scholarly journals Ontogenic succession of thermokarst thaw ponds is linked to dissolved organic matter quality and microbial degradation potential

2020 ◽  
Vol 65 (S1) ◽  
Author(s):  
Sari Peura ◽  
Maxime Wauthy ◽  
Domenico Simone ◽  
Alexander Eiler ◽  
Karólína Einarsdóttir ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Microbial Degradation ◽  
Organic Matter Quality

scholarly journals Mimicking floodplain reconnection and disconnection using <sup>15</sup>N mesocosm incubations

2012 ◽  
Vol 9 (11) ◽  
pp. 4263-4278 ◽  
Author(s):  
N. Welti ◽  
E. Bondar-Kunze ◽  
M. Mair ◽  
P. Bonin ◽  
W. Wanek ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Nitrogen Retention ◽  
Danube River ◽  
Nitrous Oxide Emissions ◽  
Organic Matter Quality ◽  
Main River Channel ◽  
Order Of Magnitude ◽  
Floodplain Reconnection ◽  
Floodplain Sediments

Abstract. Floodplain restoration changes the nitrate delivery pattern and dissolved organic matter pool in backwaters, though the effects these changes have are not yet well known. We performed two mesocosm experiments on floodplain sediments to quantify the nitrate metabolism in two types of floodplains. Rates of denitrification, dissimilatory nitrate reduction to ammonium (DNRA) and anammox were measured using 15N-NO3 tracer additions in mesocosms of undisturbed floodplain sediments originating from (1) restored and (2) disconnected sites in the Alluvial Zone National Park on the Danube River downstream of Vienna, Austria. DNRA rates were an order of magnitude lower than denitrification and neither rate was affected by changes in nitrate delivery pattern or organic matter quality. Anammox was not detected at any of the sites. Denitrification was out-competed by assimilation, which was estimated to use up to 70% of the available nitrate. Overall, denitrification was higher in the restored sites, with mean rates of 5.7 ± 2.8 mmol N m−2 h−1 compared to the disconnected site (0.6 ± 0.5 mmol N m−2 h−1). In addition, ratios of N2O : N2 were lower in the restored site indicating a more complete denitrification. Nitrate addition had neither an effect on denitrification, nor on the N2O : N2 ratio. However, DOM (dissolved organic matter) quality significantly changed the N2O : N2 ratio in both sites. Addition of riverine-derived organic matter lowered the N2O : N2 ratio in the disconnected site, whereas addition of floodplain-derived organic matter increased the N2O : N2 ratio in the restored site. These results demonstrate that increasing floodplains hydrological connection to the main river channel increases nitrogen retention and decreases nitrous oxide emissions.

Influence of bedrock geology on dissolved organic matter quality in stream water

2010 ◽  
Vol 41 (11) ◽  
pp. 1177-1188 ◽  
Author(s):  
Jennifer J. Mosher ◽  
Geoffrey C. Klein ◽  
Alan G. Marshall ◽  
Robert H. Findlay
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Stream Water ◽  
Organic Matter Quality ◽  
Bedrock Geology
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