Carbon cycle in tropical peatlands and coastal seas

Rixen, Tim; Wit, Francisca; Hutahaean, Andreas A.; Schlüter, Achim; Klemme, Alexandra; Müller, Moritz; Pranowo, Widodo Setiyo; Samiaji, Joko; Warneke, Thorsten

doi:10.1016/b978-0-12-815050-4.00011-0

Cited by 6 publications

(5 citation statements)

References 141 publications

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“…The resulting values of a440 and DOC follow the same CDOM-DOC relationship found for the various peatland-draining rivers in Sarawak (Figure S1 and Table S1 in Supporting Information, SI) (Martin et al, 2018). This indicates that the tDOC composition and optical properties are broadly similar across Southeast Asian peatlands, which is also consistent with the fact that DOC concentrations in peatland-draining rivers follow a single, strong relationship to catchment peatland cover across both Sumatra and Borneo (Rixen et al, 2022).…”

Section: Datasets Used In the Present Analysissupporting

confidence: 74%

“…The resulting riverine endmember values were corroborated by the fact that the a440 and DOC fall onto the same CDOM-DOC relationship found for the various peatland-draining rivers in Sarawak (Figure S1) (Martin et al, 2018). This suggests that peatland tDOM pools and their optical properties are quite similar across Southeast Asian peatlands, and that variation in tDOC concentration among rivers is primarily a function of catchment peatland coverage rather than reflecting differences in tDOM characteristics (Rixen et al, 2022). Marine endmember values were taken as the averages of these parameters during the late NE Monsoon and the following intermonsoon seasons (late February to March) from our timeseries data in the Singapore Strait.…”

Section: Mixing Models and Carbon Isotope Mass Balance Calculationsupporting

confidence: 52%

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The Validity of Optical Properties as Tracers of Terrigenous Dissolved Organic Carbon during Extensive Remineralization in Coastal Waters

Chen

Martin

Zhou

2023

Preprint

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Terrestrial dissolved organic carbon (tDOC) is significant for coastal carbon cycling, and absorbance and fluorescence spectroscopy of chromophoric and fluorescent dissolved organic matter (CDOM, FDOM) are widely used to study tDOC cycling. However, CDOM and FDOM are often amongst the more labile components of tDOC. Because few studies have compared CDOM and FDOM to measurements of both bulk tDOC concentration and tDOC remineralization, it remains unclear how accurately CDOM and FDOM actually trace tDOC in coastal waters when tDOC undergoes extensive remineralization. We collected a 4-year coastal timeseries in Southeast Asia, where tropical peatlands supply large tDOC inputs. A carbon stable isotope mass balance shows that on average 56% of tDOC was remineralized upstream of our site, while 77% of CDOM was bleached. Despite this extensive tDOC remineralization and preferential CDOM loss, optical properties could reliably quantify tDOC. CDOM spectral slope properties, such as S275–295, are exponentially related to tDOC; these are highly sensitive tDOC tracers at low, but not at high, tDOC concentrations. Other properties are linearly related to tDOC, and both specific ultraviolet absorbance (SUVA254) and DOC-normalized fluorescence intensity may be suitable to quantify tDOC over a wider range of concentrations. However, the optical properties did not show consistent changes with the extent of tDOC remineralization. Our data support the validity of CDOM and FDOM spectroscopy to trace tDOC across coastal gradients even after the majority of tDOC has been remineralized, but they also show that these measurements may not provide much information about tDOC biogeochemical processing.

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Section: Datasets Used In the Present Analysissupporting

confidence: 74%

Section: Mixing Models and Carbon Isotope Mass Balance Calculationsupporting

confidence: 52%

The Validity of Optical Properties as Tracers of Terrigenous Dissolved Organic Carbon during Extensive Remineralization in Coastal Waters

Chen

Martin

Zhou

2023

Preprint

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“…As a purely peatland‐draining river, the Maludam has high DOC concentrations (3,000–4,000 μmol l −1 ). Although different rivers across Sumatra and Borneo can vary around 10‐fold in DOC concentration, the DOC concentration is linearly related to the proportion of catchment area that is peatland (Rixen et al., 2022). Moreover, across multiple rivers in northwestern Borneo draining catchments with varying peatland proportions and DOC concentrations, there is a strong and linear relationship between DOC concentration and CDOM absorption (Figure S1, data from Martin et al.…”

Section: Methodsmentioning

confidence: 99%

Quantifying Photodegradation of Peatland‐Derived Dissolved Organic Carbon in the Coastal Ocean of Southeast Asia

Zhou,

Müller,

Cherukuru

et al. 2023

JGR Oceans

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Southeast Asia's peatlands are a globally significant source of terrigenous dissolved organic carbon (tDOC) to the ocean, and field observations show that this tDOC is extensively remineralized within the shelf sea. Yet the processes that drive this remineralization remain unclear. Here, we combined incubation experiments and model simulations to quantify the rate and extent of photodegradation of tDOC in the Sunda Shelf Sea. During laboratory photodegradation experiments, 26%–74% of the peatland tDOC was photomineralized, but realistic in situ rates of photodegradation have not yet been estimated in this region. Based on spectrally resolved apparent quantum yields for tDOC remineralization calculated from experiments, modeled in situ solar irradiance, and measured in‐water inherent optical properties, we simulated peatland tDOC photomineralization for two coastal regions of the Sunda Shelf Sea. These simulations show that sunlight can directly remineralize 25 ± 9% of the tDOC input over its maximum 2‐year residence time in the Sunda Shelf Sea, accounting for 38% of the total tDOC remineralization. We also found that photobleaching can remove 54 ± 4% of colored dissolved organic matter over this time‐scale. We further derived a simplified photochemical decay constant ∅ref of 0.016 day−1 for Southeast Asia's peatland‐derived tDOC, which can be used to parameterize the recently proposed UniDOM model. We conclude that direct photodegradation may be a greater sink for tDOC in Southeast Asia's coastal ocean compared to higher latitudes, although it is insufficient to account for the total tDOC remineralization observed in the Sunda Shelf Sea.

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“…The flux density between the surface and the atmosphere may be calculated using the covariance between turbulent vertical wind fluctuations and the quantity of interest [266]. This method may measure CO 2 fluxes above the treetops and quantify on-site CO 2 emissions [267]. The CO 2 flux measurement technique can be an open-or closed-path system [268].…”

Section: Eddy Covariance Flux Measurement Methodsmentioning

confidence: 99%

A Review of CCUS in the Context of Foams, Regulatory Frameworks and Monitoring

2023

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Greenhouse gas emission into the atmosphere is considered the main reason for the rise in Earth’s mean surface temperature. According to the Paris Agreement, to prevent the rise of the global average surface temperature beyond two degrees Celsius, global CO2 emissions must be cut substantially. While a transition to a net-zero emission scenario is envisioned by mid-century, carbon capture, utilization, and storage (CCUS) will play a crucial role in mitigating ongoing greenhouse gas emissions. Injection of CO2 into geological formations is a major pathway to enable large-scale storage. Despite significant recent technological advancements, mass deployment of these technologies still faces several technical and non-technical difficulties. This paper provides an overview of technical milestones reached thus far in CO2 capture, utilization, geological storage, monitoring technologies, and non-technical aspects such as regulatory frameworks and related policies in the US and the rest of the world. This paper describes different injection methods to store CO2 in various subsurface formations, the use of foams and the resulting potential gains in CO2 storage capacity, the role of nanoparticles for foam stabilization, and ensuring long-term storage safety. This work also addresses several safety-related aspects of geological storage and subsurface monitoring technologies that may mitigate risks associated with long-term storage.

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Carbon cycle in tropical peatlands and coastal seas

Cited by 6 publications

References 141 publications

The Validity of Optical Properties as Tracers of Terrigenous Dissolved Organic Carbon during Extensive Remineralization in Coastal Waters

The Validity of Optical Properties as Tracers of Terrigenous Dissolved Organic Carbon during Extensive Remineralization in Coastal Waters

Quantifying Photodegradation of Peatland‐Derived Dissolved Organic Carbon in the Coastal Ocean of Southeast Asia

A Review of CCUS in the Context of Foams, Regulatory Frameworks and Monitoring

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