Field Bicarbonate in Groundwater Testing

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Is there a field method for testing the amount of bicarbonate in groundwater? 

How is it tested in the field, which technology is used and how reliable is it? 

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5 Answers

  1. I have used titration to determine alkalinity of groundwater in the field for over 25 years. Degassing of groundwater poses a problem and you would then have to do the titration as soon as possible after sampling. The analysis can be completed in a few minutes. We use the digital titrator from Hach (https://www.hach.com/digital-titrator/product?id=7640447369) and Hach's 8203 method. We titrate with H2SO4 solution and using  Bromcresol green - methyl red as indicator. The analysis is reliable and is included for testing our ion balance (IC cation and anion analysis), which is often within a few percent. Please do contact me if you need more information.

  2. Hi, I measured bicarbonate content by HCl titration in the field (for AMD) and then the same after 5-7 hours, in the lab. Can you imagine that the difference was huge. Bicarbonate content measured in the field was twice bigger than in the lab. I repeated measurement after few days in the lab and the difference wasn't significantl.... So I think if we have contaminated water we should measure bicarbonate content in the field. 

  3. Hi Bob,

    Accurate measurement of bicarbonate of groundwater can be difficult in general due to the potential for CO2 off-gassing once sampled.  One method is to measure the pH in the field in situ and then analyse for total alkalinity in the laboratory (ensuring no CaCO3 etc precipitation occurs).  From the two you can then calculate what the bicarbonate/carbonate/hydroxide etc split of total alkalinity would be.  Speciation software like PhreeqC can be used to make this calculation a little easier.

    Cheers,

    Matt.

    Dr Matthew Brannock CEng, CSci, MIChemE, RPEQ

    matthew@​​saltwatersolutions​​​.​com.au  ​

    www.​saltwatersolutions​.​com.au  ​

    www.aqmb.net 

  4. You mean other than with HCl titration using phenolophthalein and methyl-orange indicators? 

    You need some instrument using online electrode? I do not think it exists.