Contrasting carbon export dynamics of human impacted and pristine tropical catchments in response to a short-lived discharge event

Adrian Bass, Niels Munksgaard, M Leblanc, Michael Bird

    Research output: Contribution to journalArticleResearchpeer-review

    Abstract

    Utilising newly available instrumentation, the carbon balance in two small tropical catchments was measured during two discharge events at high temporal resolution. Catchments share similar climatic conditions, but differ in land use with one draining a pristine rainforest catchment, the other a fully cleared and cultivated catchment. The necessity of high resolution sampling in small catchments was illustrated in each catchment, where significant chemical changes occurred in the space of a few hours or less. Dissolved and particulate carbon transport dominated carbon export from the rainforest catchment during high flow, but was surpassed by degassing of CO2 less than 4 h after the discharge peak. In contrast, particulate organic carbon dominated export from the cleared catchment, in all flow conditions with CO2 evasion accounting for 5–23% of total carbon flux. Stable isotopes of dissolved inorganic carbon (DIC) in the ephemeral rainforest catchment decreased quickly from ~1.5 ‰ to ~ −16 ‰ in 5 h from the flood beginning. A two-point mixing model revealed that in the initial pulse, over 90% of the DIC was of rainwater origin, decreasing to below 30% in low flow. In the cultivated catchment, δ13CDIC values varied significantly less (−11.0 to −12.2 ‰) but revealed a complex interaction between surface runoff and groundwater sources, with groundwater DIC becoming proportionally more important in high flow, due to activation of macropores downstream. This work adds to an increasing body of work that recognises the importance of rapid, short-lived hydrological events in low-order catchments to global carbon dynamics.
    Original languageEnglish
    Pages (from-to)1835-1843
    Number of pages9
    JournalHydrological Processes
    Volume28
    Issue number4
    DOIs
    Publication statusPublished - 15 Feb 2014

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    catchment
    carbon
    dissolved inorganic carbon
    rainforest
    groundwater
    peak discharge
    carbon balance
    macropore
    particulate organic carbon
    carbon flux
    degassing
    rainwater
    low flow
    instrumentation
    stable isotope
    runoff
    land use
    sampling

    Cite this

    Bass, Adrian ; Munksgaard, Niels ; Leblanc, M ; Bird, Michael. / Contrasting carbon export dynamics of human impacted and pristine tropical catchments in response to a short-lived discharge event. In: Hydrological Processes. 2014 ; Vol. 28, No. 4. pp. 1835-1843.
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    title = "Contrasting carbon export dynamics of human impacted and pristine tropical catchments in response to a short-lived discharge event",
    abstract = "Utilising newly available instrumentation, the carbon balance in two small tropical catchments was measured during two discharge events at high temporal resolution. Catchments share similar climatic conditions, but differ in land use with one draining a pristine rainforest catchment, the other a fully cleared and cultivated catchment. The necessity of high resolution sampling in small catchments was illustrated in each catchment, where significant chemical changes occurred in the space of a few hours or less. Dissolved and particulate carbon transport dominated carbon export from the rainforest catchment during high flow, but was surpassed by degassing of CO2 less than 4 h after the discharge peak. In contrast, particulate organic carbon dominated export from the cleared catchment, in all flow conditions with CO2 evasion accounting for 5–23{\%} of total carbon flux. Stable isotopes of dissolved inorganic carbon (DIC) in the ephemeral rainforest catchment decreased quickly from ~1.5 ‰ to ~ −16 ‰ in 5 h from the flood beginning. A two-point mixing model revealed that in the initial pulse, over 90{\%} of the DIC was of rainwater origin, decreasing to below 30{\%} in low flow. In the cultivated catchment, δ13CDIC values varied significantly less (−11.0 to −12.2 ‰) but revealed a complex interaction between surface runoff and groundwater sources, with groundwater DIC becoming proportionally more important in high flow, due to activation of macropores downstream. This work adds to an increasing body of work that recognises the importance of rapid, short-lived hydrological events in low-order catchments to global carbon dynamics.",
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    Contrasting carbon export dynamics of human impacted and pristine tropical catchments in response to a short-lived discharge event. / Bass, Adrian; Munksgaard, Niels; Leblanc, M; Bird, Michael.

    In: Hydrological Processes, Vol. 28, No. 4, 15.02.2014, p. 1835-1843.

    Research output: Contribution to journalArticleResearchpeer-review

    TY - JOUR

    T1 - Contrasting carbon export dynamics of human impacted and pristine tropical catchments in response to a short-lived discharge event

    AU - Bass, Adrian

    AU - Munksgaard, Niels

    AU - Leblanc, M

    AU - Bird, Michael

    PY - 2014/2/15

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    AB - Utilising newly available instrumentation, the carbon balance in two small tropical catchments was measured during two discharge events at high temporal resolution. Catchments share similar climatic conditions, but differ in land use with one draining a pristine rainforest catchment, the other a fully cleared and cultivated catchment. The necessity of high resolution sampling in small catchments was illustrated in each catchment, where significant chemical changes occurred in the space of a few hours or less. Dissolved and particulate carbon transport dominated carbon export from the rainforest catchment during high flow, but was surpassed by degassing of CO2 less than 4 h after the discharge peak. In contrast, particulate organic carbon dominated export from the cleared catchment, in all flow conditions with CO2 evasion accounting for 5–23% of total carbon flux. Stable isotopes of dissolved inorganic carbon (DIC) in the ephemeral rainforest catchment decreased quickly from ~1.5 ‰ to ~ −16 ‰ in 5 h from the flood beginning. A two-point mixing model revealed that in the initial pulse, over 90% of the DIC was of rainwater origin, decreasing to below 30% in low flow. In the cultivated catchment, δ13CDIC values varied significantly less (−11.0 to −12.2 ‰) but revealed a complex interaction between surface runoff and groundwater sources, with groundwater DIC becoming proportionally more important in high flow, due to activation of macropores downstream. This work adds to an increasing body of work that recognises the importance of rapid, short-lived hydrological events in low-order catchments to global carbon dynamics.

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    KW - High temporal resolution

    KW - Particulate organic carbon

    KW - Stable isotopes

    KW - Carbon

    KW - Carbon dioxide

    KW - Dissolution

    KW - Floods

    KW - Groundwater

    KW - Isotopes

    KW - Land use

    KW - Rivers

    KW - Runoff

    KW - Catchments

    KW - anthropogenic effect

    KW - carbon cycle

    KW - carbon dioxide

    KW - carbon flux

    KW - catchment

    KW - dissolved inorganic carbon

    KW - dissolved organic carbon

    KW - groundwater

    KW - rainforest

    KW - runoff

    KW - stable isotope

    KW - water quality

    U2 - 10.1002/hyp.9716

    DO - 10.1002/hyp.9716

    M3 - Article

    VL - 28

    SP - 1835

    EP - 1843

    JO - Hydrological Processes

    JF - Hydrological Processes

    SN - 0885-6087

    IS - 4

    ER -