Carbon Dioxide and Methane Emissions from a Wet-Dry Tropical Floodplain in Northern Australia

Bass, Adrian M.; O’Grady, Damien; Leblanc, Marc; Tweed, Sarah; Nelson, Paul N.; Bird, Michael I.

doi:10.1007/s13157-014-0522-5

Cited by 24 publications

(15 citation statements)

References 29 publications

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“…Therefore, our data suggest that wet-dry treatments significantly decreased total C emissions (CO2 + CH4). These results are consistent with previous studies where fluctuating water tables reduced C emissions (Bass et al, 2014;Olsson et al, 2015).…”

Section: 2b Carbonwet-dry Vs Floodingsupporting

confidence: 94%

Effects of salinity and wet–dry treatments on C and N dynamics in coastal-forested wetland soils: Implications of sea level rise

Liu

Ruecker

Song

et al. 2017

Soil Biology and Biochemistry

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Forested wetlands dominated by baldcypress (Taxodium distichum) and water tupelo (Nyssa aquatica) are commonly found in coastal regions of the southeastern United States. Global climate change and in particular sea level rise will alter the frequency and magnitude of wet/dry periods and salinity levels in these ecosystems. Soil microcosm experiments were set up to identify the effects of water level variations (0.4-3.0 g-water g-soil-1) and salinity changes (0, 1 and 5 ppt of NaCl) on greenhouse gas emissions (CH4, CO2 and N2O) and dissolved organic carbon (DOC) characteristics from forested wetland soils. Our results indicate that, the effect of water level was much greater than salt intrusion on C and N cycling. Wet-dry treatments significantly decreased DOC production and total CH4-C loss, aromatic and humic-like substance compounds in DOC were increased in both flooding and wet-dry treatments after 60-d incubation. The molecular weight (MW) of DOC after flooding treatments was higher than that in wet-dry treatments. A first order kinetic model showed there was a positive linear correlation (r 2 =0.73) between CO2 emission rate and DOC concentration which indicated that CO2 was mainly generated from DOC. An exponential kinetic model was applied to describe the correlation between CH4 emission rate and DOC concentration (r 2 =0.41). This study demonstrates that an increase in salinity, and in particular variations in wet-dry cycles, will lead to changes in the formation of climate-relevant greenhouse gases, such as CH4, CO2, and N2O.

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Section: 2b Carbonwet-dry Vs Floodingsupporting

confidence: 94%

Effects of salinity and wet–dry treatments on C and N dynamics in coastal-forested wetland soils: Implications of sea level rise

Liu

Ruecker

Song

et al. 2017

Soil Biology and Biochemistry

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“…In our study we found that CH 4 uptake was positively ( P < 0.05) correlated with soil temperature and air temperature (CH 4 uptake = 36.39 + 2.87S t , P < 0.01, CH 4 uptake = 50.79 + 1.53A t , P < 0.01, Table 4) and negatively correlated with soil moisture (CH 4 uptake = 87.87-0.94S m , P < 0.01, Table 4), further demonstrating that soil temperature and soil moisture are important factors affecting CH 4 uptake. Moreover, the higher the soil moisture content the less CH 4 is taken up and CH 4 oxidation rates are negatively correlated with soil moisture content and this is consistent with most in situ observations2730 in which higher CH 4 uptake has occurred at intermediate soil moisture contents and much higher or very low soil moisture contents have inhibited CH 4 uptake29. The dependence of CH 4 uptake on soil moisture content can be explained by changes in the activities of methanotrophs and methanogens31 and CH 4 soil-atmosphere exchange tends to reduce the sink of CH 4 at higher soil moisture contents32.…”

Section: Discussionsupporting

confidence: 89%

A five-year study of the impact of nitrogen addition on methane uptake in alpine grassland

Yue

Gong

et al. 2016

Sci Rep

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It remains unclear how nitrogen (N) deposition affects soil methane (CH4) uptake in semiarid and arid zones. An in situ field experiment was conducted from 2010 to 2014 to systematically study the effect of various N application rates (0, 10, 30, and 90 kg N ha−1 yr−1) on CH4 flux in alpine grassland in the Tianshan Mountains. No significant influence of N addition on CH4 uptake was found. Initially the CH4 uptake rate increased with increasing N application rate by up to 11.5% in 2011 and then there was gradual inhibition by 2014. However, the between-year variability in CH4 uptake was very highly significant with average uptake ranging from 52.9 to 106.6 μg C m−2 h−1 and the rate depended largely on seasonal variability in precipitation and temperature. CH4 uptake was positively correlated with soil temperature, air temperature and to a lesser extent with precipitation, and was negatively correlated with soil moisture and NO3−-N content. The results indicate that between-year variability in CH4 uptake was impacted by precipitation and temperature and was not sensitive to elevated N deposition in alpine grassland.

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“…Second, Rayleigh distillation processes related to microbial methanogenesis likely occurred within wetlands during the wet season, potentially enriching the riverine δ 13 C DIC downstream. Elevated methane evasion fluxes were measured in seasonal wetlands near the Howard River (Bass et al, ; Beringer et al, ), a sign of strong methanogenic activity. Methanogenesis alone might explain the ~+3‰ enrichment observed between the shallow groundwater and wetlands.…”

Section: Discussionmentioning

confidence: 99%

Seasonal Shift From Biogenic to Geogenic Fluvial Carbon Caused by Changing Water Sources in the Wet‐Dry Tropics

et al. 2020

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The riverine export of carbon is expected to be driven by changes in connectivity between source areas and streams. Yet we lack a thorough understanding of the relative contributions of different water sources to the dissolved carbon flux, and of the way these contributions vary with seasonal changes in flow connectivity. Here we assess the temporal variations in water and associated dissolved inorganic carbon (DIC) sources and fluxes in a wet‐dry tropical river of northern Australia over two years. We use linear mixing models integrated into a Bayesian framework to determine the relative contributions of rainfall, seasonal wetlands, shallow groundwater, and a deep carbonate aquifer to riverine DIC fluxes, which we relate to the age of water sources. Our results suggest extreme shifts in water and DIC sources between the wet and dry seasons. Under wet conditions, most DIC was of biogenic origin and transported by relatively young water sources originating from shallow groundwater and wetlands. As rainfall ceased, the wetlands either dried out or became disconnected from the stream network. From this stage, DIC switched to a geogenic origin, nearly entirely conveyed via older water sources from the carbonate formation. Our findings demonstrate the importance of changing patterns of connectivity when evaluating riverine DIC export from catchments. This work also illustrates the need to systematically partition DIC fluxes between biogenic and geogenic sources, if we are to quantify how the riverine export of carbon affects net carbon soil storage.

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Carbon Dioxide and Methane Emissions from a Wet-Dry Tropical Floodplain in Northern Australia

Cited by 24 publications

References 29 publications

Effects of salinity and wet–dry treatments on C and N dynamics in coastal-forested wetland soils: Implications of sea level rise

Effects of salinity and wet–dry treatments on C and N dynamics in coastal-forested wetland soils: Implications of sea level rise

A five-year study of the impact of nitrogen addition on methane uptake in alpine grassland

Seasonal Shift From Biogenic to Geogenic Fluvial Carbon Caused by Changing Water Sources in the Wet‐Dry Tropics

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