Journal of Geophysical Research: Biogeosciences最新文献

{"title":"Unveiling Soil Microbiome Adaptation and Survival Strategy Under Vanadium Stress in Nationwide Mining Environments","authors":"Han Zhang,&nbsp;Shuo Jiao,&nbsp;Yi Xing,&nbsp;Bo Jiang,&nbsp;Shungui Zhou,&nbsp;Baogang Zhang","doi":"10.1029/2023JG007655","DOIUrl":"https://doi.org/10.1029/2023JG007655","url":null,"abstract":"<p>In the soils of vanadium (V) smelters, a diverse array of microorganisms relies on metabolic activities for survival amid stress. However, the characteristics and functions of soil microbiomes in V mining environments remain unexplored on a continental scale. This study thoroughly investigates the microbial diversity, community assembly, and functional potential of soil microbiome across 90 V smelters in China. Alpha diversity decreases significantly along the V gradient, with V emerging as the primary factor influencing community structure, followed by other environmental, climatic, and geographic factors. The null model reveals that V induces homogeneous selection, shaping co-occurrence patterns and leading to increased number of positive associations, particularly with keystone genera such as <i>f_Gemmatimonadaceae</i>, <i>Nocardioides</i>, <i>Micromonospora</i>, and <i>Rubrobacter</i> under higher V concentrations (&gt;559.6 mg/kg). Moreover, a metagenomic analysis yields 67 metagenome-assembled genomes, unraveling the potential metabolic pathways of keystone taxa and their likely involvement in the V(V) reduction process. Nitrate and nitrite reductase (<i>nirK</i>, <i>narG</i>), and <i>mtrABC</i> are found to be taxonomically affiliated with <i>Micromonospora</i>. sp, <i>FEN-1250</i>. sp, <i>Nocardioides</i>. sp, etc. Additionally, the reverse citric acid cycle (rTCA) likely serves as the primary carbon fixation pathway, synthesizing alternative energy for putative V reducers, highlighting a potentially synergistic relationship between autotrophic and heterotrophic processes that supports microbial survival. Our findings comprehensively uncover the driving forces behind soil community variation under V stress, revealing robust strategies possibly employed by indigenous microorganisms to mitigate the impact of V. These insights hold potential for applications in bioremediation.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"129 7","pages":""},"PeriodicalIF":3.7,"publicationDate":"2024-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141736839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hydrodynamics Control Nitrous Oxide Production in Eutrophic Coastal Permeable Sediments","authors":"Harsha Fowdar,&nbsp;Stanley B. Grant,&nbsp;Wei Wen Wong,&nbsp;Adam Kessler,&nbsp;Perran Cook","doi":"10.1029/2023JG007715","DOIUrl":"https://doi.org/10.1029/2023JG007715","url":null,"abstract":"<p>Permeable sediments, which make up almost half of the continental shelf worldwide, are potential sources of the important greenhouse gas N₂O from coastal regions. Yet, the extent to which interactions between these sediments and anthropogenic pollution produce N₂O is still unknown. Here we use laboratory experiments and modeling to explore the factors controlling N₂O production at a eutrophic site in a temperate shallow marine embayment (Port Phillip Bay, Australia). Our results show that denitrification is the main source of N₂O production within permeable sediments, but the extent to which N₂O is actually released is determined by the rate of seawater exchange with the sediment bed (which governs solute residence time within the bed). In wave-dominated coastal areas, shallower water with more intense waves (<i>wave height</i> &gt; 1 m) release the most N₂O, with up to 0.5% of dissolved inorganic nitrogen pumped into biologically active eutrophic sediment being released as N₂O. Our results suggest rates of N₂O production in coastal permeable sediments are generally low compared to other environments.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"129 7","pages":""},"PeriodicalIF":3.7,"publicationDate":"2024-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2023JG007715","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141736838","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Flow-Dependent Color Patches in a Great Plains River","authors":"Nicholas E. Bruns,&nbsp;John R. Gardner,&nbsp;Martin Doyle","doi":"10.1029/2023JG007867","DOIUrl":"https://doi.org/10.1029/2023JG007867","url":null,"abstract":"<p>Ecosystem structure and its heterogeneity shape ecosystem processes. Ecosystem heterogeneity has been characterized in smaller stream ecosystems dominated by benthic processes. However, in larger river ecosystems structured by water column characteristics including suspended sediment and phytoplankton, ecosystem heterogeneity has not been directly observed. We assessed flow-dependent ecosystem structure along 230 km of a large, highly managed Great Plains river (The Kansas River) by analyzing 1-dimensional, downstream color profiles across flow conditions derived from satellite imagery. River color is a robust metric that reflects the combined state of several important large-river habitat features, specifically suspended sediment, chromophoric dissolved organic matter, and phytoplankton. We found that at flows above a flow threshold that we call <i>Q</i>_patch (240 m³ s⁻¹), the entire river was uniformly yellow. At flows below <i>Q</i>_patch, the river was generally greener and often had patches of very green water that occurred upstream of run-of-river dams. Comparing color with in situ data showed the color patches were likely areas of elevated chlorophyll-a concentrations from phytoplankton accumulation, indicating that the patches reflected biological processes. Flows were below <i>Q</i>_patch on 77% of days during the period of record (1985–present), indicating that the ecosystem spends significant time in a patchy state. Our findings uniquely demonstrate that the water column characteristics structuring temperate, large-river ecosystems can be patchy.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"129 7","pages":""},"PeriodicalIF":3.7,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141639527","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Variability in Ice Cover Does Not Affect Annual Metabolism Estimates in a Small Eutrophic Reservoir","authors":"Dexter W. Howard,&nbsp;Jennifer A. Brentrup,&nbsp;David C. Richardson,&nbsp;Abigail S. L. Lewis,&nbsp;Freya E. Olsson,&nbsp;Cayelan C. Carey","doi":"10.1029/2024JG008057","DOIUrl":"https://doi.org/10.1029/2024JG008057","url":null,"abstract":"<p>Temperate reservoirs and lakes worldwide are experiencing decreases in ice cover, which will likely alter the net balance of gross primary production (GPP) and respiration (R) in these ecosystems. However, most metabolism studies to date have focused on summer dynamics, thereby excluding winter dynamics from annual metabolism budgets. To address this gap, we analyzed 6 years of year-round high-frequency dissolved oxygen data to estimate daily rates of net ecosystem production (NEP), GPP, and R in a eutrophic, dimictic reservoir that has intermittent ice cover. Over 6 years, the reservoir exhibited slight heterotrophy during both summer and winter. We found winter and summer metabolism rates to be similar: summer NEP had a median rate of −0.06 mg O₂ L⁻¹ day⁻¹ (range: −15.86 to 3.20 mg O₂ L⁻¹ day⁻¹), while median winter NEP was −0.02 mg O₂ L⁻¹ day⁻¹ (range: −8.19 to 0.53 mg O₂ L⁻¹ day⁻¹). Despite large differences in the duration of ice cover among years, there were minimal differences in NEP among winters. Overall, the inclusion of winter data had a limited effect on annual metabolism estimates in a eutrophic reservoir, likely due to short winter periods in this reservoir (ice durations 0–35 days), relative to higher-latitude lakes. Our work reveals a smaller difference between winter and summer NEP than in lakes with continuous ice cover. Ultimately, our work underscores the importance of studying full-year metabolism dynamics in a range of aquatic ecosystems to help anticipate the effects of declining ice cover across lakes worldwide.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"129 7","pages":""},"PeriodicalIF":3.7,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JG008057","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141639526","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Haline Tolerance of Stomatopod (Crustacea) Larvae and Pelagic Dispersal of Two Common Species in the Western Atlantic","authors":"Laura Sanvicente-Añorve,&nbsp;Emmanuel Velázquez-Villegas,&nbsp;Mitzi Sánchez-Campos,&nbsp;Ma. Eugenia Allende-Arandía,&nbsp;Jorge Zavala-Hidalgo","doi":"10.1029/2024JG008068","DOIUrl":"https://doi.org/10.1029/2024JG008068","url":null,"abstract":"<p>Pelagic larval stages play a critical role in the dynamics of marine populations since they are the main way of dispersal and habitat colonization. Here, we examined the larval dispersal pathways of two common stomatopod species in the western Atlantic: <i>Squilla empusa</i> and <i>Lysiosquilla scabricauda</i>. To complement this goal, we also analyzed the haline tolerance of the stomatopod larvae collected in an estuary from the southern Gulf of Mexico. Larval dispersal was simulated using a Lagrangian particle-tracking module coupled to the Global HYCOM model and consisted of releasing 100 passive particles from each starting site. Results indicated a high level of larval retention in the west Florida shelf and over the narrow western shelf of the Gulf of Mexico. In the South Atlantic Bight, Central America, and northern South America the larval transport was almost unidirectional following the pattern of currents. Generally, connections were among nearby sites, but long-distance transport can also occur when larvae are trapped by great high-speed currents. Retention of larvae and connection with neighboring sites were due to local atmospheric and hydrological conditions. During fieldwork, we found two kinds of larvae: antizoea and alima. Morphological characteristics of the antizoea correspond to the superfamily Lysiosquilloidea, and those of the alima, with the superfamily Squilloidea. The antizoea larvae were found in salinity values as low as 21.9 psu, while the alima were at 23.2 psu. Salinity tolerances and dispersal potential of larvae indicate a high level of colonization of new habitats and a broad intrusion into the estuaries.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"129 7","pages":""},"PeriodicalIF":3.7,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JG008068","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141631170","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental Studies Reveal Bacteriophages Can Affect Precipitation of Mineral Phases","authors":"Paweł Działak,&nbsp;Andrzej Borkowski,&nbsp;Artur Błachowski,&nbsp;Tomasz Bajda,&nbsp;Kamil Kornaus,&nbsp;Łukasz Zych,&nbsp;Mirosław Słowakiewicz","doi":"10.1029/2023JG007953","DOIUrl":"https://doi.org/10.1029/2023JG007953","url":null,"abstract":"<p>Interesting properties and abundance of bacteriophages suggest their potential effect on precipitation of various minerals. Here we present an experimental study regarding the influence of two different bacteriophages (<i>Escherichia</i> phage P1 and <i>Pseudomonas</i> phage Φ6) on mineral precipitation. A wide range of instrumental techniques was implemented: epifluorescence microscopy (binding of phages to mineral particles); laser diffraction (size distribution); X-ray powder diffraction (mineral phases composition); ⁵⁷Fe Mössbauer spectroscopy (for better characterization of iron-bearing mineral phases); and transmission electron microscopy coupled with microcrystal-electron diffraction (for characterization of mineral particles precipitated with bacteriophages). We showed that bacteriophages can affect mineral precipitation, especially for carbonate and iron-bearing mineral phases. Bacteriophages can increase or reduce the average size of particles or agglomerates of particles depending on the type of mineral phase. It was clearly visible for carbonates, phosphates, and Fe-oxides. Importantly, changes in mineral composition of the studied mineral phases were also noted. It is therefore assumed that bacteriophages may have industrial but also environmental implications on precipitation of minerals.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"129 7","pages":""},"PeriodicalIF":3.7,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141597025","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Controls on Stable Methane Isotope Values in Northern Peatlands and Potential Shifts in Values Under Permafrost Thaw Scenarios","authors":"McKenzie A. Kuhn,&nbsp;Ruth K. Varner,&nbsp;Carmody K. McCalley,&nbsp;Clarice R. Perryman,&nbsp;Mika Aurela,&nbsp;Sophia A. Burke,&nbsp;Jeffrey P. Chanton,&nbsp;Patrick M. Crill,&nbsp;Jessica DelGreco,&nbsp;Jia Deng,&nbsp;Liam Heffernan,&nbsp;Christina Herrick,&nbsp;Suzanne B. Hodgkins,&nbsp;Cheristy P. Jones,&nbsp;Sari Juutinen,&nbsp;Evan S. Kane,&nbsp;Louis J. Lamit,&nbsp;Tuula Larmola,&nbsp;Erik Lilleskov,&nbsp;David Olefeldt,&nbsp;Michael W. Palace,&nbsp;Virginia I. Rich,&nbsp;Christopher Schulze,&nbsp;Joanne H. Shorter,&nbsp;Franklin B. Sullivan,&nbsp;Oliver Sonnentag,&nbsp;Merritt R. Turetsky,&nbsp;Mark P. Waldrop","doi":"10.1029/2023JG007837","DOIUrl":"https://doi.org/10.1029/2023JG007837","url":null,"abstract":"<p>Northern peatlands are a globally significant source of methane (CH₄), and emissions are projected to increase due to warming and permafrost loss. Understanding the microbial mechanisms behind patterns in CH₄ production in peatlands will be key to predicting annual emissions changes, with stable carbon isotopes (δ¹³C-CH₄) being a powerful tool for characterizing these drivers. Given that δ¹³C-CH₄ is used in top-down atmospheric inversion models to partition sources, our ability to model CH₄ production pathways and associated δ¹³C-CH₄ values is critical. We sought to characterize the role of environmental conditions, including hydrologic and vegetation patterns associated with permafrost thaw, on δ¹³C-CH₄ values from high-latitude peatlands. We measured porewater and emitted CH₄ stable isotopes, pH, and vegetation composition from five boreal-Arctic peatlands. Porewater δ¹³C-CH₄ was strongly associated with peatland type, with δ¹³C enriched values obtained from more minerotrophic fens (−61.2 ± 9.1‰) compared to permafrost-free bogs (−74.1 ± 9.4‰) and raised permafrost bogs (−81.6 ± 11.5‰). Variation in porewater δ¹³C-CH₄ was best explained by sedge cover, CH₄ concentration, and the interactive effect of peatland type and pH (<i>r</i>² = 0.50, <i>p</i> &lt; 0.001). Emitted δ¹³C-CH₄ varied greatly but was positively correlated with porewater δ¹³C-CH₄. We calculated a mixed atmospheric δ¹³C-CH₄ value for northern peatlands of −65.3 ± 7‰ and show that this value is more sensitive to landscape drying than wetting under permafrost thaw scenarios. Our results suggest northern peatland δ¹³C-CH₄ values are likely to shift in the future which has important implications for source partitioning in atmospheric inversion models.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"129 7","pages":""},"PeriodicalIF":3.7,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2023JG007837","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141584030","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Vertical Variations of Photosystem Energy Partitioning in the Canopy of the Subtropical Cropland","authors":"Duwei Zhong,&nbsp;Yonggang Chi,&nbsp;Zhi Huang,&nbsp;Pai Liu,&nbsp;Guoping Zhang,&nbsp;Lei Zhou","doi":"10.1029/2023JG007945","DOIUrl":"https://doi.org/10.1029/2023JG007945","url":null,"abstract":"<p>Leaf-level photosynthetic capacity exhibits vertical variations along the canopy profile. The dynamics of photosystem energy partitioning involved in dissipating absorbed light energy, namely photochemical yield (ΦP), fluorescence yield (ΦF), and the efficiency of non-photochemical quenching yield (ΦN) in dissipating excess light energy as heat, along the vertical canopy profile remain unclear. Here, vertical variations in photosystem energy partitioning and photosynthetic nitrogen allocation were measured at different canopy positions of rice using active fluorescence detection and photosynthetic gas exchange measurement in subtropical southern China. We observed the decline in leaf nitrogen per leaf mass (<i>N</i>_mass) from the top to the bottom of the canopy. ΦP significantly decreased from vegetative growth stage to ripening stage, while ΦN showed an opposite trend. The top and bottom leaves had consistent relationships between photosynthetic nitrogen allocation and photosystem energy partitioning. Our findings reveal the vertical variations in physiological traits of subtropical rice.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"129 7","pages":""},"PeriodicalIF":3.7,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141584031","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mountain Peatlands and Drought: Carbon Cycling in the Pyrenees Amidst Global Climate Change","authors":"Raphael Garisoain,&nbsp;Adrien Jacotot,&nbsp;Christine Delire,&nbsp;Stéphane Binet,&nbsp;Gael Le Roux,&nbsp;Simon Gascoin,&nbsp;Thomas Rosset,&nbsp;Sébastien Gogo,&nbsp;Franck Granouillac,&nbsp;Virginie Payre-Suc,&nbsp;Laure Gandois","doi":"10.1029/2024JG008041","DOIUrl":"https://doi.org/10.1029/2024JG008041","url":null,"abstract":"<p>This study provides a multi-year (2017–2022) Net Ecosystem Carbon Balance (NECB) of a Pyrenean mountainous peatland through the integration of field data, satellite imagery, and statistical modeling. Fluvial organic carbon export was measured at 30 min frequency, while gaseous (CO₂ and CH₄) exchanges were measured monthly using closed chambers. These measurements were combined with Sentinel-2 derived chlorophyll index and in situ high frequency (1 hr) measurements of key environmental variables such as air temperature, photosynthetically active radiation, and water table level, to develop hourly gaseous carbon flux models (<i>R</i>² = 0.69 for GPP, <i>R</i>² = 0.84 for ER, <i>R</i>² = 0.59 for CH₄). Over the 2017–2022 period, modeled average GPP (610 ± 39 gC.m⁻².year⁻¹) and ER (641 ± 59 gC.m⁻².year⁻¹) showed that the peatland acted as a weak source of CO₂ to the atmosphere, releasing 31 ± 73 gC.m⁻².year⁻¹. Considering fluvial carbon export and CH₄ exchanges, the loss of carbon from the peatland increased to 55 ± 73 gC.m⁻².year⁻¹. Dissolved organic carbon constituted 8%–106% of the NECB. The estimated long-term organic accumulation rate indicated a steady carbon accumulation rate of 16.4 gC.m⁻².year⁻¹, contrasting with the contemporary NECB, suggesting a recent shift in ecosystem functioning from a carbon sink to a source. The study underscores the role of water availability and air temperature through a drought index (DI), in shaping the NECB. The DI correlated significantly with annual carbon gaseous fluxes, except for 2022, marked by an intense drought. During this year the peatland became a large source of carbon (189 gC.m⁻².year⁻¹) to the atmosphere.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"129 7","pages":""},"PeriodicalIF":3.7,"publicationDate":"2024-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JG008041","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141565795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Seasonal Carbon Dioxide Concentrations and Fluxes Throughout Denmark's Stream Network","authors":"Kenneth Thorø Martinsen,&nbsp;Kaj Sand-Jensen,&nbsp;Victor Bergmann,&nbsp;Tobias Skjærlund,&nbsp;Johan Emil Kjær,&nbsp;Julian Koch","doi":"10.1029/2024JG008031","DOIUrl":"https://doi.org/10.1029/2024JG008031","url":null,"abstract":"<p>Streams are important freshwater habitats in large-scale carbon budgets because of their high CO₂ fluxes which are driven by high CO₂ concentrations and surface-water turbulence. High CO₂ concentrations are promoted by terrestrial carbon inputs, groundwater flow, and internal respiration, all of which vary greatly across space and time. We used environmental monitoring data to calculate CO₂ concentrations along with a wide range of predictor variables including outputs from a national hydrological model and trained machine learning models to predict spatially distributed seasonal CO₂ concentrations in Danish streams. We found that streams were supersaturated in dissolved CO₂ (mean = 118 μM) and higher during autumn and winter than during spring and summer. The best model, a Random Forest model, scored R² = 0.46, MAE = 46.0 μM, and ⍴ = 0.72 on a test set. The most important predictor variables were catchment slope, seasonality, height above nearest drainage, and depth to groundwater, highlighting the importance of landscape morphometry and soil-groundwater-stream connectivity. Stream CO₂ fluxes determined from the predicted concentrations and gas transfer velocities estimated using empirical relationships averaged 253 mmol m⁻² d⁻¹, and the annual emissions were 513 Gg CO₂ from the national stream network (area = 139 km²). Our analysis presents a framework for modeling seasonal CO₂ concentrations and estimating fluxes at a national scale by means of large-scale hydrological model outputs. Future efforts should consider further improving the temporal resolution, direct measurements of fluxes and gas transfer velocities, and seasonal variation in stream surface area.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"129 7","pages":""},"PeriodicalIF":3.7,"publicationDate":"2024-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JG008031","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141556645","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}