Labile dissolved organic carbon supply limits hyporheic denitrification

Zarnetske, Jay P.; Haggerty, R.; Wondzell, Steven M.; Baker, Michelle A.

doi:10.1029/2011jg001730

Cited by 145 publications

(183 citation statements)

References 53 publications

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“…Therefore, OC dynamics can be interpreted as a key factor explaining spatio-temporal variations in DEA and OC sources need to be thoroughly investigated. Indeed carbon supply is often considered as the major limiting factor for denitrification (Starr and Gillham, 1993;Jacinthe et al, 1998;Devito et al, 2000;Rivett et al, 2008;Zarnetske et al, 2011;Peter et al, 2012). However, bacterial richness, which was the only variable describing the bacterial community, was not related to DEA in this study.…”

Section: Environmental Factors Controlling Deacontrasting

confidence: 38%

Spatio-temporal analysis of factors controlling nitrate dynamics and potential denitrification hot spots and hot moments in groundwater of an alluvial floodplain

Bernard-Jannin

Sun

Teissier

et al. 2017

Ecological Engineering

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OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. This is an author-deposited version published in : http://oatao.univ-toulouse.fr/ Eprints ID : 15830 − ) contamination of freshwater systems is a global concern. In alluvial floodplains, riparian areas have been proven to be efficient in nitrate removal. In this study, a large spatio-temporal dataset collected during one year at monthly time steps within a meander area of the Garonne floodplain (France) was analysed in order to improve the understanding of nitrate dynamic and denitrification process in floodplain areas. The results showed that groundwater NO 3 − concentrations (mean 50 mg NO 3 − L −1 ) were primarily controlled by groundwater dilution with river water (explaining 54% of NO 3 − variance), but also by nitrate removal process identified as denitrification (explaining 14% of NO 3 − variance). Dilution was controlled by hydrological flow paths and residence time linked to river-aquifer exchanges and flood occurrence, while potential denitrification (DEA) was controlled by oxygen, high dissolved organic carbon (DOC) and organic matter content in the sediment (31% of DEA variance). DOC can originate both from the river input and the degradation of organic matter (OM) located in topsoil and sediments of the alluvial plain. In addition, river bank geomorphology appeared to be a key element explaining potential denitrification hot spot locations. Low bankfull height (LBH) areas corresponding to wetlands exhibited higher denitrification rates than high bankfull height (HBH) areas less often flooded. Hydrology determined the timing of denitrification hot moments occurring after flood events. These findings underline the importance of integrating dynamic water interactions between river and aquifer, geomorphology, and dual carbon source (river and sediment) when assessing nitrate dynamics and denitrification patterns in floodplain environments.

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Section: Environmental Factors Controlling Deacontrasting

confidence: 38%

Spatio-temporal analysis of factors controlling nitrate dynamics and potential denitrification hot spots and hot moments in groundwater of an alluvial floodplain

Bernard-Jannin

Sun

Teissier

et al. 2017

Ecological Engineering

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“…Therefore, this study nicely agrees with the observations made by Taylor and Townsend (2010) that there is clearly an anticorrelation between DOC and NO 3 − , which they found across a wide range of environments (tropical, temperate, boreal, and arctic regions). A negative though nonlinear relationship between DOC and NO 3 − was also observed in numerous other studies, e.g., by Thingstad et al (2008), Zarnetske et al (2011aZarnetske et al ( , 2011b, Trimmer et al (2012), Wickland et al (2012), Sandford et al (2013), Thomas et al (2014), and Ali et al (2015). Compared with the traditional correlation analysis shown in Table 1 and discussed above, WTC analysis revealed a stronger negative correlation if only large (seasonal and larger) timescales were accounted for and lags of several weeks allowed for.…”

Section: Wavelet Analysismentioning

confidence: 81%

“…3a and 3b) indicate that the longer the median transit time for each single raindrop, the lower the DOC concentration and the DOC/NO 3 − ratio and the higher NO 3 − concentrations will be in the stream water samples. The impact of hydrology and therefore transport pathways on DOC (Jansen et al, 2014) and NO 3 − concentrations have been shown in previous studies (e.g., Oeurng et al, 2010;Zarnetske et al, 2011aZarnetske et al, , 2011bVan Gaelen et al, 2014). These are very closely linked to biogeochemical processes, which can act longer on the water the longer it remains in the soil.…”

Section: Temporal and Spatial Changes In Dissolved Organic Carbon Andmentioning

confidence: 99%

Spatiotemporal Analysis of Dissolved Organic Carbon and Nitrate in Waters of a Forested Catchment Using Wavelet Analysis

Weigand

Bol²,

Reichert

et al. 2017

Vadose Zone Journal

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Understanding natural controls on N and C biogeochemical cycles is important to estimate human impacts on these cycles. This study examined the spatiotemporal relationships between time series of weekly monitored stream and groundwater N and C (assessed by NO 3 − and dissolved organic C [DOC]) in the forested Wüstebach catchment (Germany). In addition to traditional correlation analysis, we applied wavelet transform coherence (WTC) analysis to study variations in the correlation and lag time between the N and C time series for different time scales. Median transit times were used to connect hydrologic and water chemistry data. We defined three stream-water groups: (i) subsurface runoff dominated locations with strong seasonal fluctuations in concentrations, short transit times, and strong negative C/N correlations with short time lags, (ii) groundwater dominated locations, with weaker seasonal fluctuations, longer transit times, and weaker C/N correlations with lags of several months, and (iii) intermediate locations, with moderate seasonal fluctuations, moderate transit times, and strong C/N correlations with short time lags. Water transit times could be identified as key drivers for the C/N relationship and we conclude that C and N transport in stream water can be explained by mixing of groundwater and subsurface runoff. Complemented by transit times and the hydrochemical time series, WTC analysis allowed us to discriminate between different water sources (groundwater vs. subsurface runoff). In conclusion, we found that in time series studies of hydrochemical data, e.g., DOC and NO 3 − , WTC analysis can be a viable tool to identify spatiotemporally dependent relationships in catchments.Abbreviations: COI, cone of influence; CWT, continuous wavelet transform; DOC, dissolved organic carbon; MedTT, median transit time; WTC, wavelet transform coherence; XWT, cross wavelet transform.The cycles of nutrients such as N and C are closely linked. For example, N saturation is linked to C limitation in the soil for microbial processes (Kopáček et al., 2013). In aqueous ecosystems, increasing NO 3 − concentrations (Galloway et al., 2008) and widespread significant increases in the concentrations of dissolved organic C (DOC) in streams during the last two decades have become a major global issue (e.g., Evans et al., 2005;Galloway et al., 2008;Vitousek et al., 1997). Newly created reactive N (biologically or photochemically active) contributes to environmental problems such as air pollution, eutrophication, soil acidification, and climate change (Vitousek et al., 1997;Galloway et al., 2008). The environmental and therefore also social consequences require detailed spatiotemporal models to predict the fate of reactive N across environments (e.g., Mulholland et al., 2008;Taylor and Townsend, 2010;Barnes and Raymond, 2010). For this purpose, it might be important to understand causal links to the spatiotemporal patterns of DOC. Core Ideas• WTC analysis was used to elucidate the non-stationary C/N relationship at different time...

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“…In addition, heterotrophs often obtain elements from organic substrates, potentially decoupling demand for various inorganic nutrients Urabe 1999, Makino et al 2003). Moreover, the metabolism of primary producers may influence supplies of organic matter and thus heterotrophic metabolism, including dissimilatory processes (e.g., denitrification and dissimilatory nitrate reduction to ammonia [Burgin et al 2011]) with distinctive stoichiometry (Zarnetske et al 2011). Metabolism also responds to and in turn influences physical and chemical conditions that control geochemical reactions ( Fig.…”

Section: Introductionmentioning

confidence: 99%

Diel phosphorus variation and the stoichiometry of ecosystem metabolism in a large spring‐fed river

Cohen

Kurz

Heffernan

et al. 2013

Ecological Monographs

107

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Abstract. Elemental cycles are coupled directly and indirectly to ecosystem metabolism at multiple time scales. Understanding coupling in lotic ecosystems has recently advanced through simultaneous high-frequency measurements of multiple solutes. Using hourly in situ measurements of soluble reactive phosphorus (SRP), specific conductance (SpC), and dissolved oxygen (DO), we estimated phosphorus (P) retention pathways and dynamics in a large (discharge, Q ' 7.5 m 3 /s) spring-fed river (Ichetucknee River, Florida, USA). Across eight multi-day deployments, highly regular diel SRP variation of 3-9 lg P/L (mean ;50 lg P/ L) was strongly correlated with DO variation, suggesting photosynthetic control directly via assimilation, and/or indirectly via geochemical reactions. Consistent afternoon SRP maxima and midnight minima suggest peak removal lags gross primary production (GPP) by ;8 hours. Two overlapping processes were evident, one dominant with maximum removal near midnight, the other smaller with maximum removal near midday. Hourly [Ca] measurements during three 24-hour deployments showed consistent afternoon minima, suggesting that calcite precipitates as GPP increases pH and mineral saturation state. Resulting P coprecipitation was modeled using SpC as a [Ca] proxy, yielding a diel P signal adjusted for the primary geochemical retention pathway. P assimilation, the dominant diel signal, was computed by interpolating between daily concentration maxima, both with and without geochemical adjustment, and converting concentration deficits to fluxes using discharge and benthic area. Adjusting for calcite co-precipitation yielded assimilation rates (13.7 6 5.8 mg PÁm À2 Ád À1) strongly correlated with GPP, accounting for 72% 6 9% of gross removal, and ecosystem C:P stoichiometry (466 [6 12]:1) consistent with dominant vascular autotrophs (478 [6 24]:1). Without adjusting for co-precipitation, covariance with GPP was weaker, and C:P implausibly high. Consistent downstream P accumulation, likely from P-rich porewater seepage, varied across deployments (3-22% of total flux) and co-varied with discharge and respiration. Asynchronous N and P assimilation may arise from differential timing of protein and ribosome production, with the latter requiring maximal carbohydrate stores and minimal photolytic interference. This study demonstrates direct and indirect coupling of biological, hydrological, and geochemical processes and the utility of high-resolution time series of multiple solutes for understanding these linkages.

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Labile dissolved organic carbon supply limits hyporheic denitrification

Cited by 145 publications

References 53 publications

Spatio-temporal analysis of factors controlling nitrate dynamics and potential denitrification hot spots and hot moments in groundwater of an alluvial floodplain

Spatio-temporal analysis of factors controlling nitrate dynamics and potential denitrification hot spots and hot moments in groundwater of an alluvial floodplain

Spatiotemporal Analysis of Dissolved Organic Carbon and Nitrate in Waters of a Forested Catchment Using Wavelet Analysis

Diel phosphorus variation and the stoichiometry of ecosystem metabolism in a large spring‐fed river

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