Deposition of semivolatile organic compounds to spruce needles : II. Experimental evaluation of the relative importance of different pathways.

The accumulation of atmospheric HCB, Lindane, DDT, DDE and the PCB congeners 52, 101, 138, 153 and 180 in spruce needles (Picea abies) was investigated at outdoor locations and in greenhouses supplied with ambient air. The air supply of the greenhouses was modified to dinstinguish between gaseous and particle-associated deposition of the compounds. Accumulation of the compounds occurred in all spruce except those grown in the greenhouse where the gaseous concentration of the compounds was reduced. Spruce grown in the greenhouse supplied with particle-free ambient air behaved similarity to those grown outdoors. Protecting the spruce located outdoors from rain did not affect the accumulation. The results show that under spring and summer conditions at a typical central European rural environment dry gaseous deposition is the dominant pathway of these compounds to needles.