| 1. |
- Bansal, Sheel, et al.
(författare)
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Practical Guide to Measuring Wetland Carbon Pools and Fluxes
- 2023
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Ingår i: Wetlands (Wilmington, N.C.). - : SPRINGER. - 0277-5212 .- 1943-6246. ; 43:8
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Forskningsöversikt (refereegranskat)abstract
- Wetlands cover a small portion of the world, but have disproportionate influence on global carbon (C) sequestration, carbon dioxide and methane emissions, and aquatic C fluxes. However, the underlying biogeochemical processes that affect wetland C pools and fluxes are complex and dynamic, making measurements of wetland C challenging. Over decades of research, many observational, experimental, and analytical approaches have been developed to understand and quantify pools and fluxes of wetland C. Sampling approaches range in their representation of wetland C from short to long timeframes and local to landscape spatial scales. This review summarizes common and cutting-edge methodological approaches for quantifying wetland C pools and fluxes. We first define each of the major C pools and fluxes and provide rationale for their importance to wetland C dynamics. For each approach, we clarify what component of wetland C is measured and its spatial and temporal representativeness and constraints. We describe practical considerations for each approach, such as where and when an approach is typically used, who can conduct the measurements (expertise, training requirements), and how approaches are conducted, including considerations on equipment complexity and costs. Finally, we review key covariates and ancillary measurements that enhance the interpretation of findings and facilitate model development. The protocols that we describe to measure soil, water, vegetation, and gases are also relevant for related disciplines such as ecology. Improved quality and consistency of data collection and reporting across studies will help reduce global uncertainties and develop management strategies to use wetlands as nature-based climate solutions.
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| 2. |
- Brown, Dylan R., et al.
(författare)
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Hypersaline tidal flats as important "blue carbon" systems : a case study from three ecosystems
- 2021
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Ingår i: Biogeosciences. - : COPERNICUS GESELLSCHAFT MBH. - 1726-4170 .- 1726-4189. ; 18:8, s. 2527-2538
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Tidskriftsartikel (refereegranskat)abstract
- Hypersaline tidal flats (HTFs) are coastal ecosystems with freshwater deficits often occurring in arid or semiarid regions near mangrove supratidal zones with no major fluvial contributions. Here, we estimate that organic carbon (OC), total nitrogen (TN) and total phosphorus (TP) were buried at rates averaging 21 (+/- 6), 1.7 (+/- 0.3) and 1.4 (+/- 0.3) gm(-2) yr(-1), respectively, during the previous century in three contrasting HTF systems, one in Brazil (eutrophic) and two in Australia (oligotrophic). Although these rates are lower than those from nearby mangrove, saltmarsh and seagrass systems, the importance of HTFs as sinks for OC, TN and TP may be significant given their extensive coverage. Despite the measured short-term variability between net air-saltpan CO2 influx and emission estimates found during the dry and wet season in the Brazilian HTF, the only site with seasonal CO2 flux measurements, the OC sedimentary profiles over several decades suggest efficient OC burial at all sites. Indeed, the stable isotopes of OC and TN (delta C-13 and delta N-1(5)) along with C : N ratios show that microphytobenthos are the major source of the buried OC in these HTFs. Our findings highlight a previously unquantified carbon as well as a nutrient sink and suggest that coastal HTF ecosystems could be included in the emerging blue carbon framework.
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| 3. |
- Call, Mitchell, et al.
(författare)
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Radon-traced pore-water as a potential source of CO2 and CH4 to receding black and clear water environments in the Amazon Basin
- 2018
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Ingår i: Limnology and Oceanography Letters. - : Wiley-Blackwell. - 2378-2242. ; 3:5, s. 375-383
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Groundwater is a primary source of dissolved CO2 and CH4 in Amazonian headwaters, yet in higher order rivers, a groundwater/pore-water source is difficult to constrain due to the high spatial and temporal heterogeneity of pore-water exchange. Here, we report coupled, high resolution measurements of pCO2, CH4, and 222Rn (a natural pore-water and groundwater tracer) during receding waters in the three major water types of the Central Amazon Basin: black (Negro River); clear (Tapajós River); white (Madeira River). Considerable spatial heterogeneity was observed in pCO2, CH4, and 222Rn concentrations ranging from 460 ?atm to 8030 ?atm, 7 nM to 281 nM, and 713 dpm m?3 to 8516 dpm m?3, respectively. The significant correlations between pCO2 and CH4 to 222Rn in the black and clear waters suggests that pore-water further enhanced CO2 supersaturation by 18?47% and is a driver of CH4 dynamics in these waters.
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| 4. |
- Cotovicz Jr, Luiz C., et al.
(författare)
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Methane oxidation minimizes emissions and offsets to carbon burial in mangroves
- 2024
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Ingår i: NATURE CLIMATE CHANGE. - 1758-678X .- 1758-6798.
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Tidskriftsartikel (refereegranskat)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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| 5. |
- Reithmaier, Gloria M.S., et al.
(författare)
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Carbonate chemistry and carbon sequestration driven by inorganic carbon outwelling from mangroves and saltmarshes
- 2023
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Ingår i: Nature Communications. - 2041-1723. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- Mangroves and saltmarshes are biogeochemical hotspots storing carbon in sediments and in the ocean following lateral carbon export (outwelling). Coastal seawater pH is modified by both uptake of anthropogenic carbon dioxide and natural biogeochemical processes, e.g., wetland inputs. Here, we investigate how mangroves and saltmarshes influence coastal carbonate chemistry and quantify the contribution of alkalinity and dissolved inorganic carbon (DIC) outwelling to blue carbon budgets. Observations from 45 mangroves and 16 saltmarshes worldwide revealed that >70% of intertidal wetlands export more DIC than alkalinity, potentially decreasing thepH of coastal waters. Porewater-derived DIC outwelling (81 ± 47 mmol m−2 d−1 in mangroves and 57 ± 104 mmol m−2 d−1 in saltmarshes) was the major term in blue carbon budgets. However, substantial amounts of fixed carbon remain unaccounted for. Concurrently, alkalinity outwelling was similar or higher than sediment carbon burial and is therefore a significant but often overlooked carbon sequestration mechanism.
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| 6. |
- Reithmaier, Gloria M.S., et al.
(författare)
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Rainfall drives rapid shifts in carbon and nutrient source-sink dynamics of an urbanised, mangrove-fringed estuary
- 2021
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Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714. ; 249
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Tidskriftsartikel (refereegranskat)abstract
- © 2020 Elsevier Ltd Estuaries provide valuable ecosystem services, such as carbon storage and nutrient retention, which may be affected by episodic rainfall events. This study aimed to investigate the short-term effect of episodic rainfall on alkalinity, dissolved carbon and nutrient biogeochemistry in a small, urbanised and mangrove-fringed estuary. High temporal resolution sampling (1.5-h interval) at upper and lower estuary sites, as well as groundwater sampling, were conducted over two weeks to assess estuarine source/sink dynamics of total alkalinity (TAlk), organic alkalinity (OAlk), dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), nitrate, nitrite, ammonium and phosphate. Rapid, short-term changes in estuarine biogeochemistry and mixing were triggered by two episodic rainfall events, which delivered 26 mm over 2 h and 39 mm over 21 h. The estuary was a source for TAlk and DIC exporting 2.2 ± 1.9 and 2.2 ± 1.5 mmol/m2 catchment/d, respectively, to the coastal ocean during the observation period. On average, OAlk accounted for 8% of TAlk at the upstream and 3% at the downstream site. Unlike pristine mangrove systems, the estuary was a net sink for DOC, equivalent to ~23% of the DIC source. Rainfall increased catchment nutrient inputs into the estuary, which was a source for ammonium, but a sink for nitrate and nitrite (NOx) throughout the study period. In contrast, phosphate dynamics were less clear. Estuarine biogeochemical transformations affected the exchange with the coastal ocean, driving net TAlk export and by acting as a sink for catchment-derived nutrients. Our high-temporal resolution results suggest that rainfall events rapidly modify estuarine biogeochemistry and mixing, altering the net fluxes of TAlk, dissolved carbon and nutrients to the coastal ocean.
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