Replies to This Discussion

Permalink Reply by Elisabeth Graf Pannatier on February 12, 2013 at 13:36

Hi Nils,

In the last weeks, we have discussed the long term storage (archiving) of deposition and soil solution samples collected in the Level II plots in Switzerland. We haven't found any recommendation in the manuals of ICP-Forests (QA/QC, soil solution, deposition). We would be interested to know the opinion/strategy of the other labs. Could it be a topic for the QA/QC meeting?

Elisabeth

Permalink Reply by Nils König on February 12, 2013 at 14:28

Dear Elisabeth,

we can take it as a topic for the WG meeting, but we have not so much time for a big discussion. But we can ask for the methods the labs are usind and collect them. A longer discussion would be possible at the meeting of the heads of the labs in Croatia in September!

In my opinion it is very difficult to store samples over a long time without changing the composition. Freezing of the samples brings problems when defrosting them again; sometimes the organic compounds don´t dissolve again and also the pH sometimes changes. Storage at 4 °C after filtering of the samples without any inhibitors can lead to changings of NH4, NO3, Ntot, pH and DOC (our experience). Adding of inhibitors like chloroform or mercuric chloride does not allow to measure DOC or Cl later on.

So it´s a difficult thing!

Best wishes

Nils

Permalink Reply by Elisabeth Graf Pannatier on February 12, 2013 at 17:02

Dear Nils, thank you for your feedback. I agree with you. But on the other side, I don't feel comfortable with the idea to throw the water samples away, since they still represent a high value for new studies.

Yes, if we have time, it would interest us to hear from the other labs their archiving strategy concerning deposition and soil solution. In addition, we could ask whether there is a need to make recommendations based on literature review, own experience and tests in the lab etc.. If there is an interest from the labs, preliminary recommendations could be presented and discussed in September in Croatia.