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  • 1
    In: Methods in Ecology and Evolution, September 2014, Vol.5(9), pp.971-975
    Description: The estimation of stream metabolism represents a useful technique for characterising the ecological status of natural lotic systems. The existing tools for investigating metabolism in situ demand expert knowledge, provide only a few options, ignore possible groundwater effects and often rely on modelled input data, such as gas exchange, that could be subject to error. We have developed MeCa, a user‐friendly MATLAB toolbox that contains different options – including the groundwater correction – for the calculation of metabolism. A detailed explanation of all the calculation steps and the various calculation options is given in the Appendix S1. The functions of MeCa can be tested using the test data set provided. We conducted sensitivity tests to assess the effect of certain parameters (reaeration, travel time, groundwater oxygen concentration, mean depth and width) and other measurements (oxygen, temperature, pressure) on the metabolism estimation. Uncertainties in the parameters have a greater effect than those that apply to the measurements. The parameters reaeration coefficient and mean depth are the most sensitive input data. Results from sensitivity analyses show the complexity of metabolism studies in streams and the importance of direct calculations. MeCa includes all relevant calculation options, and thus makes a contribution towards the standardisation of metabolism studies.
    Keywords: Open‐Channel Method ; Stream Metabolism ; Two‐Station Technique ; Matlab
    ISSN: 2041-210X
    E-ISSN: 2041-210X
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  • 2
    Language: English
    In: Frontiers in Environmental Science, 01 April 2018, Vol.6
    Description: [...]it is also one of the main plant nutrients, essential for diverse biochemical processes. [...]in vegetated bodies of water, aquatic plants play an important role in nutrient turnover processes (Reddy, 1983; Reddy and De Busk, 1985; Bowden et al.,...
    Keywords: Phosphorus ; Recycling ; Nutrient Removal ; Water Quality ; Aquatic Plants ; P-Uptake Budget ; Environmental Sciences
    E-ISSN: 2296-665X
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  • 3
    Language: English
    In: Inland Waters, 01 January 2016, Vol.6(3), pp.343-351
    Description: In Europe and Asia, Elodea nuttallii is known as an invasive alien species that causes serious economic and environmental problems. This study demonstrated Elodea's ability to affect the biogeochemical character of its rhizosphere by investigating...
    Keywords: Elodea ; Elodea Nuttallii ; Iron Plaque ; Macrophytes ; Phosphorus Uptake ; Radial Oxygen Loss ; Root-Associated Microbes ; Weed Management ; Oceanography
    ISSN: 2044-2041
    E-ISSN: 2044-205X
    Source: Taylor & Francis (Taylor & Francis Group)
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  • 4
    Language: English
    In: Journal of Experimental Marine Biology and Ecology, April 2016, Vol.477, pp.23-30
    Description: Macrophytes and phytoplankton compete for inorganic nitrogen during growth, even in eutrophied coastal waters containing relatively high nitrogen concentrations. In this study we investigated, whether dissolved organic nitrogen (DON) serves as an additional nitrogen source for rooted submerged macrophytes in several key species in the nutrient-rich inner coastal waters of the Darss-Zingster-Bodden chain, located in the southern Baltic Sea. The uptake and translocation of N-labeled dissolved inorganic nitrogen (DIN, ammonium and nitrate) and DON (amino-acid mixture) were measured for three common species: , , and . A two-compartment-device was used to discriminate between the roles of roots and shoots in N uptake. The results showed that DON and DIN were taken up by all species, but ammonium (mean 0.116% N mg DW h ) was preferred over amino acids (mean 0.024% N mg DW h ) which were preferred over nitrate (mean 0.007%l N mg DW h ). To our knowledge, this is the first study to demonstrate the uptake of DON in charophytes and the submerged angiosperm . Both nitrate and ammonium, as DIN, were translocated in the basipetal and acropetal directions in Characeae, which was unexpected given the lack of vascular bundles in these species. By contrast nutrient transport was below the detection limit in the vascular macrophyte . The translocation of DON was not observed in any species or in any direction. Our findings suggest that rooted plants have an advantage over phytoplankton based on their ability to assimilate and transport nutrients not only from the water column but also from the sediments, whereas phytoplankton can only use nutrients of the water column.
    Keywords: Dissolved Organic Nitrogen ; Macrophytes ; Translocation ; Uptake ; Stable Isotopes ; Bacterial Biofilm ; Biology ; Oceanography ; Ecology
    ISSN: 0022-0981
    E-ISSN: 1879-1697
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  • 5
    Language: English
    In: Methods in Ecology and Evolution, 2014, Vol.5(9), p.971(5)
    Description: To purchase or authenticate to the full-text of this article, please visit this link: http://onlinelibrary.wiley.com/doi/10.1111/2041-210X.12207/abstract Byline: Susanne Halbedel, Olaf Buttner, Matthew Davey Keywords: Open-channel method; stream metabolism; two-station technique; MATLAB Summary The estimation of stream metabolism represents a useful technique for characterising the ecological status of natural lotic systems. The existing tools for investigating metabolism in situ demand expert knowledge, provide only a few options, ignore possible groundwater effects and often rely on modelled input data, such as gas exchange, that could be subject to error. We have developed MeCa, a user-friendly MATLAB toolbox that contains different options - including the groundwater correction - for the calculation of metabolism. A detailed explanation of all the calculation steps and the various calculation options is given in the Appendix S1. The functions of MeCa can be tested using the test data set provided. We conducted sensitivity tests to assess the effect of certain parameters (reaeration, travel time, groundwater oxygen concentration, mean depth and width) and other measurements (oxygen, temperature, pressure) on the metabolism estimation. Uncertainties in the parameters have a greater effect than those that apply to the measurements. The parameters reaeration coefficient and mean depth are the most sensitive input data. Results from sensitivity analyses show the complexity of metabolism studies in streams and the importance of direct calculations. MeCa includes all relevant calculation options, and thus makes a contribution towards the standardisation of metabolism studies. Article Note: Contributed equally. CAPTION(S): Appendix S1. Formulae and references used in the MeCa metabolism toolbox.
    Keywords: Groundwater – Physiological Aspects ; Groundwater – Analysis
    Source: Cengage Learning, Inc.
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  • 6
    Language: English
    In: Environmental Monitoring and Assessment, 2013, Vol.185(11), pp.9221-9236
    Description: The Bode catchment (Germany) shows strong land use gradients from forested parts of the National Park (23 % of total land cover) to agricultural (70 %) and urbanised areas (7 %). It is part of the Terrestrial Environmental Observatories of the German Helmholtz association. We performed a biogeochemical analysis of the entire river network. Surface water was sampled at 21 headwaters and at ten downstream sites, before (in early spring) and during the growing season (in late summer). Many parameters showed lower concentrations in headwaters than in downstream reaches, among them nutrients (ammonium, nitrate and phosphorus), dissolved copper and seston dry mass. Nitrate and phosphorus concentrations were positively related to the proportion of agricultural area within the catchment. Punctual anthropogenic loads affected some parameters such as chloride and arsenic. Chlorophyll a concentration and total phosphorus in surface waters were positively related. The concentration of dissolved organic carbon (DOC) was higher in summer than in spring, whereas the molecular size of DOC was lower in summer. The specific UV absorption at 254 nm, indicating the content of humic substances, was higher in headwaters than in downstream reaches and was positively related to the proportion of forest within the catchment. CO 2 oversaturation of the water was higher downstream compared with headwaters and was higher in summer than in spring. It was correlated negatively with oxygen saturation and positively with DOC concentration but negatively with DOC quality (molecular size and humic content). A principle component analysis clearly separated the effects of site (44 %) and season (15 %), demonstrating the strong effect of land use on biogeochemical parameters.
    Keywords: TERENO ; Land use ; Nutrients ; Heavy metals ; DOC ; Bode
    ISSN: 0167-6369
    E-ISSN: 1573-2959
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  • 7
    Language: English
    In: Chemosphere, January 2020, Vol.239, pp.124818
    Description: This article is a short, but very important comment to the often used humification index (HIX), assumed to indicate the degree of biochemical degradation of dissolved organic matter in water samples. HIX is commonly calculated by dividing the fluorescence...
    Keywords: Dissolved Organic Matter ; Hix ; Humification Index
    ISSN: 00456535
    E-ISSN: 1879-1298
    Source: MEDLINE/PubMed (U.S. National Library of Medicine)
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  • 8
    In: Protocol Exchange, 2015
    ISSN: Protocol Exchange
    E-ISSN: 20430116
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  • 9
    Language: English
    In: Environmental science & technology, 07 June 2016, Vol.50(11), pp.5685-94
    Description: Recently developed in situ NO3– sensors provide new opportunities to measure changes in stream concentration at high temporal frequencies that historically have not been feasible. In this study, we used multiparameter sensor measurements to relate assimilatory NO3– uptake to metabolic rates and calculate continuous uptake rates for two stream reaches and a whole stream network. Two years of continuous 15 min data from a forest and agricultural reach of the Selke river (456 km2) revealed a strong correlation between assimilatory NO3– uptake and growth primary production (GPP) for the forest (r2 = 0.72) and agricultural (r2 = 0.56) stream reach. The slopes of these regressions were in agreement with predicted assimilatory N-uptake based on additional metabolic data. Mean yearly assimilatory NO3– uptake rates (Ua) were 7.4 times higher in the agricultural stream reach (mean 78.3 mg N m–2 d–1, max 270 mg N m–2 d–1) than in the forest stream reach (mean 10.7 mg N m–2 d–1, max 97.5 mg N m–2 d–1). Nitrate uptake velocities (Vf,a) tended to decrease with increasing nitrate concentrations for periods with high light availability. Percentage daily assimilatory NO3– uptake peaked at 47.4% of the daily NO3– loading input to the stream network across the entire watershed, whereas the percentage yearly assimilatory NO3– uptake was 9.0% of nitrogen loading to the stream network. This is a maximum because uptake can be revered by mineralization processes. The percentage yearly assimilatory NO3– uptake was lower in the forest-dominated upstream subwatershed (4.8%) than in the lower agriculture dominated subwatershed (13.4%).
    Keywords: Nitrates -- Analysis ; Rivers -- Chemistry ; Water Pollutants, Chemical -- Analysis
    ISSN: 0013936X
    E-ISSN: 1520-5851
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  • 10
    Language: English
    In: Journal of Molecular Biology, 2007, Vol.371(3), pp.596-607
    Description: The nucleotide sequences that control transcription initiation and regulation in are poorly understood. Moreover, only few regulatory events have been reported for . We have studied changes in the global protein synthesis pattern in in response to the presence of glycerol. The and genes, encoding acetate kinase and lactate dehydrogenase, respectively, were controlled in a carbon source-dependent manner. While the gene was strongly expressed in the presence of glucose, transcription of was induced by glycerol. The promoters of both genes were mapped by primer extension analysis. Molecular analysis of transcription regulatory mechanisms in has so far not been possible due to the lack of appropriate reporter systems that can be used to study the activity of promoter fragments and their mutant derivatives . Recently, a reporter system has been developed which allows cloning of promoter fragments in front of a promoterless gene and inserting this construct into the genome of . To study the requirements of RNA polymerase for promoter recognition, a series of fusions of deletion and mutant variants of the promoter was constructed and analyzed . While mutations affecting the −10 region strongly interfered with gene expression, the −35 region seems to be of minor importance in .
    Keywords: Mycoplasma Pneumoniae ; Transcription ; Mollicutes ; Overflow Metabolism ; Proteomics ; Biology ; Chemistry
    ISSN: 0022-2836
    E-ISSN: 1089-8638
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