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1. High Intra‐Seasonal Variability in Greenhouse Gas Emissions From Temperate Constructed Ponds

   https://doi.org/10.1029/2023GL104235  

   Ray, Nicholas E.; Holgerson, Meredith A. (September 2023, Geophysical Research Letters)

   Abstract Inland waters play a major role in global greenhouse gas (GHG) budgets. The smallest of these systems (i.e., ponds) have a particularly large—but poorly constrained—emissions footprint at the global scale. Much of this uncertainty is due to a poor understanding of temporal variability in emissions. Here, we conducted high‐resolution temporal sampling to quantify GHG exchange between four temperate constructed ponds and the atmosphere on an annual basis. We show these ponds are a net source of GHGs to the atmosphere (564.4 g CO₂‐eq m⁻² yr⁻¹), driven by highly temporally variable diffusive methane (CH₄) emissions. Diffusive CH₄release to the atmosphere was twice as high during periods when the ponds had a stratified water column than when it was mixed. Ebullitive CH₄release was also higher during stratification. Building ponds to favor mixed conditions thus presents an opportunity to minimize the global GHG footprint of future pond construction. 

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2. Data from: Mixing and carbon processing in two natural ponds

   https://doi.org/10.5061/dryad.ksn02v7dp  

   Holgerson, Meredith; Ray, Nicholas; Gannon, Kathryn; Heathcote, Adam (January 2025, Dryad)

   {"Abstract":["Ponds play an important role in global carbon (C) cycling due to high, but\n variable, C burial rates and emissions of carbon dioxide (CO2) and methane\n (CH4) to the atmosphere. Here, we sampled two ponds of similar size, but\n with contrasting stratification and dominant types of primary producers.\n We quantified organic C (OC) burial rates and CO2 and CH4 concentrations\n and fluxes. The dataset includes data on thermal mixing, water chemistry,\n carbon burial, CO2 and CH4 concentrations, and ebullitive CH4 fluxes."],"Methods":["See the associated manuscript in Limnology &\n Oceanography"],"TechnicalInfo":["This readme.txt file was generated on 08-31-2024 by Meredith Holgerson\n GENERAL INFORMATION 1. Dataset Title: Mixing and Carbon Processing in Two\n Natural Ponds 2. Author Information\\ Principal Investigator Contact\n Information\\ Name: Meredith Holgerson\\ Institution: Cornell University\\\n Email:\n [meredith.holgerson@cornell.edu](mailto:meredith.holgerson@cornell.edu) 3.\n Field data collection occurred in 2021 and 2022 DATA & FILE OVERVIEW\n 1. File List: (1) 1_TemperatureSensorData.xlsx: Temperature sensor data\n with three tabs, one for each pond and a ReadMe (2)\n 2_Sonde_Nutrients_Chla.xlsx: Sonde, nutrients, and chlorophyll data, each\n with their own tab, and a ReadMe (3) 3_SedimentData.xlsx: Sediment data\n with three tabs, including loss-on-ignition for each pond (2 tabs), carbon\n burial for both ponds together (1 tab), and a ReadMe (4)\n 4_GreenhouseGasData.xlsx: Greenhouse gas data with four tabs, one each for\n water GHG concentrations, air GHG concentrations, ebullitive fluxes, and a\n ReadMe 2. Relationship between files: All files were used in analysis 3.\n "NA" in cells refer to data that are not available\n METHODOLOGICAL INFORMATION 1. Description of methods used for data\n compilation: Please see associated manuscript 2. Methods for processing\n the data: Please see associated manuscript DATA-SPECIFIC INFORMATION:\n Please see the "README" files in each of the Excel documents"]} 

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3. Water temperature and catchment characteristics drive variation in carbon dioxide and methane emissions from small ponds in a peatland‐rich, high‐altitude tropical ecosystem

   https://doi.org/10.1002/lno.70261  

   Whitmore, Keridwen M; Delvecchia, Amanda Gay; Zarate, Dani; Bautista, Martina; Emerson, Kayla; Madrigal, Amy; Suárez, Esteban; Riveros‐Iregui, Diego A (December 2025, Limnology and Oceanography)

   Abstract Inland waters release significant amounts of carbon into the atmosphere, with small ponds acting as hot spots. High variability and limited research make emissions from small waterbodies a major source of uncertainty, especially in underrepresented tropical ecosystems where unique drivers remain poorly understood. We evaluated the magnitude and sources of variability in emissions from small waterbodies of the páramo—a tropical ecoregion in the Andes mountains, characterized by carbon‐rich soils. We measured partial pressure of carbon dioxide (pCO₂), methane (pCH₄) and CO₂emissions from small (< 5000 m²) waterbodies, 11 ponds and 1 wetland, 3 times in the wet season and returned to 8 sites in the dry season. Sites were always supersaturated inpCH₄(1096 ± 1482μatm), but occasionally undersaturated inpCO₂(1224 ± 1585μatm). Variability between ponds was high and primarily driven by elevation and water temperature. Catchment soil‐water connectivity was also predictive ofpCO₂. Mean wet‐season emission rates were 0.34 ± 0.54 g CO₂‐C m⁻²d⁻¹and 0.012 ± 0.018 g CH₄‐C m⁻²d⁻¹and surface area fluctuations were a large source of seasonal variability in some ponds. Though an open‐water transect of the wetland site was similar to ponds, we measured very highpCH₄(1678 ± 2629μatm) andpCO₂(5162 ± 3207μatm) along the wetland perimeter. Our findings provide essential insights for incorporating a significant yet understudied tropical ecosystem into the global carbon budget by confirming previous observations that small ponds can emit a disproportionately large amount of carbon to the atmosphere, but also highlighting the importance of variables other than pond size in controlling emission hot spots. 

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4. Under‐Ice Oxygen Depletion and Greenhouse Gas Supersaturation in North Temperate Urban Ponds

   https://doi.org/10.1029/2024JG008120  

   Gorsky, Adrianna L; Dugan, Hilary A; Wilkinson, Grace M; Stanley, Emily H (June 2024, Journal of Geophysical Research: Biogeosciences)

   Abstract Stormwater ponds are common features in urbanized landscapes because they enhance flood reduction and nutrient retention. With shallow depths and high inputs of organic matter, these systems can be highly productive with rapid oxygen depletion when thermally stratified or ice‐covered. However, most of our understanding of the biogeochemistry of stormwater ponds comes from the open water period. We explored under‐ice oxygen dynamics in 20 stormwater ponds in Madison, WI (USA) that were ice covered from late December to early March to investigate the drivers of bottom water oxygen saturation and the impact on the accumulation of carbon dioxide (CO₂) and methane (CH₄). Winter anoxia was driven by ice transmissivity, winter nutrient concentrations, and precedent summer productivity. Oxygen depletion led to overall higher concentrations of greenhouse gases in pond surface waters. This research enhances our understanding of winter pond biogeochemistry and its links to summer productivity. 

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5. Modeling Thermal and Biogeochemical Dynamics in Two Ponds Within Alaska's Yukon–Kuskokwim Delta: Impacts of Climatic Variability on Greenhouse Gas Fluxes

   https://doi.org/10.1029/2024MS004441  

   Mullen, A L; Jafarov, E E; Hung, J_K Y; Gurbanov, K; Stepanenko, V; Rogers, B M; Watts, J D; Natali, S M; Poulin, B A (April 2025, Journal of Advances in Modeling Earth Systems)

   Abstract Fluxes of carbon dioxide (CO₂) and methane (CH₄) from open water bodies are critical components of carbon‐climate feedbacks in high latitudes. Processes governing the spatial and temporal variability of these aquatic greenhouse gas (GHG) fluxes are still highly uncertain due to limited observational data sets and lack of modeling studies incorporating comprehensive thermal and biochemical processes. This research investigates how slight variations in climate propagate through the biogeochemical cycles of ponds and resulting impacts on GHG emissions. We examine the thermal and biogeochemical dynamics of two ponds in the Yukon–Kuskokwim Delta, Alaska, under varying climatic conditions to study the impacts on CO₂, CH₄, and oxygen (O₂) concentrations and fluxes. We performed multiple numerical experiments, using the LAKE process‐based model and field measurements, to analyze how these ponds respond to variations in air temperature, shortwave radiation, and snow cover. Our study demonstrates that ice cover duration and water temperature are primary climatic drivers of GHG fluxes. Climate experiments led to reductions in ice cover duration and increased water temperatures, which subsequently enhanced CH₄and CO₂gas emissions from two study ponds. On average, cumulative CH₄and CO₂emissions were 5% and 10% higher, respectively, under increases in air temperature and shortwave radiation. Additionally, we uncovered a need to incorporate groundwater influxes of dissolved gases and nutrients in order to fully represent processes governing aquatic biochemical activity. Our work highlights the importance of understanding local‐scale processes in predicting future Arctic contributions to GHG emissions. 

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