Washed Salix purpurea 94006 roots from trees grown in petroleum hydrocarbon contaminated or control soil.

Contaminated and non-contaminated soil was gathered from the site of a former petrochemical refinery at Varennes, Canada. Contaminated soil had a C10-C50 petroleum hydrocarbon concentration of 1.3 g/kg. Salix purpurea cv. ‘Fish Creek’ cuttings were established for 8 weeks in conventional potting media before being transferred to 20 l pots containing treatment soil within a larger experiment consisting of six randomised blocks of which the randomised contamination effect is investigated here. Growth conditions were 16 h 20 °C day and 8 h 18 °C night with excess watering and individual plant pot saucers to reduce leeching. After six months of growth, six replicate rRoots and soil were harvested from six replicate trees per treatment were sampledfrom the six blocks. Trees were grown for 6 months before harvesting, where soil was removed manually and roots samples were flash frozen in liquid nitrogen within 5 minutes of the initial perturbation.