By now nearly all the samples showed a pH of 8 or higher. Yet I went on measuring water samples. Going to Zwolle, I planned three more sample locations. Two were still more or less connected: the Velumemeer and the Ijssel. The latter is a river, feeding the Ijsselmeer, but indirectly also the Markermeer, IJmeer, Gooimeer and Veluwemeer, so it could be that in the end we are more or less looking at the pH of the Ijssel’s water.
The third location however, was less connected, because it was a lake in Zwolle’s neighbourhood “Stadhagen”. The lake’s name is “Milligenplas”.
Like the full day sampling I took three samples at slightly different spots (a meter or several metres apart). After rinsing with the sampled water, the first two samples were discarded, but the third was kept for later investigations. As a result the direct measurement was in triplo.
The results won’t be sursprising by now, although the rather high pH of the IJssel is still remarkable!
Next time we will have a look at all primary values we obtained until now.