scholarly journals Characterization of Marine-Surface-Dissolved Organic Matter via Amino Acid Enantiomers and Its Implications Based on Diel and Seasonal Observations

Water ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 685
Author(s):  
Zhuo-Yi Zhu ◽  
Ying-Chun Zhou ◽  
Wen-Chao Ma ◽  
Ying Wu ◽  
Ming Li ◽  
...  
Keyword(s):  
Organic Matter ◽  
Amino Acid ◽  
Dissolved Organic Matter ◽  
Carbon Cycling ◽  
Northern South China Sea ◽  
Marine Ecosystem ◽  
Amino Acid Enantiomers ◽  
Marine Surface ◽  
High Frequency Sampling ◽  
Dom Composition

Due to the essential roles of dissolved organic matter (DOM) in both microbiol food loop and marine carbon cycling, changes in marine DOM composition have an important impact on the marine ecosystem and carbon cycling. In October 2014 and June 2015, two field investigations for the DOM in the upper 200 m were conducted in the slope region of the northern South China Sea to characterize the DOM composition via amino acid enantiomers. In June, our sampling locations were under upwelling impact induced by an eddy-pair event, whereas in October there were no eddies. High-frequency sampling (a few hours interval) over 24 h reveals that the variability of the amino acid carbon yield (min. 0.2%) and the D/L alanine ratio (min. 0.02) is larger than its corresponding analytical and propagated errors, suggesting solid short-term changes for these two molecular-based indicators. Section samples from June showed a lower D/L alanine ratio (0.43 vs. 0.53) and a GABA mol% (1.0% vs. 1.6%) relative to the section samples from October, suggesting that DOM in June is more fresh (less degraded) compared to that in October. A higher serine mol% (19.5% vs. 13.2%) and lower D/L serine ratio (0.06 vs. 0.24) from the diel observation in June relative to October further indicates that phytoplankton, rather than bacteria, plays an more important role in DOM composition alternation. This is consistent with the higher phytoplankton biomass found in June, promoted by the eddy-pair.

scholarly journals Amino acid enantiomers in old and young dissolved organic matter: Implications for a microbial nitrogen pump

2019 ◽  
Vol 247 ◽  
pp. 207-219 ◽  
Author(s):  
Taylor A.B. Broek ◽  
Amy L. Bour ◽  
Hope L. Ianiri ◽  
Thomas P. Guilderson ◽  
Matthew D. McCarthy
Keyword(s):  
Organic Matter ◽  
Amino Acid ◽  
Dissolved Organic Matter ◽  
Amino Acid Enantiomers ◽  
Microbial Nitrogen

scholarly journals DOM degradation by light and microbes along the Yukon River-coastal ocean continuum

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Brice K. Grunert ◽  
Maria Tzortziou ◽  
Patrick Neale ◽  
Alana Menendez ◽  
Peter Hernes
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Salinity Gradient ◽  
Coastal Ocean ◽  
Interactive Effects ◽  
The Arctic ◽  
Yukon River ◽  
Spring Freshet ◽  
Dom Composition

AbstractThe Arctic is experiencing rapid warming, resulting in fundamental shifts in hydrologic connectivity and carbon cycling. Dissolved organic matter (DOM) is a significant component of the Arctic and global carbon cycle, and significant perturbations to DOM cycling are expected with Arctic warming. The impact of photochemical and microbial degradation, and their interactive effects, on DOM composition and remineralization have been documented in Arctic soils and rivers. However, the role of microbes, sunlight and their interactions on Arctic DOM alteration and remineralization in the coastal ocean has not been considered, particularly during the spring freshet when DOM loads are high, photoexposure can be quite limited and residence time within river networks is low. Here, we collected DOM samples along a salinity gradient in the Yukon River delta, plume and coastal ocean during peak river discharge immediately after spring freshet and explored the role of UV exposure, microbial transformations and interactive effects on DOM quantity and composition. Our results show: (1) photochemical alteration of DOM significantly shifts processing pathways of terrestrial DOM, including increasing relative humification of DOM by microbes by > 10%; (2) microbes produce humic-like material that is not optically distinguishable from terrestrial humics; and (3) size-fractionation of the microbial community indicates a size-dependent role for DOM remineralization and humification of DOM observed through modeled PARAFAC components of fluorescent DOM, either through direct or community effects. Field observations indicate apparent conservative mixing along the salinity gradient; however, changing photochemical and microbial alteration of DOM with increasing salinity indicate changing DOM composition likely due to microbial activity. Finally, our findings show potential for rapid transformation of DOM in the coastal ocean from photochemical and microbial alteration, with microbes responsible for the majority of dissolved organic matter remineralization.

Invasive plant-derived dissolved organic matter alters microbial communities and carbon cycling in soils

2021 ◽  
pp. 108191
Author(s):  
Morgan Luce McLeod ◽  
Lorinda Bullington ◽  
Cory C. Cleveland ◽  
Johannes Rousk ◽  
Ylva Lekberg
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Microbial Communities ◽  
Carbon Cycling ◽  
Invasive Plant

Carbohydrate and amino acid composition of dissolved organic matter leached from soil

2007 ◽  
Vol 39 (11) ◽  
pp. 2926-2935 ◽  
Author(s):  
Holger Fischer ◽  
Axel Meyer ◽  
Klaus Fischer ◽  
Yakov Kuzyakov
Keyword(s):  
Organic Matter ◽  
Amino Acid ◽  
Dissolved Organic Matter ◽  
Amino Acid Composition ◽  
Acid Composition

scholarly journals Photochemical alteration of dissolved organic matter and the subsequent effects on bacterial carbon cycling and diversity

2016 ◽  
Vol 92 (5) ◽  
pp. fiw048 ◽  
Author(s):  
Christian Lønborg ◽  
Mar Nieto-Cid ◽  
Victor Hernando-Morales ◽  
Marta Hernández-Ruiz ◽  
Eva Teira ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Carbon Cycling

scholarly journals An aquatic vertebrate can use amino acids from environmental water

2016 ◽  
Vol 283 (1839) ◽  
pp. 20160996 ◽  
Author(s):  
Noboru Katayama ◽  
Kobayashi Makoto ◽  
Osamu Kishida
Keyword(s):  
Amino Acids ◽  
Organic Matter ◽  
Amino Acid ◽  
Dissolved Organic Matter ◽  
Larval Growth ◽  
Environmental Water ◽  
Acid Solutions ◽  
Aquatic Vertebrates ◽  
Amino Acid Solutions ◽  
Salamander Larvae

Conventional food-web theory assumes that nutrients from dissolved organic matter are transferred to aquatic vertebrates via long nutrient pathways involving multiple eukaryotic species as intermediary nutrient transporters. Here, using larvae of the salamander Hynobius retardatus as a model system, we provide experimental evidence of a shortcut nutrient pathway by showing that H. retardatus larvae can use dissolved amino acids for their growth without eukaryotic mediation. First, to explore which amino acids can promote larval growth, we kept individual salamander larvae in one of eight different high-concentration amino acid solutions, or in control water from which all other eukaryotic organisms had been removed. We thus identified five amino acids (lysine, threonine, serine, phenylalanine, and tyrosine) as having the potential to promote larval growth. Next, using 15 N-labelled amino acid solutions, we demonstrated that nitrogen from dissolved amino acids was found in larval tissues. These results suggest that salamander larvae can take up dissolved amino acids from environmental water to use as an energy source or a growth-promoting factor. Thus, aquatic vertebrates as well as aquatic invertebrates may be able to use dissolved organic matter as a nutrient source.

scholarly journals Assessing the Contribution of Seasonality, Tides, and Microbial Processing to Dissolved Organic Matter Composition Variability in a Southeastern U.S. Estuary

2021 ◽  
Vol 8 ◽  
Author(s):  
Rachel P. Martineac ◽  
Alexey V. Vorobev ◽  
Mary Ann Moran ◽  
Patricia M. Medeiros
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Critical Role ◽  
Bacterial Cells ◽  
Secondary Importance ◽  
Relative Contribution ◽  
Doc Concentration ◽  
Compositional Changes ◽  
Dom Composition

Uncovering which biogeochemical processes have a critical role controlling dissolved organic matter (DOM) compositional changes in complex estuarine environments remains a challenge. In this context, the aim of this study is to characterize the dominant patterns of variability modifying the DOM composition in an estuary off the Southeastern U.S. We collected water samples during three seasons (July and October 2014 and April 2015) at both high and low tides and conducted short- (1 day) and long-term (60 days) dark incubations. Samples were analyzed for bulk DOC concentration, and optical (CDOM) and molecular (FT-ICR MS) compositions and bacterial cells were collected for metatranscriptomics. Results show that the dominant pattern of variability in DOM composition occurs at seasonal scales, likely associated with the seasonality of river discharge. After seasonal variations, long-term biodegradation was found to be comparatively more important in the fall, while tidal variability was the second most important factor correlated to DOM composition in spring, when the freshwater content in the estuary was high. Over shorter time scales, however, the influence of microbial processing was small. Microbial data revealed a similar pattern, with variability in gene expression occurring primarily at the seasonal scale and tidal influence being of secondary importance. Our analyses suggest that future changes in the seasonal delivery of freshwater to this system have the potential to significantly impact DOM composition. Changes in residence time may also be important, helping control the relative contribution of tides and long-term biodegradation to DOM compositional changes in the estuary.

Using the molecular composition of dissolved organic matter in groundwater to assess the functional stability of subsurface ecosystems

2021 ◽  
Author(s):  
Simon Benk ◽  
Robert Lehmann ◽  
Kai Uwe Totsche ◽  
Gerd Gleixner
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Groundwater Resources ◽  
Molecular Composition ◽  
Composition Analysis ◽  
Essential Information ◽  
Aquifer System ◽  
Groundwater Levels ◽  
Groundwater Ecosystems ◽  
Dom Composition

<p>With surface systems changing rapidly on a global scale, it is important to understand how this will affect groundwater resources and ecosystems in the subsurface. The molecular composition of dissolved organic matter (DOM) integrates essential information on metabolic functioning and could therefore reveal changes of groundwater ecosystems in high detail. Here, we evaluate a 6-year time series of ultrahigh-resolution DOM composition analysis of groundwater from a hillslope well transect within the Hainich Critical Zone Exploratory, Germany. We predict ecosystem functionality by assigning molecular sum formulas to metabolic pathways via the KEGG database. Our data support hydrogeological characterizations of a compartmentalized fractured multi-storey aquifer system and reveal distinct metabolic functions that largely depend on the compartment’s relative surface-connectivity or isolation. We show that seasonal fluctuation of groundwater levels, coinciding with cross-stratal exchange can substantially impact the local inventory of functional metabolites in DOM. Furthermore, we find that extreme conditions of groundwater recharge following pronounced groundwater lowstand cause strong alterations of the functional metabolome in DOM even in aquifer compartments, which usually show minimal variation in DOM composition. Our findings suggest that bedrock groundwater ecosystems might be functionally vulnerable to hydrogeological extremes.</p>

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