Lateral carbon fluxes and CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; outgassing from   a tropical peat-draining river

Müller, Denise; Warneke, Thorsten; Rixen, Tim; Müller, Moritz; Jamahari, S.; Denis, N.; Mujahid, Aazani; Notholt, Justus

doi:10.5194/bg-12-5967-2015

Cited by 58 publications

(111 citation statements)

References 48 publications

(90 reference statements)

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“…7 and Table 3). This clearly suggests that deeper drainage leads to the mobilisation of older peat C into DOC and is also associated with the release of more humified (high SUVA 254 ) material, consistent with previous findings (Olefeldt et al, 2013). In general, our observed SUVA 254 values were higher than those reported previously in run-off from intact peat swamp forests (Moore et al, 2013;Gandois et al, 2013), which can be explained by a transition from plant-derived to peat-derived DOC sources following forest clearance and drainage .…”

Section: Discussionsupporting

confidence: 91%

Fluvial organic carbon fluxes from oil palm plantations on tropical peatland

et al. 2018

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Intact tropical peatlands are dense long-term stores of carbon. However, the future security of these ecosystems is at risk from land conversion and extensive peatland drainage. This can enhance peat oxidation and convert long-term carbon sinks into significant carbon sources. In Southeast Asia, the largest land use on peatland is for oil palm plantation agriculture. Here, we present the first annual estimate of exported fluvial organic carbon in the drainage waters of four peatland oil palm plantation areas in Sarawak, Malaysia. Total organic carbon (TOC) fluxes from the plantation second-and third-order drains were dominated (91 %) by dissolved organic carbon (DOC) and ranged from 34.4 ± 9.7 C m −2 yr −1 to 57.7 %, 16.3 g C m −2 yr −1 (± 95 % confidence interval). These fluxes represent a single-year survey which was strongly influenced by an El Ninõ event and therefore lower discharge than usual was observed. The magnitude of the flux was found to be influenced by water table depth, with higher TOC fluxes observed from more deeply drained sites. Radiocarbon dating on the DOC component indicated the presence of old (pre-1950s) carbon in all samples collected, with DOC at the most deeply drained site having a mean age of 735 years. Overall, our estimates suggest fluvial TOC contributes ∼ 5 % of total carbon losses from oil palm plantations on peat. Maintenance of high and stable water tables in oil palm plantations appears to be key to minimising TOC losses. This reinforces the importance of considering all carbon loss pathways, rather than just CO 2 emissions from the peat surface, in studies of tropical peatland land conversion.

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Section: Discussionsupporting

confidence: 91%

Fluvial organic carbon fluxes from oil palm plantations on tropical peatland

et al. 2018

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“…This spatial pattern was negative and strongly related to soil water content (Table 4), suggesting that, as soils become less moist and more aerated, oxidizing aerobic respiration increases, ultimately stimulating CO 2 production in the top soil layer (Müller et al, 2015). In agreement, other aerobic processes, such as N mineralization, were also higher in the intermediate and hillslope zones.…”

Section: Effects Of Soil Water Content On Soil Co 2 Effluxesmentioning

confidence: 70%

Soil water content drives spatiotemporal patterns of CO<sub>2</sub> and N<sub>2</sub>O emissions from a Mediterranean riparian forest soil

et al. 2017

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Abstract. Riparian zones play a fundamental role in regulating the amount of carbon (C) and nitrogen (N) that is exported from catchments. However, C and N removal via soil gaseous pathways can influence local budgets of greenhouse gas (GHG) emissions and contribute to climate change. Over a year, we quantified soil effluxes of carbon dioxide (CO 2 ) and nitrous oxide (N 2 O) from a Mediterranean riparian forest in order to understand the role of these ecosystems on catchment GHG emissions. In addition, we evaluated the main soil microbial processes that produce GHG (mineralization, nitrification, and denitrification) and how changes in soil properties can modify the GHG production over time and space. Riparian soils emitted larger amounts of CO 2 (1.2-10 g C m −2 d −1 ) than N 2 O (0.001-0.2 mg N m −2 d −1 ) to the atmosphere attributed to high respiration and low denitrification rates. Both CO 2 and N 2 O emissions showed a marked (but antagonistic) spatial gradient as a result of variations in soil water content across the riparian zone. Deep groundwater tables fueled large soil CO 2 effluxes near the hillslope, while N 2 O emissions were higher in the wet zones adjacent to the stream channel. However, both CO 2 and N 2 O emissions peaked after spring rewetting events, when optimal conditions of soil water content, temperature, and N availability favor microbial respiration, nitrification, and denitrification. Overall, our results highlight the role of water availability on riparian soil biogeochemistry and GHG emissions and suggest that climate change alterations in hydrologic regimes can affect the microbial processes that produce GHG as well as the contribution of these systems to regional and global biogeochemical cycles.

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“…Similarly, the CH 4 concentration range reported by Musenze et al (2014) for the Brisbane estuary, Australia, was substantially higher (31-578 nmol L −1 ) than in this study, although both the DOC concentration range and the DO saturation range were similar. This is surprising, as the peat-draining tributaries are extremely oxygen-depleted and contain large amounts of organic matter (Müller et al, 2015). These conditions are usually suitable for CH 4 production.…”

Section: Chmentioning

confidence: 99%

Nitrous oxide and methane in two tropical estuaries in a peat-dominated region of northwestern Borneo

et al. 2016

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Abstract. Estuaries are sources of nitrous oxide (N 2 O) and methane (CH 4 ) to the atmosphere. However, our present knowledge of N 2 O and CH 4 emissions from estuaries in the tropics is very limited because data are scarce. In this study, we present first measurements of dissolved N 2 O and CH 4 from two estuaries in a peat-dominated region of northwestern Borneo. Two campaigns (during the dry season in June 2013 and during the wet season in March 2014) were conducted in the estuaries of the Lupar and Saribas rivers. Median N 2 O concentrations ranged between 7.2 and 12.3 nmol L −1 and were higher in the marine end-member (13.0 ± 7.0 nmol L −1 ). CH 4 concentrations were low in the coastal ocean (3.6 ± 0.2 nmol L −1 ) and higher in the estuaries (medians between 10.6 and 64.0 nmol L −1 ). The respiration of abundant organic matter and presumably anthropogenic input caused slight eutrophication, which did not lead to hypoxia or enhanced N 2 O concentrations, however. Generally, N 2 O concentrations were not related to dissolved inorganic nitrogen concentrations. Thus, the use of an emission factor for the calculation of N 2 O emissions from the inorganic nitrogen load leads to an overestimation of the flux from the Lupar and Saribas estuaries. N 2 O was negatively correlated with salinity during the dry season, which suggests a riverine source. In contrast, N 2 O concentrations during the wet season were not correlated with salinity but locally enhanced within the estuaries, implying that there were additional estuarine sources during the wet (i.e., monsoon) season. Estuarine CH 4 distributions were not driven by freshwater input but rather by tidal variations. Both N 2 O and CH 4 concentrations were more variable during the wet season. We infer that the wet season dominates the variability of the N 2 O and CH 4 concentrations and subsequent emissions from tropical estuaries. Thus, we speculate that any changes in the Southeast Asian monsoon system will lead to changes in the N 2 O and CH 4 emissions from these systems. We also suggest that the ongoing cultivation of peat soil in Borneo is likely to increase N 2 O emissions from these estuaries, while the effect on CH 4 remains uncertain.

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Lateral carbon fluxes and CO<sub>2</sub> outgassing from a tropical peat-draining river

Cited by 58 publications

References 48 publications

Fluvial organic carbon fluxes from oil palm plantations on tropical peatland

Fluvial organic carbon fluxes from oil palm plantations on tropical peatland

Soil water content drives spatiotemporal patterns of CO<sub>2</sub> and N<sub>2</sub>O emissions from a Mediterranean riparian forest soil

Nitrous oxide and methane in two tropical estuaries in a peat-dominated region of northwestern Borneo

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Lateral carbon fluxes and CO&lt;sub&gt;2&lt;/sub&gt; outgassing from a tropical peat-draining river

Cited by 58 publications

References 48 publications

Fluvial organic carbon fluxes from oil palm plantations on tropical peatland

Fluvial organic carbon fluxes from oil palm plantations on tropical peatland

Soil water content drives spatiotemporal patterns of CO&lt;sub&gt;2&lt;/sub&gt; and N&lt;sub&gt;2&lt;/sub&gt;O emissions from a Mediterranean riparian forest soil

Nitrous oxide and methane in two tropical estuaries in a peat-dominated region of northwestern Borneo

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Product

Resources

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Lateral carbon fluxes and CO<sub>2</sub> outgassing from a tropical peat-draining river

Soil water content drives spatiotemporal patterns of CO<sub>2</sub> and N<sub>2</sub>O emissions from a Mediterranean riparian forest soil