Impact of warming on CO2 emissions from streams countered by aquatic photosynthesis

Demars, Benoît O. L.; Gíslason, Gísli Már; Ólafsson, Jón S.; Manson, J. Russell; Friberg, Nikolai; Hood, James M.; Thompson, Joshua; Freitag, Thomas E.

doi:10.1038/ngeo2807

Cited by 74 publications

(90 citation statements)

References 56 publications

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“…Riverine transport of organic and inorganic carbon and emissions of carbon dioxide (CO 2 ) and methane (CH 4 ) are significant components of the global carbon cycle [e.g., Aufdenkampe et al, 2011;Butman et al, 2016;Sutfin et al, 2016] and are likely being affected by global climatic change [Demars et al, 2016] and land use changes [Kaushal et al, 2014]. The relative importance of biological and physical processes controlling the distribution of lateral (downstream) and vertical (gas exchange with the atmosphere) river carbon fluxes remains a critical obstacle to predicting how aquatic ecosystems will respond to ongoing changes in climate and land use.…”

Section: Introductionmentioning

confidence: 99%

Biological and land use controls on the isotopic composition of aquatic carbon in the Upper Mississippi River Basin

Voß

Wickland

Aiken

et al. 2017

Global Biogeochemical Cycles

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Riverine ecosystems receive organic matter (OM) from terrestrial sources, internally produce new OM, and biogeochemically cycle and modify organic and inorganic carbon. Major gaps remain in the understanding of the relationships between carbon sources and processing in river systems. Here we synthesize isotopic, elemental, and molecular properties of dissolved organic carbon (DOC), particulate organic carbon (POC), and dissolved inorganic carbon (DIC) in the Upper Mississippi River (UMR) system above Wabasha, MN, including the main stem Mississippi River and its four major tributaries (Minnesota, upper Mississippi, St. Croix, and Chippewa Rivers). Our goal was to elucidate how biological processing modifies the chemical and isotopic composition of aquatic carbon pools during transport downstream in a large river system with natural and man‐made impoundments. Relationships between land cover and DOC carbon‐isotope composition, absorbance, and hydrophobic acid content indicate that DOC retains terrestrial carbon source information, while the terrestrial POC signal is largely replaced by autochthonous organic matter, and DIC integrates the influence of in‐stream photosynthesis and respiration of organic matter. The UMR is slightly heterotrophic throughout the year, but pools formed by low‐head navigation dams and natural impoundments promote a shift toward autotrophic conditions, altering aquatic ecosystem dynamics and POC and DIC compositions. Such changes likely occur in all major river systems affected by low‐head dams and need to be incorporated into our understanding of inland water carbon dynamics and processes controlling CO2 emissions from rivers, as new navigation and flood control systems are planned for future river and water resources management.

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Section: Introductionmentioning

confidence: 99%

Biological and land use controls on the isotopic composition of aquatic carbon in the Upper Mississippi River Basin

Voß

Wickland

Aiken

et al. 2017

Global Biogeochemical Cycles

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“…Putting our findings into the context of climate change, this would suggest that flow intermittency can lead to enhanced carbon fixation in the remaining surface water, but only for a limited period of time. Consequently, the gain of aquatic respiration with increasing temperature might not be countered by photosynthesis as suggested previously in the literature (Demars et al ), if the streams are affected by drought. The fate and pathways of newly fixed carbon then depend on the light to nutrient ratio in a stream reach, a ratio that, together with water temperature might have caused the shift of the metabolic balance in this study.…”

Section: Discussionmentioning

confidence: 78%

“…From this corrected oxygen net rate (DO net ) the mean values of each night were taken and temperature‐corrected with the following formula after Demars et al (), centring the values around the overall average temperature T all of 10.26°C, representing the ER at every minute.

ER = mean ((),, {DO}_{net,night}) \times \exp ([], E \times ((), \frac{1}{Bk \times T_{all}} - \frac{1}{Bk \times T_{mean}})) ([], mg O_{2}, {normalL}^{- 1}, \min^{- 1})

where E is the apparent activation energy (0.57 eV) for respiration taken from Yvon‐Durocher et al () for rivers and Bk is the Boltzmann constant (8.62 × 10 −5 eV K −1 ). The GPP daily was then calculated by adding the absolute values of ER to the corrected net rate and integrating the resulting values over time in order to obtain mg O 2 L −1 d −1 .…”

Section: Methodsmentioning

confidence: 99%

Experimental evidence reveals impact of drought periods on dissolved organic matter quality and ecosystem metabolism in subalpine streams

Harjung

Ejarque

Battin

et al. 2018

Limnology & Oceanography

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Subalpine streams are predicted to experience lower summer discharge following climate change and water extractions. In this study, we aimed to understand how drought periods impact dissolved organic matter (DOM) processing and ecosystem metabolism of subalpine streams. We mimicked a gradient of drought conditions in stream‐side flumes and evaluated implications of drought on DOM composition, gross primary production, and ecosystem respiration. Our experiment demonstrated a production and release of DOM from biofilms and leaf litter decomposition at low discharges, increasing dissolved organic carbon concentrations in stream water by up to 50%. Absorbance and fluorescence properties suggested that the released DOM was labile for microbial degradation. Dissolved organic carbon mass balances revealed a high contribution of internal processes to the carbon budget during low flow conditions. The flumes with low discharge were transient sinks of atmospheric CO2 during the first 2 weeks of drought. After this autotrophic phase, the metabolic balance of these flumes turned heterotrophic, suggesting a nutrient limitation for primary production, while respiration remained high. Overall our experimental findings suggest that droughts in subalpine streams will enhance internal carbon cycling by transiently increasing primary production and more permanently respiration as the drought persists. We propose that the duration of a drought period combined with inorganic nutrient availability are key variables that determine if more carbon is respired in situ or exported downstream.

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“…Warmer water generally favors net consumption of oxygen in streams, through increased rates of respiration relative to production (Demars et al. ; Song et al. ).…”

Section: Resultsmentioning

confidence: 99%

Spatiotemporal Variability in Water Sources Controls Chemical and Physical Properties of a Semi‐arid Urban River System

Shah

Jameel

Smith

et al. 2019

J American Water Resour Assoc

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We conducted synoptic surveys over three seasons in one year to evaluate the variability in water sources and geochemistry of an urban river with complex water infrastructure in the state of Utah. Using stable isotopes of river water (δ18O and δ2H) within a Bayesian mixing model framework and a separate hydrologic mass balance approach, we quantified both the proportional inputs and magnitude of discharge associated with “natural” (lake, groundwater, and tributary inputs) and “engineered” (effluent and canal inflows) sources. The relative importance of these major contributors to streamflow varied both spatially and seasonally. Spatiotemporal patterns of dissolved oxygen, temperature, pH, calcium, chloride, nitrate, and orthophosphate indicated seasonal shifts in dominant sources of river water played an important role in determining water quality. We show although urban rivers are clearly influenced by novel water sources created by water infrastructure, they continue to reflect the imprint of “natural” water sources, including diffuse groundwater. Resource managers thus may need to account for the quantity of both surface waters and also historically overlooked groundwater inputs to address water quality concerns in urban rivers.

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Impact of warming on CO2 emissions from streams countered by aquatic photosynthesis

Cited by 74 publications

References 56 publications

Biological and land use controls on the isotopic composition of aquatic carbon in the Upper Mississippi River Basin

Biological and land use controls on the isotopic composition of aquatic carbon in the Upper Mississippi River Basin

Experimental evidence reveals impact of drought periods on dissolved organic matter quality and ecosystem metabolism in subalpine streams

Spatiotemporal Variability in Water Sources Controls Chemical and Physical Properties of a Semi‐arid Urban River System

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