scholarly journals A blueprint for blue carbon: toward an improved understanding of the role of vegetated coastal habitats in sequestering CO 2

2011 ◽  
Vol 9 (10) ◽  
pp. 552-560 ◽  
Author(s):  
Elizabeth Mcleod ◽  
Gail L Chmura ◽  
Steven Bouillon ◽  
Rodney Salm ◽  
Mats Björk ◽  
...  
Keyword(s):  
Blue Carbon ◽  
Coastal Habitats

scholarly journals Unrecognized controls on microbial functioning in Blue Carbon ecosystems: The role of mineral enzyme stabilization and allochthonous substrate supply

2020 ◽  
Vol 10 (2) ◽  
pp. 998-1011 ◽  
Author(s):  
Peter Mueller ◽  
Dirk Granse ◽  
Stefanie Nolte ◽  
Magdalena Weingartner ◽  
Stefan Hoth ◽  
...  
Keyword(s):  
Blue Carbon ◽  
Enzyme Stabilization ◽  
Substrate Supply

scholarly journals Sequestration of macroalgal carbon: the elephant in the Blue Carbon room

2018 ◽  
Vol 14 (6) ◽  
pp. 20180236 ◽  
Author(s):  
Dorte Krause-Jensen ◽  
Paul Lavery ◽  
Oscar Serrano ◽  
Núria Marbà ◽  
Pere Masque ◽  
...  
Keyword(s):  
Paradigm Shift ◽  
Carbon Sink ◽  
Blue Carbon ◽  
Coastal Habitats ◽  
Management Actions ◽  
Carbon Burial

Macroalgae form the most extensive and productive benthic marine vegetated habitats globally but their inclusion in Blue Carbon (BC) strategies remains controversial. We review the arguments offered to reject or include macroalgae in the BC framework, and identify the challenges that have precluded macroalgae from being incorporated so far. Evidence that macroalgae support significant carbon burial is compelling. The carbon they supply to sediment stocks in angiosperm BC habitats is already included in current assessments, so that macroalgae are de facto recognized as important donors of BC. The key challenges are (i) documenting macroalgal carbon sequestered beyond BC habitat, (ii) tracing it back to source habitats, and (iii) showing that management actions at the habitat lead to increased sequestration at the sink site. These challenges apply equally to carbon exported from BC coastal habitats. Because of the large carbon sink they support, incorporation of macroalgae into BC accounting and actions is an imperative. This requires a paradigm shift in accounting procedures as well as developing methods to enable the capacity to trace carbon from donor to sink habitats in the ocean.

When “Blue Carbon” turns white: Isotopic evidence of calcification-driven CO2 emissions in a carbonate seagrass meadow

2021 ◽  
Author(s):  
Mary Zeller ◽  
Bryce Van Dam ◽  
Christian Lopes ◽  
Ashley Smyth ◽  
Michael Böttcher ◽  
...  
Keyword(s):  
Seagrass Meadow ◽  
Solid Phase ◽  
Blue Carbon ◽  
Total Alkalinity ◽  
Carbonate Content ◽  
Carbonate Precipitation ◽  
Seagrass Meadows ◽  
Organic Carbon Burial ◽  
Seagrass Density

<p>Seagrasses are often considered important players in the global carbon cycle, due to their role in sequestering and protecting sedimentary organic matter as “Blue Carbon”.  However, in shallow calcifying systems the ultimate role of seagrass meadows as a sink or source of atmospheric CO<sub>2</sub> is complicated by carbonate precipitation and dissolution processes, which produce and consume CO<sub>2</sub>, respectively.  In general, microbial sulfate, iron, and nitrate reduction produce total alkalinity (TA), and the reverse reaction, the re-oxidation of the reduced species, consumes TA. Therefore, net production of TA only occurs when these reduced species are protected from re-oxidation, for example through the burial of FeS<sub>x</sub> or the escape of N<sub>2</sub>.  Seagrasses also affect benthic biogeochemistry by pumping O2 into the rhizosphere, which for example may allow for direct H2S oxidation.</p><p>Our study investigated the role of these factors and processes (seagrass density, sediment biogeochemistry, carbonate precipitation/dissolution, and ultimately air-sea CO<sub>2</sub> exchange), on CO<sub>2</sub> source-sink behavior in a shallow calcifying (carbonate content ~90%) seagrass meadow (Florida Bay, USA), dominated by Thalassia testudinum. We collected sediment cores from high and low seagrass density areas for flow through core incubations (N<sub>2</sub>, O<sub>2</sub>, DI<sup>13</sup>C, sulfide, DO<sup>13</sup>C flux), solid phase chemistry (metals, PO<sup>13</sup>C, Ca<sup>13</sup>C<sup>18</sup>O<sub>3</sub>, AVS: FeS + H<sub>2</sub>S, CRS: FeS<sub>2</sub> + S<sup>0</sup>), and porewater chemistry (major cations, DI<sup>13</sup>C, sulfide, <sup>34</sup>S<sup>18</sup>O<sub>4</sub>). An exciting aspect of this study is that it was conducted inside the footprint of an Eddy Covariance tower (air-sea CO<sub>2</sub> exchange), allowing us to directly link benthic processes with CO<sub>2</sub> sink-source dynamics.</p><p>During the course of our week long study, the seagrass meadow was a consistent source of CO<sub>2</sub> to the atmosphere (610 ± 990 µmol·m<sup>-2</sup>·hr<sup>-1</sup>).  Elevated porewater DIC near 15 cmbsf suggests rhizosphere O<sub>2</sub> induced carbonate dissolution, while consumption of DIC in the top 5-10 cm suggests reprecipitation.  With high seagrass density, enriched δ<sup>13</sup>C<sub>DIC </sub>in the DIC maximum zone (10-25 cm) suggests continual reworking of the carbonates through dissolution/precipitation processes towards more stable PIC, indicating that seagrasses can promote long-term stability of PIC.  We constructed a simple elemental budget, which suggests that net alkalinity consumption by ecosystem calcification explains >95% of the observed CO<sub>2</sub> emissions.  Net alkalinity production through net denitrification (and loss of N<sub>2</sub>) and net sulfate reduction (and subsequent burial of FeS<sub>2</sub> + S<sup>0</sup>), as well as observed organic carbon burial, could only minimally offset ecosystem calcification.   </p>

scholarly journals Coastal morphology explains global blue carbon distributions

2018 ◽  
Author(s):  
Robert R Twilley ◽  
André S Rovai ◽  
Pablo Riul
Keyword(s):  
Ghg Emissions ◽  
Terrestrial Ecosystem ◽  
Global Scale ◽  
Blue Carbon ◽  
Mangrove Forests ◽  
Coastal Morphology ◽  
C Storage ◽  
C Cycle ◽  
C Stocks

Because mangroves store greater amounts of carbon (C) per area than any other terrestrial ecosystem, conservation of mangrove forests on a global scale represents a potentially meaningful strategy for mitigating atmospheric greenhouse‐gas (GHG) emissions. However, analyses of how coastal ecosystems influence the global C cycle also require the mapping of ecosystem area across the Earth's surface to estimate C storage and flux (movement) in order to compare how different ecosystem types may mitigate GHG enrichment in the atmosphere. In this paper, we propose a new framework based on diverse coastal morphology (that is, different coastal environmental settings resulting from how rivers, tides, waves, and climate have shaped coastal landforms) to explain global variations in mangrove C storage, using soil organic carbon (SOC) as a model to more accurately determine mangrove contributions to global C dynamics. We present, to the best of our knowledge, the first global mangrove area estimate occupying distinct coastal environmental settings, comparing the role of terrigenous and carbonate settings as global “blue carbon” hotspots. C storage in deltaic settings has been overestimated, while SOC stocks in carbonate settings have been underestimated by up to 50%. We encourage the scientific community, which has largely focused on blue carbon estimates, to incorporate coastal environmental settings into their evaluations of C stocks, to obtain more robust estimates of global C stocks.

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