Chapter 14: Inland Waters. Second State of the Carbon Cycle Report

Butman, David; Striegl, Robert G.; Stackpoole, S. M.; Giorgio, Paul del; Prairie, Yves T.; Pilcher, Darren J.; Raymond, Peter A.; Pellat, Fernando Paz; Alcocer, Javier; Birdsey, Richard A.; Mayes, Melanie A.; Najjar, R.; Reed, Sasha C.; Romero‐Lankao, Patricia; Zhu, Zhiliang

doi:10.7930/soccr2.2018.ch14

Cited by 18 publications

(19 citation statements)

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“…2, m.local for GPP > m.local for ER), cumulative riverine CO2 production increases faster than watershed size because larger rivers continue to be net heterotrophic and 6 BSA increases at a faster rate than watershed area. The median estimate of CO2 derived from riverine metabolism for the 7 th order watershed (4.6 g m -2 of watershed area yr -1 ) is comparable to a global estimate of 6.7 g m -2 yr -1 , derived from estimates of total riverine emissions of CO2 28 and an average value of riverine contribution to CO2 flux 9 . We conclude that because of superlinear scaling of BSA and a tendency for increasing GPP and ER (m.local > 0) the contribution of riverine processes to watershed-scale CO2 emissions increases as watershed area increases, with respiration in large rivers (> 4 th order) contributing significantly because of large relative BSA and net CO2 production.…”

Section: Superlinear Scaling Of Cumulative River Network Function Witsupporting

confidence: 56%

“…Finally, we also applied an empirically-derived zero-order scenario to demonstrate how allometric scaling of biogeochemical function vs. watershed size is relevant to an important issue currently being addressed by the research community, the role of surface waters in the net carbon balance in the earth system 4,9,28 . Functions of local GPP and ER versus watershed area of the river reach (Equation 2) were derived from a broad synthesis of measured stream metabolism 34 across a range of stream sizes (1 -10,000 km 2 ).…”

Section: River Network Modelmentioning

confidence: 99%

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Superlinear scaling of riverine biogeochemical function with watershed size

Wollheim

Harms

Robison

et al. 2021

Preprint

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River networks are a crucial component of the earth system because they regulate carbon and nutrient exchange between continents, the atmosphere, and oceans. Quantifying the role of river networks at broad spatial scales must accommodate spatial heterogeneity, discharge variability, and upstream-downstream connectivity. Allometric scaling relationships of cumulative biogeochemical function with watershed size integrate these factors, providing an approach for understanding the role of fluvial networks in the earth system. Here we demonstrate that allometric scaling relationships of cumulative river network function are linear (power exponent ~ 1) when biogeochemical reactivity is high and river discharges are low, but become increasingly superlinear (power exponent > 1) as reactivity declines or discharge increases. Superlinear scaling indicates that biogeochemical function of entire river networks within a watershed is an emergent property that increases disproportionately with increasing watershed size. Expanding observation networks will increase precision in riverine fluxes of carbon and nutrients estimated by allometric scaling functions.

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Section: Superlinear Scaling Of Cumulative River Network Function Witsupporting

confidence: 56%

Section: River Network Modelmentioning

confidence: 99%

Superlinear scaling of riverine biogeochemical function with watershed size

Wollheim

Harms

Robison

et al. 2021

Preprint

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“…As a rough approximation of watershed‐level ebullitive CH 4 emissions (mg CH 4 m −2 watershed area d −1 ), we estimated the overall flux for each stream as the product of the average daily flux rate and the total stream surface area, normalized by watershed size as follows:

where benthic surface area (km 2 ) is estimated using a product of stream lengths derived from 2 m digital elevation models and estimates of stream width from a survey of each stream (Table S2 ). Watershed flux is converted to mg CH 4 m −2 watershed area d −1 to compare with watershed carbon fluxes from streams in previous studies (Crawford et al 2014 ; Butman et al 2018 ). This analysis assumes the ebullitive fluxes calculated for a reach is consistent throughout the entire stream.…”

Section: Methodsmentioning

confidence: 99%

“…However, a comprehensive understanding of controls on emissions of these gases both spatially and temporally is needed to accurately scale to continental or global extents (Kirschke et al 2013 ; Saunois et al 2020 ). In particular, measurements of CH 4 dynamics in streams and rivers are scarce (Stanley et al 2016 ), and as a result these ecosystems are rarely included in global CH 4 inventories (Butman et al 2018 ). Observations of CH 4 concentrations and fluxes across studies suggest most streams are sources of CH 4 to the atmosphere (Stanley et al 2016 ).…”

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confidence: 99%

Spatial and temporal heterogeneity of methane ebullition in lowland headwater streams and the impact on sampling design

Robison

Wollheim

Turek

et al. 2021

Limnology & Oceanography

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Headwater streams are known sources of methane (CH 4 ) to the atmosphere, but their contribution to global scale budgets remains poorly constrained. While efforts have been made to better understand diffusive fluxes of CH 4 in streams, much less attention has been paid to ebullitive fluxes. We examine the temporal and spatial heterogeneity of CH 4 ebullition from four lowland headwater streams in the temperate northeastern United States over a 2-yr period. Ebullition was observed in all monitored streams with an overall mean rate of 1.00 AE 0.23 mmol CH 4 m À2 d À1 , ranging from 0.01 to 1.79 to mmol CH 4 m À2 d À1 across streams. At biweekly timescales, rates of ebullition tended to increase with temperature. We observed a high degree of spatial heterogeneity in CH 4 ebullition within and across streams. Yet, catchment land use was not a simple predictor of this heterogeneity, and instead patches scale variability weakly explained by water depth and sediment organic matter content and quality. Overall, our results support the prevalence of CH 4 ebullition from streams and high levels of variability characteristic of this process. Our findings also highlight the need for robust temporal and spatial sampling of ebullition in lotic ecosystems to account for this high level of heterogeneity, where multiple sampling locations and times are necessary to accurately represent the mean rate of flux in a stream. The heterogeneity observed likely indicates a complex set of drivers affect CH 4 ebullition from streams which must be considered when upscaling site measurements to larger spatial scales.

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“…Riverine transport of carbon (C), as dissolved inorganic (DIC), dissolved organic C (DOC), and particulate organic C (POC), is increasingly recognized as contributing to the global C cycle (Battin et al, 2009; Cole et al, 2007; Drake et al, 2017; Tranvik et al, 2009). As a result, the quantification of C movement across the land‐water interface, which is estimated at >5.0 Pg yr −1 globally (Butman et al, 2018; Drake et al, 2017), and how the speciation of this flux varies across ecosystem types are essential topics of study within the aquatic and Earth sciences (Csank et al, 2019; Tomco et al, 2019). Previous studies in small forested catchments show that rainfall‐runoff processes are key drivers of the lateral export of terrestrial C to surface waters (Boyer et al, 1997; Hinton et al, 1997; Raymond & Saiers, 2010; Vaughan et al, 2019), with the bulk of annual catchment DOC export typically occurring during high flow events (Raymond et al, 2016; Wiegner et al, 2009; Wilson et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Stormflows Drive Stream Carbon Concentration, Speciation, and Dissolved Organic Matter Composition in Coastal Temperate Rainforest Watersheds

et al. 2020

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Stream water carbon concentrations can be highly dynamic on the time scales of both individual storm events and seasonal hydroclimatic shifts. We collected stream water daily over a 6-day storm from three headwater subcatchments of varying landcover (poor fen, forested wetland, and upland forest) and the catchment outlet to evaluate how precipitation events impact the concentration and speciation of carbon (organic vs. inorganic) as well as the composition of dissolved organic matter (DOM) exported laterally from coastal temperate rainforest catchments. Dissolved and particulate organic carbon concentrations increased during the storm at all sites, while dissolved inorganic carbon concentrations were diluted during peak flows. These results highlight the importance of quantifying all forms of lateral carbon export when evaluating the role of storms in catchment-scale carbon cycling. Isotopic hydrograph separation using stream water δ 18 O showed that percent new water was significantly related to carbon concentration and form providing a clear link between stream water sources (i.e., recent event water) and soil carbon source areas that become connected to surface water during storms. Furthermore, ultrahighresolution mass spectrometry showed that stream water DOM exported from the upland forest contained the greatest molecular diversity of the three landscape types and had the largest changes in composition over the storm suggesting that the wetland-dominated subcatchments were less compositionally diverse with regard to soil DOM pools active during the storm. Overall, this study provides insight into hydrobiogeochemical drivers that control lateral carbon export from forested catchments in a region where an increasing fraction of precipitation is falling as rain. Plain Language Summary Streams transport large amounts of terrestrially derived carbon to the ocean, especially during large rainstorms. We collected water samples daily over a 6-day storm from small drainage areas of varying landcover to see how the concentration and type of carbon changed over the course of a storm. Our results show that the amount and type of carbon in the stream changed dramatically during the storm and originated from different areas of the landscape. The flow of water through the soil also changed during the storm and was related to the type and amount of carbon entering the stream. Storm events not only impact carbon entering the stream but also may impact its transfer to coastal marine ecosystems. Climate in the study region is projected to become warmer and wetter in coming decades. These shifts in climate could lead to more carbon export during storms, especially during winter because of more precipitation falling as rain rather than snow.

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Chapter 14: Inland Waters. Second State of the Carbon Cycle Report

Cited by 18 publications

References 0 publications

Superlinear scaling of riverine biogeochemical function with watershed size

Superlinear scaling of riverine biogeochemical function with watershed size

Spatial and temporal heterogeneity of methane ebullition in lowland headwater streams and the impact on sampling design

Stormflows Drive Stream Carbon Concentration, Speciation, and Dissolved Organic Matter Composition in Coastal Temperate Rainforest Watersheds

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