Biogeosciences最新文献

{"title":"Linking geomorphological processes and wildlife microhabitat selection: nesting birds select refuges generated by permafrost degradation in the Arctic","authors":"Madeleine-Zoé Corbeil-Robitaille, Elia Duchesne, Daniel Fortier, Christophe Kinnard, J. Bêty","doi":"10.5194/bg-21-3401-2024","DOIUrl":"https://doi.org/10.5194/bg-21-3401-2024","url":null,"abstract":"Abstract. To gain better insight into the cascading impact of warming-induced changes in the physical landscape on biodiversity, it is crucial to better understand links between abiotic and ecological processes governing species distribution. Abiotic processes shaping the physical characteristics of the environment could significantly influence predator movements in the landscape and ultimately affect biodiversity through interspecific interactions. In the Arctic tundra, the main terrestrial predator (Arctic fox) avoids patches of wetlands composed of ponds with islets that can act as refuges for prey. Little is known about the geomorphological processes generating islets selected by prey species. Our study aimed to identify (i) the physical characteristics of islets selected by Arctic-nesting birds and (ii) the geomorphological processes generating islets available in the landscape. Over two breeding seasons, we determined the occurrence of nesting birds (cackling goose, glaucous gull, and red-throated loon) on islets (N=396) found over a 165 km2 area on Bylot Island (Nunavut, Canada). Occupied islets were located further away from the shore (10.6 m ± 7.3 SD vs. 7.4 m ± 6.8 SD) and surrounded by deeper water (33.6 cm ± 10.6 SD vs. 28.1 cm ± 11.5 SD) than unoccupied islets. As expected, all three bird species selected islets less accessible to Arctic foxes, with nesting occurrence increasing with distance to shore and water depth around islets. Based on high-resolution satellite imagery and field observations, we found that ice-wedge polygon degradation generated the majority of islets (71 %) found in the landscape. Those islets were on average farther from the shore and surrounded by deeper water than those generated by other processes. As polygon degradation is projected to accelerate in response to warming, new refuges will likely emerge in the Arctic landscape, but current refuges could also disappear. Changes in the rate of polygon degradation may thus affect Arctic tundra biodiversity by altering predator–prey interactions.\u0000","PeriodicalId":502171,"journal":{"name":"Biogeosciences","volume":"65 37","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141806628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The impacts of modelling prescribed vs. dynamic land cover in a high-CO2 future scenario – greening of the Arctic and Amazonian dieback","authors":"S. Kou‐Giesbrecht, V. K. Arora, Christian Seiler, Libo Wang","doi":"10.5194/bg-21-3339-2024","DOIUrl":"https://doi.org/10.5194/bg-21-3339-2024","url":null,"abstract":"Abstract. Terrestrial biosphere models are a key tool in investigating the role played by land surface in the global climate system. However, few models simulate the geographic distribution of biomes dynamically, opting instead to prescribe them using remote sensing products. While prescribing land cover still allows for the simulation of the impacts of climate change on vegetation growth and the impacts of land use change, it prevents the simulation of climate-change-driven biome shifts, with implications for the projection of future terrestrial carbon sink. Here, we isolate the impacts of prescribed vs. dynamic land cover implementations in a terrestrial biosphere model. We first introduce a new framework for evaluating dynamic land cover (i.e., the spatial distribution of plant functional types across the land surface), which can be applied across terrestrial biosphere models alongside standard benchmarking of energy, water, and carbon cycle variables in model intercomparison projects. After validating simulated land cover, we then show that the simulated terrestrial carbon sink differs significantly between simulations with dynamic vs. prescribed land cover for a high-CO2 future scenario. This is because of important range shifts that are only simulated when dynamic land cover is implemented: tree expansion into the Arctic and Amazonian transition from forest to grassland. In particular, the projected change in net land–atmosphere CO2 flux at the end of the 21st century is twice as large in simulations with dynamic land cover than in simulations with prescribed land cover. Our results illustrate the importance of climate-change-driven biome shifts for projecting future terrestrial carbon sink.\u0000","PeriodicalId":502171,"journal":{"name":"Biogeosciences","volume":"25 24","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141806168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The biological and preformed carbon pumps in perpetually slower and warmer oceans","authors":"Benoît Pasquier, Mark Holzer, Matthew A. Chamberlain","doi":"10.5194/bg-21-3373-2024","DOIUrl":"https://doi.org/10.5194/bg-21-3373-2024","url":null,"abstract":"Abstract. The marine carbon cycle is vitally important for climate and the fertility of the oceans. However, predictions of future biogeochemistry are challenging because a myriad of processes need parameterization and the future evolution of the physical ocean state is uncertain. Here, we embed a data-constrained model of the carbon cycle in slower and warmer ocean states as simulated under the RCP4.5 and RCP8.5 (RCP: Representative Concentration Pathway) scenarios for the 2090s and frozen in time for perpetuity. Focusing on steady-state changes from preindustrial conditions allows us to capture the response of the system integrated over all the timescales of the steady-state biogeochemistry, as opposed to typical transient simulations that capture only sub-centennial timescales. We find that biological production experiences only modest declines (of 8 %–12 %) because the reduced nutrient supply due to a more sluggish circulation and strongly shoaled mixed layers is counteracted by warming-stimulated growth. Organic-matter export declines by 15 %–25 % due to reductions in both biological production and export ratios, the latter being driven by warming-accelerated shallow respiration and reduced subduction of dissolved organic matter. The perpetual-2090s biological pump cycles a 30 %–70 % larger regenerated inventory accumulated over longer sequestration times, while preformed DIC is shunted away from biological utilization to outgassing. The regenerated and preformed DIC inventories both increase by a similar magnitude. We develop a conceptually new partitioning of preformed DIC to quantify the ocean's preformed carbon pump and its changes. Near-surface paths of preformed DIC are more important in the slower circulations, as weakened ventilation isolates the deep ocean. Thus, while regenerated DIC cycling becomes slower, preformed DIC cycling speeds up.\u0000","PeriodicalId":502171,"journal":{"name":"Biogeosciences","volume":"38 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141807266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Climate-based prediction of carbon fluxes from deadwood in Australia","authors":"Elizabeth S. Duan, Luciana Chavez Rodriguez, N. Hemming-Schroeder, Baptiste J. Wijas, Habacuc Flores‐Moreno, A. Cheesman, L. Cernusak, M. Liddell, P. Eggleton, A. Zanne, Steven D. Allison","doi":"10.5194/bg-21-3321-2024","DOIUrl":"https://doi.org/10.5194/bg-21-3321-2024","url":null,"abstract":"Abstract. Deadwood is an important yet understudied carbon pool in tropical ecosystems. Deadwood degradation to CO2 through decomposer (microbial, termite) activities is driven by wood moisture and temperature, which are in turn strongly influenced by local climate. Thus, climate data could be used to predict CO2 fluxes from decaying wood. Given the increasing availability of gridded climate data, this link would allow for the rapid estimation of deadwood-related CO2 fluxes from tropical ecosystems worldwide. In this study, we adapted a mechanistic fuel moisture model that uses weather variables (e.g., air temperature, precipitation, solar radiation) to simulate wood moisture and temperature along a rainfall gradient in Queensland, Australia. We then developed a Bayesian statistical relationship between wood moisture and temperature and CO2 flux from pine (Pinus radiata) blocks and combined this relationship with our simulations to predict CO2 fluxes from deadwood at 1 h temporal resolution. We compared our pine-based simulations to the moisture–CO2 relationships from stems of native tree species deployed at the wettest and driest sites. Finally, we integrated fluxes over time to estimate the amount of carbon entering the atmosphere and compared these estimates to measured mass loss in pines and native stems. Our statistical model showed a positive relationship between CO2 fluxes and wood moisture and temperature. Comparing cumulative CO2 with wood mass loss, we observed that carbon from deadwood decomposition is mainly released as CO2 regardless of the precipitation regime. At the dry savanna, only about 20 % of the wood mass loss was decomposed within 48 months, compared to almost 100 % at the wet rainforest, suggesting longer residence times of deadwood compared to wetter sites. However, the amount of carbon released in situ as CO2 is lower when wood blocks are attacked by termites, especially at drier sites. These results highlight the important but understudied role of termites in the breakdown of deadwood in dry climates. Additionally, mass loss–flux relationships of decaying native stems deviated from those of pine blocks. Our results indicate that wood moisture and temperature are necessary but not sufficient for predicting CO2 fluxes from deadwood degradation. Other factors, such as wood traits (wood quality, chemical composition, and stoichiometry) and biotic processes, should be considered in future modeling efforts.\u0000","PeriodicalId":502171,"journal":{"name":"Biogeosciences","volume":"10 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141813511","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessment of carbon mass in a Mediterranean downy oak ecosystem using airborne lidar and NASA Global Ecosystem Dynamics Investigation (GEDI) data","authors":"Maëlie Chazette, P. Chazette, I. Reiter, X. Shang, J. Totems, Jean-Philippe Orts, Irène Xueref-Remy, Nicolas Montes","doi":"10.5194/bg-21-3289-2024","DOIUrl":"https://doi.org/10.5194/bg-21-3289-2024","url":null,"abstract":"Abstract. Forest systems are the main carbon sink after the oceans. However, due to climate change, an alarming number of tree species of the Northern Hemisphere are at risk of migrating northwards or becoming extinct. This is the case for the downy oak (Quercus pubescens), one of the main species constituting the forests close to the Mediterranean Sea in France. Our aim is to retrieve aboveground carbon (AGC) and underground root carbon (UGC) stocks of the downy oak forest at the Observatoire de Haute-Provence (OHP), located about 80 km north of Marseille, in order to provide a baseline against which to assess the effect of climate change on this model species. The study presented here is based on airborne lidar observations performed on May 2012 and field measurements from 2012, 2018 and 2023 in the OHP forest. The OHP forest consists of ∼ 75 % downy oak, which is highly sensitive to global warming. Field measurements indicate minimal changes in tree growth and density between 2012 and 2023, and thus its carbon storage efficiency remains stationary. As retrieved by lidar measurements, tree top heights (TTHs) are mostly between 5 and 12 m, with an uncertainty of around 1 m. The slow evolution of trees at the OHP site makes it appropriate to use lidar data recorded in 2012 to assess the carbon stock trapped in current forest biomass. By coupling allometric laws established from field measurements with lidar observations, we show that the quantities of carbon trapped in aboveground biomass are double those trapped in the root system. Over an area of ∼ 24 ha, mean values of 15 ± 14 tC ha−1 are assessed for the aerial biomass against 8–10 ± 3–7 tC ha−1 for the roots of diameter larger than 1 cm for low and high assessments. These values depend heavily on the height of the sampled trees themselves, as well as on their location on the OHP plateau (smaller trees, 5–6 m) or on the slope (tallest trees, 10–12 m). Using a Monte Carlo approach, the relative uncertainties in AGC were calculated to be of the order of 17 % and 11 % for trees 5–6 m and 10–12 m tall, respectively. For UGC, the relative uncertainties were calculated as 8 % and 5 % for the same tree heights, but the assumptions of the allometric model are associated with biases that can easily reach 100 %. Although the surface footprints are different, we show that there is a reasonable agreement between our airborne lidar measurements and the level 2B (TTH) and (aboveground biomass) operational products of the Global Ecosystem Dynamics Investigation (GEDI) mission on the International Space Station for data acquired between 2019 and 2022.\u0000","PeriodicalId":502171,"journal":{"name":"Biogeosciences","volume":" 449","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141823797","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Composite calcite and opal test in Foraminifera (Rhizaria)","authors":"Julien Richirt, Satoshi Okada, Yoshiyuki Ishitani, K. Uematsu, Akihiro Tame, Kaya Oda, Noriyuki Isobe, Toyoho Ishimura, Masashi Tsuchiya, H. Nomaki","doi":"10.5194/bg-21-3271-2024","DOIUrl":"https://doi.org/10.5194/bg-21-3271-2024","url":null,"abstract":"Abstract. Foraminifera are unicellular eukaryotes known to have a shell, called a test, generally made of secreted calcite (CaCO3). For the first time, we report a foraminifera with a composite calcite–opal test in the cosmopolitan and well-studied benthic species Bolivina spissa (Rotaliida), sampled from Sagami Bay in Japan at 1410 m depth. Based on comprehensive investigations including scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS) and Fourier-transform infrared (FTIR) spectroscopy, we inspect the morphology and composition of the novel opaline layer coating the inside part of the calcitic test. Using scanning transmission electron microscopy (STEM) and EDS analyses, we detected probable silica deposition vesicles (SDVs), organelles involved in opal precipitation in other silicifying organisms, confirming that the foraminifera itself secretes the opal layer. The layer was systematically found in all studied individuals and had no apparent substructure. Its thickness showed a growth pattern analogous to the calcitic shell of B. spissa, being the thickest in the oldest chamber (proloculus) and becoming thinner toward the younger chambers (apertural side). Its absence in the youngest chambers indicates that silicification occurs subsequent to calcification, probably discontinuously. We further discuss the potential function(s) of this composite test and propose that the opal layer may serve as a protective barrier against predators using either mechanical drilling or chemical etching of the calcitic test. Isotopic composition measurements performed separately on the proloculus part and the apertural side of B. spissa suggest that the presence of an opal layer may alter the calcitic isotopic signal and impact palaeoenvironmental proxies using foraminiferal test composition. If silicification in Foraminifera were found to be more widespread than previously thought, it could possibly have important implications for foraminiferal evolution, palaeoceanographic reconstructions, and the silica cycle at global scale.\u0000","PeriodicalId":502171,"journal":{"name":"Biogeosciences","volume":"107 46","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141821645","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Distinguishing mature and immature trees allows estimating forest carbon uptake from stand structure","authors":"Samuel M. Fischer, Xugao Wang, Andreas Huth","doi":"10.5194/bg-21-3305-2024","DOIUrl":"https://doi.org/10.5194/bg-21-3305-2024","url":null,"abstract":"Abstract. Relating forest productivity to local variations in forest structure has been a long-standing challenge. Previous studies often focused on the connection between forest structure and stand-level photosynthesis (gross primary production – GPP). However, biomass production (net primary production – NPP) and net ecosystem exchange (NEE) are also subject to respiration and other carbon losses, which vary with local conditions and life history traits. Here, we use a simulation approach to study how these losses impact forest productivity and reveal themselves in forest structure. We fit the process-based forest model FORMIND to a 25 ha inventory of an old-growth temperate forest in China and classify trees as “mature” (fully grown) or “immature” based on their intrinsic carbon use efficiency. Our results reveal a strong negative connection between the stand-level carbon use efficiency and the prevalence of mature trees: gross primary production (GPP) increases with the total basal area, whereas net primary production (NPP) and NEE are driven by the basal area of immature trees. Accordingly, the basal area entropy, a structural proxy for the prevalence of immature trees, correlated well with NPP and NEE and had a higher predictive power than other structural characteristics, such as the Shannon diversity and height standard deviation. Our results were robust across spatial scales (0.04–1 ha) and yield promising hypotheses for field studies and new theoretical work.\u0000","PeriodicalId":502171,"journal":{"name":"Biogeosciences","volume":" 852","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141823472","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The influence of plant water stress on vegetation–atmosphere exchanges: implications for ozone modelling","authors":"T. Emmerichs, Yen-Sen Lu, D. Taraborrelli","doi":"10.5194/bg-21-3251-2024","DOIUrl":"https://doi.org/10.5194/bg-21-3251-2024","url":null,"abstract":"Abstract. Evapotranspiration is important for Earth's water and energy cycles as it strongly affects air temperature, cloud cover, and precipitation. Leaf stomata are the conduit of transpiration, and their opening is sensitive to weather and climate conditions. This feedback can exacerbate heat waves and can play a role in their spatiotemporal propagation. Sustained high temperatures strongly favour high ozone levels, with significant negative impacts on air quality and thus on human health. Our study evaluates the process representation of evapotranspiration in the atmospheric chemistry–climate European Centre for Medium-Range Weather Forecasts – Hamburg(ECHAM)/Modular Earth Submodel System (MESSy) Atmospheric Chemistry model. Different water stress parameterizations are implemented in a stomatal model based on CO2 assimilation. The stress factors depend on either soil moisture or leaf water potential, which act on photosynthetic activity, and mesophyll and stomatal conductance. The new functionalities reduce the initial overestimation of evapotranspiration in the model globally by more than an order of magnitude, which is most important in the Southern Hemisphere. The intensity of simulated warm spells over continents is significantly improved. For ozone, we find that a realistic model representation of plant water stress suppresses uptake by vegetation and enhances photochemical production in the troposphere. These effects lead to an overall increase in simulated ground-level ozone, which is most pronounced in the Southern Hemisphere over the continents. More sophisticated land surface models with multi-layer soil schemes could address the uncertainties in representing plant dynamics representation due to too-shallow roots. In regions with low evaporative loss, the representation of precipitation remains the largest uncertainty.\u0000","PeriodicalId":502171,"journal":{"name":"Biogeosciences","volume":" 10","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141829113","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Isotopomer labeling and oxygen dependence of hybrid nitrous oxide production","authors":"Colette L. Kelly, N. M. Travis, P. Baya, C. Frey, Xin Sun, Bess B. Ward, K. Casciotti","doi":"10.5194/bg-21-3215-2024","DOIUrl":"https://doi.org/10.5194/bg-21-3215-2024","url":null,"abstract":"Abstract. Nitrous oxide (N2O) is a potent greenhouse gas and ozone depletion agent, with a significant natural source from marine oxygen-deficient zones (ODZs). Open questions remain, however, about the microbial processes responsible for this N2O production, especially hybrid N2O production when ammonia-oxidizing archaea are present. Using 15N-labeled tracer incubations, we measured the rates of N2O production from ammonium (NH4+), nitrite (NO2-), and nitrate (NO3-) in the eastern tropical North Pacific ODZ and the isotopic labeling of the central (α) and terminal (β) nitrogen (N) atoms of the N2O molecule. We observed production of both doubly and singly labeled N2O from each tracer, with the highest rates of labeled N2O production at the same depths as the near-surface N2O concentration maximum. At most stations and depths, the production of 45N2Oα and 45N2Oβ were statistically indistinguishable, but at a few depths there were significant differences in the labeling of the two nitrogen atoms in the N2O molecule. Implementing the rates of labeled N2O production in a time-dependent numerical model, we found that N2O production from NO3- dominated at most stations and depths, with rates as high as 1600 ± 200 pM N2O d−1. Hybrid N2O production, one of the mechanisms by which ammonia-oxidizing archaea produce N2O, had rates as high as 230 ± 80 pM N2O d−1 that peaked in both the near-surface and deep N2O concentration maxima. Based on the equal production of 45N2Oα and 45N2Oβ in the majority of our experiments, we infer that hybrid N2O production likely has a consistent site preference, despite drawing from two distinct substrate pools. We also found that the rates and yields of hybrid N2O production were enhanced at low dissolved oxygen concentrations ([O2]), with hybrid N2O yields as high as 20 % at depths where [O2] was below detection (880 nM) but nitrification was still active. Finally, we identified a few incubations with [O2] up to 20 µM where N2O production from NO3- was still active. A relatively high O2 tolerance for N2O production via denitrification has implications for the feedbacks between marine deoxygenation and greenhouse gas cycling.\u0000","PeriodicalId":502171,"journal":{"name":"Biogeosciences","volume":" 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141829524","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Variable contribution of wastewater treatment plant effluents to downstream nitrous oxide concentrations and emissions","authors":"Weiyi Tang, Jeff Talbott, Timothy Jones, Bess B. Ward","doi":"10.5194/bg-21-3239-2024","DOIUrl":"https://doi.org/10.5194/bg-21-3239-2024","url":null,"abstract":"Abstract. Nitrous oxide (N2O), a potent greenhouse gas and ozone-destroying agent, is produced during nitrogen transformations in both natural and human-constructed environments. Wastewater treatment plants (WWTPs) produce and emit N2O into the atmosphere during the nitrogen removal process. However, the impact of WWTPs on N2O emissions in downstream aquatic systems remains poorly constrained. By measuring N2O concentrations at a monthly resolution over a year in the Potomac River estuary, a tributary of the Chesapeake Bay in the eastern United States, we found a strong seasonal variation in N2O concentrations and fluxes: N2O concentrations were larger in fall and winter, but the flux was larger in summer and fall. Observations at multiple stations across the Potomac River estuary revealed hotspots of N2O emissions downstream of WWTPs. N2O concentrations were higher at stations downstream of WWTPs compared to other stations (median: 21.2 nM vs. 16.2 nM) despite the similar concentration of dissolved inorganic nitrogen, suggesting the direct discharge of N2O from WWTPs into the aquatic system or a higher N2O production yield in waters influenced by WWTPs. Meta-analysis of N2O measurements associated with WWTPs globally revealed variable influence of WWTPs on downstream N2O concentrations and emissions. Since wastewater production has increased substantially with the growing population and is projected to continue to rise, accurately accounting for N2O emissions downstream of WWTPs is important for constraining and predicting future global N2O emissions. Efficient N2O removal, in addition to dissolved nitrogen removal, should be an essential part of water quality control in WWTPs.\u0000","PeriodicalId":502171,"journal":{"name":"Biogeosciences","volume":" 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141828940","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}