Sorption of lipophilic organic compounds to wood and implications for their environmental fate

The sorption from water to wood (K-Wood) Of 10 organic chemicals (log K-OW, 1.48-6.20) was experimentally determined for oak (Quercus robur) and basket willow (Salix viminalis). Linear regression yielded log K-Wood = -0.27 (+/- 0.25) + 0.632 (+/- 0.063)log K-OW for oak (r = 0.90, n = 27) and log K-Wood = -0.28 (+/- 0.40) + 0.668 (+/- 0.103)(log) K-OW for willow (r = 0.79, n = 27). According to an equilibrium-partitioning model, wood should be an important storage compartment for lipophilic environmental chemicals, but this is contrary to analytical results. Diffusive uptake from air into wood was estimated to be a relevant transport process only for chemicals with a high K-AW. Uptake of chemicals from soil via xylem into stem was simulated with a dynamic one-compartment model. This pathway seems to be important for chemicals with low and intermediate lipophilicity. In large trees, the chemicals are retained for a long time. If metabolism inside the stem occurs, wood can serve as a safe sink for environmental chemicals. This might be of use in phytoremediation.