User Defined Analytes and Total Alkalinity

[NZ_Geo]

Hi All,

 

It has been a few years since I last used GWB. I'm looking forward to getting started again!

 

I've been having a few difficulties with loading up a large number of user defined anlaytes. Specifically, I want to add the following:

 

Site ID Abs. 440 nm B (mg/L) Ca (mg/L) Mg (mg/L) Na (mg/L) K (mg/L) SO4 (mg/L) Cl (mg/L) F (mg/L) I (mg/L) FeII (mg/L) MnII (mg/L) Si (mg/L) D.O. (mg/L) d13C-DIC (‰, V-PDB) DIC (mmol/L) DNPOC (mg/L) NPOC (mg/L) TOC (mg/L) SpC (us/cm) Total Hardness (mg/L, CaCO3) d18O-H2O (‰, V-SMOW) d2H-H2O (‰, V-SMOW) DKN (mg/L) TDN (mg/L) TKN (mg/L) TN (mg/L) ORP (mV) Turbidity (NTU) Water Temp. (◦C) pH Talk (mg/L) HCO3 Alk. (mg/L) Carbonate Alk (mg/L) Br (mg/L) Cd (mg/L) Clarity B.D. (m) E. coli (CFU) Faecal Coliform (CFU) NNN (mg/L) Nitrate-N (mg/L) Nitrite-N (mg/L) TAM (mg/L) DOP (mg/L) DRP (mg/L) TDP (mg/L) TP (mg/L) SSC (mg/L) TSS (mg/L) VSS (mg/L) Zn (mg/L), Abs. 440 nm B (mg/L) Ca (mg/L) Mg (mg/L) Na (mg/L) K (mg/L) SO4 (mg/L) Cl (mg/L) F (mg/L) I (mg/L) FeII (mg/L) MnII (mg/L) Si (mg/L) D.O. (mg/L) d13C-DIC (‰, V-PDB) DIC (mmol/L) DNPOC (mg/L) NPOC (mg/L) TOC (mg/L) SpC (us/cm) Total Hardness (mg/L, CaCO3) d18O-H2O (‰, V-SMOW) d2H-H2O (‰, V-SMOW) DKN (mg/L) TDN (mg/L) TKN (mg/L) TN (mg/L) ORP (mV) Turbidity (NTU) Water Temp. (◦C) pH Talk (mg/L) HCO3 Alk. (mg/L) Carbonate Alk (mg/L) Br (mg/L) Cd (mg/L) Clarity B.D. (m) E. coli (CFU) Faecal Coliform (CFU) NNN (mg/L) Nitrate-N (mg/L) Nitrite-N (mg/L) TAM (mg/L) DOP (mg/L) DRP (mg/L) TDP (mg/L) TP (mg/L) SSC (mg/L) TSS (mg/L) VSS (mg/L) Zn (mg/L)

 

So far I can add the normal basis species. However, when I need to specify user defined analytes, of which I have many, I'm finding that GWB is using mmol/kg as default units. I've attempted to edit these to specify mg/L but it defaults back to mmol/kg. An additional issue, and perhaps the root cause (?), is that I do not have molar mass for some of these species (e.g., Total Organic Carbon, Dissolved Non-purgeable Organic Carbon etc).

 

Secondly, I was wondering how folk deal with adding measures of carbonate alkalinity into GSS? The lab data we use reports Total Alaklnity (mg/L as CaCO3), Bicarbonate Alkalinity and Carbonate (CO3) Alkalinity. As GWB uses alkalinity to assign major ion facies I was hoping someone had experience with adding alkalinity measures (all 3)?

 

Any pointers on either of the above would be gratefully received.

 

Kind regards (Cheers),

 

Clint

[Brian Farrell]

Hi Clint,

I’m happy to hear that you’re using the GWB again. The problem you’re having with units probably arises because you’re not including the mole weight and charge of your user-defined analytes. As far as I’m aware Total Organic Carbon is reported as the mass of carbon itself – no oxygen, hydrogen, etc are included. In that case, you’d just use 12.011 for the mole weight and 0 for the charge. Does that fix your problem?

The built-in Chemical parameter carbonate alkalinity accounts for the HCO3- and CO3-- species in solution. I’m not sure exactly what data you have, but if your bicarbonate and carbonate alkalinity are the individual contributions of the HCO3- and CO3-- ions to a fluid’s total alkalinity, then you can add them together (remembering that CO3--can neutralize twice the acid of the HCO3-) to use for the GWB’s carbonate alkalinity. You can certainly add total alkalinity as a user-defined analyte. And if you want, you can also create separate user-defined bicarbonate alkalinity and user-defined carbonate alkalinity.

Please keep in mind that the user-defined analytes are not used in calculations by the GWB. You use the Chemical parameters and the Basis and Redox species to specify the composition of your fluids for any calculations you wish to make, such as determining the concentrations of free species in solution, the fugacity of gases, and the saturation state of minerals.

Hope this helps,

Brian Farrell

Aqueous Solutions LLC