River ecosystem metabolism and carbon biogeochemistry in a changing world

Abstract

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Inland Water Greenhouse Gas Budgets for RECCAP2: 2. Regionalization and Homogenization of Estimates

“…Our synthesized estimate of global inland water CO 2 emissions would represent only about 1%–2% of continental ecosystem respiration (cf. Battin et al., 2023; Ciais et al., 2021), a proportion much lower than the uncertainties related to the quantification of this flux at global scale. However, inland water emissions are in the order of magnitude of net‐CO 2 uptake by terrestrial ecosystems (land C sink minus LUC emissions, Friedlingstein et al., 2020), and should thus be represented in detailed CO 2 budgets.…”

“…But also inland water CO 2 emissions, which are important in terms of GWP and total flux in the overall GHG budget of inland waters, are relatively small compared to other flux components of the continental CO 2 budget. Being mostly fed by autotrophic and heterotrophic respiration in upland soils, wetlands and aquatic systems (Abril & Borges, 2019; Battin et al., 2023), it is fair to consider inland water CO 2 emissions as a fraction of continental ecosystem respiration. Our synthesized estimate of global inland water CO 2 emissions would represent only about 1%–2% of continental ecosystem respiration (cf.…”

Models of underlying autotrophic biomass dynamics fit to daily river ecosystem productivity estimates improve understanding of ecosystem disturbance and resilience

“…The appropriate modeling framework to understand carbon fluxes in river ecosystems depends on the primary purpose of the model, ranging from gaining inference from specific parameters to high prediction accuracy (Currie, 2019;Rastetter, 2017;Tredennick et al, 2021). A diversity of modeling approaches that expand beyond only incorporating light and flow as the dominant controls on river metabolism (Bernhardt et al, 2022) will advance our collective understanding of the ecological processes underlying carbon fluxes in river ecosystems and how these fluxes are responding to environmental change (Battin et al, 2023).…”

Inland Water Greenhouse Gas Budgets for RECCAP2: 1. State‐Of‐The‐Art of Global Scale Assessments

“…Most studies currently assess inland waters net-CO 2 emissions rather as a black box that is fed by allochthonous C inputs. The recent study by Battin et al (2023) has nevertheless demonstrated that the inclusion of NEP estimates can help to disentangle autochthonous CO 2 production from allochthonous CO 2 inputs even at global scale. This study corroborates the assumption that most of the aquatic CO 2 evasion is derived from external CO 2 inputs.…”

“…They receive considerable amounts of reactive organic matter from terrestrial ecosystems, promoting the production of GHGs like carbon dioxide (CO 2 ), methane (CH 4 ), and nitrous oxide (N 2 O). Inland waters are usually net‐heterotrophic, meaning CO 2 production through respiration exceeds CO 2 consumption by aquatic production (Battin et al., 2023). An additional source of inland water GHG emission comes from terrestrial and wetland runoff and drainage that can be oversaturated in dissolved CO 2 produced by microbial and root respiration (Abril & Borges, 2019).…”