scholarly journals High-frequency measurements explain quantity and quality of dissolved organic carbon mobilization in a headwater catchment

2019 ◽  
Vol 16 (22) ◽  
pp. 4497-4516 ◽  
Author(s):  
Benedikt J. Werner ◽  
Andreas Musolff ◽  
Oliver J. Lechtenfeld ◽  
Gerrit H. de Rooij ◽  
Marieke R. Oosterwoud ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
High Frequency ◽  
Riparian Zone ◽  
Quality Parameters ◽  
Riparian Zones ◽  
Frequency Measurements ◽  
Seasonal Scale ◽  
Headwater Catchment

Abstract. Increasing dissolved organic carbon (DOC) concentrations and exports from headwater catchments impact the quality of downstream waters and pose challenges to water supply. The importance of riparian zones for DOC export from catchments in humid, temperate climates has generally been acknowledged, but the hydrological controls and biogeochemical factors that govern mobilization of DOC from riparian zones remain elusive. A high-frequency dataset (15 min resolution for over 1 year) from a headwater catchment in the Harz Mountains (Germany) was analyzed for dominant patterns in DOC concentration (CDOC) and optical DOC quality parameters SUVA254 and S275−295 (spectral slope between 275 and 295 nm) on event and seasonal scales. Quality parameters and CDOC systematically changed with increasing fractions of high-frequency quick flow (Qhf) and antecedent hydroclimatic conditions, defined by the following metrics: aridity index (AI60) of the preceding 60 d and the quotient of mean temperature (T30) and mean discharge (Q30) of the preceding 30 d, which we refer to as discharge-normalized temperature (DNT30). Selected statistical multiple linear regression models for the complete time series (R2=0.72, 0.64 and 0.65 for CDOC, SUVA254 and S275−295, resp.) captured DOC dynamics based on event (Qhf and baseflow) and seasonal-scale predictors (AI60, DNT30). The relative importance of seasonal-scale predictors allowed for the separation of three hydroclimatic states (warm and dry, cold and wet, and intermediate). The specific DOC quality for each state indicates a shift in the activated source zones and highlights the importance of antecedent conditions and their impact on DOC accumulation and mobilization in the riparian zone. The warm and dry state results in high DOC concentrations during events and low concentrations between events and thus can be seen as mobilization limited, whereas the cold and wet state results in low concentration between and during events due to limited DOC accumulation in the riparian zone. The study demonstrates the considerable value of continuous high-frequency measurements of DOC quality and quantity and its (hydroclimatic) key controlling variables in quantitatively unraveling DOC mobilization in the riparian zone. These variables can be linked to DOC source activation by discharge events and the more seasonal control of DOC production in riparian soils.

scholarly journals High-frequency measurements of dissolved organic carbon quantity and quality in a headwater catchment

2019 ◽  
Author(s):  
Benedikt J. Werner ◽  
Andreas Musolff ◽  
Oliver J. Lechtenfeld ◽  
Gerrit H. de Rooij ◽  
Marieke R. Oosterwoud ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
High Frequency ◽  
Riparian Zone ◽  
Aridity Index ◽  
Quality Parameters ◽  
Riparian Zones ◽  
Statistical Regression ◽  
Seasonal Scale ◽  
Headwater Catchment

Abstract. Increasing dissolved organic carbon (DOC) exports from headwater catchments impact the quality of downstream waters and pose challenges to water supply. The importance of riparian zones for DOC export from catchments in humid, temperate climates has generally been acknowledged, but the hydrological controls and biogeochemical factors that govern mobilization of DOC from riparian zones remain elusive. A one-year high-frequency (15 minutes) dataset from a headwater catchment in the Harz Mountains (Germany) was analyzed for dominant patterns in DOC concentration (CDOC) and optical DOC quality parameters SUVA254 and S275-295 (spectral slope between 275 nm and 295 nm) on event and seasonal scale. Quality parameters and CDOC systematically changed with increasing fractions of high-frequency quick flow (Qhf) and antecedent hydroclimatic conditions, defined by the following metrics: Aridity Index (AI60) of the preceding 60 days, mean temperature (T30) and discharge (Q30) of the preceding 30 days and the quotient T30/Q30 which we refer to as discharge-normalized temperature (DNT30). Selected statistical regression models for the complete time series (R² = 0.72, 0.64 and 0.65 for CDOC, SUVA254 and S275-295, resp.) captured DOC dynamics based on event (Qhf and baseflow) and seasonal-scale predictors (AI60, DNT30). The relative importance of seasonal-scale predictors allowed for the separation of three hydroclimatic states (warm & dry, cold & wet and intermediate). The specific DOC quality for each state indicates a shift in the activated source zones and highlights the importance of antecedent conditions and its impact on DOC accumulation and mobilization in the riparian zone. The warm & dry state results in high DOC concentrations during events and low concentrations between events and thus can be seen as mobilization limited, whereas the cold & wet state results in low concentration between and during events due to limited DOC accumulation in the riparian zone. We conclude that the high concentration variability of DOC in the stream can be explained by only a few controlling variables. These variables can be linked to DOC source activation by discharge events and the more seasonal control of DOC production in riparian soils.

scholarly journals Supplementary material to "High-frequency measurements of dissolved organic carbon quantity and quality in a headwater catchment"

2019 ◽  
Author(s):  
Benedikt J. Werner ◽  
Andreas Musolff ◽  
Oliver J. Lechtenfeld ◽  
Gerrit H. de Rooij ◽  
Marieke R. Oosterwoud ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
High Frequency ◽  
Frequency Measurements ◽  
Supplementary Material ◽  
Headwater Catchment

scholarly journals Concentrations and fluxes of dissolved organic carbon in runoff from a forested catchment: insights from high frequency measurements

2013 ◽  
Vol 10 (2) ◽  
pp. 905-916 ◽  
Author(s):  
S. Strohmeier ◽  
K.-H. Knorr ◽  
M. Reichert ◽  
S. Frei ◽  
J. H. Fleckenstein ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
High Frequency ◽  
Groundwater Table ◽  
Wetland Soils ◽  
Short Term ◽  
Fluorescence Excitation ◽  
Riparian Wetland ◽  
Forested Catchment ◽  
Frequency Measurements

Abstract. Concentrations of dissolved organic carbon (DOC) in runoff from catchments are often subject to substantial short-term variations. The aim of this study was to identify the compartmental sources of DOC in a forested catchment and the causes for short-term variations in runoff. Furthermore, we investigated the implication of short-term variations for the calculation of annual runoff fluxes. High frequency measurements (30 min intervals) of DOC in runoff, of discharge and groundwater table were conducted for one year in the 4.2 km2 forested Lehstenbach catchment, Germany. Riparian wetland soils represent about 30% of the catchment area. The quality of DOC was investigated by three dimensional fluorescence excitation-emission matrices in samples taken from runoff, deep groundwater and shallow groundwater from the riparian wetland soils. The concentrations of DOC in runoff were highly variable at an hourly to daily time scale, ranging from 2.6 mg L−1 to 34 mg L−1 with an annual average of 9.2 mg L−1. The concentrations were positively related to discharge, with a counter clockwise hysteresis. Relations of DOC to discharge were steeper and the degree of hysteresis larger in the summer/fall than in the winter/spring period. Dynamics of groundwater table, discharge, DOC concentrations and DOC quality parameters indicated that DOC in runoff originated mainly from the riparian wetland soils, both under low and high flow conditions. The annual export of DOC from the catchment was 84 kg C ha−1 yr−1 when calculated from the high frequency measurements. If the annual export was calculated by simulated samplings of >2 days intervals substantial deviations resulted. Predicted changes in precipitation and discharge patterns as well as generally increasing temperatures likely will cause raising DOC exports from this catchment.

scholarly journals Concentrations and fluxes of dissolved organic carbon in runoff from a forested catchment: insights from high frequency measurements

2012 ◽  
Vol 9 (8) ◽  
pp. 11925-11959 ◽  
Author(s):  
S. Strohmeier ◽  
K.-H. Knorr ◽  
M. Reichert ◽  
S. Frei ◽  
J. H. Fleckenstein ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
High Frequency ◽  
Groundwater Table ◽  
Wetland Soils ◽  
Short Term ◽  
Fluorescence Excitation ◽  
Riparian Wetland ◽  
Forested Catchment ◽  
Frequency Measurements

Abstract. Concentrations of dissolved organic carbon (DOC) in runoff from catchments are often subject to substantial short term variations. The aim of this study was to identify the spatial sources of DOC and the causes for short term variations in runoff from a forested catchment. Furthermore, we investigated the implication of short term variations for the calculation of annual runoff fluxes. High frequency measurements (30 min intervals) of DOC in runoff, of discharge and groundwater table were conducted for one year in the 4.2 km2 forested Lehstenbach catchment, Germany. Riparian wetland soils represent about 30% of the catchment area. The quality of DOC was investigated by three dimensional fluorescence excitation-emission matrices in samples taken from runoff, deep groundwater and shallow groundwater from the riparian wetland soils. The concentrations of DOC in runoff were highly variable at an hourly to daily time scale, ranging from 2.6 mg l−1 to 34 mg l−1 with an annual average of 9.2 mg l−1. The concentrations were positively related to discharge, with a pronounced, counter clockwise hysteresis. Relations of DOC to discharge were steeper in the summer/fall than in the winter/spring season. Dynamics of groundwater table, discharge, DOC concentrations and DOC quality parameters indicated that DOC in runoff originated mainly from the riparian wetland soils, both under low and high flow conditions. The annual export of DOC from the catchment was 84 kg C ha−1 yr−1 when calculated from the high frequency measurements. If the annual export was calculated by simulated random fortnightly samplings, the range was 47 to 124 kg C ha−1 yr−1. Calculations of DOC export fluxes might result in significant errors when based on infrequent (e.g. fortnightly) sampling intervals. Future changes in the precipitation and discharge patterns will influence the DOC dynamics in this catchment, with largest effects in the summer season.

scholarly journals Elucidating sources of dissolved organic carbon in the riparian zone of a small, forested catchment

2021 ◽  
Author(s):  
Katharina Blaurock ◽  
Stefan Peiffer ◽  
Luisa Hopp ◽  
Benjamin Gilfedder ◽  
Phil Garthen ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Riparian Zone ◽  
Forested Catchment

Elucidating sources and pathways of dissolved organic carbon in a small, forested catchment – A qualitative assessment of stream, soil and shallow groundwater

2021 ◽  
Author(s):  
Katharina Blaurock ◽  
Phil Garthen ◽  
Benjamin S. Gilfedder ◽  
Jan H. Fleckenstein ◽  
Stefan Peiffer ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Soil Water ◽  
Riparian Zone ◽  
Stream Water ◽  
Shallow Groundwater ◽  
Drinking Water Treatment ◽  
Base Flow ◽  
Qualitative Assessment ◽  
Fluorescence Characteristics

<p>Dissolved organic carbon (DOC) constitutes the biggest portion of carbon that is exported from soils. During the last decades, widespread increases in DOC concentrations of surface waters have been observed, affecting ecosystem functioning and drinking water treatment. However, the hydrological controls on DOC mobilization are still not completely understood.</p><p>We sampled two different topographical positions within a headwater catchment in the Bavarian Forest National Park: at a steep hillslope (880 m.a.s.l.) and in a flat and wide riparian zone (770 m.a.s.l.). By using piezometers, pore water samplers (peepers) and in-stream spectrometric devices we measured DOC concentrations as well as DOC absorbance (A<sub>254</sub>/A<sub>365</sub> and SUVA<sub>254</sub>) and fluorescence characteristics (fluorescence and freshness indices) in soil water, shallow ground water and stream water in order to gain insights into the DOC source areas during base-flow and during precipitation events.</p><p>High DOC concentrations (up to 80 mg L<sup>-1</sup>) were found in soil water from cascading sequences of small ponds in the flat downstream part of the catchment that fill up temporarily. The increase of in-stream DOC concentrations during events was accompanied by changing DOC characteristics at both locations, for example increasing freshness index values. As the freshness index values were approaching the values found in the DOC-rich ponds in the riparian zone, these ponds seem to be important DOC sources during events. Our preliminary results point to a change of flow pathways during events.</p>

scholarly journals Potential for long‐term transfer of dissolved organic carbon from riparian zones to streams in boreal catchments

2015 ◽  
Vol 21 (8) ◽  
pp. 2963-2979 ◽  
Author(s):  
José L. J. Ledesma ◽  
Thomas Grabs ◽  
Kevin H. Bishop ◽  
Sherry L. Schiff ◽  
Stephan J. Köhler
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Riparian Zones

scholarly journals Concentration of Total Organic Carbon and Its Fractions in Surface Water in Poland and Germany

Proceedings ◽  
2020 ◽  
Vol 51 (1) ◽  
pp. 35
Author(s):  
Patrycja Sobczak ◽  
Agata Rosińska
Keyword(s):  
Drinking Water ◽  
Surface Water ◽  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Total Organic Carbon ◽  
Rhine River ◽  
Bacteriological Quality ◽  
Quality Of Water ◽  
Biodegradable Dissolved Organic Carbon

Total organic carbon (TOC) present in surface water consists of different fractions like dissolved organic carbon (DOC) or biodegradable dissolved organic carbon (BDOC). BDOC may have an impact on the bacteriological quality of water as it can be a source of carbon and energy for microorganisms. It is important to consider this parameter in case of the distribution of drinking water. The aim of this research was to compare the qualities of chosen surface water in Poland and Germany in terms of concentration of total organic carbon and its fractions. The samples were taken from the reservoir in Poland and Rhine River in Germany. The first one is a source of drinking water for humans. The research showed that, considering the analyzed compounds, the water from the river has better quality.

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