Plotting SIs over time

[Assaf]

Hi there,

 

I have a lot of geochemical data from an experiment, where samples were taken at different times, and for each time I have metal concentration results (and sometimes anions too). My "goal" is to create plots of time vs. saturation indices of different minerals.

 

I managed to figure out how to import my data into GSS, how to export from GSS to SpecE8, and how to run all the "samples" in SpecE8 automatically one after another. So far so good.

 

The problem is that SpecE8 saves each "sample" analysis as a separate file, and Gtplot can only plot one file at a time. This means that I cannot get a consolidated plot of SIs versus time. The tedious workaround that I've been using is to manually copy SIs from Gtplot and paste in Excel, for each separate "sample" (=time stamp).

 

Is there a better way of plotting all the results (not just SIs) as a function of time?

 

Thanks,

Assaf

[Brian Farrell]

Hi Assaf,

 

Launching SpecE8 from GSS is great for when you want detailed information for multiple samples (e.g. concentration, activity, fugacity, saturation, etc. for every species, gas, mineral...). If you are interested in the saturation state of one mineral in particular (or a small number), you can add calculated analytes one-by-one to your GSS spreadsheet. Simply click the "+ analyte" button at the bottom of the spreadsheet, choose calculate - Mineral saturation - Mineral... and this analyte will be calculated for each sample. You can calculate other analytes, including concentration, activity, activity coefficient, fugacity, TDS, etc. in this same way.

 

Then just create a time series plot from within GSS by going to the top row of options, choosing Graphs - Time Series Plot. Gtplot will launch with all of your samples together.

 

Hope this helps,

Brian Farrell

Aqueous Solutions LLC

[Assaf]

Thanks Brian,

 

the method you suggested works, but I encountered another problem:

 

GSS allows to me add carbonate to the system only as CO32- (or C). I do not have carbonate (or TIC) data, but I do have CO2 fugacity data (I conduct experiments under very specific P(CO2)).

GSS seems to be able to calculate fugacities based on dissolved species, but not the other way around. Without calculated carbonate I cannot proceed to calculate SIs for calcite, dolomite etc.

 

I suppose I could run separate simulations in SpecE8 with only carbonate (substituted for CO2), Ca and pH, and then plug in the aqueous CO3 results back to GSS... Yet that is not the most efficient way.

 

Cheers,

Assaf