Sunday, June 16, 2013

More hydrochemistry!

Frantic water sampling has occured over the last few days, even on Saturday teams of students returned to the field to collect precious water to unravel the secret chemical composition. Tomorrow in the morning, I'll visit the student's house to pick up their samples, acidify them for conservation, check their data files and then send them off by courier to our hydrochemistry laboratory at the VU University for analysis. John will do this quickly and even before they are back in the Netherlands, they may already have the analytical results of this week's samples. In the previous post, I already mentioned some ways of getting water out of the soil to get a sample. Here follows another one that's unique to our Hydrology MSc course. It is what we call "the VU Spiral Auger Sampler for Extraction of Shallow Groundwater In Sandy Soils" or in short the VUSASESGISS. It is new, it is exciting! Here you see one of the teams in action, getting it into a not so sandy soil...

This VUSASESGISS is a very sensitive device that needs gentle treatment. I did not know this either as we had only used it on the beach where it always gave ample water no matter what you did. Hey, that is strange - there's no water, said Corné when Joris pulled the syringe and no water emerged for the tenth time that day. At some stage Joris got the idea to suck on the tube rather than to use the syringe, and suddenly water did emerge. Now we were in business. Seemed that we had pulled the syringe to eagerly all the time. This opened up a whole new venue for sampling and Anne was the first to profit taking a 10 cm resolution soil water profile for analysis.

Spiral auger sampling on ancient  dunes, but now a just logged pine plantation
The next day, the Presa velha group also decided that they should use it and got some samples from a hardpan soil.

Bob and (headless) Vince pulling water from the soil using the VUSASESGISS
Perhaps very wisely, the other teams did not try out this device yet. In the process, all my sample bottles have been used by this very active lot of students. And that's great!

In the meantime, the sapflow system had been operating and Louise and Patricia decided that it was time to collect some data and change the heater battery. Wisely they brought an umbrella as computer screens and sunshine do not work together well.

Patricia and Louise downloading sapflow data in the Mesas catchment
Today, Sunday, Michel and I did some more spiral auger water sampling for our colleague Pieter Stuyfzand, who is into dune groundwater very much. So we went to the beach and a pine forest to get him some water... and now it rains again, but only drizzle. Time to go to bed...

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