Leaching from field test stakes. Results from two different methods of analysis
F G Evans, M-L Edlund
Field test stakes treated with Boliden K33 containing copper, chromium and arsenic exposed at three different fields in Sweden and rejected due to decay, have in two studies been analysed regarding leaching and remaining preservatives. The stakes have been exposed during 20 to 43 years. The density of the stakes and content of copper, chromium and arsenic have been determined in the top part of the stakes (above ground) and bottom part (in ground) separately. The density of the stakes after exposure were similar in the top and in the bottom of the stakes while it was lower in the middle, ground line part. Leaching from small sections of the stakes indicate that 23% of copper, 19% of chromium and 25% of arsenic leached from the wood during exposure. Leaching from stakes to the environment, including the preservative in the totally lost decayed part, is, according to the analyses, 50% for copper, -4% for chromium and 36% for arsenic as an average for all stakes. The results from the two studies give different results. This focuses on the importance of sampling and methods of analyses as well as the necessity of being careful when evaluating the results.