Mixing in GSS

[forrie]

Hi

 

In the patch description the following:

 

"We have released GWB 8.0.7, which addresses the following issues:

•In GSS, allow mixing of samples in arbitrary mass ratios."

 

First problem: Ive downloaded the patch but I cant see where to change the mixing ratios in GSS.

(One can still mix it yourself in excel but it would be nice if it can be done automatically).

 

Second problem: why dont GSS mix alkalinities?

 

Help will be appreciated

Regards

J

[forrie]

I have only downloadedinstalled the latest patch 808

[Tom Meuzelaar]

Hi Johan:

 

Have a look at page 36 of the Essentials guide, which addresses both of these issues.

 

First problem: Ive downloaded the patch but I cant see where to change the mixing ratios in GSS.

(One can still mix it yourself in excel but it would be nice if it can be done automatically).

 

You can change mixing ratios by adding a Mass solution analyte to the spreadsheet, and specifying a different mass for each solution. For example, to mix fluid A with fluid B in a 3:1 ratio, set a mass of 3 kg for fluid A, and 1 kg for fluid B in the Mass solution field.

 

Second problem: why dont GSS mix alkalinities?

 

Some analytes, such as pH and alkalinity, are not conserved during mixing. You'll need to make sure the mass of each component representing the analyte is present in the datasheet- for Alkalinity, this is HCO3- (if you have pH, you'll want to make sure the H+ component is present as well). You can calculate these component concentrations via the Data -> Calculate menu option (set Variable Type to Components in Fluid, and choose HCO3-, H+). Then mix the samples, and save the mixture as a new sample in the spreadsheet - you can now back calculate pH and alkalinity, again via the Data -> Calculate menu option.

 

I hope that helps,

 

Tom Meuzelaar

RockWare, Inc.

[forrie]

Tom, thanks a lot.

GSS is really nice to work with your chemical data.

 

Regards

Johan

[TanyaNE]

Hi Johan:

 

Have a look at page 36 of the Essentials guide, which addresses both of these issues.

 

 

 

You can change mixing ratios by adding a Mass solution analyte to the spreadsheet, and specifying a different mass for each solution. For example, to mix fluid A with fluid B in a 3:1 ratio, set a mass of 3 kg for fluid A, and 1 kg for fluid B in the Mass solution field.

 

 

 

Some analytes, such as pH and alkalinity, are not conserved during mixing. You'll need to make sure the mass of each component representing the analyte is present in the datasheet- for Alkalinity, this is HCO3- (if you have pH, you'll want to make sure the H+ component is present as well). You can calculate these component concentrations via the Data -> Calculate menu option (set Variable Type to Components in Fluid, and choose HCO3-, H+). Then mix the samples, and save the mixture as a new sample in the spreadsheet - you can now back calculate pH and alkalinity, again via the Data -> Calculate menu option.

 

I hope that helps,

 

Tom Meuzelaar

RockWare, Inc.

 

I have run into a similar but expanded version of this problem. I calculated the bicarbonate from the measured alkalinity and mixed the samples, which resulted in a mixed sample containing bicarbonate; however, when I try to produce Piper or Stiff diagrams for the new mixed sample, the diagrams display the sample with zero bicarbonate/carbonate content. Similarly, I have not been able to back calculate the alkalinity for the mixed sample. After the calculation, the alkalinity cell is still empty but changes to the blue color for calculated cells. Could you provide me with some insight for this?

 

Thanks, TanyaNHPC water chem 2b.gss

[Brian Farrell]

Hi Tanya,

 

I think the problem is that you are only calculating the mass of the HCO3- component, but you need to do the same for the H+ component, then mix your samples. After this step, you should be able to calculate the alkalinity and pH of your mixture and plot your samples.

 

Which version of GWB are you using (e.g. 8.0.12, 9.0. 9.0.3?). There might be an issue with the units when component mass is calculated, as described here.

 

Hope this helps,

 

Brian Farrell

Aqueous Solutions LLC