| 1. |
- Wilson, Samuel T., et al.
(författare)
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Ideas and perspectives : A strategic assessment of methane and nitrous oxide measurements in the marine environment
- 2020
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 17:22, s. 5809-5828
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Tidskriftsartikel (refereegranskat)abstract
- In the current era of rapid climate change, accurate characterization of climate-relevant gas dynamics – namely production, consumption, and net emissions – is required for all biomes, especially those ecosystems most susceptible to the impact of change. Marine environments include regions that act as net sources or sinks for numerous climate-active trace gases including methane (CH4) and nitrous oxide (N2O). The temporal and spatial distributions of CH4 and N2O are controlled by the interaction of complex biogeochemical and physical processes. To evaluate and quantify how these mechanisms affect marine CH4 and N2O cycling requires a combination of traditional scientific disciplines including oceanography, microbiology, and numerical modeling. Fundamental to these efforts is ensuring that the datasets produced by independent scientists are comparable and interoperable. Equally critical is transparent communication within the research community about the technical improvements required to increase our collective understanding of marine CH4 and N2O. A workshop sponsored by Ocean Carbon and Biogeochemistry (OCB) was organized to enhance dialogue and collaborations pertaining to marine CH4 and N2O. Here, we summarize the outcomes from the workshop to describe the challenges and opportunities for near-future CH4 and N2O research in the marine environment.
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| 2. |
- Ray, Nicholas E., et al.
(författare)
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A review of how we assess denitrification in oyster habitats and proposed guidelines for future studies
- 2021
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Ingår i: Limnology and Oceanography. - : Wiley. - 1541-5856. ; 19:10, s. 714-731
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Forskningsöversikt (refereegranskat)abstract
- Excess nitrogen (N) loading and resulting eutrophication plague coastal ecosystems globally. Much work is being done to remove N before it enters coastal receiving waters, yet these efforts are not enough. Novel techniques to remove N from within the coastal ecosystem are now being explored. One of these techniques involves using oysters and their habitats to remove N via denitrification. There is substantial interest in incorporating oyster-mediated enhancement of benthic denitrification into N management plans and trading schemes. Measuring denitrification, however, is expensive and time consuming. For large-scale adoption of oyster-mediated denitrification into nutrient management plans, we need an accurate model that can be applied across ecosystems. Despite significant effort to measure and report rates of denitrification in oyster habitats, we are unable to create such a model, due to methodological differences between studies, incomplete data reporting, and inconsistent measurements of environmental variables that may be used to predict denitrification. To make a model that can predict denitrification in oyster habitats a reality, a common sampling and reporting scheme is needed across studies. Here, we provide relevant background on how oysters may stimulate denitrification, and the importance of oyster-mediated denitrification in remediating excess N loading to coastal systems. We then summarize methods commonly used to measure denitrification in oyster habitats, discuss the importance of various environmental variables that may be useful for predicting denitrification, and present a set of guidelines for measuring denitrification in oyster habitats, allowing development of models to support incorporation of oyster-mediated denitrification into future policy decisions.
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| 3. |
- Ray, Nicholas E., et al.
(författare)
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Negligible Greenhouse Gas Release from Sediments in Oyster Habitats
- 2021
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 55:20, s. 14225-14233
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Tidskriftsartikel (refereegranskat)abstract
- After centuries of decline, oyster populations are now on the rise in coastal systems globally following aquaculture development and restoration efforts. Oysters regulate the biogeochemistry of coastal systems in part by promoting sediment nutrient recycling and removing excess nitrogen via denitrification. Less clear is how oysters alter sediment greenhouse gas (GHG) fluxes—an important consideration as oyster populations grow. Here, we show that sediments in oyster habitats produce carbon dioxide (CO2), with highest rates in spring (2396.91 ± 381.98 μmol CO2 m–2 h–1) following deposition of seasonal diatom blooms and in summer (2795.20 ± 307.55 μmol CO2 m–2 h–1) when temperatures are high. Sediments in oyster habitats also consistently released methane to the water column (725.94 ± 150.34 nmol CH4 m–2 h–1) with no seasonal pattern. Generally, oyster habitat sediments were a sink for nitrous oxide (N2O; −36.11 ± 7.24 nmol N2O m–2 h–1), only occasionally releasing N2O in spring. N2O release corresponded to high organic matter and dissolved nitrogen availability, suggesting denitrification as the production pathway. Despite potential CO2 production increases under aquaculture in some locations, we conclude that in temperate regions oysters have an overall negligible impact on sediment GHG cycling.
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| 4. |
- Snelgrove, Paul V. R., et al.
(författare)
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Global Carbon Cycling on a Heterogeneous Seafloor
- 2018
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Ingår i: Trends in Ecology & Evolution. - : Elsevier BV. - 0169-5347 .- 1872-8383. ; 33:2, s. 96-105
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Forskningsöversikt (refereegranskat)abstract
- Diverse biological communities mediate the transformation, transport, and storage of elements fundamental to life on Earth, including carbon, nitrogen, and oxygen. However, global biogeochemical model outcomes can vary by orders of magnitude, compromising capacity to project realistic ecosystem responses to planetary changes, including ocean productivity and climate. Here, we compare global carbon turnover rates estimated using models grounded in biological versus geochemical theory and argue that the turnover estimates based on each perspective yield divergent outcomes. Importantly, empirical studies that include sedimentary biological activity vary less than those that ignore it. Improving the relevance of model projections and reducing uncertainty associated with the anticipated consequences of global change requires reconciliation of these perspectives, enabling better societal decisions on mitigation and adaptation.
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