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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. Depth-resolved carbon dioxide and methane concentrations in 522 lakes, ponds, and reservoirs worldwide

   https://doi.org/10.1038/s41597-026-06751-0  

   Rabaey, Joseph S; Lewis, Abigail_S L; Attermeyer, Katrin; Aurich, Patrick; Bansal, Sheel; Bartosiewicz, Maciej; Bertolet, Brittni L; Bussmann, Ingeborg; Cadieux, Sarah B; Calamita, Elisa; et al (December 2026, Scientific Data)

   Abstract Lakes, ponds, and reservoirs (hereafter: “lakes”) are important sources of the greenhouse gases carbon dioxide (CO₂) and methane (CH₄). Emissions of CO₂and CH₄from lakes are regulated in part by in-lake processes, including the production and storage of gases in the lower parts of the water column (bottom waters). However, while substantial efforts have been made to improve estimates of greenhouse gas emissions from lakes, limited data on gas concentrations along depth profiles have prevented the incorporation of bottom-water processes in global emission estimates. Here, we present GHG-depths: the largest existing dataset of depth-profile CO₂and CH₄measurements worldwide, including 522 lakes across 38 countries and all seven continents. These data include contributions from 45 research teams and 56 published studies, totaling 2558 discrete sampling events. As global change continues to alter biogeochemical cycling in lakes, these data can help improve mechanistic models to better predict greenhouse gas production and emission from lakes worldwide. 

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4. Contrasting CO ₂ Fluxes Among Arctic Pond Types Are Driven by Differences in Carbon Lability, Terrestrial Inputs, and Benthic Respiration

   https://doi.org/10.1029/2025JG009318  

   Marvy, Asher J; Andresen, Christian G; Spera, Alina C; Lougheed, Vanessa L (March 2026, Journal of Geophysical Research: Biogeosciences)

   Abstract Small freshwater tundra ponds are hotspots for greenhouse gas release into the atmosphere. As the Arctic warms, thermokarst processes drive changes in tundra pond geomorphology, with implications for their contribution to carbon cycling in these regions. To understand how these morphological changes affect pond biogeochemistry, we compared low‐centered polygonal (LCP) ponds and thermokarst trough (TKT) ponds that are formed through ice‐wedge permafrost thaw. We found substantially higher levels of carbon, nutrients, and algal biomass in TKT ponds as compared to LCP ponds located in the Arctic Coastal Plain near Utqiaġvik, AK. These differences were likely driven by TKT ponds receiving increased terrestrial inputs due to discrete thermokarst events and slumping, lateral inflow of carbon and nutrients from surrounding soils, higher lability of TKT carbon, and greater rates of benthic respiration. Together, these factors create ponds that are more productive and greater sources of CO₂to the atmosphere than LCPs. During the peak growing season (July‐August), CO₂uptake from macrophyte‐dominated habitat in LCP ponds compensates for CO₂release from open water, making LCP ponds net CO₂sinks (−4 ± 3 gCO₂/m²/d), whereas TKT ponds are CO₂sources (3 ± 6 gCO₂/m²/d), despite TKT macrophyte‐dominated habitat also being a site of CO₂uptake. The net atmospheric greenhouse gas contribution of these ponds will likely be altered with high latitude warming, as air temperature influenced factors including vegetation cover, precipitation, water temperature, and thermokarsting alter rates of CO₂flux from tundra ponds. 

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5. 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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