Determining the fate of preservatives in commercial wood products is essential to minimize their losses and improve treatment techniques. The fate of triazole fungicides in ponderosa pine wood (typically used for window manufacturing) was investigated in both outdoor and controlled-environment experiments using a representative triazole, <sup>14</sup>C-labelled tebuconazole (TAZ). We have demonstrated that a significant fraction of the original TAZ (~75%) remained in the wood despite six-month harsh environmental exposure, assuring the wood’s performance and quality as well as minimal environmental impact. To differentiate bound and unbound TAZ, a multi-step extraction technique was developed consisting of two sonications followed by an overnight Soxhlet extraction. Unbound TAZ extracted through two sonications (thus weakly interacting with the wood matrix or sorbed near the surface) accounted for 90% of the total TAZ. Bound TAZ, extracted only with an exhaustive Soxhlet extraction (thus strongly embedded within the wood matrix) accounted for the remaining 10%. As expected, losses of unbound TAZ were observed from cross-sectional surface areas (as shown in a figure below) when exposed to rain, high humidity and sunlight for six months. The overall loss of TAZ was ~25%.<br/>Tebuconazole sorbed in wood was shown to remain intact as the controlled-environment study ruled out its bio-, photo- and thermal degradation. Considering the weather conditions throughout the outdoor study, triazole evaporation was negligible. Water leaching was deemed to be the major route leading to TAZ losses from wood. Based on obtained kinetic data, up to 32% of unbound TAZ may have escaped from the exposed wood during the six-month period due to leaching.

Fate of triazole fungicides in softwood after environmental exposure

253rd National Meeting (2017)

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