Plankton raise the Alk of your Alk test kit

[Boomer]

Yup That is the latest news

Contribution of phytoplankton and bacterial cells to the measured alkalinity of seawater. Hyun-Cheol Kim, Kitack Lee and Wonyong Choi Pohang Limnol. Oceanogr., 51(1), 331–338.

ABSTRACT: We report the first direct measurements of the contribution of phytoplankton and bacterial cells to the measured alkalinity of unfiltered seawater. Phytoplankton and bacterial cells suspended in seawater make a significant contribution to the measured alkalinity of unfiltered seawater; their contribution is probably next to that of borate ion in most seawater samples. This nonnegligible contribution of particulate organic matter to the measured alkalinity is due largely to the presence of negatively charged surface groups on the phytoplankton and bacterial cells that react with protons during titration with hydrochloric acid. The contribution of organic particles to the measured alkalinity of unfiltered seawater could potentially be an important factor when evaluating the accuracy of presently available carbonate thermodynamic models using at-sea carbon system parameters that include measured alkalinity.

 

[Frankie]

Very interesting Boomer! This explains a lot about the success of the zeovit system from what I have been reading up on and how we are able to keep lower amounts of alk by keeping a lower nutrient system. Is there a link to where I can read more about this?

 

[Boomer]

Well in short, none of us really have to be concerned about this. I thought it was just a interesting article. For us it will have nil effect if any at all, even in Zeo systems.


where I can read more about this?


I can not post it here it is to big, even as a pdf. I have the real deal. No, there is no place to get it. You will just end up at academic site where you have to pay like $30 for it. I had some one get it for me.

Here is something a buddy of mine, Chris, just wrote up on it do to the over-concern of it effecting Alk kits. This article is popping up everywhere lately.

Our test kits can usually test precisely down to ~+/- 0.3 meq/l. The precision/accuracy typically attained with standard methods for seawater analysis by oceanographers is on the order of +/- 0.001- 0.003 meq/kg. We can accurately measure and are interested in differences 2 orders of magnitude smaller than aquarists can accurately measure.

They looked at phytoplankton cultures and found that POC concentrations up to 200 umol/L the contribution of phytoplankton to total alkalinity was on the order of 0.003-0.005 meq/kg (3-5 ueq/kg). This is important for oceanographers and big enough to make a difference in our measurments, but it's still 2 orders of magnitude smaller than aquarists can measure!

In real-world water samples, one does not see 200 umol/L of POC from phytoplankton. The range they report for the coastal ocean there is 1-80 umol/L, and caused a negligible difference in TA. In other words, in even high-productivity natural waters, the contribution of phytoplankton to TA was smaller than oceanographers can accurately measure, say nothing for hobbyist test kits which are 2 orders of magnitude less precise.

They impact of bacterial biomass was similarly negligible on TA measurments for our purposes, though potentially significant to oceanographers.

So no guys, phytoplankton and/or bacteria in the water column are not impacting your alkalinity measurments. You would need a test kit a couple orders of magnitude more precise to begin to worry about this effect