Fig. 4.

Diffusion of pure VOCs along a distance of 12 cm in soil. VOCs were collected with PDMS tubes for 30 and 60 min at different distances in the connected glass tubes 1 and 2, respectively (a). Data show mean values and standard errors (N = 6) for each synthetic compound after 60 min of collection (b). Filled and open symbols represent VOCs initially detected for Carex roots and F. culmorum in soil, respectively. A reliable detection directly at the release point in the central vessel was not possible because of surface saturation on the PDMS tubes