, Vol.22(10), pp.7485-7494
    Description: Nanomaterial (NM) release into wastewater treatment plants (WWTPs) is inevitable due to increased production and application throughout past decades and in the future. Concern arose about environmental risks and impact on activated sludge. Environmental risk assessment (ERA) for NMs according to established guidelines is considered not suitable, because NMs exhibit unique characteristics. For hazard identification on activated sludge, standard test organisms for aquatic toxicity testing are not meaningful. In this study, we developed an acute toxicity test for ciliates ( Paramecium tetraurelia ) as representatives of the important functional group of microbial predators and filter feeders. We chose silver nanoparticles (nAg) exemplarily for ion releasing nanoparticles and regarded toxicity by ions as well. Our results indicate that ions are more toxic (EC 50 0.73 mg/L) than nanoparticles themselves (EC 50 2.15 mg/L). However, nAg must be considered as a source of ions and requires size, surface coating, and compartment-specific ERA. We strived to develop such ERA based on our results, modeled environmental concentration data from literature, and surface area concentrations. Results indicated a probable risk toward activated sludge. This likely has effects on effluent water quality. We conclude that carefully modeled environmental concentrations are vital for more exact ERA for nAg and other NMs.
    Keywords: Silver nanoparticles ; Ciliates ; Wastewater treatment plant ; Toxicity
    ISSN: 0944-1344
    E-ISSN: 1614-7499
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