scholarly journals Carbon sink services for tropical coastal seagrass are far lower than anticipated when accounting for black carbon

2018 ◽  
Author(s):  
John B. Gallagher ◽  
Chee Hoe Chuan ◽  
Tzuen-Kiat Yap ◽  
W Farahain
Keyword(s):  
Organic Carbon ◽  
Black Carbon ◽  
Carbon Sink ◽  
Stock Assessment ◽  
Organic Carbon Content ◽  
Urban Centre ◽  
Seagrass Meadows ◽  
Marine Park ◽  
Major Urban Centre ◽  
Coastal Meadows

Valuing the sedimentary ‘blue carbon’ stocks of seagrass meadows in mitigating greenhouse gas emissions requires the exclusion of allochthonous recalcitrant forms, such as black carbon (BC) from the stock assessment. Regression models constructed across a tropical estuary predicted that carbon sinks within the more abundant sandy meadows of coastal bays likely support a significant but modest BC fraction. We tested the prediction by measuring BC fractions of total organic carbon (TOC) across three coastal meadows of the same region. One patchy meadow was located close to a major urban centre while the remaining two continuous meadows where contained in separate open embayments of a rural marine park, differing in fetch and species. In all cases, the BC/TOC fractions were significantly greater than predicted constituting a major component of the organic carbon content, 28% ± 1.6, and 26% ± 4.9 to 36% ± 1.5 (±95% confidence intervals) for urban and marine park meadows respectively. The higher BC/TOC fractions were explained by site-specific variability in BC atmospheric supply, patchy coverage, and a presumed increase in the loss of seagrass litter, as determined by the canopy height and proximity to the meadows exposed edge.

scholarly journals Carbon stocks of coastal seagrass in Southeast Asia may be far lower than anticipated when accounting for black carbon

2019 ◽  
Vol 15 (5) ◽  
pp. 20180745 ◽  
Author(s):  
John B. Gallagher ◽  
Chee Hoe Chuan ◽  
Tzuen-Kiat Yap ◽  
Wydia Farhain Fredelina Dona
Keyword(s):  
Black Carbon ◽  
Confidence Intervals ◽  
Sediment Resuspension ◽  
Carbon Stocks ◽  
Urban Centre ◽  
Seagrass Meadows ◽  
Marine Park ◽  
Major Urban Centre ◽  
Forms Of Carbon ◽  
Coastal Meadows

Valuing sedimentary ‘blue carbon’ stocks of seagrass meadows requires exclusion of allochthonous recalcitrant forms of carbon, such as black carbon (BC). Regression models constructed across a Southeast Asian tropical estuary predicted that carbon stocks within the sandy meadows of coastal embayments would support a modest but not insignificant amount of BC. We tested the prediction across three coastal meadows of the same region: one patchy meadow located close to a major urban centre and two continuous meadows contained in separate open embayments of a rural marine park; all differed in fetch and species. The BC/total organic carbon (TOC) fractions in the urban and rural meadows with small canopies were more than double the predicted amounts, 28 ± 1.6% and 36 ± 1.5% (±95% confidence intervals), respectively. The fraction in the rural large-canopy meadow remained comparable to the other two meadows, 26 ± 4.9% (±95% confidence intervals) but was half the amount predicted, likely owing to confounding of the model. The relatively high BC/TOC fractions were explained by variability across sites of BC atmospheric supply, an increase in loss of seagrass litter close to the exposed edges of meadows and sediment resuspension across the dispersed patchy meadow.

Carbon, nitrogen and phosphorus storage in subtropical seagrass meadows: examples from Florida Bay and Shark Bay

2012 ◽  
Vol 63 (11) ◽  
pp. 967 ◽  
Author(s):  
James W. Fourqurean ◽  
Gary A. Kendrick ◽  
Laurel S. Collins ◽  
Randolph M. Chambers ◽  
Mathew A. Vanderklift
Keyword(s):  
Organic Carbon ◽  
Carbon Content ◽  
Primary Productivity ◽  
Florida Bay ◽  
Organic Carbon Content ◽  
Nitrogen And Phosphorus ◽  
Organic C ◽  
Shark Bay ◽  
Seagrass Meadows ◽  
C Storage

Seagrass meadows in Florida Bay and Shark Bay contain substantial stores of both organic carbon and nutrients. Soils from both systems are predominantly calcium carbonate, with an average of 82.1% CaCO3 in Florida Bay compared with 71.3% in Shark Bay. Soils from Shark Bay had, on average, 21% higher organic carbon content and 35% higher phosphorus content than Florida Bay. Further, soils from Shark Bay had lower mean dry bulk density (0.78 ± 0.01 g mL–1) than those from Florida Bay (0.84 ± 0.02 mg mL–1). The most hypersaline regions of both bays had higher organic carbon content in surficial soils. Profiles of organic carbon and phosphorus from Florida Bay indicate that this system has experienced an increase in P delivery and primary productivity over the last century; in contrast, decreasing organic carbon and phosphorus with depth in the soil profiles in Shark Bay point to a decrease in phosphorus delivery and primary productivity over the last 1000 y. The total ecosystem stocks of stored organic C in Florida Bay averages 163.5 MgCorg ha–1, lower than the average of 243.0 MgCorg ha–1 for Shark Bay; but these values place Shark and Florida Bays among the global hotspots for organic C storage in coastal ecosystems.

scholarly journals Can mud (silt and clay) concentration be used to predict soil organic carbon content within seagrass ecosystems?

2016 ◽  
Author(s):  
O. Serrano ◽  
P. S. Lavery ◽  
C. M. Duarte ◽  
G. A. Kendrick ◽  
A. Calafat ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Carbon Content ◽  
Clay Content ◽  
Cost Effective ◽  
Blue Carbon ◽  
Organic Carbon Content ◽  
Terrestrial Organic Matter ◽  
Seagrass Meadows ◽  
Clay Concentration ◽  
Seagrass Ecosystems

Abstract. The emerging field of blue carbon science is seeking cost-effective ways to estimate the organic carbon content of soils that are bound by coastal vegetated ecosystems. Organic carbon (Corg) content in terrestrial soils and marine sediments has been correlated with mud content (i.e. silt and clay), however, empirical tests of this theory are lacking for coastal vegetated ecosystems. Here, we compiled data (n = 1345) on the relationship between Corg and mud (i.e. silt and clay, particle sizes <63 μm) contents in seagrass ecosystems (79 cores) and adjacent bare sediments (21 cores) to address whether mud can be used to predict soil Corg content. We also combined these data with the δ13C signatures of the soil Corg to understand the sources of Corg stores. The results showed that mud is positively correlated with soil Corg content only when the contribution of seagrass-derived Corg to the sedimentary Corg pool is relatively low, such as in small and fast growing meadows of the genera Zostera, Halodule and Halophila, and in bare sediments adjacent to seagrass ecosystems. In large and long-living seagrass meadows of the genera Posidonia and Amphibolis there was a lack of, or poor relationship between mud and soil Corg content, related to a higher contribution of seagrass-derived Corg to the sedimentary Corg pool in these meadows. The relative high soil Corg contents with relatively low mud contents (i.e. mud-Corg saturation) together with significant allochthonous inputs of terrestrial organic matter could overall disrupt the correlation expected between soil Corg and mud contents. This study shows that mud (i.e. silt and clay content) is not a universal proxy for blue carbon content in seagrass ecosystems, and therefore should not be applied generally across all seagrass habitats. Mud content can only be used as a proxy to estimate soil Corg content for scaling up purposes when opportunistic and/or low biomass seagrass species (i.e. Zostera, Halodule and Halophila) are present (explaining 34 to 91% of variability), and in bare sediments (explaining 78% of the variability).

scholarly journals Major role of marine vegetation on the oceanic carbon cycle

2005 ◽  
Vol 2 (1) ◽  
pp. 1-8 ◽  
Author(s):  
C. M. Duarte ◽  
J. J. Middelburg ◽  
N. Caraco
Keyword(s):  
Organic Carbon ◽  
Salt Marshes ◽  
Total Carbon ◽  
Organic Carbon Content ◽  
Top Down ◽  
Coastal Habitats ◽  
Bottom Up ◽  
Seagrass Meadows ◽  
Carbon Burial ◽  
Oceanic Carbon

Abstract. The carbon burial in vegetated sediments, ignored in past assessments of carbon burial in the ocean, was evaluated using a bottom-up approach derived from upscaling a compilation of published individual estimates of carbon burial in vegetated habitats (seagrass meadows, salt marshes and mangrove forests) to the global level and a top-down approach derived from considerations of global sediment balance and a compilation of the organic carbon content of vegeatated sediments. Up-scaling of individual burial estimates values yielded a total carbon burial in vegetated habitats of 111 Tmol C y-1. The total burial in unvegetated sediments was estimated to be 126 Tg C y-1, resulting in a bottom-up estimate of total burial in the ocean of about 244 Tg C y-1, two-fold higher than estimates of oceanic carbon burial that presently enter global carbon budgets. The organic carbon concentrations in vegetated marine sediments exceeds by 2 to 10-fold those in shelf/deltaic sediments. Top-down recalculation of ocean sediment budgets to account for these, previously neglected, organic-rich sediments, yields a top-down carbon burial estimate of 216 Tg C y-1, with vegetated coastal habitats contributing about 50%. Even though vegetated carbon burial contributes about half of the total carbon burial in the ocean, burial represents a small fraction of the net production of these ecosystems, estimated at about 3388 Tg C y-1, suggesting that bulk of the benthic net ecosystem production must support excess respiration in other compartments, such as unvegetated sediments and the coastal pelagic compartment. The total excess organic carbon available to be exported to the ocean is estimated at between 1126 to 3534 Tg C y-1, the bulk of which must be respired in the open ocean. Widespread loss of vegetated coastal habitats must have reduced carbon burial in the ocean by about 30 Tg C y-1, identifying the destruction of these ecosystems as an important loss of CO2 sink capacity in the biosphere.

scholarly journals Can mud (silt and clay) concentration be used to predict soil organic carbon content within seagrass ecosystems?

2016 ◽  
Vol 13 (17) ◽  
pp. 4915-4926 ◽  
Author(s):  
Oscar Serrano ◽  
Paul S. Lavery ◽  
Carlos M. Duarte ◽  
Gary A. Kendrick ◽  
Antoni Calafat ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Carbon Content ◽  
Low Cost ◽  
Cost Effective ◽  
Scaling Up ◽  
Blue Carbon ◽  
Organic Carbon Content ◽  
Terrestrial Organic Matter ◽  
Seagrass Meadows ◽  
Seagrass Ecosystems

Abstract. The emerging field of blue carbon science is seeking cost-effective ways to estimate the organic carbon content of soils that are bound by coastal vegetated ecosystems. Organic carbon (Corg) content in terrestrial soils and marine sediments has been correlated with mud content (i.e., silt and clay, particle sizes < 63 µm), however, empirical tests of this theory are lacking for coastal vegetated ecosystems. Here, we compiled data (n =  1345) on the relationship between Corg and mud contents in seagrass ecosystems (79 cores) and adjacent bare sediments (21 cores) to address whether mud can be used to predict soil Corg content. We also combined these data with the δ13C signatures of the soil Corg to understand the sources of Corg stores. The results showed that mud is positively correlated with soil Corg content only when the contribution of seagrass-derived Corg to the sedimentary Corg pool is relatively low, such as in small and fast-growing meadows of the genera Zostera, Halodule and Halophila, and in bare sediments adjacent to seagrass ecosystems. In large and long-living seagrass meadows of the genera Posidonia and Amphibolis there was a lack of, or poor relationship between mud and soil Corg content, related to a higher contribution of seagrass-derived Corg to the sedimentary Corg pool in these meadows. The relatively high soil Corg contents with relatively low mud contents (e.g., mud-Corg saturation) in bare sediments and Zostera, Halodule and Halophila meadows was related to significant allochthonous inputs of terrestrial organic matter, while higher contribution of seagrass detritus in Amphibolis and Posidonia meadows disrupted the correlation expected between soil Corg and mud contents. This study shows that mud is not a universal proxy for blue carbon content in seagrass ecosystems, and therefore should not be applied generally across all seagrass habitats. Mud content can only be used as a proxy to estimate soil Corg content for scaling up purposes when opportunistic and/or low biomass seagrass species (i.e., Zostera, Halodule and Halophila) are present (explaining 34 to 91 % of variability), and in bare sediments (explaining 78 % of the variability). The results obtained could enable robust scaling up exercises at a low cost as part of blue carbon stock assessments.

scholarly journals Major role of marine vegetation on the oceanic carbon cycle

2004 ◽  
Vol 1 (1) ◽  
pp. 659-679 ◽  
Author(s):  
C. M. Duarte ◽  
J. J. Middelburg ◽  
N. Caraco
Keyword(s):  
Organic Carbon ◽  
Salt Marshes ◽  
Total Carbon ◽  
Organic Carbon Content ◽  
Top Down ◽  
Coastal Habitats ◽  
Bottom Up ◽  
Seagrass Meadows ◽  
Carbon Burial ◽  
Oceanic Carbon

Abstract. The carbon burial in vegetated sediments, ignored in past assessments of carbon burial in the ocean, was evaluated using a bottom-up approach derived from upscaling a compilation of published individual estimates of carbon burial in vegetated habitats (seagrass meadows, salt marshes and mangrove forests) to the global level and a top-down approach derived from considerations of global sediment balance and a compilation of the organic carbon content of vegeatated sediments. Up-scaling of individual burial estimates values yielded a total carbon burial in vegetated habitats of 111 Tg C y-1. The total burial in unvegetated sediments was estimated to be 126 Tg C y-1, resulting in a bottom-up estimate of total burial in the ocean of 244 Tg C y-1, two-fold higher than estimates of oceanic carbon burial that presently enter global carbon budgets. The organic carbon concentrations in vegetated marine sediments exceeds by 2 to 10-fold those in shelf/deltaic sediments. Top-down recalculation of ocean sediment budgets to account for these, previously neglected, organic-rich sediments, yields a top-down carbon burial estimate of 197 Tg C y-1, with vegetated coastal habitats contributing about 50%. Even though vegetated carbon burial contribute about half of the total carbon burial in the ocean, burial represents a small fraction of the net production of these ecosystems, estimated at about 3031 Tg C y-1, suggesting that bulk of the benthic NEP must support excess respiration in other compartments, such as unvegetated sediments and the coastal pelagic compartment. The total excess organic carbon available to be exported to the ocean is estimated at between 769 to 3177 Tg C y-1, the bulk of which must be respired in the open ocean. Widespread loss of vegetated coastal habitats must have reduced carbon burial in the ocean by about 30 Tg C y-1, identifying the destruction of these ecosystems as an important loss of CO2 sink capacity in the biosphere.

scholarly journals Seagrass contribution to blue carbon in a shallow karstic coastal area of the Gulf of Mexico

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e12109
Author(s):  
Tania C. Cota Lucero ◽  
Jorge A. Herrera-Silveira
Keyword(s):  
Organic Carbon ◽  
Carbon Stock ◽  
Carbon Sink ◽  
Anthropogenic Impacts ◽  
Regional Scale ◽  
Mitigation Strategies ◽  
Conservation Strategies ◽  
Seagrass Meadows ◽  
Seagrass Community ◽  
Organic Carbon Stock

Seagrass meadows provide multiple ecosystem services, including carbon sequestration. However, seagrass meadows are among the most threatened ecosystems worldwide. Determining the magnitude of the carbon stocks in seagrass meadows at the regional scale allows for the estimation of their global magnitude and identification of their importance in regional environmental mitigation strategies. The objective of the present study was to determine the structure of seagrass meadows in the Los Petenes Biosfera Reserve (LPBR) and evaluate their contributions to sinks of carbon in this system, located in Yucatan, which is considered the region with the largest seagrass extension in Mexico. Analyses of the seagrass meadows were executed following standardized protocols (spectral analysis, and isotope and carbon stock analyses). The LPBR stores an average of 2.2 ± 1.7 Mg C ha−1 in living biomass and 318 ± 215 Mg C ha−1 in sediment (top 1 m), and this carbon stock decreases with water depth. The seagrass community extends 149,613 ha, which represents the largest organic carbon stock (47 Tg C) documented in seagrass meadows in Mexico. Macroalgae and seagrass represent 76% of the organic carbon stored in sediment. If LPBR seagrass meadows are lost due to natural or anthropogenic impacts, 173 Tg CO2eqemissions could be released, which corresponds to the emissions generated by fossil fuel combustion of 27% of the current Mexican population. This information emphasizes the importance of seagrass meadows as a carbon sink in the region and their contribution to climate change mitigation, thus allowing for the implementation of necessary conservation strategies.

The decomposition rate of the organic carbon content of suspended particulate matter in the tropical seagrass meadows

2021 ◽  
Vol 40 (8) ◽  
pp. 44-52
Author(s):  
A’an Johan Wahyudi ◽  
Karlina Triana ◽  
Afdal Afdal ◽  
Hanif Budi Prayitno ◽  
Edwards Taufiqurrahman ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Organic Carbon ◽  
Carbon Content ◽  
Suspended Particulate Matter ◽  
Decomposition Rate ◽  
Organic Carbon Content ◽  
Seagrass Meadows ◽  
Suspended Particulate

scholarly journals Inferring absorbing organic carbon content from AERONET data

2011 ◽  
Vol 11 (1) ◽  
pp. 215-225 ◽  
Author(s):  
A. Arola ◽  
G. Schuster ◽  
G. Myhre ◽  
S. Kazadzis ◽  
S. Dey ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Black Carbon ◽  
Biomass Burning ◽  
Urban Areas ◽  
Organic Carbon Content ◽  
Industrialized Countries ◽  
Brown Carbon ◽  
Newly Industrialized Countries ◽  
Absorbing Aerosols ◽  
India And China

Abstract. Black carbon, light-absorbing organic carbon (often called "brown carbon") and mineral dust are the major light-absorbing aerosols. Currently the sources and formation of brown carbon aerosol in particular are not well understood. In this study we estimated the amount of light–absorbing organic carbon and black carbon from AERONET measurements. We find that the columnar absorbing organic carbon (brown carbon) levels in biomass burning regions of South America and Africa are relatively high (about 15–20 mg m−2 during biomass burning season), while the concentrations are significantly lower in urban areas in US and Europe. However, we estimated significant absorbing organic carbon amounts from the data of megacities of newly industrialized countries, particularly in India and China, showing also clear seasonality with peak values up to 30–35 mg m−2 during the coldest season, likely caused by the coal and biofuel burning used for heating. We also compared our retrievals with the modeled organic carbon by the global Oslo CTM for several sites. Model values are higher in biomass burning regions than AERONET-based retrievals, while the opposite is true in urban areas in India and China.

scholarly journals Inferring absorbing organic carbon content from AERONET data

2010 ◽  
Vol 10 (8) ◽  
pp. 18365-18388 ◽  
Author(s):  
A. Arola ◽  
G. Schuster ◽  
G. Myhre ◽  
S. Kazadzis ◽  
S. Dey ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Black Carbon ◽  
Biomass Burning ◽  
Urban Areas ◽  
Organic Carbon Content ◽  
Industrialized Countries ◽  
Brown Carbon ◽  
Newly Industrialized Countries ◽  
Absorbing Aerosols ◽  
India And China

Abstract. Black carbon, light-absorbing organic carbon (often called "brown carbon") and mineral dust are the major light-absorbing aerosols. Currently the sources and formation of brown carbon aerosol in particular are not well understood. In this study we estimated globally the amount of light-absorbing organic carbon and black carbon from AERONET measurements. We find that the columnar absorbing organic carbon (brown carbon) levels in biomass burning regions of South-America and Africa are relatively high (about 15–20 mg/m2 during biomass burning season), while the concentrations are significantly lower in urban areas in US and Europe. However, we estimated significant absorbing organic carbon amounts from the data of megacities of newly industrialized countries, particularly in India and China, showing also clear seasonality with peak values up to 30–35 mg/m2 during the coldest season, likely caused by the coal and biofuel burning used for heating. We also compared our retrievals with the modeled organic carbon by global Oslo CTM for several sites. Model values are higher in biomass burning regions than AERONET-based retrievals, while opposite is true in urban areas in India and China.

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