Yes, You understood perfectly. I thought it was way more complicated than this.

Thank you very much for your detailed explanation!

Best regards

I do agree with Dr. Towe.

Thank you Prof. Ashfaque Ahmed. I'm still a PhD student and I'm trying to understand properly soil GHG fluxes. I apologise if I'm asking naive questions. 

Many thanks to everyone!

Regarding units selection: my advice is to use g CO2-C/m2/h if your research project deals with C-cycle of soil/terrestrial  ecosystem. If you are dealing with chemical reactions in soil, then molar units are more appropriate. The mmol or umol, per sec or per day -- does not matter although some pedantic people strongly adhere to the International System. I am sure the reading convenience is the primary argument, limit number of zeros in your final result. Say, 2.0 g CO2-C/m2/h is much better than 0.000556 g C/m2/s.

I totaly Agree. Indeed I'm using an IRGA system that gives me Soil CO2 Efflux in g CO2 M-2 S-1. I noticed that somebody use C instead of CO2 in their manuscripts and I wanted to be sure about the conversion! 

Hi there,

Depends on whether you are a µmeteorologist or a biologist/ecologist. A µmeteorologist expresses carbon fluxes in gCO2/m²/s1 when he is working with fluxtower measurements (NEE (day) and repiration (night).

A biologist would express it as carbon equivalents, because he looks at other carbon species in ecosystems as well, certainly when he is looking at carbon sequestration. Hence carbon fluxes are expressed as gC/m²/day which can be NEE, NPP, GPP or autotrphic / heterotrophic respiratory fluxes or litter fall and biomass consumption (by animals) or burning (by forest fires) where carbon is released as CO2 and with litterfall sequestered as a carbon species (humus components) .As it happens falling leaves are not CO2 falling down, hence, the litter mass flux is expressed (pro exemplia) as carbon/m2/day or pêr year, whetever the inegration period you are consdiering. Simple as that mate.

One advise, don't mixup your units too much, do it according to the scientific discipline you are educated in and according to the integration times you use.

Cheers,

Frank

Dear Dr. Francioni

Actually you have introduced a very nice question and I have learned a lot from the discussion going on in RG regarding your question. Hope for the best of luck!!

Regards

In the volcanology/geothermal literature, CO2 flux measurements (accumulation chamber method) are often reported as g m-2 d-1.  Just another unit to be aware of.

Hello,

knowing that one mol of CO2 = 12g (C) + 2x16 (O2) = 44g and contains one mol of C, one mol of CO2, that is, 44g of CO2 corresponds to 12g of C.

Consequently, X mol CO2 = X * (12/44) g C

Kenneth... sorry for my previous answer. I am not familiar with RG and I did not see that answers section already contained one full page! Fortunately my answer was consensual with yours!

Hai Sir,

Will u please help me in doing calculation, I am a Ph D scholar working in CO2 Emission by using EGM - 4. 

We get CO2 emission mean value of 0.38 g CO2/m2/hr, it was divided by 0.1585 to get 2.386 μmol CO2 m-2 s-1.

Then how to convert it for t CO 2 ha -1 yr-1.?

For knowing how much CO2 have been emitted during a year, please suggest me.

Hello, 

Attached you will find an excel file with a step by step conversion. I do not understand why you converted g into μmol when you need t.

However keep in mind that if you are searching for the annual CO2 emission perhaps you need a cumulative CO2 emission.  If you are interested in this I suggest you to use the linear interpolation. Roughly you assume that between the dates of measurements (I guess that with an EGM-4 you measured CO2 once or twice a week) there is a linear increament/decrement. Thus It is enough to calculate the linear equation with an Excel scatter plot. Make sure CO2 is on the Y axe and dates of measurements  on the X. 

You can also use the formula for linear prediction: =FORECAST.LINEAR(x, known_y's, known_x's)

Dear Sir,

EGM-4 is being used for measuring Carbon dioxide emission from soil under different forest covers using SRC-1 chamber along with temperature probe. Data has been recorded on monthly basis for 24 months. After downloading the files and computing, it has been observed that the first three readings are zero (0) for all the observations (datasets) for all the months. An exemplary file is attached herewith for your kind perusal please (wherein zero reading (Input F) are marked in red colored text).

However, this zero is distorting data sets when statistically analyzed. The precision of the results obtained is being affected by these three initial zero readings. We had a discussion and came to a common understanding that the instrument is perhaps calibrating itself for the first three readings and returning them as zero.

Keeping above in view, kindly consider clarifying as to why these initial three readings are zero? Are we right in assuming that it is due to calibration or some other issue? If so, we can take a decision on whether to include these or exclude from the statistical analytical procedures.

Hello Sir,

I used SRS-SD 1000 for soil respiration and the values i got are in range from Ce 72 to 146 but i don,t know how to convert it into µmol CO2 m−2 s−1 and what is the unit usually we use for soil respiration??

looking forward for your eminent reply

Dear S. Sivaranjani

Sorry for the late response. I've just noticed that you replied to my previous comment (I can answer also by private message, no problem!).

When I start the EGM-4 I just set the machine with END (thus, I dont choose ALL). In this way I got only on value which corresponds to the g m2 h-1of CO2.

I strongly suggest to set the machine in the same way I do. By doing so you will not have 27 (if I rember correctely) values for one measurement where the first 3 are 0.

Hope I was clear enough

Hi Saif Ullah

First you need to now what are your Ce 72 to 146 (maybe grams? Milligrams?). Please check in the manual of your SRS-SD 1000. Then we cann find a solution to convert them, should be a simple procedure.

Usually you can find papers that reports soil Co2 Dynamics in:

- g CO2 m-2 h-1

- g C m-2 h-1

. μmol CO2 m-2 s-1

each of them are acceptable to report a soil respiration dynamics. If you report cumulative annual values, than I would switch to

- t C ha-1 y-1

Simply because it gives you the exact idea of how much carbon is lost in an 10000 m2 (1 ha) in a year

Thank you so much Matteo Francioni

Caner Yerli please note that EGM5 should give you the water in millibars and not in ppm

Hi there - I realize that this is an old thread, but I see an incorrect answer in the discussion regarding the conversion between μmol CO2 and g C and I wanted to address it. Each mole of CO2 has one mol C in it, or more formally 1 mol C/ 1 mol CO2. One mole of C has a molecular weight of 12 g / mol C. And 1 mol CO2 has 1e6 umols CO2 in it (1 mol CO2/ 1e6 umol CO2).

So x umol CO2 * (1 mol CO2 / 1e6 umol CO2) * (1 mol C/ 1 mol CO2) * (12 g C/ 1 mol C) = 12/1e6 g C

And similarly x mol CO2 * (1 mol C/ 1 mol CO2) * (12 g C/ 1 mol C) = 12 g C

I find it easiest to do unit conversions by writing them out as fractions and cancelling units that occur in both the numerator and the denominator of your expression. That way you can't miss anything.

In summary, there are 12 g C in each mole of CO2, which should also make intuitive sense because a mole of CO2 contains one mole of carbon and that is its molecular weight.

Hi Rose Abramoff

How to convert the ffCO2 emission from gC/m2/day to gC/year?

Farhan Mustafa

you miss the surface in the second one. Let's say you want to convert your flux from gC/m2/day to tC/ha/year:

from g to t = x 10-6

from m2 to ha = x 104

from day to year = x 365

assuming a flux of 0.25 gC/m2/day --> 0.91 tC/ha/year

Matteo Francioni I am sorry I didn't write the question in detail. I don't want the area in the unit. I have a global ffCO2 emission dataset with a spatial resolution of 1x1 degree. The unit of the datasets in gC/m2/day. I need to convert it into gC/year. The formula I am using is as follow:

emission * area * 365

I have calculated the area in m2. Is it the correct approach?

Hi there,

I want to ask about the conversion between

mmol CO2 m-2 h-1 (x)

and

mg CO2 m-2 h-1 (y)

is y=x•44.01 right? thank you.

I think this form can help you. You can help me check whether my calculation is correct.

How i can convert ug CO2 m^2 h-1 to mg CO2 g-1 h-1?

Emmanuel Rodriguez Rivera

conversion from micrograms (μg) to milligrams (mg) = x/1000

e.g. --> 5 μg CO2 m2 h-1 = 0.005 mg CO2 m2 h-1

Then it seems you are trying to convert m2 (an area) to g (a mass), which makes no sense.

Did you mean something like m2 to cm2 or to ha-1? (all areas)

Or maybe you are doing some incubation experiments and you are interested in measuring the CO2 flux from a certain amount of soil? e.g. --> 0.005 mg CO2 200g soil h-1

If your case is the latter then you might need other parameters to calculate the efflux, like for example the height of your respiration chamber, assuming you are using a similar system.