Measurements of Methane emissions by gas chromatography and photo acoustic

gas monitor

HOANG TRONG NGHIASupervisors:

Dr. Bjoern Ole Sander

Dr. Agnes Tirol Padre Dr. Reiner Wassmann

IRRI, 2017

INTRODUCTION

CH4 and N2O Emissions from rice fields

Global Warming Potential: CH4 = 28 CO2eq; N2O = 298 CO2eq

Rice fields account for 5 -20 % of all global methane sourcesMethane is responsible for 20 % of the greenhouse effect

Research objectives

To assess the performance of the semi-automated photo-acoustic gas monitor in tandem with a dew-point generator formeasuring CH4 emissions in a paddy rice field in comparisonwith manual gas sampling and analysis by gas chromatography

To conduct nighttime measurements with static chambers andextended chamber closure time to assess its use for reliableemission assessments, and to define a methodology for high-throughput screening of rice varieties that will vastly reducesampling requirements as compared to daytime

To study the effect of compost on greenhouse gas emission inagriculture production.

Methodology

Study sites

Gas sampling in Compost exp.Gas sampling at Block UY exp. Gas sampling at Block H exp.

Gas chromatograph Photo-acoustic Gas Analyzer

Methodology

Manual gas sampling

30-min measurements of CH4 emissions from manual chambers at 3-hr intervals using the PAS and GC

Results

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Plot 1

PAS GCCH4 mg m-2 d-1

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Plot 3CH4 mg m-2 d-1

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Plot 4

CH4 mg m-2 d-1

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Plot 5CH4 mg m-2 d-1

Continuous nighttime monitoring of CH4 emissions inside manual chambers by PAS and GC

y = 0.2312x + 13.13R² = 0.9986

y = 0.2365x + 1.0964R² = 0.9973

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MINUTES

PAS+DPG GC

CF

6 PM - 12 AM

Measurement date: 24 March 2017

Plot 4a

ppm CH4

y = 0.0618x + 9.7229R² = 0.9887

y = 0.062x + 2.3586R² = 0.9949

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PAS GCppm CH4

Plot 4a

CF

6 PM - 12 AM

Measurement date: 31 Mar 2017

Continuous night time monitoring of CH4 emissions by manual gas sampling from static chambers by GC analysis during

R² = 0.996

R² = 0.999

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m C

H4

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Chamber 1

Chamber 2

Chamber 3

(a) Low emisions field, 74 DAT

R2 = 0.998

R² = 0.997

R² = 0.999

R² = 0.962

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m C

H4

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Chamber 4

Chamber 5

Chamber 6

(b) High emissions field, 74 DAT

R² = 0.999

R² = 0.999

R² = 0.998

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Chamber 1

Chamber 2

Chamber 3

(c) Low emissions field, 81 DAT

R² = 0.995

R² = 0.999

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m C

H4

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Chamber 4

Chamber 5

Chamber 6

(d) high emissions field, 81 DAT

R2 = 0.961

CH4 and N2O emission from compost experiment

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Without ANC With ANC

Day 1-42 Day 43-93N2O Emission (kg CO2eq ha-1)

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Without ANC With ANC

Day 1-42 Day 43-93CH4 Emission (kg CO2eq ha-1)

Conclusion

• CH4 emission rates measured from rice paddies by PAS intandem with a DPG were comparable with that measured byGC.

• Closure times of the chambers during night time can beexpanded to several hours since a linear increase in CH4

emissions was found from 6 PM to 12 midnight. This entailsmuch higher end concentrations for CH4 and eases the precisedetection of flux rates.

• Composting contributes to GHG emission by 9047 kg CO2-eqha-1 from CH4 Emission, 318 kg CO2-eq ha-1 from N2OEmission. Hence, evaluation of greenhouse gas emission fromcompost is necessary in rice production.

Application

Study can contribute to development of methodologies foradaptation and mitigation research:

• Results show that PAS can be a suitable alternative to GC foreasy but reliable and globally comparable CH4 emissionmeasurements for the improvement GHG mitigationstrategies and eventually for the development of policies formitigating climate change

• Results from the nighttime CH4 emission measurementsprovide proof of concept to define a methodology for high-throughput screening of rice varieties for low CH4 emissionsthat will vastly reduce sampling requirements as compared todaytime measurements.

Output

• 1 publication

• “Screening of methane emission rates for a high number of rice varieties: Improved methodology based on nighttime measurements”

• The paper is under review in PlosOne journal

Acknowledge

I would like to thank:

The CGIAR Research Program on Climate Change,

Agriculture and Food Security (CCAFS), through it is

Samples Program and CLIFF network, and International

Rice Research Institute (IRRI), contribute to this research.

Dr. Bjoern Ole Sander, Dr. Reinner Wassmann and Dr.

Agnes Tirol-Padre for scholastic and guidance from the

beginning to the completion of this research work.

All the staffs of Climate Change unit, CESD for helping me

in gas sampling/ analyzing collected samples of the

experiment.

Thanks for your attention!!!