Dear Monir,

     If you want to simulate the natural conditions, I don't think you should make an air-tight seal continuously, you can use Parafilm M Laboratory film that is air permeable but water resistant to seal it routinely. 

Best regards.

Hongjun

For calculating the CO2 emission from the  incubation experiment, you keep the vial containing NaOH (known vol. and strength) and sealed it. Periodically you have to keep out the vial and back titrate wit the acid to know the free NaOH present. Amount of NaOH Consumed will give the idea of CO2 flux.

For detailed set up you can see my paper on this topic in Agrochimica. other wise many literature are available, you just check that one.

Hi,

I think if you would like to simulate the filed condition, I totally agree with Hongjun Wang. If you want to calculate the gas emission, you should definitely know the water content of your soil, the concentrations of the gases, the volume of your container, the temperature of your incubation, you can search the ideal gas equation.

The question is why you need to flush with N2? Do you really need anaerobic condition?

Best wishes,

Xin

Thank Dr. Hongjun Wang and Xin. I really appreciate your sincere and kind help. Yes, I agree with you, it is not necessary to impose anaerobic condition by sealing bottles. However, for gas collection, I just wan to know the accumulated gas (CH4, CO2) for 12 hours. In that case, should I flush with N2, seal and collect gas after 12 hours since sealing? I have three levels of water content (60%WHC, 100%WHC and Flooded) condition. Can you provide me some suggestions regarding this issue.

Once again, I greatfully acknowledge your kind help.

Thank you.

Monir

Hi Monir,

If you flush with N2, then it is anaerobic condition. Then the CO2 is produced by anaerobic microbes. I have used a sealed vial without N2 flushing, which means only air in it. In addition, you have set 3 levels of water, for 100% WHC and flooded, you already gave them anaerobic condition. So I think it is not necessary to flush with N2.

Xin

Hi Monir

I have done soil respiration analysis which measures the amount of CO2 released from the soil by microbes respiring. I have attached my spreadsheet with the results I have found over time. I think you can use it to find out your CO2 gas emission.

Hope this helps.