scholarly journals Molecular size of riverine dissolved organic matter influences coastal phytoplankton communities

2010 ◽  
Vol 409 ◽  
pp. 17-25 ◽  
Author(s):  
T Fagerberg ◽  
T Jephson ◽  
P Carlsson
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Molecular Size ◽  
Phytoplankton Communities ◽  
Coastal Phytoplankton

scholarly journals Excitation-Dependent Fluorescence Quantum Yield for Freshwater Chromophoric Dissolved Organic Matter from Northern Russian Lakes

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Svetlana Patsaeva ◽  
Daria Khundzhua ◽  
Oleg A. Trubetskoj ◽  
Olga E. Trubetskaya
Keyword(s):  
Organic Matter ◽  
Quantum Yield ◽  
Dissolved Organic Matter ◽  
Fluorescence Quantum Yield ◽  
Molecular Size ◽  
Reversed Phase ◽  
Chromophoric Dissolved Organic Matter ◽  
Excitation Wavelength ◽  
Fluorescence Detector ◽  
Wide Range

Advanced fluorescence analysis within the wide range of excitation wavelengths from 230 to 510 nm accompanied with chromatography was used to study natural chromophoric dissolved organic matter (CDOM) from three freshwater Karelian lakes. The influence of excitation wavelength (λex) on fluorescence quantum yield and emission maximum position was determined. The CDOM fluorescence quantum yield has reached a minimum at λex∼270–280 nm and a maximum at λex∼340–360 nm. It was monotonously decreasing after 370 nm towards longer excitation wavelengths. Analytical reversed-phase high-performance liquid chromatography with multiwavelength fluorescence detector characterized distribution of fluorophores between hydrophilic/hydrophobic CDOM parts. This technique revealed “hidden” protein-like fluorophores for some CDOM fractions, in spite of the absence of protein-like fluorescence in the initial CDOM samples. The humic-like fluorescence was documented for all hydrophilic and hydrophobic CDOM chromatographic peaks, and its intensity was decreasing along with peaks’ hydrophobicity. On contrary, the protein-like fluorescence was found only in the hydrophobic peaks, and its intensity was increasing along with peaks’ hydrophobicity. This work provides new data on the CDOM optical properties consistent with the formation of supramolecular assemblies controlled by association of low-molecular size components. In addition, these data are very useful for understanding the CDOM function in the environment.

scholarly journals Short-Term Effects of Fertilization on Dissolved Organic Matter in Soil Leachate

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1617 ◽  
Author(s):  
Alexandra Tiefenbacher ◽  
Gabriele Weigelhofer ◽  
Andreas Klik ◽  
Matthias Pucher ◽  
Jakob Santner ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Sandy Loam ◽  
Organic Fertilizer ◽  
Molecular Size ◽  
Pig Slurry ◽  
Silt Loam ◽  
Short Term ◽  
Soil Leachate ◽  
Calcium Ammonium Nitrate

Besides the importance of dissolved organic matter (DOM) in soil biogeochemical processes, there is still a debate on how agricultural intensification affects the leaching of terrestrial DOM into adjacent aquatic ecosystems. In order to close this linkage, we conducted a short-term (45 day) lysimeter experiment with silt loam and sandy loam undisturbed/intact soil cores. Mineral (calcium ammonium nitrate) or organic (pig slurry) fertilizer was applied on the soil surface with a concentration equivalent to 130 kg N ha−1. On average, amounts of leached DOC over 45 days ranged between 20.4 mg (silt loam, mineral fertilizer) and 34.4 mg (sandy loam, organic fertilizer). Both, mineral and organic fertilization of a silt loam reduced concentration of dissolved organic carbon (DOC) in the leachate and shifted its composition towards a microbial-like signature (BIX) with a higher aromaticity (Fi) and a lower molecular size (E2:E3). However, in sandy loam only mineral fertilization affected organic matter leaching. There, lowered DOC concentrations with a smaller molecular size (E2:E3) could be detected. The overall effect of fertilization on DOC leaching and DOM composition was interrelated with soil texture and limited to first 12 days. Our results highlight the need for management measures, which prevent or reduce fast flow paths leading soil water directly into aquatic systems, such as surface flow, fast subsurface flow, or drainage water.

DISPERSION OF KAOLINITE BY DISSOLVED ORGANIC MATTER FROM DOUGLAS-FIR ROOTS

1984 ◽  
Vol 64 (3) ◽  
pp. 445-455 ◽  
Author(s):  
PHILIP B. DURGIN ◽  
JESSE G. CHANEY
Keyword(s):  
Organic Matter ◽  
Carboxylic Acid ◽  
Dissolved Organic Matter ◽  
Molecular Size ◽  
Douglas Fir ◽  
Specific Adsorption ◽  
Polycarboxylic Acids ◽  
Molecular Sizes ◽  
Dispersing Ability ◽  
Hydrophobic Acids

The organic constituents of water extracts from Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco var. menziesii) roots that cause kaolinite dispersion were investigated. The dissolved organic matter was fractionated according to molecular size and chemical characteristics into acids, neutrals, and bases of the hydrophilic and hydrophobic groups. The dominant fraction causing dispersion included the hydrophobic acids and organics with molecular sizes greater than 104 nominal molecular weight. Partial oxidation of the dissolved organic matter increased its carboxylic acid content and dispersion potential. Organic acids promoting kaolinite dispersion included aliphatic and aromatic carboxylic acids. The dispersing ability of a carboxylic acid was related to its charge and charge density. Kaolinite has a pH-dependent surface charge; specific adsorption of carboxyl groups makes the clay more negative and promotes dispersion. Polycarboxylic acids appear to play the major role in kaolinite dispersion by dissolved organic matter in forests. Key words: Fulvic acid, specific adsorption, carboxylic acid, fractionation

scholarly journals Seasonal changes in optical properties of two contrasting tropical freshwater systems

2016 ◽  
Author(s):  
Luciana P.M. Brandão ◽  
Peter A. Staehr ◽  
José F. Bezerra-Neto
Keyword(s):  
Organic Matter ◽  
Optical Properties ◽  
Dissolved Organic Matter ◽  
Spectral Characteristics ◽  
Molecular Size ◽  
Winter Period ◽  
Freshwater Systems ◽  
Chl A ◽  
Rainy Period ◽  
Tropical Freshwater

<p>We investigated how allochthonous and autochthonous sources of dissolved organic matter (DOM) affected the optical conditions and chemical characteristics of two contrasting tropical freshwater systems (Dom Helvécio-DH and Pampulha reservoir) in a dry and rainy period in 2013. We analyzed PAR (photosynthetically active radiation) and UV (ultraviolet) attenuation coefficients, nutrients, chlorophyll-a (Chl-a), dissolved organic matter (DOC) and spectral characteristics of CDOM (colored dissolved organic matter). Significant differences in CDOM sources and quantity were observed, with a dominantly terrestrial input in DH during the rainy period with approximately 50% higher DOC and Chl-a levels, and a doubling in total nitrogen (TN) and total phosphorus (TP) compared to the dry winter period. The eutrophic Pampulha had several fold higher levels of DOC, Chl-a, TN and TP, with organic matter of mostly originating from phytoplankton in both seasons. Differences in source and quantity had strong implications on water transparency, DOC concentrations, CDOM quality and its susceptibility to photo- and biodegradation. DH was several fold clearer in both the UV and PAR spectrum. In DH transparency to both UV and PAR radiation was highest during the summer, suggesting elevated photo- and biodegradation during stratification. Pampulha was most transparent in the dry period even during period of algal bloom. In both systems we observed seasonal variations in concentrations of nutrients and Chl-a, and in DH differences were also found in DOC concentrations as well as the specific UV absorbance (SUVA<sub>254</sub>) and molecular size (M). Our results documents that different sources of DOM and seasonal inputs reflect in the seasonality of apparent and inherent optical properties and nutrients availability with implications for water quality and aquatic community. </p>

scholarly journals Fluorescent characteristics of dissolved organic matter produced by bloom-forming coastal phytoplankton

2014 ◽  
Vol 36 (3) ◽  
pp. 685-694 ◽  
Author(s):  
Koji Fukuzaki ◽  
Ichiro Imai ◽  
Keitaro Fukushima ◽  
Ken-Ichiro Ishii ◽  
Shigeki Sawayama ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Coastal Phytoplankton
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