Characteristics of colored dissolved organic matter (CDOM) in the Arctic outflow in the Fram Strait: Assessing the changes and fate of terrigenous CDOM in the Arctic Ocean

2012 ◽  
Vol 117 (C12) ◽  
pp. n/a-n/a ◽  
Author(s):  
Mats A. Granskog ◽  
Colin A. Stedmon ◽  
Paul A. Dodd ◽  
Rainer M. W. Amon ◽  
Alexey K. Pavlov ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Arctic Ocean ◽  
The Arctic ◽  
Fram Strait ◽  
Colored Dissolved Organic Matter ◽  
The Arctic Ocean

Seasonality in Lena River biogeochemistry and dissolved organic matter

2020 ◽  
Author(s):  
Bennet Juhls ◽  
Pier Paul Overduin ◽  
Colin Andrew Stedmon ◽  
Anne Morgenstern ◽  
Hanno Meyer ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Arctic Ocean ◽  
The Arctic ◽  
Research Station ◽  
Lena River ◽  
Continuous Sampling ◽  
The Arctic Ocean ◽  
Frequency Sampling ◽  
Sampling Program

<p>The carbon export by rivers to the Arctic Ocean is expected to increase in response to the rapidly changing climate in the Arctic (Camill, 2005; Freeman et al., 2001; Frey and Smith, 2005). This is in part due to thawing permafrost and mobilization of particulate and dissolved organic matter (DOM). The Lena River delivers approximately one fifth of the total river discharge to the Arctic Ocean and is the main source of DOM in the Laptev Sea shelf (Thibodeau et al., 2014). To date river fluxes of DOM have been based on sparse coverage of sample across the hydrograph about 700 km upstream (Cooper et al 2005; Raymond et al 2007; Stedmon et al 2011; Amon et al 2012). The effects of low frequency sampling on load estimates are unknown and potentially large for systems such as these where there are considerable changes across the hydrograph.   Here we present results from a unique high frequency sampling program and evaluate its viability to monitor export fluxes of DOM and its biogeochemistry in the Lena River. The sampling takes place close to the river mouth at the research station Samoylov in the central Lena River Delta. The Samoylov research station allows a unique chance for continuous sampling since it operates throughout the year. The sampling program includes measurements of several water parameters, such as temperature, electric conductivity, dissolved organic carbon (DOC), spectral CDOM absorption (aCDOM), fluorescent dissolved organic matter (FDOM) and water stable isotopes.<br>The data facilitated the identification of the main drivers behind the seasonality of DOM concentration and biogeochemistry of the Lena River. Three main water sources could be identified (1) (snow) melt water, (2) rain water and (3) subsurface water. Melt and rain water are found to be the prevailing water sources that combined transport 5.8 Tg C dissolved organic matter (~ 85 % of annual flux (6.8 Tg C)) into the Lena River. The high number of samples throughout the whole year allowed flux calculations that are independently from load models that likely lead to a large variation of earlier studies.<br>The absorption properties of DOM revealed changing composition and sources of DOM throughout the year. Decreasing SUVA values during the summer point towards an increasing fraction of old DOM which potentially originates from degrading permafrost. In contrast, during the spring freshet, high SUVA indicate mostly fresh organic matter with high molecular weight and high aromaticity.<br>This dataset represents the first year of a planned long-term monitoring program at the Research Station Samoylov Island and provides a baseline data set against which future change of this large integrative system may be measured. A continuous sampling of Arctic River water will facilitate to identify intra and inter-annual trends with ongoing climate change.</p>

scholarly journals Dynamics of organic matter and bacterial activity in the Fram Strait during summer and autumn

2020 ◽  
Vol 378 (2181) ◽  
pp. 20190366 ◽  
Author(s):  
Anabel von Jackowski ◽  
Julia Grosse ◽  
Eva-Maria Nöthig ◽  
Anja Engel
Keyword(s):  
Organic Matter ◽  
Arctic Ocean ◽  
Bacterial Activity ◽  
Ecosystem Dynamics ◽  
The Arctic ◽  
Fram Strait ◽  
Biological Communities ◽  
Coomassie Blue ◽  
The Arctic Ocean ◽  
The Impact

The Arctic Ocean is considerably affected by the consequences of global warming, including more extreme seasonal fluctuations in the physical environment. So far, little is known about seasonality in Arctic marine ecosystems in particular microbial dynamics and cycling of organic matter. The limited characterization can be partially attributed to logistic difficulties of sampling in the Arctic Ocean beyond the summer season. Here, we investigated the distribution and composition of dissolved organic matter (DOM), gel particles and heterotrophic bacterial activity in the Fram Strait during summer and autumn. Our results revealed that phytoplankton biomass influenced the concentration and composition of semi-labile dissolved organic carbon (DOC), which strongly decreased from summer to autumn. The seasonal decrease in bioavailability of DOM appeared to be the dominant control on bacterial abundance and activity, while no temperature effect was determined. Additionally, there were clear differences in transparent exopolymer particles (TEP) and Coomassie Blue stainable particles (CSP) dynamics. The amount of TEP and CSP decreased from summer to autumn, but CSP was relatively enriched in both seasons. Our study therewith indicates clear seasonal differences in the microbial cycling of organic matter in the Fram Strait. Our data may help to establish baseline knowledge about seasonal changes in microbial ecosystem dynamics to better assess the impact of environmental change in the warming Arctic Ocean. This article is part of the theme issue ‘The changing Arctic Ocean: consequences for biological communities, biogeochemical processes and ecosystem functioning’.

scholarly journals Laterally spreading iron, humic-like dissolved organic matter and nutrients in cold, dense subsurface water of the Arctic Ocean

2014 ◽  
Vol 4 (1) ◽  
Author(s):  
Nanako Hioki ◽  
Kenshi Kuma ◽  
Yuichirou Morita ◽  
Ryouhei Sasayama ◽  
Atsushi Ooki ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Arctic Ocean ◽  
The Arctic ◽  
Subsurface Water ◽  
The Arctic Ocean

Differential responses of bacteria to diatom-derived dissolved organic matter in the Arctic Ocean

2018 ◽  
Vol 82 (1) ◽  
pp. 59-72 ◽  
Author(s):  
L Dadaglio ◽  
J Dinasquet ◽  
I Obernosterer ◽  
F Joux
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Arctic Ocean ◽  
The Arctic ◽  
The Arctic Ocean ◽  
Differential Responses
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