2.3. Plant and pore water investigations
Equilibrated amended soil was transferred to triplicate plastic
pots (2 l), each placed on a saucer (Fig. 1) to prevent loss of
leachate from the system, and sown with 2 g of ryegrass seed (L.
perenne L. var. Cadix) in August 2008. Additionally identical triplicate
pots of only green waste compost (green waste compost
reference; GWCR) were included as a control. The ryegrass was
grownin a temperature-controlled greenhouse 18 ◦C, watered daily
with distilled water (approximately 150–200 ml, as required) and
subsequently harvested at 3 successive intervals (Oct, Nov and Dec
2008). Ryegrass biomass was harvested by cutting 1 cm above the
soil surface in each pot. Shoots were washed in deionised water,
gently blotted with tissue, weighed and then oven-dried at 45 ◦C
for 24 h. Oven-dried samples were re-weighed, then ground in a
Cyclotec 1093 electric mill. Aliquots of the ground material were
weighed (0.2 g) into digestion vessels, 10 ml of 14M Analar grade
HNO3 was added, and samples were extracted using microwave
digestion (as previously described). Plant digests were analysed for
metal concentration by ICP-MS (XSERIES 2 ICP-MS, Thermo Scientific,
MA, USA).