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

scholarly journals Changes in dissolved organic matter quality in a peatland and forest headwater stream as a function of seasonality and hydrologic conditions

2017 ◽  
Vol 21 (4) ◽  
pp. 2035-2051 ◽  
Author(s):  
Tanja Broder ◽  
Klaus-Holger Knorr ◽  
Harald Biester
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Riparian Zone ◽  
Stream Water ◽  
Surface Protein ◽  
Molecular Size ◽  
Organic Matter Quality ◽  
Near Surface ◽  
Export Dynamics ◽  
Hydrologic Conditions

Abstract. Peatlands and peaty riparian zones are major sources of dissolved organic matter (DOM), but are poorly understood in terms of export dynamics and controls thereof. Thereby quality of DOM affects function and behavior of DOM in aquatic ecosystems, but DOM quality can also help to track DOM sources and their export dynamics under specific hydrologic preconditions. The objective of this study was to elucidate controls on temporal variability in DOM concentration and quality in stream water draining a bog and a forested peaty riparian zone, particularly considering drought and storm flow events. DOM quality was monitored using spectrofluorometric indices for aromaticity (SUVA254), apparent molecular size (SR) and precursor organic material (FI), as well as PARAFAC modeling of excitation emission matrices (EEMs). Indices for DOM quality exhibited major changes due to different hydrologic conditions, but patterns were also dependent on season. Stream water at the forested site with mineral, peaty soils generally exhibited higher variability in DOM concentrations and quality compared to the outflow of an ombrotrophic bog, where DOM was less susceptible to changes in hydrologic conditions. During snowmelt and spring events, near-surface protein-like DOM pools were exported. A microbial DOM fraction originating from groundwater and deep peat layers was increasing during drought, while a strongly microbially altered DOM fraction was also exported by discharge events with dry preconditions at the forested site. This might be due to accelerated microbial activity in the peaty riparian zone of the forested site under these preconditions. Our study demonstrated that DOM export dynamics are not only a passive mixing of different hydrological sources, but monitoring studies have to consider that DOM quality depends on hydrologic preconditions and season. Moreover, the forested peaty riparian zone generated the most variability in headwater DOM quantity and quality, as could be tracked by the used spectrofluorometric indices.

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.

scholarly journals Agricultural Practices and Hydrologic Conditions Shape the Temporal Pattern of Soil and Stream Water Dissolved Organic Matter

Ecosystems ◽  
2019 ◽  
Vol 23 (7) ◽  
pp. 1325-1343 ◽  
Author(s):  
Guillaume Humbert ◽  
Thomas B. Parr ◽  
Laurent Jeanneau ◽  
Rémi Dupas ◽  
Patrice Petitjean ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Temporal Pattern ◽  
Stream Water ◽  
Agricultural Practices ◽  
Hydrologic Conditions

scholarly journals Dissolved organic matter characterization in soils and streams in a small coastal low-arctic catchment

2021 ◽  
Author(s):  
Niek Jesse Speetjens ◽  
George Tanski ◽  
Victoria Martin ◽  
Julia Wagner ◽  
Andreas Richter ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Source Apportionment ◽  
Active Layer ◽  
Stream Water ◽  
The Arctic ◽  
Storm Events ◽  
Large Variability ◽  
Small Catchment ◽  
Arctic Rivers

Abstract. Ongoing climate warming in the western Canadian Arctic is leading to thawing of permafrost soils and subsequent mobilization of its organic matter pool. Part of this mobilized terrestrial organic matter enters the aquatic system as dissolved organic matter (DOM) and is laterally transported from land to sea. Mobilized organic matter is an important source of nutrients for ecosystems as it is available for microbial breakdown, and thus a source of greenhouse gases. We are beginning to understand spatial controls on the release of DOM as well as the quantities and fate of this material in large arctic rivers. Yet, these processes remain systematically understudied in small, high-arctic watersheds, despite the fact that these watersheds experience the strongest warming rates in comparison. Here, we sampled soil (active layer and permafrost) and water (porewater and stream water) from a small catchment along the Yukon coast, Canada, during the summer of 2018. We assessed the organic carbon (OC) quantity (using dissolved (DOC) and particulate OC (POC) concentrations and soil OC content), quality (δ13C-DOC, optical properties, source-apportionment), and bioavailability (incubations, optical indices such as slope ratio (Sr) and humification index (HIX)) along with stream water properties (T, pH, EC, water isotopes). We classify and compare different landscape units and their soil horizons that differ in microtopography and hydrological connectivity, giving rise to differences in drainage capacity. Our results show that porewater DOC concentrations and yield reflect drainage patterns and waterlogged conditions in the watershed. DOC yield (in mg DOC g soil OC−1) generally increases with depth but shows a large variability near the transition zone (around the permafrost table). Active layer porewater DOC generally is more labile than permafrost DOC, due to various reasons (heterogeneity, presence of a paleo-active layer, and sampling strategies). Despite these differences, the very long transport times of porewater DOC indicate that substantial processing occurs in soils prior to release into streams. Within the stream, DOC strongly dominates over POC, illustrated by DOC/POC ratios around 50, yet storm events decrease that ratio to around 5. Source-apportionment of stream DOC suggests a contribution of around 50 % from permafrost/deep-active layer OC, which contrasts to patterns observed in large arctic rivers (12 ± 8 % Wild et al., 2019). Our 10-day monitoring period demonstrated temporal DOC patterns on multiple scales (i.e. diurnal patterns, storm-events, and longer-term trend) underlining the need for high-resolution long-term monitoring. First estimates of Black Creek annual DOC (8.2 ± 6.4 t DOC yr−1) and POC (0.21 ± 0.20 t yr−1) export allowed us to make a rough upscaling towards the entire Yukon Coastal Plain (447 ± 313 t DOC yr−1 and 8.95 ± 9.7 t POC yr−1). With raising arctic temperatures, increases in runoff, soil OM leaching, permafrost thawing and primary production are likely to increase the net lateral OC flux. Consequently, altered lateral fluxes may have strong impacts on the arctic aquatic ecosystems and arctic carbon cycling.

scholarly journals Discharge and Temperature Controls of Dissolved Organic Matter (DOM) in a Forested Coastal Plain Stream

Water ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 2919
Author(s):  
Yuehan Lu ◽  
Peng Shang ◽  
Shuo Chen ◽  
Yingxun Du ◽  
Marco Bonizzoni ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
High Temperatures ◽  
Coastal Plain ◽  
Stream Water ◽  
Water Discharge ◽  
Low Flow ◽  
Fluorescence Excitation ◽  
In Situ Modification ◽  
Total Fluorescence

Streams in the southeastern United States Coastal Plains serve as an essential source of energy and nutrients for important estuarine ecosystems, and dissolved organic matter (DOM) exported from these streams can have profound impacts on the biogeochemical and ecological functions of fluvial networks. Here, we examined hydrological and temperature controls of DOM during low-flow periods from a forested stream located within the Coastal Plain physiographic region of Alabama, USA. We analyzed DOM via combining dissolved organic carbon (DOC) analysis, fluorescence excitation–emission matrix combined with parallel factor analysis (EEM-PARAFAC), and microbial degradation experiments. Four fluorescence components were identified: terrestrial humic-like DOM, microbial humic-like DOM, tyrosine-like DOM, and tryptophan-like DOM. Humic-like DOM accounted for ~70% of total fluorescence, and biodegradation experiments showed that it was less bioreactive than protein-like DOM that accounted for ~30% of total fluorescence. This observation indicates fluorescent DOM (FDOM) was controlled primarily by soil inputs and not substantially influenced by instream production and processing, suggesting that the bulk of FDOM in these streams is transported to downstream environments with limited in situ modification. Linear regression and redundancy analysis models identified that the seasonal variations in DOM were dictated primarily by hydrology and temperature. Overall, high discharge and shallow flow paths led to the enrichment of less-degraded DOM with higher percentages of microbial humic-like and tyrosine-like compounds, whereas high temperatures favored the accumulation of high-aromaticity, high-molecular-weight, terrestrial, humic-like compounds in stream water. The flux of DOC and four fluorescence components was driven primarily by water discharge. Thus, the instantaneous exports of both refractory humic-like DOM and reactive protein-like DOM were higher in wetter seasons (winter and spring). As high temperatures and severe precipitation are projected to become more prominent in the southeastern U.S. due to climate change, our findings have important implications for future changes in the amount, source, and composition of DOM in Coastal Plain streams and the associated impacts on downstream carbon and nutrient supplies and water quality.

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