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- Cotovicz Jr, Luiz C., et al.
(author)
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Methane oxidation minimizes emissions and offsets to carbon burial in mangroves
- 2024
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In: NATURE CLIMATE CHANGE. - 1758-678X .- 1758-6798. ; 14, s. 275-281
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Journal article (peer-reviewed)abstract
- Maximizing carbon sequestration in mangroves is part of the global effort to combat the climate crisis. However, methane (CH4) emissions can partially offset carbon sequestration in mangroves. Previous estimates have suggested that CH4 emissions offset organic carbon burial by 20% in mangroves with substantial freshwater inputs and/or in highly impacted mangroves. Here we resolve the magnitude and drivers of the mangrove CH4 offset using multiple isotopic tracers across a latitudinal gradient. CH4 emission offsets were smaller in high-salinity (similar to 7%) than in freshwater-influenced (similar to 27%) mangroves. Carbon sequestration was disproportionally high compared with CH4 emissions in understudied tropical areas. Low CH4 emissions were explained by minor freshwater inputs minimizing CH4 production in saline, high-sulfate conditions and intense CH4 oxidation in porewaters and surface waters. CH4 oxidation in mangrove surface waters reduced potential aquatic CH4 emissions by 10-33%. Overall, carbon sequestration through mangrove preservation and restoration is less affected by CH4 emissions than previously thought.
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3. |
- Wilson, Stephanie J., et al.
(author)
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Global subterranean estuaries modify groundwater nutrient loading to the ocean
- 2024
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In: Limnology And Oceanography Letters. - 2378-2242.
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Journal article (peer-reviewed)abstract
- Terrestrial groundwater travels through subterranean estuaries before reaching the sea. Groundwater-derived nutrients drive coastal water quality, primary production, and eutrophication. We determined how dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP), and dissolved organic nitrogen (DON) are transformed within subterranean estuaries and estimated submarine groundwater discharge (SGD) nutrient loads compiling > 10,000 groundwater samples from 216 sites worldwide. Nutrients exhibited complex, nonconservative behavior in subterranean estuaries. Fresh groundwater DIN and DIP are usually produced, and DON is consumed during transport. Median total SGD (saline and fresh) fluxes globally were 5.4, 2.6, and 0.18 Tmol yr−1 for DIN, DON, and DIP, respectively. Despite large natural variability, total SGD fluxes likely exceed global riverine nutrient export. Fresh SGD is a small source of new nutrients, but saline SGD is an important source of mostly recycled nutrients. Nutrients exported via SGD via subterranean estuaries are critical to coastal biogeochemistry and a significant nutrient source to the oceans.
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