The effect of nHA on contaminant extractability was evaluated using de-ionized water (DW) 2.5 g
soil were added to 25mL DW in 50mL polypropylene centrifuge tubes, which were then shaken for 1h on
a wrist-action shaker, centrifuged for 20 min at 1,1000×g, and then filtered through a 0.22-μm pore-size
Millipore filter.