Sediment Carbon Stocks Research Articles

Carbon stocks in Norwegian eelgrass meadows across environmental gradients

Seagrass meadows are well-known for their capacity to capture and store blue carbon in sediments. However carbon stocks vary significantly between meadows, spanning more than three orders of magnitude on both local and global scales. Understanding the drivers of seagrass carbon stocks could help improve strategies for incorporating blue carbon into management plans. Here, we measured sediment carbon stocks in eelgrass (Zostera marina) meadows and unvegetated areas along the Norwegian coast, spanning wide gradients in temperature, wave exposure, water depth, salinity, and eelgrass biomass. Carbon stocks were generally higher in eelgrass meadows than in adjacent unvegetated areas, yet they displayed considerable variation (400 − 30 000 g C m−2 at 50 cm sediment depth) even among nearby sites. Overall, the highest carbon stocks were found in deeper, muddier, sheltered meadows near river mouths. These sites likely have the highest input and retention of carbon from different sources. Consequently, they should be prioritized as conservation targets for preserving coastal blue carbon stocks. Despite ever-increasing efforts to quantify seagrass blue carbon globally, high uncertainties still persist, partly due to differing methodologies, processes, and environmental context. Blue carbon stock estimates could be improved through the coordination of standardised mapping and sampling methods.

Mapping and Identification of Ecosystem Services Hotspots in the Brazilian Pampa Biome.

The intensification and expansion of changes in land use and land cover (LULC) can reduce the availability and quality of natural habitats and ecosystem services (ES). These changes have generated environmental damage in different parts of the world, especially in biomes more susceptible to modifications, such as the Pampa biome in the extreme south of Brazil. The Pampa biome has been neglected by environmental protection laws, despite its broad ecosystem and social importance. In this study, we used InVEST models to map and quantify five ES provided (i.e., water supply, carbon stock, groundwater stock, sediment retention and habitat quality) by 14 watersheds distributed in the Brazilian Pampa biome as well as determine ES hotspots by summing the areas with high provision of ES. We identified low availability of water supply and groundwater stock in practically the entire study area. High sediment retention and carbon stock were reported in areas with the presence of native vegetation. In addition, despite the large degraded areas, we observed high habitat quality associated with native vegetation in all studied watersheds. The hotspots varied spatially in the study area according to the proposed scenarios, the supply and the overlap of ES. Scenario 1 (>50% of ES) presented a larger area of high provision of ES. In contrast, scenario 2 (>75% of ES) presented smaller patches of areas with high provision of ES distributed across different watershed. We observed that large territorial extensions with high and medium provision of ES are vulnerable to the negative effects of LULC. Our study presented scenarios that indicate areas of high provision of ES, contributing to a more practical application, being a simplified and useful tool that can assist conservation and sustainable policies.

Relationship between seagrass community structure and carbon stocks on the coasts of Karimunjawa Marine National Park, Indonesia

The seagrass ecosystem is considered one of the most effective coastal ecosystems in storing carbon. Carbon stock estimation for a certain ecosystem is highly affected by factors such as species diversity and habitat type. This study aims to investigate the relationship between plant community structure and carbon stocks in the seagrass ecosystem using a case study of six coastal sites in Karimunjawa Marine National Park, Indonesia. In this region, eight seagrass species were recorded, i.e., Enhalus acoroides, Thalassia hemprichii, Cymodocea rotundata, Halodule pinifolia, Halophila ovalis, Halophila minor, Syringodium isoetifolium, and Oceana serrulata. From the six study sites, the highest estimated carbon stock was 426.2 Mg C ha−1 (Site 5; Telaga, dominated by E. acoroides). Meanwhile, the lowest estimated carbon stock was 127.4 Mg C ha−1 (Site 4; Koin, dominated by T. hemprichii). The density of E. acoroides was positively correlated with the total seagrass biomass carbon stocks (r = 0.97; p < 0.01), while its dominance was positively correlated with sediment carbon stocks (r = 0.92; p < 0.05) and total seagrass ecosystem carbon stocks (r = 0.92; p < 0.05). Seagrass ecosystems with different community structures showed different carbon storage capacities. Seagrass ecosystems dominated by large-sized species such as E. acoroides showed higher estimated carbon stocks thus suggesting the importance of considering the variability of community structure in managing seagrass ecosystems for carbon sequestration and storage.

Adaptive stacked species distribution modelling: Novel approaches to large scale quantification of blue carbon to support marine management

This study introduces a novel concept of ‘Adaptively Stacked’ Species Distribution Models (AS-SDMs) to predict blue carbon habitat distribution, abundance, carbon stocks, and carbon sequestration potential in Orkney. AS-SDMs are built from Weighted Boosted Regression Trees (WBRTs) that adaptively stack blue carbon sediment thickness, sediment carbon content, and sequestration potential to predicted abundance. A novel method to describe substrate types by relative inputs of mud, sand, and gravel is detailed that better characterises the determining factors of seagrass, maerl, and horse mussel abundance. This study also introduces a novel use of indexes to mitigate double counting issues of mixed species distribution models.Seagrass, maerl, horse mussel, and mixed seagrass and maerl (SGM) habitats are estimated to cover a maximum area of 657 km2 in Orkney, have a total sediment carbon stock of 16 Mt. C, and sequester 6000 t C yr−1. Applying a conservative threshold of 50 % abundance to habitat predictions, six key potential areas of blue carbon offset projects are identified. These areas cover just over 9 km2, have a total carbon stock of 330,000 t C, and sequester 330 t C yr−1. When applied to UK carbon credit value, assuming integration with voluntary markets and compliance with accreditation criteria, the habitats in these areas have a potential value of £24.5 million. If applied as annual values, these areas have carbon stocks with a potential value of £0.93 million yr−1 and a carbon sequestration potential value of £24,000 yr−1.

Carbon stock, density, and biomass of seagrass in South Bangka, Indonesia

Abstract. Supratman O, Farhaby AM, Henri, Septiyati MU, Adi W. 2024. Carbon stock, density, and biomass of seagrass in South Bangka, Indonesia. Biodiversitas 25: 1736-1742. As a component of the carbon ecosystem, seagrass meadows play a crucial role in preventing climatic change. The execution of Indonesian programs pertaining to carbon economic value, carbon trading, and other endeavors aimed at attaining the Nationally Determined Contribution (NDC) requires estimated data on seagrass carbon stocks. The present study investigates the seagrass density, vegetation carbon stock, and sediment carbon stock of South Bangka, Indonesia. The investigation is carried out in the following stages: i) data collection on-site, ii) laboratory sample analysis, and iii) data analysis. The accumulation of data on-site utilizes a square transect method, which includes the gathering of sediment, sample biomass, and density information. The carbon composition of sediment and seagrass vegetation is ascertained through laboratory analysis employing the Loss of Ignition (LOI) method. The investigation uncovered eight species of seagrass in South Bangka. Cymondocea rotundata, Enhalus acoroides, Halophila ovalis, Halodule pinifolia, Halodule uninervis, Oceana serrulata, Siringodium isotifolium, and Thalassia Hemprichii are the identified species of seagrass. In South Bangka, the combined carbon stock of seagrass (above and below ground carbon) varies between 0.049±0.057 and 1.323±1.581 Mg C Ha-1. The range of sediment carbon is 110.53±42.07 Mg Corg Ha-1 extrapolated to a depth of 1 m. The results of this study suggest that the seagrass meadows in South Bangka are characterized by a significant species diversity and effectively sequester carbon in the form of biomass and sediment. This supports the National Climate Change Mitigation Program for Blue Carbon Ecosystems, an initiative that seeks to mitigate the adverse effects of climate change by utilizing the carbon sequestration capabilities of mangrove forests, seagrass meadows, and tidal marshes.

Restoration of Aegiceras corniculatum Mangroves May Not Increase the Sediment Carbon, Nitrogen, and Phosphorus Stocks in Southeastern China

Mangrove ecosystems play important roles in mitigating climate change but are suffering from an area decrease. The sediment in a mangrove ecosystem is a crucial component in estuarine carbon and nutrient cycles. However, it is unclear whether the restoration of mangroves enhances their sediment carbon sequestration and nutrient storage. To investigate the restoration effects of native Aegiceras corniculatum mangrove forests, the contents and density of sediment organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) were quantified in an unvegetated mudflat (MF), an area with mature A. corniculatum (AC), and two restored A. corniculatum mangroves planted in 2002 (02AC) and 2008 (08AC) in Quanzhou, southeastern China. Compared with the MF, mangrove restoration increased the SOC and TN contents in the sediment, primarily at the 0–40 cm depth for SOC and 0–20 cm for TN, while the TP content was not impacted by restoration. The sediment under AC showed a higher SOC content only at the 0–10 cm and 20–40 cm depths compared to restored 02AC and 08AC. The restoration of A. corniculatum mangroves did not significantly increase the stock of sediment SOC, TN, and TP relative to the MF, which might be attributed to the decrease in bulk density and the relatively short restoration period. Thus, further continuous monitoring is needed to verify whether the sediment carbon pool can be promoted on a longer-term scale by the restoration of A. corniculatum.

Contributions of plant‐ and microbial‐derived residuals to mangrove soil carbon stocks: Implications for blue carbon sequestration

Abstract Coastal blue carbon ecosystems, particularly mangroves, are becoming increasingly recognised for their importance in mitigating climate change. Still, the specific patterns and drivers of plant lignin components and microbial necromass accumulation in these ecosystems are unclear. In response, we carried out a study along a 40‐year mangrove restoration chronosequence, measuring lignin phenol and amino sugar concentrations in soil profiles (0–100 cm) as indicators of plant‐based and microbial‐derived residues, respectively. Our results showed that restoration significantly increased plant lignin phenol and amino sugar concentrations, with mature mangroves having much higher concentrations than tidal flats. During restoration, the fungal necromass was greater than the bacterial necromass. The factors influencing the lignin phenols were tree biomass, total nitrogen, pH and salinity, while those influencing the formation of amino sugars were total biomass, soil C: N ratio and pH. While the amino sugars decreased, the lignin phenols increased with the content of SOC, providing evidence of the important role lignin phenol components play in the formation of SOC in mangrove. Synthesis: By separating soil carbon into plant‐based and microbial‐derived components, our results demonstrate that the carbon stock in mangrove sediments is vulnerable to disturbances and that changes from anaerobic to aerobic conditions cause significant carbon mineralisation. The precise identification of soil carbon sources in blue carbon ecosystems could aid in elucidating the mechanisms of soil carbon sequestration and their responses to environmental changes. Read the free Plain Language Summary for this article on the Journal blog.

Estimation of carbon stocks in mangrove sediments in Ruyung Village, Mesjid Raya District, Aceh Besar Regency

Exploration related to blue carbon has increased recently. As one of the blue carbon ecosystems, the mangrove ecosystem is one of the coastal ecosystems that can absorb and store carbon. This research aims to calculate mangrove density and estimate carbon stocks in sediments in the mangrove ecosystem in Ruyung Village, Mesjid Raya District, Aceh Besar Regency. Mangrove density was calculated at three stations within 10 x 10 m transects. Sediment samples were also taken compositely, and carbon analysis was carried out in the sediment using the LOI (loss on ignition) method. There were two species of mangroves found at the research location, namely Rhizophora apiculata and Avicennia officionalis. The research results show that the average mangrove density at the research location is 0.20 ind/m2. The average soil density and sediment carbon stock at all research stations is 1.24 g/cm3 and 271.66 MgC/ha respectively. The mangrove ecosystem, both biomass and surrounding sediment, can store carbon, which is one of the ways to mitigate global warming.

Substantial blue carbon sequestration in the world’s largest seagrass meadow

Seagrass meadows are important sinks for organic carbon and provide co-benefits. However, data on the organic carbon stock in seagrass sediments are scarce for many regions, particularly The Bahamas, which accounts for up to 40.7% of the documented global seagrass area, limiting formulation of blue carbon strategies. Here, we sampled 10 seagrass meadows across an extensive island chain in The Bahamas. We estimate that Bahamas seagrass meadows store 0.42–0.59 Pg organic carbon in the top-meter sediments with an accumulation rate of 2.1–2.9 Tg annually, representing a substantial global blue carbon hotspot. Autochthonous organic carbon in sediments decreased from ~1980 onwards, with concomitant increases in cyanobacterial and mangrove contributions, suggesting disturbance of seagrass ecosystems, likely caused by tourism and maritime traffic activities. This study provides seagrass blue carbon data from a vast, understudied region and contributes to improving climate action for The Bahamas and the Greater Caribbean region.

The carbon stock potential of the restored mangrove ecosystem of Pasarbanggi, Rembang, Central Java

Mangrove ecosystems can absorb significant amounts of carbon and help mitigate climate change. However, their existence continues to be endangered by natural and human forces. Therefore, mangrove restoration is regarded as a crucial component of the global climate change agenda. This study aims to estimate the potential total carbon stock of restored mangrove ecosystems in Pasarbanggi, Rembang, Central Java. The above-below-ground (root) carbon stock was calculated using several published allometric equations. The loss-on-ignition method analyzed leaf litter and sediment carbon stocks. This study estimates the Pasarbanggi mangrove ecosystem's total carbon stock potential at 0.02 × 106 MgC, which is equivalent to the potential CO2 emission of 0.08 × 106 MgCO2e, with up to 65% stored in sediments. This study highlights the critical role of restored mangrove ecosystems on the climate change mitigation agenda by reducing the concentration of atmospheric CO2.

Sediment Carbon Stock in Natural and Transplanted Mangroves in Bahrain, Arabian Gulf

Mangroves in the Arabian Gulf provide several biological, ecological, and environmental services. They are also considered among the largest carbon sinks. However, mangroves along the coastlines of the Arabian Gulf have degraded in recent decades, mainly due to urbanization and coastal development. Therefore, restoration and afforestation programs have been initiated to enhance the services and functions of mangrove ecosystems and as part of national targets to mitigate climate change. Increasing carbon sinks by quadrupling the current areas covered by mangroves through afforestation programs by 2035 is one of the strategies to mitigate climate change in Bahrain. The aim of the present study was to estimate the organic carbon stocks in the sediments of natural and transplanted mangroves in Bahrain. Within the protected areas of Tubli and Arad Bays, sediment samples were taken down to a depth of 70 cm from natural and transplanted mangroves as well as a bare mudflat. The findings of the present study indicated that the total sediment organic carbon concentrations at three sampling sites of natural and transplanted mangroves and the mudflat were 200.54 ± 24.52, 112.36 ± 55.51, and 81.56 ± 8.92 Mg C/ha, respectively. The natural mangroves in Tubli Bay differed considerably from those in Arad Bay (p ≤ 0.001), based on the concentrations of organic carbon in sediments. However, there was a noticeable similarity seen in the organic carbon of the mangroves in Arad Bay that were transplanted 25 years prior and the natural mangroves in Tubli Bay, indicating the importance of a long-term mangrove afforestation strategy to mitigate climate change in the Arabian Gulf.

Blue carbon stock heterogeneity in Brazilian mangrove forests: A systematic review

This is the first systematic review and meta-analysis of blue carbon stocks in Brazilian mangroves. We evaluated the effect of characteristics and site status (impacted versus non-impacted) on carbon stocks found in the various compartments on total ecosystem carbon stock (TECS). TECS followed an inverse trend with the latitudinal position: the highest values were found on the North coast (mean 511 Mg C ha−1), followed by the Northeast and Southeast. A similar latitudinal trend was observed for sediment and above-ground biomass carbon stocks. Site status also significantly affected TECS and sediment carbon stocks. The heterogeneity observed in carbon stocks suggests that tidal regime, latitudinal position, climate, and human impacts jointly drive the processes related to sequestration and storage. Brazilian mangroves store ~0.44 PgC, representing 10–12 % of the world TECS. This highlights Brazilian mangroves as a global blue carbon hotspot, and as an efficient nature-based solution for carbon dioxide removal.

Little change in surface sediment carbon stock following seagrass restoration in Shark Bay, Western Australia

Seagrass restoration might contribute to climate change mitigation efforts by restoring carbon sequestration capacity where it has been lost. However, there have been few empirical investigations into the rate and magnitude of changes in sediment organic carbon stock following seagrass restoration. This study aims to compare patterns of sediment organic carbon stock in the early stages after restoration (6 months, 2 years, 2.5 years, and 5 years) of the seagrass Posidonia australis with adjacent unvegetated sand and continuously vegetated seagrass in Shark Bay, Western Australia. Sediment carbon stock in all restored areas were not significantly different from unvegetated sand, regardless of age. Organic carbon concentrations in surface sediments were similar throughout the top 3 cm. In addition, δ13C of organic carbon of sediment from newly restored seagrass meadows was not significantly different from δ13C of organic carbon from unvegetated sediment. These results indicate that carbon sequestration capacity had not returned up to 5 years after restoration. There is increasing evidence that sediment carbon stocks show little recovery in the early stages of restoration and can take >5 years to return to quantities expected from seagrass meadows.

Multiple drivers for carbon stocks and fluxes in different types of mangroves

Mangroves are highly efficient in sequestering carbon from the atmosphere and can accumulate carbon in sediments for millennials. However, The fate of mangrove carbon has not been well constrained due to the lack of data on different pools of sediment carbon sinks and sources. This study examined the variation of carbon stocks and fluxes at the water-sediment-air interface in both estuarine mangroves (natural: Mai Po, restored: Gei Wai) and oceanic mangroves (Ting Kok). There are divergent patterns in biogeochemical variables at the sediment-water-air interface, likely due to significant variation within sites. Total sediment carbon stocks (TCs) ranked in the order of restored estuarine mangroves (392.5 ± 8.8 Mg ha−1), natural estuarine mangroves affected by aquaculture (315.2 ± 21.4 Mg ha−1) and oceanic mangroves (229.1 ± 32.3 Mg ha−1). Sediment organic carbon stocks (SOC) and inorganic carbon stocks (SIC) accounted for 84.1–90.2 % and 9.8–15.9 % of TC, respectively. The highest sediment-air CO2 and CH4 fluxes occurred in restored and natural estuarine mangroves affected by aquaculture, respectively. The isotope of CO2 fluxes (δ13C-CO2) indicates higher contributions from the degradation of mangrove-derived organic carbon in restored (−25.94 ‰ ± 3.37 ‰) and natural estuarine mangroves affected by aquaculture (−25.54 ‰ ± 0.96 ‰) than in oceanic mangroves (−21.55 ‰ ± 1.36 ‰). The isotope of CH4 fluxes (δ13C-CH4) indicates CH4 production dominated by acetate fermentation in restored estuarine mangroves but dominated by the reduction of CO2 for other sites. Future studies should better constrain the fate of mangrove carbon by considering local drivers.

Stok Karbon Organik Sedimen di Kawasan Ekosistem Mangrove Pesisir Kabupaten Kolaka Sulawesi Tenggara

Mangrove ecosystem can absorb and store carbon stock in their biomass and sediment. This ecosystem plays an important role in the carbon cycle. This study aimed to analyze the C-organic content and organic carbon stock of sediment, also CO2 absorption. The sediment sampling was conducted in the Kolaka Coastal line mangroves using a Peat Auger for 1 m of sediment depth. Then the sediment was separated into four layers. Then the sediment samples were oven dried at 50°C for 1 week for sediment bulk density analysis (SBD). The analysis of the C-organic content of sediment was done by the LOI method. The estimation of sediment carbon stock using sediment C-organic data and SBD data. The results showed that the highest average of C-organic content was in station 3 (4.12±0.15%). In the othher hand, the highest average of SBD was in station 1 (0.67±0.02 g cm-3). Overall, the total of sediment C-organic stock in station 1 was higher than other station (233.67±11.90 Mg C ha-1). The total capacity of CO2 absorption by sediment in the station 1 was also higher than other station (856.77±37.66 Mg CO2 ha-1). The sediment C-organic stock was influenced by C-organic content and SBD value.

Sedimentary seagrass carbon stock and sources of organic carbon across contrasting seagrass meadows in Indonesia.

Seagrass meadows are an important component of coastal ecosystems globally, and they capture and store organic carbon in living biomass and sediments. Geographical estimates of blue carbon in seagrass habitats are regionally biased, with limited information from the Indo-Pacific region, including Indonesia. Seagrass extent in Indonesia is declining rapidly, and it has been suggested that marine protected areas (MPAs) are an important instrument to support protection of seagrass ecosystems and their services. Thus, this study is aimed at quantifying and comparing sedimentary carbon stocks and sources of organic carbon from seagrass meadows located in undisturbed areas outside MPA, disturbed areas outside MPA, and within MPA in three small islands in Indonesia. The sediment carbon stocks from this study ranged from 19.81 to 117.49 Mg C ha-1, with the highest stock measured inside MPA (77.15 ± 1.38 Mg C ha-1), followed by undisturbed outside MPA (36.08 Mg C ha-1), and the lowest stock at disturbed outside MPA (21.86 ± 0.31 Mg C ha-1). The predominant source of organic carbon in disturbed meadows was from coastal POM (particulate organic matter, ~ 36%), while in MPA and undisturbed sites, the main source was from seagrass, with ~ 38% and ~ 60% contributions, respectively. The results of this study add more data and information on seagrass blue carbon potential from three different islands with different degrees of disturbance in Indonesia.

The Variability of Sedimentary Carbon Stock in Seagrass Ecosystem in Central Tapanuli, Indonesia

Blue carbon is a term to underline coastal ecosystem such as mangrove, seagrass, and tidal marshes capability as carbon sequestration where the organic carbon that stored in coastal sediment is greater than the organic carbon in living biomass. This study analysed the variability of sediment carbon stock in seagrass ecosystem in Central Tapanuli, Indonesia. LOI method was used to determine the carbon stock. Regression analysis showed that depth, and dry bulk density strongly influence the sedimen carbon stock in seagrass ecosystem (R2 = 0.77 in Hajoran and R2 = 0.79 in Jago-jago) where the total organic carbon stock in upper layer and denser sediment was higher than the organic carbon stock in middle/bottom layer sediment. Moreover, sediment type also influenced the carbon stock where sediment with finer grain size (11.80 – 13.46 Mg C/ha) captured more organic carbon than sand (6.54 – 10.34 Mg C/ha). By knowing this capacity, monitoring and maintaining coastal sediment and vegetation should become priority to mitigate the climate change.

Prevalent fingerprint of marine macroalgae in arctic surface sediments

Macroalgal forests export much of their production, partly supporting food webs and carbon stocks beyond their habitat, but evidence of their contribution in sediment carbon stocks is poor. We test the hypothesis that macroalgae contribute to carbon stocks in arctic marine sediments. We used environmental DNA (eDNA) fingerprinting on a large-scale set of surface sediment samples from Greenland and Svalbard. We evaluated eDNA results by comparing with traditional survey and tracer methods. The eDNA-based survey identified macroalgae in 94 % of the sediment samples covering shallow nearshore areas to 1460 m depth and 350 km offshore, with highest sequence abundance nearshore and with dominance of brown macroalgae. Overall, the eDNA results reflected the potential source communities of macroalgae and eelgrass assessed by traditional surveys, with the most abundant orders being common among different methods. A stable isotope analysis showed a considerable contribution from macroalgae in sediments although with high uncertainty, highlighting eDNA as a great improvement and supplement for documenting macroalgae as a contributor to sediment carbon stocks. Conclusively, we provide evidence for a prevalent contribution of macroalgal forests in arctic surface sediments, nearshore as well as offshore, identifying brown algae as main contributors.

ESTIMATION OF CARBON RESERVES IN SEDIMENTS IN THE MANGROVE ECOSYSTEM OF BUKIT BATU VILLAGE, BENGKALIS REGENCY, RIAU

This research was carried out in December 2021. Sampling and water quality measurements were carried out in the Bukit Batu Muara River, Bengkalis Regency, Riau Province. Sample analysis was continued at the Marine Chemistry Laboratory, Department of Marine Science, Faculty of Fisheries and Marine, Universitas Riau. The purpose of this study was to determine the estimation of carbon stocks in sediments, the comparison of carbon stocks between transects, and the relationship between density and carbon stocks in the Muara Sungai Bukit Batu mangrove area, Bengkalis Regency, Riau Province. The method used in this study is a survey method. Parameters measured included mangrove density (Ind/Ha), organic matter content, and carbon stock in sediments. In addition, water quality was also measured in the form of temperature, salinity, and degree of acidity. Analysis of carbon stock using the loss on ignition method. The result of the average density of mangroves throughout the transect is 3733.33 (Ind/Ha). The lowest carbon stock value in sediments is in transect 2 with medium mangrove density with a value of 29.26 tons/ha, while the highest carbon stock value is in transect 3 with high-density mangrove areas with a value of 36.15 tons/ha. The results of a simple linear regression to determine the relationship between mangrove density and carbon stock show a coefficient of determination R² = 0.023, which means that 2.3% of total carbon stock is affected by density, while 97.7% is influenced by other factors. The value of R = 0.152, which means that the relationship between density and carbon stock in the Bukit Batu River estuary area, Bengkalis Regency, is low.

Unraveling the link between sediment acoustics and organic carbon

The top meter of marine sediments is estimated to store a total of 2322 Pg of carbon [Atwood et al., 2020. Front. Mar. Sci., vol. 7 p.165], which is twice that of terrestrial soils. Physical disturbance and remineralization of these carbon stocks could further accelerate climate change. Rapid and accurate quantification of sediment carbon stocks can (1) better inform carbon budgets and management of human activities in the ocean to minimize carbon remineralization and (2) monitor changes in sediment carbon stocks due to anthropogenic and natural disturbances. Sediment acoustics, which have been linked with sediment total organic carbon/content in mud banks, seagrass beds, and estuarine environments, can be measured in situ and offer a scalable solution toward rapid estimation of carbon stocks. However, before this modality can be applied broadly, a fundamental understanding between sediment acoustic properties and sediment organic/inorganic constituents must be realized. Here, direct ex situ measurements of sediment acoustic properties, sediment organic carbon, and grain size distribution will be compiled and compared across a variety of sediment types and locations from our own measurements and from published datasets. The development of a non-site-specific constitutive-based relationship will be discussed. [Work supported in part by ONR.]