scholarly journals Land cover and nutrient enrichment regulates low‐molecular weight dissolved organic matter turnover in freshwater ecosystems

2021 ◽  
Author(s):  
Francesca L. Brailsford ◽  
Helen C. Glanville ◽  
Miles R. Marshall ◽  
Christopher A. Yates ◽  
Alun T. Owen ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Land Cover ◽  
Dissolved Organic Matter ◽  
Nutrient Enrichment ◽  
Freshwater Ecosystems ◽  
Low Molecular Weight ◽  
Organic Matter Turnover

Photoformation of Low-Molecular-Weight Organic Acids from Brown Water Dissolved Organic Matter

2003 ◽  
Vol 37 (18) ◽  
pp. 4190-4198 ◽  
Author(s):  
Thomas Brinkmann ◽  
Philip Hörsch ◽  
Daniel Sartorius ◽  
Fritz H. Frimmel
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Organic Acids ◽  
Low Molecular Weight

Effects of dissolved organic matter on sorption of benzotriazole to soil

2020 ◽  
Author(s):  
Lin Wu ◽  
Jin’e Dai ◽  
Erping Bi
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Organic Contaminants ◽  
Low Molecular Weight ◽  
Sorption Equilibrium ◽  
Solution Ph ◽  
Environmental Behaviors ◽  
Unsaturated Zones ◽  
Molecular Weight Fractions

<p>Dissolved organic matter (DOM) plays an important role in affecting the environmental behaviors of organic contaminants. Effects of two representative DOMs (dissolved humic acid (HA) and tannic acid (TA)) on sorption of benzotriazole (BTA) to a reference soil were investigated by batch experiments. The results indicated that TA had stronger sorption to soil than HA (initial solution pH=6.0±0.1). This is because that TA contains more carboxylic and phenolic groups than those of HA. In the solution with DOM, the enhanced sorption of BTA was caused by cumulative sorption resulting from sorbed DOM. Hydrogen bonding was proposed as the main binding mechanism between BTA and the sorbed DOM. When the solution pH at sorption equilibrium increased from 6.5 to 10.5, the electrostatic repulsion inhibited the sorption of BTA in solution with/without HA. In addition, less hydrogren bonds made the effect of HA in promoting BTA sorption decrease when solution pH changed from 6.5 to 10.5. Higher molecular weight fractions of HA could be preferentially sorbed by the soil, its enhancement on BTA sorption was more obvious than that of the low molecular weight fractions. These findings are conducive to a better understanding of environmental behaviors of BTA as well as other organic compounds with similar structure in the unsaturated zones.</p>

scholarly journals Sea cucumbers reduce chromophoric dissolved organic matter in aquaculture tanks

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4344 ◽  
Author(s):  
Seyed Mohammad Sadeghi-Nassaj ◽  
Teresa S. Catalá ◽  
Pedro A. Álvarez ◽  
Isabel Reche
Keyword(s):  
Water Quality ◽  
Molecular Weight ◽  
Time Series ◽  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Chromophoric Dissolved Organic Matter ◽  
Low Molecular Weight ◽  
Optical Parameters ◽  
Absorption Coefficients ◽  
Sea Cucumbers

Background Mono-specific aquaculture effluents contain high concentrations of nutrients and organic matter, which affect negatively the water quality of the recipient ecosystems. A fundamental feature of water quality is its transparency. The fraction of dissolved organic matter that absorbs light is named chromophoric dissolved organic matter (CDOM). A sustainable alternative to mono-specific aquaculture is the multitrophic aquaculture that includes species trophically complementary named “extractive” species that uptake the waste byproducts. Sea cucumbers are recognized as efficient extractive species due to the consumption of particulate organic matter (POM). However, the effects of sea cucumbers on CDOM are still unknown. Methods During more than one year, we monitored CDOM in two big-volume tanks with different trophic structure. One of the tanks (−holothurian) only contained around 810 individuals of Anemonia sulcata, whereas the other tank (+holothurian) also included 90 individuals of Holothuria tubulosa and Holothuria forskali. We routinely analyzed CDOM absorption spectra and determined quantitative (absorption coefficients at 325 nm) and qualitative (spectral slopes) optical parameters in the inlet waters, within the tanks, and in their corresponding effluents. To confirm the time-series results, we also performed three experiments. Each experiment consisted of two treatments: +holothurians (+H) and –holothurians (−H). We set up three +H tanks with 80 individuals of A. sulcata and 10 individuals of H. tubulosa in each tank and four –H tanks that contained only 80 individuals of A. sulcata. Results In the time-series, absorption coefficients at 325 nm (a325) and spectral slopes from 275 to 295 nm (S275−295) were significantly lower in the effluent of the +holothurian tank (average: 0.33 m−1 and 16 µm−1, respectively) than in the effluent of the −holothurian tank (average: 0.69 m−1 and 34 µm−1, respectively), the former being similar to those found in the inlet waters (average: 0.32 m−1 and 22 µm−1, respectively). This reduction in the absorption of the dissolved organic matter appears to be mediated by the POM consumption by holothurians. The experiments confirmed the results observed in the time-series. The a325 and S275−295 values were significantly lower in the treatment with holothurians than in the treatment without holothurians indicating a reduction in the concentration of chromophoric organic compounds, particularly of low molecular weight. Discussion Consequently, sea cucumbers appear to improve water transparency in aquaculture tanks. The underlying mechanism of this improvement might be related to the POM consumption by holothurians, which reduces the concentration of CDOM derived from POM disaggregation or to the direct assimilation of dissolved compounds of low molecular weight as chromophoric amino acids.

scholarly journals Linkage between the temporal and spatial variability of dissolved organic matter and whole-stream metabolism

2013 ◽  
Vol 10 (8) ◽  
pp. 5555-5569 ◽  
Author(s):  
S. Halbedel ◽  
O. Büttner ◽  
M. Weitere
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Primary Production ◽  
Gross Primary Production ◽  
Complex Structure ◽  
Low Molecular Weight ◽  
Stream Metabolism ◽  
Temporal And Spatial ◽  
Dom Composition

Abstract. Dissolved organic matter (DOM) is an important resource for microbes, thus affecting whole-stream metabolism. However, the factors influencing its chemical composition and thereby also its bio-availability are complex and not thoroughly understood. It was hypothesized that whole-stream metabolism is linked to DOM composition and that the coupling of both is influenced by seasonality and different land-use types. We tested this hypothesis in a comparative study on two pristine forestry streams and two non-forestry streams. The investigated streams were located in the Harz Mountains (central Europe, Germany). The metabolic rate was measured with a classical two-station oxygen change technique and the variability of DOM with fluorescence spectroscopy. All streams were clearly net heterotrophic, whereby non-forestry streams showed a higher primary production, which was correlated to irradiance and phosphorus concentration. We detected three CDOM components (C1, C2, C3) using parallel factor (PARAFAC) analysis. We compared the excitation and emission maxima of these components with the literature and correlated the PARAFAC components with each other and with fluorescence indices. The correlations suggest that two PARAFAC components are derived from allochthonous sources (C1, C3) and one is derived autochthonously (C2). The chromophoric DOM matrix was dominated by signals of humic-like substances with a highly complex structure, followed by humic-like, fulfic acids, low-molecular-weight substances, and with minor amounts of amino acids and proteins. The ratios of these PARAFAC components (C1 : C2, C1 : C3, C3 : C2) differed with respect to stream types (forestry versus non-forestry). We demonstrated a significant correlation between gross primary production (GPP) and signals of autochthonously derived, low-molecular-weight humic-like substances. A positive correlation between P / R (i.e. GPP/daily community respiration) and the fluorescence index FI suggests that the amount of autochthonously produced DOM increased overall with increasing GPP. In accordance with the coupling between DOM and the metabolism, our data also indicate that the composition of DOM is subject to seasonal fluctuations. We concluded that temporal and spatial differences in DOM composition are driven by whole-stream metabolism, in addition to pronounced effects coming from allochthonous sources.

Photo- and Biolability of Pyrogenic Dissolved Organic Matter: A Laboratory study of Thermal Series of Laboratory-Prepared Char Leachates

2020 ◽  
Author(s):  
Andrew R. Zimmerman ◽  
Kyle Bostick ◽  
Aleksandar Goranov ◽  
Siddhartha Mitra ◽  
Patrick Hatcher ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Low Molecular Weight ◽  
Pore Waters ◽  
Solar Simulator ◽  
Organic C ◽  
Pyrogenic Carbon ◽  
Soils And Sediments ◽  
Higher Temperature

<p>Pyrogenic carbon (pyC) or fire-derived organic C (e.g., charcoal and soot), while generally considered stable in soils and sediments, can leach into pore waters forming dissolved pyrogenic organic carbon (pyDOC). This pyDOC may be exported to the ocean (about 10% riverine DOC may be pyrogenic). Yet, the processes which control this export and how pyrogenic dissolved organic matter (pyDOM) lability is related to its chemical composition are poorly understood. Thus, pyDOM was leached from a thermal series of oak and grass chars (250-650 °C) and photoirradiated in a solar simulator. About 10-20% of oak char leachate pyDOC was mineralized over five days, with greater proportions lost from leachates of higher temperature parent chars. Proton NMR revealed decreased relative amounts of aryl-C and increased low molecular weight C1 and alkyl-C components during the photo-incubation. Quantification of benzenepolycarboxylic acid (BPCA), molecular markers for condensed aromatic carbon (ConAC), indicated that 75-94% of ConAC was lost during the first five days of photoincubation, the majority of which occurred within the first 2 days, with a preference toward loss of ConAC of larger cluster sizes. Over 96-day microbial incubations, 37 to 48% of pyDOC was lost with modelled half-lives of about 13 days. Much of this was low molecular weight C1 compounds, while only 1 to 2% of ConAC was lost, with a preference for losses of smaller cluster size ConAC. Slightly greater proportions of both total pyC and ConAC was lost from pre-photodegraded pyDOM leachates. These results highlight the large portion of pyDOM that is potentially remineralized or transformed in aquatic systems at short timescales, and the need to examine both condensed and non-condensed portions of pyDOM to understand the effects of fires on aquatic biogeochemistry.</p>

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