BLUE CARBON SEQUESTRATION IMPACTED BY A LATE HOLOCENE HIGH ENERGY SAND DEPOSIT IN A SALT MARSH, ROCKPORT MA

2017 ◽  
Author(s):  
Shadya El-ashkar ◽  
◽  
J. Bradford Hubeny ◽  
Renee Knudstrup
2020 ◽  
Author(s):  
Kai Xiao ◽  
Alicia M. Wilson ◽  
Hailong Li ◽  
Isaac R. Santos ◽  
Joseph Tamborski ◽  
...  

2021 ◽  
Author(s):  
Otmane Khalfaoui ◽  
laurent Dezileau ◽  
Jean-Philippe Degeai ◽  
Maria Snoussi

<p>The Atlantic coast of Morocco has been confronted with several marine submersion events. Historically, some of them have resulted in significant economic and human damage, including the 1755 AD event (known as the tsunami of Lisbon). This indicates the need to implement adaptation and mitigation strategies, based on long-term studies of these extreme events to deduce their spatial and temporal variability. Using two cores (TAH17-1 and TAH17-3) collected from the Tahaddart estuary (NW of Morocco), this work aims to identify deposits, set up by these high energy events during the mid to late Holocene period. The sedimentological, geochemical and geochronological analyses carried out on these geological archives show two fining-upward sequences, indicating a progressive change from a purely sandy marine facies, between 6500 and 3500 BP, to another finer and more terrigenous one. The fine sedimentation, which has dominated in the estuary during the last 3500 years, has facilitated the recording of several marine submersion events in the form of isolated sandy layers. Chronological data have made it possible to date four deposits. Two (1-E1 and 3-E1) were put in place about 250 years ago, which corresponds, according to historical records, to the 1755 AD Lisbon tsunami. Two other deposits (1-E13 and 1-E14) are dated around 3200 BP and represent unknown submersion events on the Moroccan Atlantic coast.</p>


2022 ◽  
Vol 4 ◽  
Author(s):  
Andre S. Rovai ◽  
Robert R. Twilley ◽  
Thomas A. Worthington ◽  
Pablo Riul

Mangroves are known for large carbon stocks and high sequestration rates in biomass and soils, making these intertidal wetlands a cost-effective strategy for some nations to compensate for a portion of their carbon dioxide (CO2) emissions. However, few countries have the national-level inventories required to support the inclusion of mangroves into national carbon credit markets. This is the case for Brazil, home of the second largest mangrove area in the world but lacking an integrated mangrove carbon inventory that captures the diversity of coastline types and climatic zones in which mangroves are present. Here we reviewed published datasets to derive the first integrated assessment of carbon stocks, carbon sequestration rates and potential CO2eq emissions across Brazilian mangroves. We found that Brazilian mangroves hold 8.5% of the global mangrove carbon stocks (biomass and soils combined). When compared to other Brazilian vegetated biomes, mangroves store up to 4.3 times more carbon in the top meter of soil and are second in biomass carbon stocks only to the Amazon forest. Moreover, organic carbon sequestration rates in Brazilian mangroves soils are 15–30% higher than recent global estimates; and integrated over the country’s area, they account for 13.5% of the carbon buried in world’s mangroves annually. Carbon sequestration in Brazilian mangroves woody biomass is 10% of carbon accumulation in mangrove woody biomass globally. Our study identifies Brazilian mangroves as a major global blue carbon hotspot and suggest that their loss could potentially release substantial amounts of CO2. This research provides a robust baseline for the consideration of mangroves into strategies to meet Brazil’s intended Nationally Determined Contributions.


Eos ◽  
2019 ◽  
Vol 100 ◽  
Author(s):  
Sarah Stanley

A new two-model approach could reduce uncertainties in calculated rates of “blue carbon” accumulation within soils of seagrass, tidal marsh, and mangrove habitats.


2006 ◽  
Vol 66 (2) ◽  
pp. 288-302 ◽  
Author(s):  
W. Roland Gehrels ◽  
Katie Szkornik ◽  
Jesper Bartholdy ◽  
Jason R. Kirby ◽  
Sarah L. Bradley ◽  
...  

AbstractCores and exposed cliff sections in salt marshes around Ho Bugt, a tidal embayment in the northernmost part of the Danish Wadden Sea, were subjected to 14C dating and litho- and biostratigraphical analyses to reconstruct paleoenvironmental changes and to establish a late Holocene relative sea-level history. Four stages in the late Holocene development of Ho Bugt can be identified: (1) groundwater-table rise and growth of basal peat (from at least 2300 BC to AD 0); (2) salt-marsh formation (0 to AD 250); (3) a freshening phase (AD 250 to AD 1600?), culminating in the drying out of the marshes and producing a distinct black horizon followed by an aeolian phase with sand deposition; and (4) renewed salt-marsh deposition (AD 1600? to present). From 16 calibrated AMS radiocarbon ages on fossil plant fragments and 4 calibrated conventional radiocarbon ages on peat, we reconstructed a local relative sea-level history that shows a steady sea-level rise of 4 m since 4000 cal yr BP. Contrary to suggestions made in the literature, the relative sea-level record of Ho Bugt does not contain a late Holocene highstand. Relative sea-level changes at Ho Bugt are controlled by glacio-isostatic subsidence and can be duplicated by a glacial isostatic adjustment model in which no water is added to the world's oceans after ca. 5000 cal yr BP.


2007 ◽  
Vol 44 (10) ◽  
pp. 1453-1465 ◽  
Author(s):  
Julia F Daly ◽  
Daniel F Belknap ◽  
Joseph T Kelley ◽  
Trevor Bell

Differential sea-level change in formerly glaciated areas is predicted owing to variability in extent and timing of glacial coverage. Newfoundland is situated close to the margin of the former Laurentide ice sheet, and the orientation of the shoreline affords the opportunity to investigate variable rates and magnitudes of sea-level change. Analysis of salt-marsh records at four sites around the island yields late Holocene sea-level trends. These trends indicate differential sea-level change in recent millennia. A north–south geographic trend reflects submergence in the south, very slow sea-level rise in the northeast, and a recent transition from falling to rising sea-level at the base of the Northern Peninsula. This variability is best explained as a continued isostatic response to deglaciation.


2021 ◽  
Author(s):  
Aspen Tabar ◽  
Susan Guiteras ◽  
Jeff Tabar

<p>Prime Hook National Wildlife Refuge and its adjacent water bodies are important natural features along western Delaware Bay, USA. Historically salt and brackish marsh habitats, portions of the Refuge were diked and managed as freshwater impoundments starting in the early 1980s. Over the past decade, some of these impoundments have reverted to saline conditions, largely due to several storm events (including Hurricane Sandy in 2012) that have caused flooding, erosion, and opened several breaches between the Refuge and Delaware Bay. Because of these significant morphologic changes, the United States Fish and Wildlife Service (USFWS) completed a series of surveys, numerical modeling using Delft3D and coastal engineering analyses to aid in developing restoration alternatives for managing the Refuge and its marshlands. This work will review the results of the strategic planning used to recommend a preferred restoration alternative for managing the Refuge under the new environmental regime aimed at resilience. As a result of this effort, a project for restoring and managing the Refuge was recommended and constructed in 2018. Total cost of the project was $40 million US and was the largest restoration/recovery project authorized to address the impacts of Hurricane Sandy.</p><p>The project included two major components: 1) shoreline reconstruction and 2) marsh restoration.  The shoreline reconstruction portion of the project included placing approximately 1.2 million cubic meters of sand from an offshore borrow area along the shoreline to reconstruction a 12 m wide dune, 45 m beach berm and 30 m back-bay marsh platform (essentially rebuilding the entire barrier island). In addition, the project included a major marsh restoration effort including dredging 48 km of conveyance channels and “thin layer” disposal of 460,000 cubic meters of sediment to create 2,000 hectares of salt marsh.</p><p>Herein will present findings from an analysis using monitoring data and observations to evaluate converting freshwater wetlands to saltwater marshes and the resulting increase in carbon sequestration. As tidal marshes are restored, harmful emissions decline as the project site transforms from a freshwater to a saltwater environment. Therefore, carbon is stored in the soils more readily under tidal marsh conditions. The findings will show the increase in carbon sequestration as a result of the vegetation community response and discuss future projections.  Methodologies used for identifying vegetation community response included:</p><ul><li>Salt Marsh Integrity (SMI) and Saltmarsh Habitat & Avian Research Program (SHARP)</li> <li>Mid-Atlantic Tidal Rapid Assessment Method (MidTRAM)</li> <li>Normalized Difference Vegetation Index (NDVI)</li> </ul><p>This work will show the importance of incorporating coastal restoration projects and carbon sequestration into policies and management in the coastal zone.</p>


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