scholarly journals Automatic high-frequency measurements of full soil greenhouse gas fluxes in a tropical forest

2018 ◽  
Author(s):  
Elodie Alice Courtois ◽  
Clément Stahl ◽  
Benoit Burban ◽  
Joke Van den Berge ◽  
Daniel Berveiller ◽  
...  
Keyword(s):  
High Frequency ◽  
Co2 Flux ◽  
Appropriate Technology ◽  
Flux Chamber ◽  
Soil Co2 Flux ◽  
Reliable Estimation ◽  
Closure Time ◽  
N2o Fluxes ◽  
Ch4 And N2o ◽  
Carbon Dioxide Co2

Abstract. Measuring in situ soil fluxes of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) continuously at high frequency requires appropriate technology. We tested the combination of a commercial automated soil CO2 flux chamber system (LI-8100A) with a CH4 and N2O analyzer (Picarro G2308) in a tropical rainforest for 4 months. A chamber closure time of 2 minutes was sufficient for a reliable estimation of CO2 and CH4 fluxes (100 % and 98.5 % of fluxes were above Minimum Detectable Flux – MDF, respectively). This closure time was generally not suitable for a reliable estimation of the low N2O fluxes in this ecosystem but was sufficient for detecting rare major peak events. A closure time of 25 minutes was more appropriate for reliable estimation of most N2O fluxes (85.6 % of measured fluxes are above MDF ± 0.002 nmol m−2 s−1). Our study highlights the importance of adjusted closure time for each gas.

scholarly journals Automatic high-frequency measurements of full soil greenhouse gas fluxes in a tropical forest

2019 ◽  
Vol 16 (3) ◽  
pp. 785-796 ◽  
Author(s):  
Elodie Alice Courtois ◽  
Clément Stahl ◽  
Benoit Burban ◽  
Joke Van den Berge ◽  
Daniel Berveiller ◽  
...  
Keyword(s):  
High Frequency ◽  
Co2 Flux ◽  
Appropriate Technology ◽  
Flux Chamber ◽  
Soil Co2 Flux ◽  
Reliable Estimation ◽  
Closure Time ◽  
N2o Fluxes ◽  
Ch4 And N2o ◽  
Carbon Dioxide Co2

Abstract. Measuring in situ soil fluxes of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) continuously at high frequency requires appropriate technology. We tested the combination of a commercial automated soil CO2 flux chamber system (LI-8100A) with a CH4 and N2O analyzer (Picarro G2308) in a tropical rainforest for 4 months. A chamber closure time of 2 min was sufficient for a reliable estimation of CO2 and CH4 fluxes (100 % and 98.5 % of fluxes were above minimum detectable flux – MDF, respectively). This closure time was generally not suitable for a reliable estimation of the low N2O fluxes in this ecosystem but was sufficient for detecting rare major peak events. A closure time of 25 min was more appropriate for reliable estimation of most N2O fluxes (85.6 % of measured fluxes are above MDF ± 0.002 nmol m−2 s−1). Our study highlights the importance of adjusted closure time for each gas.

Net exchange of greenhouse gases from soils in an unimproved pasture and regenerating indigenous Kunzea ericoides shrubland in New Zealand

Soil Research ◽  
2010 ◽  
Vol 48 (5) ◽  
pp. 385 ◽  
Author(s):  
Sally Price ◽  
David Whitehead ◽  
Robert Sherlock ◽  
Tony McSeveny ◽  
Graeme Rogers
Keyword(s):  
New Zealand ◽  
Root Zone ◽  
Forest Succession ◽  
Co2 Flux ◽  
Base Temperature ◽  
Soil Co2 Flux ◽  
Oxidation Rates ◽  
N2o Fluxes ◽  
Carbon Dioxide Co2 ◽  
Kunzea Ericoides

Monthly measurements of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) fluxes were made at 3 sites along a sequence of naturally regenerating Kunzea ericoides shrubland in New Zealand, consisting of unimproved pasture (UP), young (8–12 years) Kunzea trees (YK), and old (80 years) Kunzea trees (OK). The CO2 flux at a base temperature of 10°C was highest at the OK site (0.51 g CO2/m2.h) and lowest at the UP site (0.26 g CO2/m2.h). Values of CO2 flux were regulated by soil temperature (Ts) throughout the year, and water availability modified the response to Ts when root-zone water content, (θ), fell below 0.27–0.29 m3/m3 in spring and summer. The soils were mostly CH4 sinks, although there were net CH4 emissions during wet periods at the YK site. The maximum CH4 flux at the YK site was –49.7 μg CH4/m2.h compared with –33.4 μg CH4/m2.h for the UP (and –90.4 μg CH4/m2.h for OK), indicating the potential for rapid recovery of methanotrophic populations in the YK shrubland over 8–12 years. However, on an annual basis our data suggest that CH4 oxidation rates decrease as land reverts from unimproved pasture to shrubland. Methane oxidation rates were strongly dependent on θ and only weakly dependent on Ts. Measurements of N2O fluxes were below the minimum detectable limit throughout the year at the UP and YK sites, and low but dependent on both Ts and θ at the OK site. Annual estimates of soil CO2 flux were 39.9, 23.3, and 21.9 × 103 kg CO2/ha.year at the OK, YK, and UP sites, respectively. All 3 sites were a net sink for CH4, with the highest oxidation rate of –5.1 kg CH4/ha.year at the OK site compared with –1.52 kg CH4/ha.year at the UP site. On a CO2-equivalent basis, the OK site was a greater CH4 sink (–127.3 kg CO2-e/ha.year) than a N2O source (77.5 kg CO2-e/ha.year), demonstrating the potential for soils to oxidise CH4 with forest succession as a possible mitigation strategy for land managers to reduce net emissions.

scholarly journals Methane and nitrous oxide sources and emissions in a subtropical freshwater reservoir, South East Queensland, Australia

2014 ◽  
Vol 11 (18) ◽  
pp. 5245-5258 ◽  
Author(s):  
K. Sturm ◽  
Z. Yuan ◽  
B. Gibbes ◽  
U. Werner ◽  
A. Grinham
Keyword(s):  
Nitrous Oxide ◽  
Water Column ◽  
Water Flux ◽  
No Production ◽  
Pore Waters ◽  
Ch4 Production ◽  
N2o Fluxes ◽  
Ch4 And N2o ◽  
Diffusive Fluxes ◽  
Carbon Dioxide Co2

Abstract. Reservoirs have been identified as an important source of non-carbon dioxide (CO2) greenhouse gases with wide ranging fluxes for reported methane (CH4); however, fluxes for nitrous oxide (N2O) are rarely quantified. This study investigates CH4 and N2O sources and emissions in a subtropical freshwater Gold Creek Reservoir, Australia, using a combination of water–air and sediment–water flux measurements and water column and pore water analyses. The reservoir was clearly a source of these gases as surface waters were supersaturated with CH4 and N2O. Atmospheric CH4 fluxes were dominated by ebullition (60 to 99%) relative to diffusive fluxes and ranged from 4.14 × 102 to 3.06 × 105 μmol CH4 m−2 day−1 across the sampling sites. Dissolved CH4 concentrations were highest in the anoxic water column and sediment pore waters (approximately 5 000 000% supersaturated). CH4 production rates of up to 3616 ± 395 μmol CH4 m−2 day−1 were found during sediment incubations in anoxic conditions. These findings are in contrast to N2O where no production was detected during sediment incubations and the highest dissolved N2O concentrations were found in the oxic water column which was 110 to 220% supersaturated with N2O. N2O fluxes to the atmosphere were primarily through the diffusive pathway, mainly driven by diffusive fluxes from the water column and by a minor contribution from sediment diffusion and ebullition. Results suggest that future studies of subtropical reservoirs should monitor CH4 fluxes with an appropriate spatial resolution to ensure capture of ebullition zones, whereas assessment of N2O fluxes should focus on the diffusive pathway.

scholarly journals Differential Responses and Controls of Soil CO2 and N2O Fluxes to Experimental Warming and Nitrogen Fertilization in a Subalpine Coniferous Spruce (Picea asperata Mast.) Plantation Forest

Forests ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 808 ◽  
Author(s):  
Dandan Li ◽  
Qing Liu ◽  
Huajun Yin ◽  
Yiqi Luo ◽  
Dafeng Hui
Keyword(s):  
Co2 Flux ◽  
N Fertilization ◽  
Response Patterns ◽  
Soil Co2 ◽  
Plantation Forest ◽  
Soil Co2 Flux ◽  
Soil Microbial ◽  
Picea Asperata ◽  
Negative Effect ◽  
N2o Fluxes

Emissions of greenhouse gases (GHG) such as CO2 and N2O from soils are affected by many factors such as climate change, soil carbon content, and soil nutrient conditions. However, the response patterns and controls of soil CO2 and N2O fluxes to global warming and nitrogen (N) fertilization are still not clear in subalpine forests. To address this issue, we conducted an eight-year field experiment with warming and N fertilization treatments in a subalpine coniferous spruce (Picea asperata Mast.) plantation forest in China. Soil CO2 and N2O fluxes were measured using a static chamber method, and soils were sampled to analyze soil carbon and N contents, soil microbial substrate utilization (MSU) patterns, and microbial functional diversity. Results showed that the mean annual CO2 and N2O fluxes were 36.04 ± 3.77 mg C m−2 h−1 and 0.51 ± 0.11 µg N m−2 h−1, respectively. Soil CO2 flux was only affected by warming while soil N2O flux was significantly enhanced by N fertilization and its interaction with warming. Warming enhanced dissolve organic carbon (DOC) and MSU, reduced soil organic carbon (SOC) and microbial biomass carbon (MBC), and constrained the microbial metabolic activity and microbial functional diversity, resulting in a decrease in soil CO2 emission. The analysis of structural equation model indicated that MSU had dominant direct negative effect on soil CO2 flux but had direct positive effect on soil N2O flux. DOC and MBC had indirect positive effects on soil CO2 flux while soil NH4+-N had direct negative effect on soil CO2 and N2O fluxes. This study revealed different response patterns and controlling factors of soil CO2 and N2O fluxes in the subalpine plantation forest, and highlighted the importance of soil microbial contributions to GHG fluxes under climate warming and N deposition.

Soil CO2 flux affected by Aporrectodea caliginosa earthworms

2010 ◽  
Vol 5 (3) ◽  
pp. 364-370 ◽  
Author(s):  
Miloslav Šimek ◽  
Václav Pižl
Keyword(s):  
Co2 Emissions ◽  
Co2 Flux ◽  
Co2 Concentration ◽  
Experimental Period ◽  
Aporrectodea Caliginosa ◽  
Soil Co2 Flux ◽  
Soil Air ◽  
Soil Microbial ◽  
Carbon Dioxide Co2 ◽  
Soil Accumulation

AbstractThe effects of Aporrectodea caliginosa earthworms on both carbon dioxide (CO2) accumulation in and emissions from soil, as well as the simultaneous impact of earthworms on soil microbiological properties were investigated in a microcosm experiment carried out over 5.5 months. Concentration of CO2 in soil air was greater at a depth of 15 cm when compared with a depth of 5 cm, but varied during the season both in control and earthworm-inhabited chambers. Peaks of CO2 concentrations at both depths occurred in both treatments during August, approximately 80 days after the experiment started. Generally, the presence of earthworms increased the CO2 concentration at 15-cm depth. Larger CO2 emissions were consistently recorded in conjunction with higher amounts of CO2 in soil air when chambers were inhabited by earthworms. The total CO2 emissions during the experimental period covering 161 days were estimated at 118 g CO2-C m−2 and 99 g CO2-C m−2 from chambers with and without earthworms respectively. Moreover, the presence of earthworms increased microbial biomass in the centre and at the bottom of chambers, and enhanced both dehydrogenase activity and nitrifying enzyme activity in the soils. We suggest that the effect of earthworms on both the enhanced soil accumulation of CO2 as well as emissions of CO2 was mostly indirect, due to the impacts of earthworms on soil microbial community.

scholarly journals Combining two complementary micrometeorological methods to measure CH<sub>4</sub> and N<sub>2</sub>O fluxes over pasture

2015 ◽  
Vol 12 (18) ◽  
pp. 15245-15299 ◽  
Author(s):  
J. Laubach ◽  
M. Barthel ◽  
A. Fraser ◽  
J. E. Hunt ◽  
D. W. T. Griffith
Keyword(s):  
Large Fraction ◽  
Industrial Sector ◽  
N2o Emissions ◽  
Emission Rates ◽  
Co2 Fluxes ◽  
Nitrogen Inputs ◽  
Animal Excreta ◽  
N2o Fluxes ◽  
Ch4 And N2o ◽  
Carbon Dioxide Co2

Abstract. New Zealand's largest industrial sector is pastoral agriculture, giving rise to a large fraction of the country's emissions of methane (CH4) and nitrous oxide (N2O). We designed a system to continuously measure CH4 and N2O fluxes at the field scale on two adjacent pastures that differed with respect to management. At the core of this system was a closed-cell Fourier-transform infrared spectrometer (FTIR), measuring the mole fractions of CH4, N2O and carbon dioxide (CO2) at two heights at each site. In parallel, CO2 fluxes were measured using eddy-covariance instrumentation. We applied two different micrometeorological ratio methods to infer the CH4 and N2O fluxes from their respective mole fractions and the CO2 fluxes. The first is a variant of the flux-gradient method, where it is assumed that the turbulent diffusivities of CH4 and N2O equal that of CO2. This method was reliable when the CO2 mole-fraction difference between heights was at least 4 times greater than the FTIR's resolution of differences. For the second method, the temporal increases of mole fractions in the stable nocturnal boundary layer, which are correlated for concurrently-emitted gases, are used to infer the unknown fluxes of CH4 and N2O from the known flux of CO2. This method was sensitive to "contamination" from trace gas sources other than the pasture of interest and therefore required careful filtering. With both methods combined, estimates of mean daily CH4 and N2O fluxes were obtained for 60 % of days at one site and 77 % at the other. Both methods indicated both sites as net sources of CH4 and N2O. Mean emission rates for one year at the unfertilised, winter-grazed site were 8.2 (± 0.91) nmol CH4 m−2 s−1 and 0.40 (± 0.018) nmol N2O m−2 s−1. During the same year, mean emission rates at the irrigated, fertilised and rotationally-grazed site were 7.0 (± 0.89) nmol CH4 m−2 s−1 and 0.57 (± 0.019) nmol N2O m−2 s−1. At this site, the N2O emissions amounted to 1.19 (± 0.15) % of the nitrogen inputs from animal excreta and fertiliser application.

scholarly journals Different responses of CO<sub>2</sub>, CH<sub>4</sub>, and N<sub>2</sub>O fluxes to seasonally asymmetric warming in an alpine grassland of Tianshan Mountains

2020 ◽  
Author(s):  
Yanming Gong ◽  
Ping Yue ◽  
Kaihui Li ◽  
Anwar Mohammat ◽  
Yanyan Liu
Keyword(s):  
Temperature Increase ◽  
Response Rate ◽  
Co2 Flux ◽  
Growing Season ◽  
Tianshan Mountains ◽  
Alpine Grassland ◽  
Ch4 Flux ◽  
Greenhouse Gas Flux ◽  
N2o Fluxes ◽  
Ch4 And N2o

Abstract. An experiment was conducted to investigate the effect of seasonally asymmetric warming on CO2, CH4, and N2O fluxes in alpine grassland of Tianshan Mountains of Central Asia, from October 2016 to September 2019. Our results indicated that the CO2, CH4 and N2O fluxes varied in the range 0.56–98.03 mg C m−2 h−1, −94.30–0.23 μg C m−2 h−1, and −1.28–10.09 μg N m−2 h−1, respectively. The CO2 and N2O fluxes were negatively correlated with soil temperature, but the CH4 fluxes decreased with the increase in temperature. Furthermore, the variation in greenhouse gas flux under seasonally asymmetric warming was different between the growing season (June to September) and the non-growing season (October to May). In addition, the response rates of CO2 and N2O fluxes to temperature increases was significantly reduced due to warming throughout the year. Warming during the growing season led to a significant decrease in the response rate of CO2 flux to temperature increases. However, warming during the non-growing season caused a significant increase in the response rate of CO2 flux to temperature increases. The response rate of CH4 flux was insensitive to temperature increase under seasonally asymmetric warming. Thus, the main finding of our results was that seasonally asymmetric warming resulted in different responses in the fluxes of individual greenhouse gases to rising temperatures in the alpine grassland.

scholarly journals Combining two complementary micrometeorological methods to measure CH<sub>4</sub> and N<sub>2</sub>O fluxes over pasture

2016 ◽  
Vol 13 (4) ◽  
pp. 1309-1327 ◽  
Author(s):  
Johannes Laubach ◽  
Matti Barthel ◽  
Anitra Fraser ◽  
John E. Hunt ◽  
David W. T. Griffith
Keyword(s):  
Large Fraction ◽  
Industrial Sector ◽  
N2o Emissions ◽  
Emission Rates ◽  
Co2 Fluxes ◽  
Nitrogen Inputs ◽  
Animal Excreta ◽  
N2o Fluxes ◽  
Ch4 And N2o ◽  
Carbon Dioxide Co2

Abstract. New Zealand's largest industrial sector is pastoral agriculture, giving rise to a large fraction of the country's emissions of methane (CH4) and nitrous oxide (N2O). We designed a system to continuously measure CH4 and N2O fluxes at the field scale on two adjacent pastures that differed with respect to management. At the core of this system was a closed-cell Fourier transform infrared (FTIR) spectrometer, which measured the mole fractions of CH4, N2O and carbon dioxide (CO2) at two heights at each site. In parallel, CO2 fluxes were measured using eddy-covariance instrumentation. We applied two different micrometeorological ratio methods to infer the CH4 and N2O fluxes from their respective mole fractions and the CO2 fluxes. The first is a variant of the flux-gradient method, where it is assumed that the turbulent diffusivities of CH4 and N2O equal that of CO2. This method was reliable when the CO2 mole-fraction difference between heights was at least 4 times greater than the FTIR's resolution of differences. For the second method, the temporal increases of mole fractions in the stable nocturnal boundary layer, which are correlated for concurrently emitted gases, are used to infer the unknown fluxes of CH4 and N2O from the known flux of CO2. This method was sensitive to “contamination” from trace gas sources other than the pasture of interest and therefore required careful filtering. With both methods combined, estimates of mean daily CH4 and N2O fluxes were obtained for 56 % of days at one site and 73 % at the other. Both methods indicated both sites as net sources of CH4 and N2O. Mean emission rates for 1 year at the unfertilised, winter-grazed site were 8.9 (±0.79) nmol CH4 m−2 s−1 and 0.38 (±0.018) nmol N2O m−2 s−1. During the same year, mean emission rates at the irrigated, fertilised and rotationally grazed site were 8.9 (±0.79) nmol CH4 m−2 s−1 and 0.58 (±0.020) nmol N2O m−2 s−1. At this site, the N2O emissions amounted to 1.21 (±0.15) % of the nitrogen inputs from animal excreta and fertiliser application.

scholarly journals The Effect of Land-Use Change on Soil CH4 and N2O Fluxes: A Global Meta-Analysis

Ecosystems ◽  
2019 ◽  
Vol 22 (6) ◽  
pp. 1424-1443 ◽  
Author(s):  
M. D. McDaniel ◽  
D. Saha ◽  
M. G. Dumont ◽  
M. Hernández ◽  
M. A. Adams
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Meta Analysis ◽  
N2o Fluxes ◽  
Ch4 And N2o
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