Spatiotemporal Heterogeneity of Water Flowpaths Controls Dissolved Organic Carbon Sourcing in a Snow-Dominated, Headwater Catchment

Radke, Anna; Godsey, Sarah E.; Lohse, Kathleen A.; McCorkle, E. P.; Perdrial, Julia; Seyfried, M. S.; Holbrook, W. S.

doi:10.3389/fevo.2019.00046

Cited by 16 publications

(36 citation statements)

References 94 publications

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“…CC BY 4.0 License. contribution can be affected by the vertical distribution of reacting materials (Musolff et al, 2017;Bishop et al, 2004;Seibert et al, 2009;Winterdahl et al, 2016) and the relative volume contribution of source water (soil water vs groundwater below the soil-weathered rock interface) to the stream (Zhi et al, 2019;Radke et al, 2019;Weigand et al, 2017). With the shale bedrock, the groundwater contribution to the stream is relatively small (~7.5%) at Shale Hills.…”

Section: Regulation Of C-q Patternsmentioning

confidence: 99%

Temperature controls production but hydrology controls export of dissolved organic carbon at the catchment scale

Wen¹,

Perdrial²,

Bernal³

et al. 2019

Preprint

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Abstract. Lateral carbon flux through river networks is an important and poorly-understood component of the global carbon budget. This work investigates how temperature and hydrology control the production and export of dissolved organic carbon (DOC) in the Susquehanna Shale Hills Critical Zone Observatory in Pennsylvania, USA. We applied the catchment-scale hydro-biogeochemical reactive transport model BioRT-Flux-PIHM to simulate the DOC dynamics. We estimated the daily DOC production rate (Rp; the sum of local DOC production rates in individual modeling grid cell) and the daily DOC export rate (Re; the product of concentration and discharge at the stream outlet) to downstream ecosystems. Simulations showed that Rp varied by less than an order of magnitude and primarily hinged on seasonal temperature change. In contrast, Re varied by more than three orders of magnitude with a strong dependence on discharge and hydrological connectivity. During summer, high temperatures led to high atmospheric water demand (and evapotranspiration) that dried and disconnected hillslope to stream. Rp reached its maximum but Re was at its minimum. The stream only exported DOC from the organic-poor groundwater and from soil water in the narrow organic-rich swales with enriched DOC such that DOC accumulated in the catchment. During the wet period (winter and spring), Rp reached its minimum but Re peaked because the stream was re-connected to a greater uphill area, flushing out the stored DOC. The model reproduced the observed concentration discharge (C–Q) relationship characterized by a flushing-dilution pattern with a rise in concentrations to a maximum (flushing) at a threshold discharge and then followed a general dilution with concentrations decreasing with discharge. This pattern was explained by the comparable contribution of organic-poor deeper groundwater and soil water from organic-rich swales at the minimum flow, maximized percentage contribution of soil water from organic-rich swales at the low flow regime, and increased contribution of uphill soil water interflow from uphill with less DOC at the high flow regime. This pattern persisted regardless of DOC production rate as long as the contribution of deeper groundwater flow remained low ( 18 %, the flushing-dilution C–Q pattern shifted towards a flushing-only pattern with DOC concentrations increasing with discharge. This study illustrates the temporal asynchrony of DOC production, mostly controlled by temperature, and DOC export, primarily governed by hydrological flow paths at the catchment scale. The occurrence of warmer and more extreme hydrological events in the future could accentuate this asynchrony, with major lateral export of DOC dominated by a few major storm events whereas DOC is produced and stored in the catchment in the prolonged drought periods.

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Section: Regulation Of C-q Patternsmentioning

confidence: 99%

Temperature controls production but hydrology controls export of dissolved organic carbon at the catchment scale

Wen¹,

Perdrial²,

Bernal³

et al. 2019

Preprint

Self Cite

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“…First, we calculated unburned JD's and burned MC's isotopic intercepts with the LMWL (Tappa et al, 2016) using each monthly regression (Fritz and Clark, 1997) and evaluated temporal shifts. We then compared the stream's LMWL-intercepts to the mean rain, snow, and groundwater samples collected by Radke et al (2019) in a nearby but higher elevation watershed within RC CZO (Reynolds Mountain East ∼2,100 m elevation). In this way, isotopic means of rain (δ 2 H −66.5 ± 12.7 and δ 18 O −8.4 ± 2.4, mean ± SE), snow (δ 2 H −129 ± 10.2 and δ 18 O −16.8 ± 1.3, mean ± SE) and groundwater samples (δ 2 H −121 ± 1.04 and δ 18 O −16.4 ± 0.18, mean ± SE) were assumed to be reasonable endmembers for our sites as well.…”

Section: Groundwater Influencementioning

confidence: 99%

“…We also plotted Sr against DIC for each month because a previous study showed Sr to be a good indicator of groundwater at the RC CZO (Radke et al, 2019). We calculated RC CZO groundwater and precipitation (rain and snow) averages from samples collected by Radke et al (2019) in late summer (August 2017), and used these values as endmembers in our analysis. Sr averaged 142.74 ± 8.77 ppb (mean ± SE) and DIC averaged 21.20 ± 0.55 mg C/L (mean ± SE).…”

Section: Groundwater Influencementioning

confidence: 99%

“…Dynamic dissolved organic carbon (DOC) patterns in streams have been linked to springtime upland snowmelt and lateral flushing in alpine catchments of the Rocky Mountains (Boyer et al, 1997). However, the flushing process in the headwaters at Reynolds Creek Critical Zone Observatory (RC CZO) located in southwest Idaho was found to be slightly more complex (Radke et al, 2019) than Boyer et al's (1997) lateral flushing paradigm. At RC CZO, geophysical and hydrochemical evidence pointed to vertical and then lateral springtime flushing.…”

Section: Introductionmentioning

confidence: 99%

“…The prior year's soil-water and DOC flushed vertically to the saprolite during snowmelt and then laterally along this interface to the stream. DOC in the stream was primarily allochthonous, presumably sourced from DOC that had accumulated in the soil matrix during the dry summer rather than from in-stream processes (Radke et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

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Influence of Drying and Wildfire on Longitudinal Chemistry Patterns and Processes of Intermittent Streams

et al. 2020

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Stream drying and wildfire are projected to increase with climate change in the western United States, and both are likely to impact stream chemistry patterns and processes. To investigate drying and wildfire effects on stream chemistry (carbon, nutrients, anions, cations, and isotopes), we examined seasonal drying in two intermittent streams in southwestern Idaho, one stream that was unburned and one that burned 8 months prior to our study period. During the seasonal recession following snowmelt, we hypothesized that spatiotemporal patterns of stream chemistry would change due to increased evaporation, groundwater dominance, and autochthonous carbon production. With increased nutrients and reduced canopy cover, we expected greater shifts in the burned stream. To capture spatial chemistry patterns, we sampled surface water for a suite of analytes along the length of each stream with a high spatial scope (50-m sampling along ~2,500 m). To capture temporal variation, we sampled each stream in April (higher flow), May, and June (lower flow) in 2016. Seasonal patterns and processes influencing stream chemistry were generally similar in both streams, but some were amplified in the burned stream. Mean dissolved inorganic carbon (DIC) concentrations increased with drying by 22% in the unburned and by 300% in the burned stream. In contrast, mean total nitrogen (TN) concentrations decreased in both streams, with a 16% TN decrease in the unburned stream and a 500% TN decrease (mostly nitrate) in the burned stream. Contrary to expectations, dissolved organic carbon (DOC) concentrations varied more in space than in time. In addition, we found the streams did not become more evaporative relative to the Local Meteoric Water Line (LMWL) and we found weak evidence for evapoconcentration with drying. However, consistent with our expectations, strontium-DIC ratios indicated stream water shifted toward groundwater-dominance, especially in the burned stream. Fluorescence and absorbance measurements showed considerable spatial variation in DOC sourcing each month in both streams, and mean values suggested a temporal shift from allochthonous toward autochthonous carbon sources in the burned stream. Our findings suggest that the effects of fire may magnify some chemistry patterns but not the biophysical controls that we tested with stream drying.

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Influence of groundwater and topography on stream drying in semi‐arid headwater streams

Warix

Godsey

Lohse

et al. 2021

Hydrological Processes

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Non-perennial streams comprise over half of the global stream network and impact downstream water quality. Although aridity is a primary driver of stream drying globally, surface flow permanence varies spatially and temporally within many headwater streams, suggesting that these complex drying patterns may be driven by topographic and subsurface factors. Indeed, these factors affect shallow groundwater flows in perennial systems, but there has been only limited characterisation of shallow groundwater residence times and groundwater contributions to intermittent streams.Here, we asked how groundwater residence times, shallow groundwater contributions to streamflow, and topography interact to control stream drying in headwater streams. We evaluated this overarching question in eight semi-arid headwater catchments based on surface flow observations during the low-flow period, coupled with tracer-based groundwater residence times. For one headwater catchment, we analysed stream drying during the seasonal flow recession and rewetting period using a sensor network that was interspersed between groundwater monitoring locations, and linked drying patterns to groundwater inputs and topography. We found a poor relationship between groundwater residence times and flowing network extent (R 2 < 0.24). Although groundwater residence times indicated that old groundwater was present in all headwater streams, surface drying also occurred in each of them, suggesting old, deep flowpaths are insufficient to sustain surface flows. Indeed, the timing of stream drying at any given point typically coincided with a decrease in the contribution from near-surface sources and an increased relative contribution of groundwater to streamflow at that location, whereas the spatial pattern of drying within the stream network typically correlated with locations where groundwater inputs were most seasonally variable. Topographic metrics only explained $30% of the variability in seasonal flow permanence, and surprisingly, we found no correlation with seasonal drying and down-valley subsurface storage area. Because we found complex spatial patterns, future studies should pair dense spatial observations of subsurface properties, such as hydraulic conductivity and transmissivity, to observations of seasonal flow permanence.

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Spatiotemporal Heterogeneity of Water Flowpaths Controls Dissolved Organic Carbon Sourcing in a Snow-Dominated, Headwater Catchment

Cited by 16 publications

References 94 publications

Temperature controls production but hydrology controls export of dissolved organic carbon at the catchment scale

Temperature controls production but hydrology controls export of dissolved organic carbon at the catchment scale

Influence of Drying and Wildfire on Longitudinal Chemistry Patterns and Processes of Intermittent Streams

Influence of groundwater and topography on stream drying in semi‐arid headwater streams

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