Perkin Elmer Optima 5300 DV) was used. Considering that
nitrate salts of above-mentioned heavy metal ions were used
in the present study during spiked events, the estimation of
nitrate in the runoff was intentionally avoided as unrealistically
high concentration of nitrate was expected at the
inlet. To maintain consistency, the study also neglected
estimation of other ions such as phosphate in the runoff. The
bulk density of substrate components was calculated as the
ratio of the dry mass (dried at 105 C) to the volume of the
undisturbed sample. Bulk density (at maximum water holding
capacity) was measured as per FLL guidelines (FLL, 2002).
Hydraulic conductivity was determined through constanthead
or falling-head tests depending on the substrate size
(Budhu, 2007). The water holding capacity (WHC) and air filled
porosity (AFP) were determined according to the Australian
Standard Methods for potting mixes (Standards
Australia, 2003).