Effect of soil contact on reacted copper(II) levels in micronized copper treated wood
IRG/WP 13-30616
Wei Xue, P Kennepohl, Xingguo Jin, J N R Ruddick
Small 3 to 4 mm thick and approximately 80 to 100 mm long, samples were removed from wood treated with micronized copper quat (MCQ) or micronized copper azole (MCA) and buried full length in a soil bed. Samples were removed after 2, 4 and 8 weeks. The total copper was determined by x-ray fluorescence (XRF) spectroscopy and the amount of reacted micronized copper measured by electron paramagnetic resonance (EPR) spectroscopy. The results showed that the amount of total copper retention decreased slightly with time, whereas the reacted copper levels increased with increasing soil exposure time, eventually reaching a maximum of 0.24% Cu for MCQ and 0.28% Cu for MCA. This observation confirms that mobilization of micronized copper can continue in treated wood in ground contact provided that there is unreacted micronized copper carbonate present.